Lake Effect Tonight and Frost Tomorrow Night

Lake Effect

Lake effect rain and snow showers will likely get started shortly after sunset tonight and will continue throughout the overnight.  At this point it looks like if you are inland of Lake Ontario that the atmosphere should be cold enough in the low levels for a complete changeover to snow by midnight.  This activity will start across the northern half of Jefferson and Lewis Counties and sink south to around southern Jefferson and central Lewis Counties around midnight.  By sunrise the lake effect rain and snow will centered across the Tug Hill area.  As temperatures warm with sunrise, the lake effect snow will begin to change back to all rain by late morning and the band itself will continue to sink south slowly, perhaps reaching a few areas just south of the Tug Hill region.  By early afternoon if any lake effect rain is around it should begin to break up quickly as 850 mb temperatures warm and create a less favorable environment for lake effect.  The band may also move slightly north before dissipating.  To the right is what I expect for snowfall totals tonight and early tomorrow morning.  The gray area will have snowflakes possible tonight, the light blue area will have snowflakes likely with a dusting of snow possible, and the darker blue area will probably see a dusting a snow and perhaps up to an inch or so in some areas.

The Frost

Tomorrow night we transition to colder temperatures than tonight even.  Without the lake effect clouds and the stronger winds helping keep the temperature a bit warmer at the surface, temperatures will plummet.  A widespread frost can be expected for all areas in the north country with the exception of a few areas near the lake shore that will be protected by the warmer lake waters.  While most areas will see temperatures fall to between 27 and 32, a few areas could see mid 20s for low temperatures.  Regardless, everyone should take measures to protect their plants tomorrow night (and tonight also).  Fruit trees that have blossomed should only receive minimal damage to their blossoms but if temperatures do fall into the mid 20s, preventive measures to save the yield of the trees will be needed.  To the right are the predicted lows from the National Weather Service for tomorrow night.

Stay warm everyone, warmer weather is on the way!

Lake Effect Snow Sunday Night!?

Please tell me this is a joke!

I wish I could...  It may be mid-May but unusually cold air associated with a deep upper trough will affect Upstate New York and other areas of the upper Midwest and Northeast one more time (this should be the last frost for northern New York until fall).  Lows Sunday night will drop into the low 30s, resulting in frost in some areas of northern New York.  By Monday night, temperatures will likely drop into the upper 20s for regions away from Lake Ontario.  This will result in a widespread frost for many areas of northern New York.  As if this was not enough shock for everyone who has been waiting to kick Old Man Winter for good this year, some residents to the east of Lake Ontario may witness a certain white precipitation on Sunday night into early Monday morning.  I am talking of course about snow.

The Technical Stuff

Sunday night surface air temperatures will drop into the low 30s, as mentioned previously.  Meanwhile 850 mb temperatures are forecast to drop at least to the low 20s and perhaps the upper teens.  This magnitude of cold air aloft will be enough to create instability across Lake Ontario, as the current water temperature of the lake is 44.  Typically, at least a 13 degree Celsius temperature difference between the 850 mb temperature and the lake temperature is needed to be favorable for lake effect snow development.  Sunday night this temperature difference will exist from shortly after sunset into Monday morning.  The temperature profile will also be conducive to any precipitation that does form to fall in the form of snow away from the lake shore area.  Other parameters that are needed for lake effect snow development that will be in place Sunday night include less than a 30 degree wind shift between the surface and the 850 mb level, with most of the night having less than a 15 degree shift, and abundant moisture for the majority of the night in the boundary layer.  Additionally, the lake equilibrium level will be right around 10,000 feet the entire night, which is also favorable for lake effect snow development.

Where might this occur?

Taking all of this into consideration, it appears likely that at least a band of lake effect snow showers will set up on Sunday night to the east of Lake Ontario.  The band appears at this time that it will form over central Jefferson and north/central Lewis Counties and shift southward throughout the overnight.  The snow band will likely fall apart around sunrise Monday morning over the Tug Hill region.

Do I need to break out my shovel and snowbrush again?

Probably not.  While snowflakes will be in the air across the region, accumulations are probably not likely at this point.  Due to recent warm weather, ground temperatures have warmed significantly and the snow will probably not become heavy enough or last long enough in any one area for accumulations to occur.  However, minor accumulations under a half inch are not impossible if the band happened to become heavier or sits in one place for a few hours.  Minor accumulations are most likely on elevated surfaces, such as your car or hand railings.

Optimistic Closing Remarks (for those of you I just severely depressed...)

Now that I have you dreading Sunday night and contemplating your choice of living in northern New York, I will tell you that after this cold snap the weather will turn nice again.  Next week temperatures will slowly climb back to normal and next weekend we may even see slightly above normal temperatures again!  And there are some indications that more summer like weather may start to set in by late May into early June.

March 18-19 Winter Storm

A winter storm is currently moving into upstate New York and will affect the North Country region this evening into Tuesday.  I just wanted to make a few quick notes on this system for everyone.

Timing:

The snow should begin moving into the southern portions of northern New York just before sunset and quickly spread across the rest of the eastern Lake Ontario region within the couple hours after sunset.  The snow will continue all night, becoming heavy at times.  The snow will continue Tuesday though it should be lighter for the most part.  However, there could still be a few heavier snow showers around at times.  The snow should come to an end Tuesday evening.  However, some areas to the east of Lake Ontario will immediately begin to pick up lake effect snow after this system pushes away, leaving no true break in the snowfall.

Precipitation Amounts:

The snow will be somewhat heavy at times across the region but there appears to be some large differences in where the snow will stay steadiest the longest.  The heaviest snow will likely fall in the few hours around the midnight hour.  The 18Z run of the NAM model (right) depicts liquid equivalent precipitation totals ranging from a quarter inch to around one inch.  In this scenario the heaviest snow would fall in the Tug Hill region and the lower totals would be across central St. Lawrence County.  Meanwhile, the 12Z run of the ECMWF model tends to show the same areas of high and low precipitation totals but the higher amounts across the Tug Hill are only around 3/4 of an inch.  The 12Z Canadian GEM model appears to have a similar solution to the 12Z ECMWF but may also bring through a heavier area of precipitation early Tuesday morning.  The 12Z run of the GFS model (right) is potentially the worst (best) case scenario, blanketing the north country in at least half an inch of precipitation with areas of near or just over an inch across a large area.  This would result in snowfalls of 6 inches or more across the entire area if this were to come true.

Snow Ratios and Amounts:

The snow growth region for this event will begin around 12,000 to 14,000 feet, which means there is a lot of time for riming to occur (condensing of the snowflakes).  However, the region below the snow growth region should remain at or below freezing all night.  Taking this into consideration, it appears that snow will begin with a snow ratio around 15:1 tonight.  Tomorrow, as the snow growth region falls and the only concern becomes the temperature of the surface, snow ratios will increase to 20:1 for much of the day and likely to around 30:1 by nightfall (this is when the lake effect would be beginning and the general show showers would be wrapping up).  Some areas may see a changeover to rain during portions of the afternoon tomorrow closer to the lake shore.

So knowing the ratios and the precipitation totals, it is possible to come up with some snow amounts for the area.  I think on the low end, 2 to 3 inches should be expected for the whole area.  However, higher amounts will likely occur for many areas, especially the Tug Hill area.  Across the Tug Hill, amounts up to a foot may fall before the lake effect starts up tomorrow night.  My map to the right is my best general prediction at this point of how much snow may fall by tomorrow evening.  The gray area will see the lowest amounts, generally 2 to 4 inches in this region.  The blue region can expect 3 to 7 inches with perhaps a few isolated areas up to 10 inches.  The heaviest amounts will be in the pink region where amounts of 6 inches or more will be likely.  A few areas in this region could get a foot or more of snow, as I mentioned previously.

Lake Effect:

I will not comment that much on this in this post, but figured that I should mention it.  There will be a period of lake effect snow following this system for Tuesday night into Wednesday.  The most likely area to receive this will be east of Lake Ontario and amounts will likely prompt a Lake Effect Snow Warning for this region.

Impacts:

Travel will become difficult after nightfall this evening as snow moves into the area and will likely stick to roads fairly quickly with the sun being down already.  Additionally, winds will become stronger tonight and thus have promoted a wind advisory for the area.  This will cause blowing and drifting snow and lead to whiteout conditions.  Winds will become sustained around 20 mph with gusts to 50 mph in some areas, especially those favored for high winds under a southeast flow, such as areas to the northwest of the Tug Hill Plateau.  Take it easy, especially tonight, if you need to travel.  Winter is not over yet!

Update: February 7-9 Northeast Winter Storm

Surface chart as of late this afternoon

A major winter storm is set to begin tonight and continue through Saturday night in some areas of the Northeast.  A low pressure system, currently located around northern Illinois, will move east tonight into northern Ohio by morning.  Meanwhile, another low pressure system, currently located along the Georgia and Florida border, will push up the east coast tonight reaching the North Carolina coast by morning.  By Friday evening, the coastal low will be located off the coast of New Jersey and Delaware, where it will merge with the energy from the Midwest low pressure.  As this happens, the coastal low will deepen dramatically reaching sub 980 mb readings according to the 18Z runs of the NAM and GFS.  The peak strength of this low will be overnight Friday off the coast of New England.  This will be when the heaviest snow falls and when the gustiest winds occur then.  By Saturday morning, the low will start to weaken and move slowly to the east throughout the day.  Only a few lingering snow showers will likely remain across portions of New England, especially near the coast, by the time Saturday night comes around.

So when can you expect the precipitation to begin in your area?

To the right is a map I made depicting the onset of the precipitation from either of the lows.  The earliest onset of precipitation is occurring right now across areas near Lake Ontario as snow slowly begins to cover this area.  By tomorrow morning, snow will be covering many areas across Upstate New York, Vermont, and the western portion of New Hampshire, Massachusetts, and Connecticut.  Most of this will be in the form of snow associated with the low originating from the Midwest.  Precipitation will also be occurring across Ohio from this low.  Meanwhile, the coastal low will be responsible for rain, snow, and sleet starting by tomorrow morning across eastern Pennsylvania, New Jersey, and the lower portion of New York and Connecticut.  By midday precipitation will encompass most of the Northeast.  Northern Maine will be the last are to see the onset of snow, occurring either tomorrow afternoon or tomorrow night.  It should be noted that this denotes only when the precipitation will begin for an area and not when the heaviest snow will be.

So when will the heaviest snow fall in your area?

To the right is a map I made showing when the heaviest snow will likely fall in each area.  Keep in mind that this is the heaviest snow with respect to each area.  This means that some areas will receive heavier snow than others but this map does not take that into account.  In general, the areas receiving the heaviest snowfall will begin in the west and move toward the north and east as the time period progresses.

So how much snow can you expect?

Snowfall totals are still in question for some areas as the exact track of the lows, especially the coastal low, could result in drastic changes in snowfall.  For instance, in the 18Z run of the NAM and GFS models, the NAM runs the coastal low a little closer to the coast.  This means the difference between 18" plus of snowfall for New York City with the NAM track and 5" to 10" for the GFS track.  With that in mind, to the right is my prediction for snowfall totals starting this evening through Saturday night from this system.  This will be the first major winter storm for many of these areas in nearly two years.  The heaviest snowfall

totals appear as though they will span from near New York City northeastward into southern Maine.  One thing to consider is that especially along the coast, strong winds will also accompany this snowfall resulting in blowing and drifting snow.  To the right is what I expect for wind gusts during the event.  For most areas wind gusts will only cause minor drifting and blowing.  However for coastal Maine, southeast New Hampshire, eastern Massachusetts, Rhode Island, Connecticut, and Long Island, winds could cause major drifting of any accumulated snow and result in some isolated power outages from falling limbs and perhaps a few trees.  People in these areas should be prepared for the worst case scenario that they could be without power during the winter.  Temperatures Saturday night after the storm will be quite cold too with most areas getting down to 20 or lower.  Some areas will even see temperatures at or below zero.

Bottom line, if you do not need to travel during this storm, don't!  Stay safe everyone.

February 7-9 Northeast Winter Storm

A winter storm will impact portions of the Northeast beginning Friday and continuing through Saturday Night.  While confidence is high that this winter storm will form, differences in model tracks and timing have left some questions.  Below are the 12Z and 18Z GFS and NAM model runs depicting snowfall through Saturday evening.

The main difference here is the GFS starts the formation of the low pressure off the coast of the Carolinas about 6 hours sooner than the NAM model does.  This time difference results in the precipitation shield reaching the Northeast sooner and more of the precipitation falling overnight.  The nighttime temperatures will be more conducive for snow or sleet to occur at the surface and thus accumulations could occur.

The other difference is in the track and strength of the low pressure.  The 18Z GFS model is depicted to the right and the 18Z NAM model is depicted below that.  The NAM model takes longer to mature the low and keeps it farther off the coast than the GFS model.  The result is a more impressive look to the GFS but the NAM is still able to achieve similar snowfall amounts in most areas due to its higher QPF (Quantitative Precipitation Forecast) totals.  This is likely due to its better understanding of processes related to the deformation zone as well as stronger PVA (Positive Vorticity Advection).

Another major difference has to do with the phasing of the energy between the shortwave cutting through Michigan and Upstate New York and the Coastal Low.  The NAM model appears to hold off on phasing these energies until after the Coastal Low is north of New York City.  Meanwhile, the GFS phases the energies much sooner, in the vicinity of New York City, about at the point when the low begins to push more east, rather than north.  This earlier phasing helps to strengthen the low and produce heavier precipitation amounts across the New York City area instead of out to sea and along coastal Maine as the NAM does.

Keeping in mind these model differences, a major snowstorm will impact portions of the Northeast beginning Thursday night.  Given what the current American models are thinking, I would lean closer to the GFS solution as it seems to have a slightly better handle on how the energy will evolve.  Additionally, it has been the more accurate model thus far for this event, predicting better what would happen today over Texas with a portion of the energy that will help create this Coastal Low.  The Arctic Oscillation is also forecast to be slightly negative, which could be further evidence for favoring the GFS solution.  Another way to verify this thinking is to consult the ECMWF model.

The ECMWF model has a track of the low that is very similar to the GFS model.  One reason for the similarities in these models is they are both global models, which means they are able to take into account information from the whole globe and produce an output for the globe.  The NAM model on the other hand only takes into account information from around North America and therefore only has an output in that same area.  One major similarity between the ECMWF and GFS then is that they both forecast a strong area of high pressure (ridging) that results in the stalling of the Coastal Low off the coast of New England (as shown in the image with the black line showing the blocking ridge).  This results in a longer period of precipitation as the low slowly moves and may have been why the GFS phased the energies better as previously mentioned.  The NAM model does not depict as strong of a high pressure due to its limited domain.  Therefore, it continues the Coastal Low on a northern track instead of stalling it.  Now it is likely that as the event draws nearer that the NAM model will understand the effects of the high pressure more, but for now this is a major influencer of the Coastal Low track that the NAM is missing.  The GFS and ECMWF both forecast the ridge to begin breaking down over the Atlantic Ocean late Saturday night.  This would allow the Coastal Low to begin moving out to sea as opposed to northward as the NAM model has depicted.  This will result in major snowfall forecast differences in the northern portions of Maine, New Hampishere, and Vermont.

So what am I thinking in the way of snowfall amounts then?

Well, given the overall better solution of the track via the GFS and ECMWF but better feedback via the deformation zone by the NAM and ECMWF, I will go with a blend of the best qualities of all of these models.  Below is my snowfall totals for the event across the Northeast.  This is subject to change but as of right now this is my best estimate.

The snow will be combined with strong, gusty winds in many areas, especially along the coast too.  This will result in blowing and drifting snow, making travel almost impossible at times Friday and Saturday.  Stay tuned to this evolving situation.

A New Meaning to Nuclear Winter!

With a sharp shot of cold air having pushed its way into the United States, many in the eastern half of the nation are currently experiencing the coldest air of the season.  Below is the 00Z NAM model sounding for Pittsburgh at 10PM this evening.

The modeled surface temperature at this hour was around -14 degrees Celsius.  This means that the snow growth region actually occurs right at and just above the surface.  Knowing this information, what could possibly be showing up on the Pittsburgh radar?



This precipitation is located just north of Pittsburgh and was remaining fairly stationary over time.  Give up?  Let me give you a little more information.  As you may have noticed in the model sounding from above, the forecasted wind direction near the surface was from the west northwest.  Notice how this band of precipitation is also located in this orientation.  Now I know many of you may be thinking, oh well it must be some kind of lake effect then.  Well it kind of is, but what is the source of the water?  Need help?



The red dot located just to the west northwest of the band is the Beaver Valley Nuclear Generating Station.  It is so cold that the steam being output from the nuclear power plant is forming into dendritic ice crystals and falling as snow across the northern suburbs of Pittsburgh!  In fact, the National Weather Service in Pittsburgh has actually received reports of accumulating snowfall up to one inch from this band of snow.  Try forecasting that one!

Snow Potential for Starkville!

With little to no winter weather precipitation last year, parts of the Deep South received an icy blast from old man winter over the past few days.  Ice accumulations from freezing rain piled up across parts of Louisiana, Arkansas, Tennessee, Mississippi, and Alabama while other areas of these states received flooding rainfall.  Now snow could become an issue for some areas tonight and tomorrow morning.  Below are my thoughts on how this event could evolve tonight and tomorrow for Starkville, MS.  Current radar imagery reveals lingering showers over the Golden Triangle Region with temperatures hanging out mainly in the mid 30s.

Rain showers will continue overnight but as a cold upper-level low continues to move closer to the area, the above surface air will begin to cool off.  This will result in the elevated melting layer disappearing throughout the overnight as evidenced by the 18Z NAM run for 3am local time below.  During the couple hours leading up to this time period, the elevated melting layer would be shallow and cold enough to support sleet but other issues will likely prevent this.  The issue is that the best snow growth region does not occur until around 17,000 feet at 3am.  Snow could form at lower levels possibly down near 12,000 feet but even at that height, the cloud height is not reaching these levels.  Therefore it is my concern that while the atmosphere could support snow, dendritic crystal growth will not start to occur and thus precipitation will fall as either rain or freezing rain depending on the surface temperature.



Just a couple hours later though, the 18Z NAM does show the cloud heights growing to a point where dendritic crystal growth could occur, though not optimally.  At this stage an hour or two before sunrise, I would expect very wet snow to begin falling with low snowfall ratios as most of the layer is near freezing, nearly maximizing riming potential.



As the sunrise nears, the clouds will finally reach an area for optimal dendritic crystal growth and as the layer continues to cool, snowfall ratios will increase.  Snow will likely continue to fall all morning before mixing with rain around noon and ending as rain showers in the early afternoon.  The 18Z GFS also supports a solution similar to this.

This specific event does have a few things going for it.  One, the NAM specifically has really struggled with understanding just how cold this air mass is.  Today’s high should have been in the low 40s according to the NAM in the Starkville area but the actual high was only 37 at KGTR.  Additionally, upper air temperatures upstream have been confirming a couple degrees cooler than the model soundings have been showing.  These two model errors could mean cooler temperatures at the surface and above the surface overnight resulting in a higher chance of freezing rain and some potential at a quicker turnover to snow.

Taking a look at precipitation amounts now, strong PVA should effect the region tomorrow morning, enhancing uplift.  Diffluent flow aloft will also help uplift during the early morning and mid-morning hours however, the left rear quadrant of the jet may hinder some of this uplift later in the morning.  Additionally, warm air advection from the north may help with uplift.  The below image from the 18Z NAM depicts this uplift occurring around sunrise tomorrow.



So what am I expecting for snow totals?  The 18Z GFS would support a couple inches whereas the 18Z NAM supports anywhere from 2 to 4 inches.  I expect these snowfall totals will be about correct given the upper air support but given that this is the first snow of the year for this area, the wet ground conditions, and near freezing surface temperatures, I expect ground accumulations to be limited.  Snow will stick first to colder surfaces such as grass and trees where up to an inch may be possible but on roadways I would expect all snow to melt except on bridges where some slush could develop.



If some heavier snow can develop, as sometimes occurs with these kinds of systems in the Deep South, it would not be out of the question that minor accumulations could occur on area roadways but at this time I would not expect this to occur.  Nevertheless, be sure to allow extra time to travel tomorrow and to follow winter weather driving tips such as limiting the use of your brakes and allowing extra distance between you and the vehicle in front of you.

Northeast Snowstorm Recap

Originally posted on ZoomRadar

After a mild winter, a historic late season snowstorm hit parts of the interior Northeast over the past couple days. Snow showers are finally coming to an end across the areas affected as the storm system continues its push northward. Many daily snowfall records were broken and some areas saw storm snow totals of over one foot! Below is an image depicting the snow depth as of this morning. Keep in mind that this snow will melt fairly quickly and some of it has already started to do so.

The image does show that the snow piled up and still existed this morning across the hills and mountains of West Virginia northward into Pennsylvania and parts of upstate New York. Additionally some areas in Vermont, New Hampshire, and Maine picked up some light snowfall. Some of the higher preliminary snowfall reports from the storm are from Laurel Summit, PA where 23.2″ fell, Sinclairville, NY where 15″ fell, Cattaraugus, NY where 12.8″ fell, Warsaw, NY where 12″ fell, near Sylvania, PA where 11″ fell, Oakland, PA where 8″ fell, Estcourt, ME where 8″ fell, and Frostburg, MD where 6″ fell.

The track of the storm, shown below in a few images, varied somewhat from what the models were predicting on Friday afternoon when I last wrote about this storm system. The eventual track of the storm actually started off in good agreement with the 12Z Friday GFS before beginning to look more like the 12Z ECMWF. The problem was that no model really forecasted the initial low to weaken as it continued north out of New York City and for a secondary low to form off to its east and take a track toward the north from there. This initial pull of the track farther east than many expected was the reason that Sunday night into Monday morning, many areas on the eastern edge of where the snow occurred were surprised. Residents of those areas went to sleep thinking they may wake up to a dusting of snow or maybe even an inch and instead woke up to inches of snow with newly posted winter weather advisories and winter storm warnings.

Storm system just after it makes landfall on Monday morning with the low pressure traveling northward from central New Jersey to New York City where it reached 986 mb.

Storm system on early Monday afternoon with low near Albany, NY at 988 mb.

Storm system on late Monday afternoon with low over the Adirondack Mountains at 987 mb.

Storm system on Monday evening with initial low over the Adirondack Mountains at 988 mb and a new low over the eastern end of Lake Ontario at 989 mb.

Storm system in the early morning hours on Tuesday with initial low over northern Vermont weakening now at 990 mb and new low deepening over eastern Lake Ontario at 986 mb.

Storm system now with only the new low just north of Lake Ontario at its lowest pressure of 985 mb just before sunrise on Tuesday morning.

Storm system Tuesday mid-morning as it continues to push northward and begins to weaken with the lowest pressure now only at 986 mb.

The surprise snow caught some off guard though it should have been expected in my opinion. The exact track of this storm was never fully certain and therefore deviations of tens of miles were quite possible which would lead to deviations in the areas receiving snowfall. My alma mater, Cornell University, which is located in Ithaca, NY picked up right around 6″ of this surprise snowfall on Sunday night. The fact that the storm system dumped much of its snow on areas farther east than expected on Sunday night actually helped keep storm snowfall totals down as Monday night the snow fell over areas further to the west where it was predicted to fall. While this did cut down on the amount of damage done to trees and power lines, some areas still saw their fair share of damage and power outages. Despite the damages, the snow came as good news to some such as Seven Springs Mountain Resort which had previously closed their resort to skiing and snowboarding, announced that they will open the resort for one last day of skiing Tuesday. This will be the latest date this ski resort has offered skiing and snowboarding since it opened.

Snow for Parts of the Northeast?!

Originally posted on ZoomRadar

Following a winter which was very warm and had little snow when compared to average, who would believe that we would be talking about a chance of snow in late April? Well, believe it. Although the weather models are not quite in agreement on where this snow will hit, they are in agreement that some places will be under the gun for a late April snowfall. Let’s take a look at what the NAM, GFS, and the ECMWF models are predicting right now as we get ready for what could be a very historic late season event.

A low pressure system is expected to form over the Gulf of Mexico Saturday afternoon just off the coast of Florida. From here the low will ride the eastern seaboard up the coast. This is what the models agree on. Where they differ is on the exact track of the low once it reaches the northeast. The image below is of the NAM model predicting what this low may look like on Monday morning. The NAM has the low the deepest of any of the models at 980mb and almost directly over central New Jersey. I have done my best job to highlight the past path and future path of the low as depicted by the NAM in orange. As you can see, the NAM projects the low to continue heading toward the northwest into western New York throughout Monday. The NAM model only goes out 84 hours so it is unclear where this model may take the low after this but if the other models are any indication it will most likely begin to head northward. The other thing of note here are the wind speeds, reaching at least 20 knots and in some areas 30 knots plus. These wind speeds coupled with the snow that would be falling could very well create for blizzard like conditions in western New York and parts of northeast Pennsylvania.

The GFS model on the other hand does not depict as strong of winds but the winds still could be quite gusty under this scenario, shown below. The GFS leaves the low a little farther out to sea instead being located over the New York City area on Monday morning as a 988 mb low, which is not nearly as intense as the NAM predicted and thus why the winds are weaker. From here the low is modeled to move toward the north northwest into northern New York before retrograding into Ontario and moving north.

The ECMWF track, which I show below on a simple U.S. map, has about the same position over central New Jersey as the NAM model did for Monday morning but the intensity of the low only ever reaches 984 mb and is only 988 mb at this point on Monday morning. The track from here is very interesting as it progresses a little more northerly than the NAM track did putting it on the eastern shore area of Lake Ontario before it retrogrades to almost the opposite shore of Lake Ontario and then begins to head northward.

Despite the track differences, enough cold air will exist to create snow on the western side of the low. Below are images from the NAM showing the 1000-500 mb thickness near the onset of snowfall and then again on Monday evening when the storm would probably start to move northward after retrograding some. It is of note here that the GFS depicts a very similar looking scenario but has less wrapping of the cold air occurring around the south end of the low and less wrapping of the warm air occurring north of the low. This is most likely due to the GFS predicting a less intense low pressure. The line to note in these images is the 540 line which typically depicts the rain/snow line in these storms though in late season storms, snow can occur at thicknesses of 5460 or less. So areas in blue would be cold enough for snow and maybe even the lightest first shade of green.





Now this does not mean just because an area is below the 540 or 546 thickness threshold it will snow, as moisture and cold temperatures at the surface still need to be present. There will be plenty of moisture with this system as shown by the HPC’s image below showing precipitation over the next five days. Many areas across the northeast will pick up at least two inches of precipitation with some areas seeing in excess of four inches.

The cold temperatures will be the tricky part of the forecast and something that will need to be monitored as the event gets closer. Some areas are for sure cold enough for snow at the surface and other areas will be right around the freezing mark with what could play out as interesting temperature profiles aloft. The one threat that has not been mentioned by anyone yet with this storm is freezing rain. At this time it does not appear this will be a big freezing rain maker but if the NAM is right and the low deepens more, wrap around warm air advection could allow profiles to warm enough aloft to lead to some freezing rain in areas north of the low.

Below are the current predicted snowfall depths from the NAM (top) and GFS (bottom). The GFS image is from 12 hours after the NAM image and therefore the NAM may actually have more snowfall falling than is depicted in this image. As you can see the NAM is predicting more snowfall than the GFS but both of these models have come into some agreement on a general area of snowfall from the mountains of West Virginia northward into western New York and Ontario.

The ECMWF on the other hand appears to give a solution more similar to the GFS with a little more snow expected for parts of northern New York. It will certainly be interesting to see how this plays out but the threats of heavy rain, wind, snow, and maybe some freezing rain are apparent. Below is a map of what I am thinking could be the threats as far as precipitation type goes.

The green areas should be ready for rain, of which some could be locally heavy in excess of four inches. The orange area is the mixed bag area. Here we could see all rain, all snow, or something in between. These are the areas that really need to monitor the future forecasts on this storm to see if they need to prepare for any snow or freezing precipitation. Areas particularly in danger could be northern New York, especially the Adirondacks, and parts of the mountains in southern New York and Pennsylvania. If the low does not deepen as much these areas could see more snowfall as less warm air wraps around the low. The area that should see all snow is highlighted in blue with dark blue depicting an area that is at the greatest risk right now. This greatest risk area could see snowfall amounts in excess of six inches which could cause power outages due to the fact that many trees have their leaves or have started getting their leaves. This heavy snow coupled with blustery winds could mean many trees and power lines would be down across this area. Definitely pay close attention to the developments on this storm throughout the weekend as the forecasts for this storm are anything but set in stone.

Snow and Tornadoes?

Originally posted on ZoomRadar

Here is something truly interesting, snow and tornadoes. In a recent blog post by Taylor, his review article of last week’s tornado outbreaks showed an image of a tornado that occurred in Nebraska (shown below). As he stated, this was the first tornado ever recorded in Nebraska history in February.

If you notice at the bottom of the image, there appears to be snow and ice on the ground in the ditches. Below is an image depicting the snow cover on the morning of that tornado. It does show an area with a couple inches of snow just to the west of where this tornado touched down in the Gandy area. Also if you look really closely you can pick out a few areas around this that have lesser amounts of snow. So is it possible that this was actually snow?



Going back to a couple days before this, the areas showing snow depth around Gandy were larger in area and thus it is very probable that this was some snow or ice that had yet to melt. A comment received on that post by Cliff, who states that he lives about 5 miles from where this tornado touched down, stated that the white stuff in that picture is actually snow, confirming the satellite data and my thoughts. This is a pretty rare scenario indeed.

Not quite as rare as this, but still fairly rare is the snow that fell across and is currently falling across parts of Illinois, Indiana, and into Kentucky. Now snow itself this time of year across those states is not that rare at all. However, it is rare that some of these areas that are receiving this snowfall are the same areas that were struck by tornadoes just a few days ago. Below is an image that shows the snow depth as of this morning.

And here is the current radar image from the ZoomRadar Map showing snow beginning to end now over parts of Ohio, West Virginia, and eastern Kentucky where some areas reported over 6 inches of fresh snow.

This is creating for some rare and shocking sites today. The images below display the graphic scenes of tornado damage covered in this fresh snowfall.

Henryville, Indiana where an EF4 tornado occurred Friday. (Reuters / JOHN SOMMERS II)

Henryville, Indiana where an EF4 tornado occurred Friday. (Reuters / JOHN SOMMERS II)

Marysville, Indiana where an EF4 tornado occurred Friday. (AP / Nam Y. Huh)

While rare, snow does fall on tornado damage, and even rarer yet is the fact that tornadoes can occur in areas with snow on the ground. Spring is always a time for wild weather swings across the nation and this year is certainly no exception. March has surely come in like a lion, but will it go out like a lamb? Only time will tell.

Cold Air Invasion!

Originally posted on ZoomRadar

The United States is being invaded by a threat to our people, plants, pets, and pipes. No it’s not some kind of biochemical warfare, it’s just a little gift from the season many of us forgot existed this year, winter! One of the largest blasts of cold air this season is currently affecting temperatures across the United States. After a winter that bottled most of the cold air up north of the United States and Canadian Border, this blast will bring freezing temperatures all the way to the Gulf of Mexico and Mexican border in spots. The current surface analysis shows the big picture with a large cold front now off of the east coast and a secondary cold front trailing this just across the Appalachian Mountains.



Strong north and northwest winds are helping aid in pushing this cold air south and creating for some stinging wind chills, especially later tonight. Current air temperatures as of 18Z show a 31°F reading at Little Rock, 16°F in Chicago, and just 5°F at Bemidji, MN all of which will be dropping much lower tonight. Many areas across the south are under frost advisories and freeze warnings for tonight as cold air like this has not really penetrated into these areas this year. Additionally, the strong winds behind the reinforcing cold front have prompted wind advisories and even a few high wind warnings with gusts up to 60mph in a few areas this evening and tonight in the Appalachians.



Taking a look at the NAM model below, depicting temperatures for 12Z tomorrow morning, one can see the 0°C line sinking all the way into northern Florida, just a little north of the Gulf of Mexico, and even dipping down to the Texas/Mexican border in parts of west Texas. In fact, most of the United States will see temperatures at or below freezing tonight! That is certainly something we have not been able to say this winter.

Taking a look at the 850mb level at 0Z this evening, the NAM model shows the strong cold air advection that is occurring behind the cold front, aiding in dropping those low temperatures tonight.

As mentioned above, wind chills will also be a factor tonight. Below is the apparent temperatures for tomorrow morning as predicted by the National Weather Service. It will feel like it is in the teens for parts of northern Florida, Georgia, Alabama, Mississippi, and Louisiana tomorrow morning. Many of these areas are not well prepared for temperatures of this nature and precautions will need to be taken in order to protect the life of plants and infrastructure such as water pipes. Farther north, temperatures will feel like they are below zero in many spots as far south as northern Texas across to Missouri and in the Appalachians down into northern Georgia and western North Carolina. Not to be outdone though, the typical cold spot up in International Falls, MN will expect to see an apparent temperature of -29°F on Sunday morning.

With all this talk of cold air, snow chances are probably one of the first things everyone is thinking about. As a low pressure system continues to develop over the Rockies, some areas could pick up a few inches of snow as well as some ice accumulations. Considering many areas at risk for this snow and ice have received little, if any winter weather precipitation this season, this could create for some travel issues. This situation will have to be monitored carefully over the next few hours as Winter Storm Watches are just beginning to be issued for parts of Texas, New Mexico, and Arkansas. Stay tuned for future blog posts on this topic!

So will there be more cold air outbreaks for the lower 48 states in the near future. Taking a look at the models, it does not appear we should expect anything of this magnitude at least for the next 10 days which would bring us into mid to late February. However, it does appear there is a lot of cold air bottled up in the polar regions so it will definitely be something to continue to monitor.