North East and Mid Atlantic Weather

Very Heavy Rain, Snow, Flash Flooding 3/29-3/30 North East

By: Pcroton, 11:19 PM GMT on March 26, 2014

3/30 7AM

UPDATE


Updates begin Post #141

Flash Flooding, Rain, Snow, Freezing Rain continues across the Middle Atlantic and North East states.
















Flooding is a legitimate concern.

A lot of water remains in the present snow pack. In Vermont, New Hampshire, and Maine you have 6 to as much as 20 inches of water retained in your snow packs.



Your Liquid Equivalent snow pack in inches. This is the water in the snow pack. If you have 2" of water in your snow pack and are getting 2" of rain - this is equal to a heavy fast falling 4" rain event.

Prepare now for flooding.





3/26 - BLOG HEADER

Data below is not updated.


A cold night follows in the wake of our super storm still affecting the Canadian Maritimes. A warmup featuring temps in the 50s with rain both Friday and Saturday could end with some snow on Sunday.






With a select few winter storms some impressive surprise features can develop. With guidance occasionally showing the potential for a double low structure or perhaps an inverted trough our storm discussion had transitioned from the progressive pattern that would deny us the chance of a bit hit to the potential of these surprise features. In the end we saw perhaps as perfect of a secondary surprise as one could expect at this time of year and watched the Middle Atlantic states accumulate snow in the 4 to 8 inch range.


MODIS color image of the Middle Atlantic snowfall swath.




Some select totals.

NEW JERSEY

...ATLANTIC COUNTY...SOMERS POINT 4.8
...CAPE MAY COUNTY...CAPE MAY 6.5

DELAWARE

...KENT COUNTY...HARRINGTON 5.2
...SUSSEX COUNTY...GREENWOOD 7.5

MARYLAND

...MONTGOMERY COUNTY...GAITHERSBURG 4.0


VIRGINIA

...CULPEPER COUNTY...CARDOVA 5.0
...FAUQUIER COUNTY...WARRENTON 5.3
...GREENE COUNTY...STANARDSVILLE 6.0
...LOUDOUN COUNTY...DULLES INTERNATIONAL 3.8





As our storm continues across the Canadian Maritimes a strong north west flow will usher in what might be the coldest night until next season across the Middle Atlantic states.

Tonights Lows illustrated by the GFS model guidance.







Thereafter a disturbance currently in the Southern Plains organizes and moves towards the East Coast on Friday bringing showers and thundershowers along with temperatures in the 50s.






Temperatures Friday Afternoon







On Saturday a second disturbance develops in the wake of Friday's system and moves towards the region.




This disturbance could tap some colder air and trigger a moderate snowfall event from Pennsylvania into the Upper Middle Atlantic and Southern New England. At this time of year it will be difficult to accumulate snows during the daytime especially with marginal temperatures. It is worthwhile to note we're several days out from this event and things can and always do change.











After a couple of days of near normal temperatures another round of below normal temperatures invades the country accompanied with above normal precipitation.




Winter Weather Flood

Updated: 11:29 AM GMT on March 30, 2014

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Strong NorEaster Tues-Wed Mid Atlantic-North East

By: Pcroton, 11:38 AM GMT on March 18, 2014

March 26 5AM

Updates Begin Post 677


Tracking our deepening Nor'Easter off the New England coast today.







March 25 8AM

Morning Discussion Post #490
12Z Models begin Post #537


Good Morning. A few factors we have been discussing here the past couple of days is now showing up strongly on guidance. A second area of low pressure is forming much further north and west and becoming the dominant feature. While the storm itself is still going to head out to sea there will be increased impacts along the middle atlantic coasts.







How far north along the middle atlantic coast does this western feature get before it retrogrades and becomes absorbed into the depating and bombing low is the question and answer to how much snow along the coast and how far north. We don't know at this juncture.

0Z CMC illustrates wonderfully the relationship.




Read further below for more on this situation.



March 24 9PM

Morning Discussion Post #363
Afternoon 12Z Discussion Post #452
Evening 18Z Discussion and latest maps Post #464



Good Evening. We are seeing the beginnings of our low development along the cold front in the Gulf of Mexico.




This massive nor'easter will provide a glancing blow to the Upper Middle Atlantic before clipping Eastern New England with more significant effects. Nova Scotia and Newfoundland are in store for a very severe storm event.





A general threat of 2-6" still exists for the Upper Middle Atlantic as various pieces of the puzzle remain yet unsolved.



While the models are in good agreement of a storm track just south and east of the 70/40 benchmark and limited precipitation effects from the primary low itself we are still monitoring the potential for an inverted trough and secondary low pressure system closer to the coastline.







Features such as these can bring surprise snowfall totals where they hit but unfortunately long range model guidance does a poor job at providing consistent solutions. These are very tricky to predict and are best left as a nowcast once we see them evolving.

The differences in coastal effects between a storm with a trough and without is significant.









The evolution of these troughs are also very tricky. They will move northward in tandem with the low and you watch this band of heavier snow push north along the coast. At some point as the primary low deepens and the upper trough goes negative you will see the inverted trough halt it's northward progress and then retrograde SE along the back side of the low pulling the moisture with it back out to sea. Predicting where this will occur is very difficult and the models differ on where exactly to halt the northern progress.






What can happen as well is a certain small area of real estate can see a high training effect from this feature. The snowfall moves into the region, the trough halts, then it retrogrades and pulls out of the area - and some folks will get a higher hit of precipitation as their duration under this feature expands with the evolution.

An older NAM run shows an extreme side these troughs and their evolution can produce:





We will NowCast the event throughout the day tomorrow and attempt to figure out just how strong this feature will be and just how far north it will migrate before being pulled out to sea. At this time it appears the trough will reach somewhere into the NJ area. The cutoff will be quite sharp so areas too far north of the trough will see next to nothing additional outside of the upper level energy that will be passing through.




REVAMPED BLOG HEADER 3/22 6PM

A strong nor'easter will begin to deepen rapidly east of the Middle Atlantic states on Tuesday brining a potentially moderate snowfall threat to the immediate coastlines of MD, DE, and NJ before heading past Eastern New England with more severe impacts from Rhode Island, Cape Cod to Nova Scotia and Newfoundland possible.


The wind and wave potential with this system is going to be on the severe side.







One of the most important features with this storm system is where and when the energy phases and how soon the upper trough can go negative and pull the surface low closer to the coast. A second part of this is how soon does the 500mb low cut off. The sooner these processes occur the higher the chances for significant snowfall along the middle atlantic coasts.

At this time the majority of the model guidance hints at a later phase and cutoff low thus keeping significant snowfall chances bottled up in Eastern New England.


We have a very progressive flow featuring a strong upper level low pushing to the coast of British Columbia. This feature will prevent the western Ridge from amplifying which in turn could inhibit the eastern US trough from going negative quickly enough to produce a significant snowfall threat in the Philly to NYC corridor.




The inhibiting factors shown here on the GFS model on Tuesday are all too real.






A lack of blocking in the Canadian Maritimes is also a contributing factor to a potentially out to sea solution that would deliver only a glancing blow to the Middle Atlantic states.




There are some model runs that do show an earlier phasing and cutoff which could fight against the progressive pattern and deliver more significant impacts further west.

The UKMet is the most prominent one and is good for the what-if illustration purposes.





There is even yet another facet to this storm that we will be watching. Many models show moisture being pulled into the negative trough thus increasing the chances of precipitation along the upper middle atlantic coasts. As far east as some models are at this time the CMC and Euro are still putting a high probability of six inches or more of snowfall along the immediate NJ coastline due to this feature.


GFS Interpretation:







Looking ahead it appears we are going to remain on the cooler side of things well into April. We will however be out from under the well below normal temperature anomalies of the winter which will come to a close this week.








CFS2 Climate Model, Temperature Anomalies:





Winter Weather

Updated: 9:09 AM GMT on March 26, 2014

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Snow Threat Sunday-Monday - Middle Atlantic States

By: Pcroton, 12:08 AM GMT on March 14, 2014

Update Section, March 16, 4PM

Afternoon analysis shows that the earlier model solutions showed the high pressure suppression as too strong and storm impacts have nudged northward through Central NJ.


Updates begin on Post #267







March 16, 8AM

Snow and Ice threatens the Middle Atlantic states while Severe Weather hits the Gulf Coast and Florida.

Updates Posts 228-233





Updates Posts 228-233






Blog Opening, March 13, 9PM

A potential snow storm threat exists for the Middle Atlantic States for Sunday into Monday.






Two pieces of energy will combine over the Southern Plains on Saturday.








Here are the 12Z Models from 3/13 - centered at 96hr time frame - 8AM Monday.





Notice the amount of energy we are dealing with of which the models have resolved strung out along the frontal system. These scenarios frequently change as guidance nears in on the event. It would be unwise to trust any model guidance at this distance. Recently we have been somewhere in the 48 to 72 hour window where guidance has locked in. This would be the Friday 12Z runs or perhaps Saturday 0Z runs.




Recently guidance has been struggling with storm systems due to the pattern changing and the split flow patterns in the 500MB layer. The result is wildly ranging model solutions both individually and as a group. Note how wild the pattern is through the Pacific and Western US/Canada. These multiple stream splits will undoubtedly give the models fits.






What we know is a system will enter the Southern Plains on Saturday bringing the chance of severe weather. How the storm tracks from here is in question at this time.








The HPC appears to be fairly interested in the threat.

HPC guidance through 8AM Monday.











The NAO is once again going to be near neutral timed with yet another storm threat. While we've never gotten the "strong negative NAO" we heard was coming most of the winter (and never did) there was always this little dip that coincided with our storm threats along the upper middle atlantic coast.







Taking a peek at the long term it appears the Pacific features that were driving our cold weather outbreaks has begun to break up.


The dominating North Pacific SST anomaly has been relaxing.







The PNA is heading negative.







Our jet stream will feature quite an amplified yet fast moving pattern resulting in quite the temperature roller coaster. No longer are we locked into a persistently strong East Pacific ridge and thus Eastern trough.









Looking ahead we appear to be remaining on the cool side although not nearly as brutal as before.







Here are your CFS2 Temperature and Precipitation Maps. It appears through at least April we will remain cool.


The weeklies:















April Monthly:






Winter Weather

Updated: 7:54 PM GMT on March 16, 2014

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Major Winter Storm March 12-13 NY State to New England

By: Pcroton, 1:49 PM GMT on March 03, 2014

3/12 8AM

Heavy Snow continues to impact north east New England.

Today's updates begin on Post #559






We continue to watch another storm system for early next week. These models have been all over the place with type of storm and track the past three days so I think at this time guidance is largely useless and should be considered very low confidence.








============================================
March 3, 2014
(the following consists of old information)

Winter Pattern Continues


Modeling and Analsysis continue to show that the winter pattern is going to continue for at least another two weeks.

We are getting late in the season and winter is relaxing it's grip but there are a number of factors that could allow a few more systems to produce before we head into Spring.

We still have the North Pacific Anomaly that has been so prevalent in this winter's pattern so while that still exists it is difficult to envision a rapid change.





We will still have the reloading pattern of a strong Pacific ridge and an Eastern US trough which has occurred time and again this season.






We still have cold air available as a result of not only the pattern but the long duration of the cold and snow pack involved and the frozen great lakes.













What we need to keep in mind is that our average highs are pushing into the 50s now in NJ and southward. So while we may remain well below normal we would now require absolutely perfect timing and storm track to get a significant snowfall threat. Most events should remain on the light to moderate side or more of the onset snow quickly changing over variety. We're still not done but the threat is dwindling. It is just that time of year.

While we wonder about Spring and while the significant snowfall threats decrease we still can't count out more snow. In what form and intensity is never a known factor but the elements are in place to continue with renewed arctic fronts, clippers, and a couple of coastal events. When we near these events we will focus in on them closer and try to see what they are really up to.


The most interesting item on the menu appears to be a late week coastal event. Energy from a storm currently affecting the northern Gulf Coast heads east and becomes stretched out and stalls before a second disturbance from the central plains renews cyclogenesis off the coastline.




At this time range it is difficult to ascertain impacts but one could assume we see at least fringe effects from the system. This time of year timing becomes more crucial with each day in regards to frozen versus liquid and how much so it doesn't pay to start guessing.

Friday:





Later on Sunday there are hints of another arctic cold front that could feature a low pressure development before it moves out. On the following Tuesday we also see yet another clipper disturbance affect the region.





After that one storm that is already generating buzz as the one to watch comes in around March 15th.




As we can see the cold and active winter pattern continues. Just exactly what affects the region and in what form remains to be seen.



Winter Weather

Updated: 11:53 AM GMT on March 13, 2014

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About Pcroton

Located in Monmouth County in central NJ. Watching the weather from North Carolina to Maine.