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Feb 7th snow threat


UlsterCountySnowZ

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4 minutes ago, Juliancolton said:

The NAM gets the warm tongue around 900mb all the way up to +8C imby. Not the most conducive to sleet, that.

That’s definitely a red flag for a good period of freezing rain. The surface warmth is still overdone IMO. There’s nothing to me that would surge surface warm air in if the surface low goes east of you. It might edge up to 33 at the end-latent heat from freezing can increase temps a couple of degrees I guess. 

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mt holly nws update.

going down with the ship.

 

SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
930 pm update: An analysis of the latest high-resolution model
output and the 18Z operational model suite suggests the
forecast is generally on track, though uncertainty remains,
particularly regarding the timing of precipitation type
transitions and resultant influences on storm total snow and ice
amounts. There seems to be an additional trend toward warmer
solutions, which increases the icing threat in the northern CWA
and slightly reduces it south of I-78. However, I am somewhat
skeptical.

Model sounding analysis (NAM/RAP/HRRR) at KPHL during the
morning rush indicates the potential for a couple hours of a
wintry mix (primarily freezing rain and sleet) before transition
to rain by mid to late morning. There are also indications that
locations along/south of the I-76/I-276/I-195 corridors may see
a brief break in precipitation before steadier rain moves in
during the afternoon (as boundary-layer temperatures warm above
freezing).

Farther to the north, the transition will be slower, and I
cannot help but wonder if models are too fast with the
transition in general (especially with Sunday`s event freshly in
mind). Though I expect a gradual transition to rain in much of
the region south of I-78 by afternoon, the 10-15 degree dew
point depressions observed this evening give me some pause.
After wet-bulbing cools temperatures down, I think it will be
more challenging to warm the near-surface layer as quickly as
many of the models are projecting. For example, the latest HRRR
has Reading and Allentown at rain by early afternoon. While
certainly plausible given the good model agreement with the RAP
and 18Z NAM Nest, models were universally too aggressive in
warming areas northwest of the Fall Line for Sunday`s event.
This requires close monitoring through the event, as a slower
transition would prolong the wintry threat in these areas, which
is concerning given the forecast precipitation amounts and the
implied potential for a decent duration of freezing rain.

The warming trend in models would temper snow amounts in the
warning area somewhat, but would also increase the icing
potential...think of it as a meteorological Hobson`s choice.

With all of the above said, think the way to go is to let the
forecast ride for now, continue to monitor short-term trends,
and adjust as needed.
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41 minutes ago, jm1220 said:

That’s definitely a red flag for a good period of freezing rain. The surface warmth is still overdone IMO. There’s nothing to me that would surge surface warm air in if the surface low goes east of you. It might edge up to 33 at the end-latent heat from freezing can increase temps a couple of degrees I guess. 

That last part is usually what sways me to hedge against significant icing without a source of cold air replenishment. At least some guidance has the sfc low going over my head, with the NAM sending it over Scranton... and the HRRR over the Finger Lakes, heh.

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3 minutes ago, Rtd208 said:

Don't worry we will probably have a blizzard in March lol.

It's not really about how much snow anyone gets. Even on 1/4 the models were pretty awful from even 2-3 days out. And with this one the profiles have just been terrible -- so much drag north in the last 12 hours.  

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