fxus61 kphi 262345 

Area forecast discussion 
National Weather Service Mount Holly New Jersey 
645 PM EST sun Feb 26 2017 

high pressure will move off shore tomorrow. Low pressure approaching 
from the west will lift a warm front through the region on Tuesday. 
That low will track from the Great Lakes region into eastern Canada 
on Wednesday. The associated cold front will move through the East 
Coast by Thursday morning. An upper trough builds into the northeast 
for the end of the week. 


Near term /until 6 am Monday morning/... 
water vapor imagery depicts the strong vort Max affecting our region 
yesterday moving into the Canadian Maritimes with the trailing end 
becoming elongated zonally by the upper-level jet streak 
encompassing much of the eastern half of the U.S. Cold air advection 
is waning as a surface high approaches the East Coast. Stratocumulus 
deck is eroding from southeast to northwest as northwest flow 
weakens. As the surface high reaches the coast this evening, 
surface winds will begin to decrease. With the clearing skies and 
light winds, should see a fairly decent drop in temperatures this 
evening. However, low-level isentropic ascent will commence by late 
tonight as return flow on the upstream side of the surface high 
moves in. Clouds will begin to increase late tonight, especially in 
the southern cwa, which may curb more substantial cooling in this 
area. As a result, I stuck close to guidance given the competing 
factors in place -- but it is possible the places most susceptible 
to radiational cooling could be cooler than what is forecast. These 
trends will be monitored this evening to see if temperatures need to 
be lowered a little bit. 


Short term /6 am Monday morning through 6 PM Monday/... 
as the surface high moves farther east into the Atlantic, southwest 
surface winds will become established across the area on Monday. 
Substantial near-surface warm air advection will contribute to a 
much warmer day Monday, with temperatures returning to well above 
average values. A perturbation in the west-southwesterly upper-level 
flow will approach the mid-Atlantic by 00z Tuesday, with cloud cover 
continuing to increase. However, residual dry air in the low levels 
and generally weak large-scale ascent should prevent much if any 
precipitation from occurring before sunset. Notably, model guidance 
has been all over the place in the handling of this system for days, 
rendering confidence much below average in the details -- even for a 
12-24 hour forecast. 

There are at least some indications lift may become sufficient to 
produce light precipitation to the west of the area (generally the 
Appalachians westward in southern PA and adjacent Maryland/VA/wv) by late 
morning or early afternoon. However, the aforementioned limiting 
factors seem too much to overcome for generating precipitation in 
the County Warning Area by the end of the short term period. Thus, reduced pops on 
Monday to non-mentionable levels. 

Guidance has struggled mightily with temperatures in warm air 
advection patterns this past month. Went slightly above guidance 
for highs based on the expected cloud cover present -- otherwise, I 
would have gone well above guidance. However, would not be at all 
surprised to see highs several degrees warmer than forecast, 
especially if the models are overdoing the moist air advection in 
the 900-700 mb layer. 


Long term /Monday night through Sunday/... 
a very active pattern continues through the long term. 

Monday night through Tuesday night...warm front will lift north 
through the region. Some weak lift is expected with the front 
followed closely by a local vorticity maxima associated with the low 
lifting into the Great Lakes region. It isn't exactly an 
impressive set up for widespread precip, but models continue to 
depict quantitative precipitation forecast across the region through this period. It looks like 
the best chance through this period would be Tuesday afternoon 
and evening, when we still have a slight onshore component to 
the low level flow. 

Wednesday and Wednesday night...this is the period of greatest focus 
as it looks like our region will once again be solidly in the warm 
sector as a pre-frontal trough slides offshore and the cold front 
approaches from the west. With continued southwesterly flow, should 
see temperatures once again well above normal, approaching record 
highs (see climate section below). The combination of the very warm 
boundary layer (resulting in a relatively unstable profile with 
modest cape values) and a mid and upper level southwesterly jet 
(resulting in bulk shear values above 50kt) means there is once 
again a risk for strong or severe storms. The biggest source of 
uncertainty right now is the timing, primarily of the cold front. 
There are considerable differences with the GFS showing the most 
progressive solution, bringing the cold front through Wednesday 
evening, while most of the rest of the guidance shows a cold frontal 
passage late Wednesday night. The GFS solution would be the highest 
risk as the warmest conditions would be coincident with the best 
lift. Even with the slower solutions, there remains some risk for 
severe storms, it would just be a more limited period. 

As for The Hazards, it looks like the primary hazard would be strong 
winds. Current model soundings show limited instability in the hail 
growth region, limiting the threat of large hail. If there is 
widespread rain on Tuesday leading in to the event, then the risk 
for poor drainage flooding could increase for Wednesday. 

Thursday and Friday...strong cold air advection with breezy 
northwesterly winds. At this point, it looks like we will have at 
least 2 consecutive days of below normal temperatures. A fast moving 
low may dig across the region, though there remains considerable 
uncertainty with the track. 

Saturday and Sunday...high builds south, keeping US in the cold air 
for a few more days, although there may be a modest warming trend by 
Sunday as winds shift more westerly. 


Aviation /00z Monday through Friday/... 
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg, 
kmiv, kacy and surrounding areas. 

VFR through Monday afternoon, with only a few/scattered stratocumulus 
deck around 5,000-6,000 feet dissipating through this evening. 
Northwest winds will continue diminish through this evening, 
becoming mostly light westerly or even variable by late evening. 
After a period of mostly clear skies through about 09z, clouds 
will increase with cigs of 8-15 kft expected after 12z. 
Southwest winds will develop tomorrow, sustained winds should 
generally remain below 10 kts, with some gusts around 15-18 
knots for a few hours during the afternoon. 


Tuesday...should begin as VFR, but ceilings could lower to MVFR 
later in the day as rain begins to move in. 

Wednesday and Wednesday night...thunderstorms are likely, primarily 
Wednesday afternoon or Wednesday night. With any storms or showers, 
MVFR or even IFR conditions are expected. There will be an abrupt 
shift to breezy northwesterly winds with the cold front which should 
arrive Wednesday night. 

Thursday and Friday...mostly VFR conditions. There is a small chance 
of lower conditions with rain and snow showers Thursday night into 
Friday. Very breezy northwesterly winds are possible both days. 


winds have lowered below advisory levels for the Delaware Bay 
and southern New Jersey and Delaware Atlantic coastal waters. 
Therefore we've let the Small Craft Advisory expire for these 
areas. The Small Craft Advisory remains in place from little egg 
northward as winds continue to gust around 25 knots. But Small 
Craft Advisory conditions should end later this evening. Sub- 
advisory conditions are forecast thereafter through Monday 


Tuesday through Wednesday...southwesterly winds at or above 25 kt 
likely, especially on the coastal waters. Periods of showers and 
thunderstorms possible, especially on Wednesday. 

Wednesday night...thunderstorms and showers possible. An abrupt 
shift to northwesterly winds is expected with a cold front either 
late Wednesday night or Thursday morning. 

Thursday and Friday...northwesterly winds gusting above 25 kt are 
likely through out the period. There is also a chance for gale force 
gusts, primarily Friday afternoon and Friday night. 


record Max temps for Wednesday March 1. 

1972 was the year for most, except Ged 

Acy 72-1972 

Phl 76-1972 

Ilg 75-1972 

Abe 67-1972 

Ttn 74-1972 

Ged 73-1976 

Ridge 74-1972 

Mpo 67-1972 

The following monthly and seasonal average temperatures were 
calculated with todays Max/min and the 330 PM Mount Holly 
forecast from today- Sunday 2/26/17. 

**Record warm february** and a top 10 warmest winter, again! 

Records date back to the late 19th century. Details below. 


Phl 44.2. #1 normal 35.7 record 42.2-1925 por 1874 

Abe 39.4 #1 normal 30.7 record 38.6-1998 por 1922 

Acy 43.2 #1 normal 35.3 record 41.6-1890 por 1874 

Ilg 43.0 #1 normal 35.1 record 42.3-1903 por 1895 

Winter (djf) 

Phl 40.4 #6 (last winter was 3#) 4 of top 10 since 2000. 

Abe 36.0 #5 (last winter was #2) 4 of top 10 since 2000 

Acy 39.9 #9 (last winter was #5) 4 of top 10 since 2000 

Ilg 39.4 #5 tie (ditto last winter) 4 of top 10 since 2000 

Past two years of monthly average temperatures through February 
2017, a summary of above normal months listed below: 

For abe: 23 consecutive months of above normal temps! 

For phl: 22 of the past 23 months have been above normal. 

For acy: 19 of the past 23 months have been above normal. For ilg: 
17 of the past 23 months have been above normal. 

(Jan-Feb-March 2015 was the last time we had significant and 
persistent below normal monthly temps.) 

Allentown established a new record for February...three 
consecutive record breaking days of 70+. Allentown did have 3 
consecutive days of record breaking heat in 1991...but the 
records were in the 60s (3rd-5th). Allentown has established 6 
days of record high temperatures this month. 

Snow: February least on record: 

Atlantic City will be tied for 5th with 0.3". 


Phi watches/warnings/advisories... 
New Jersey...none. 
Marine...Small Craft Advisory until 9 PM EST this evening for anz450- 


near term...cms 

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