Area forecast discussion 
National Weather Service Mount Holly New Jersey 
954 PM EDT Monday Jul 28 2014 


Synopsis... 
low pressure moving across New England this evening is shoving a 
cold front off the middle Atlantic coast. Weak high pressure will 
follow later Tuesday through Wednesday. It then merges into the 
western Atlantic high pressure system late this week. 
Meanwhile...the front will be lurking just off the coast as a 
stationary front. 


&& 


Near term /until 6 am Tuesday morning/... 
a middle level short wave trough will continue to lift over New 
England during the night. Meanwhile, surface low pressure located 
over Maine will lift northward. The low will continue to pull a 
cold front through the southern part of our region and off the 
coast. 


The rain showers associated with the cold front were almost 
entirely gone by 930 PM. We are anticipating a slow decrease in 
cloud cover as dry air continues to filter into our region from 
the northwest. 


Low temperatures should be mainly in the 50s and lower 60s. 


&& 


Short term /6 am Tuesday morning through 6 PM Tuesday/... 
a nice Tuesday ahead as cooler, drier air continues to move in 
across the area as weak high pressure begins to build in from the 
west. With precipitable water values below one inch and no significant short 
wave/vorticity impulses, Tuesday is expected to be dry across the 
area. 


Temperatures will be cooler than the last couple of days as 
925/850 mb temperatures and thicknesses decrease into Tuesday. Used a 
blend of mav/met MOS, mosguide, and mixed 925 mb temperatures for highs 
on Tuesday which ends up being several degrees below normal. 


&& 


Long term /Tuesday night through Monday/... 
500 mb: a large trough in the east will slowly weaken late this 
week into early next week. 


Temperatures: about 5 degrees below normal Wednesday warming to 
near normal this coming weekend and early next week. 


Forecast basis: unless otherwise noted the long term period of 
this forecast is generally based on a 50 50 blend of the 12z/28 
NAM/GFS MOS for the period Tuesday night - Wednesday night... the 
12z/28 GFS MOS Thursday and Thursday night and then thereafter 
(friday onward) the 1522z/28 wpc gridded guidance for all elements 
except have applied the warmer 12z/28 mexmos temperatures. All this was 
checked against the 12z/28 European model (ecmwf) to ensure we're in the ballpark 
(barring midday overcast skies and rain) with European model (ecmwf) cyclically 
persistent 18z 2meter temperatures. The precipitation probability 
guidance was checked against the 09z/28 sref probability of precipitation for .01 in 3 hours 
through 00z Friday and thereafter the 12z/28 gefs 6hr probability of precipitation for 
0.05 . 


The dailies... 
it sort of looks like we're primarily in a weak surface ridge 
region this 6 day period and not favorable for much rain. 


Basically for now its a generally fair weather forecast this 6 
day period. 


There is a chance for late day or evening convection NE PA and northwest 
New Jersey later in the week but for now is Chancey and low confidence. 


As for the lurking quasi stationary along the coast... it may 
drift closer to the shore by the weekend as a warm front with its 
convection possibly spreading ashore but confidence for this 
scenario is also below average. 


It does appear this quasi stationary boundary will eventually 
dissipate and as it does...higher humidity should slowly return to 
the area late this weekend into early next week. 


Temperatures and probability of precipitation as described above in the forecast basis. 


&& 


Aviation /02z Tuesday through Saturday/... 
the following discussion is for kphl, kpne, kttn, kabe, krdg, 
kilg, kmiv, kacy and surrounding areas. 


VFR conditions are expected through the taf period. 


A west northwest wind around 5 to 10 knots is anticipated. The sea 
breeze front may reach kacy early on Tuesday afternoon. 


Outlook... 
Tuesday night-Wednesday night...mainly VFR. 


Thursday- Saturday...mainly VFR. Isolated showers/thunderstorms 
possible each day but low confidence on occurrence. Patchy IFR fog 
or stratus is possible Friday night. 


&& 


Marine... 
the Small Craft Advisory for the Delaware Bay and the southern 
half of the Atlantic coastal waters was extended through midnight 
tonight as winds are gusting around 25-30 knots. As the frontal 
boundary moves through, the gusts will switch from west to 
northwest and drop off slight, and seas should lower as well. The 
seas may remain longer on the northern waters a few more hours, so 
we leave the northern half ending at 6 am Tuesday. 


Outlook... 
Tuesday night-Saturday...no headlines anticipated. Looks like 
good weather for being on the waters in this time frame. 


We are monitoring the GFS operational run depiction (for several 
forecast cycles) of a tropical system in the Atlantic Basin for 
early next week but the European model (ecmwf) operational version still doesnt 
have it. 


&& 


Phi watches/warnings/advisories... 
PA...none. 
New Jersey...none. 
Delaware...none. 
Maryland...none. 
Marine...Small Craft Advisory until midnight EDT tonight for anz430-431- 
452>455. 
Small Craft Advisory until 6 am EDT Tuesday for anz450-451. 


&& 


$$ 


Synopsis...drag 
near term...iovino 
short term...Robertson 
long term...drag/Robertson 
aviation...drag/iovino 
marine...drag/Robertson 












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