fxus61 kphi 212310 

Area forecast discussion 
National Weather Service Mount Holly New Jersey 
710 PM EDT sun Oct 21 2018 

high pressure will remain across the region through tonight before 
starting to shift to the north on Monday. A cold front will cross 
the region on Tuesday. High pressure will return on Wednesday and 
persist through the end of the week. A developing coastal storm may 
impact the mid Atlantic over the weekend. 


Near term /until 6 am Monday morning/... 
6 PM...gusty winds will continue to subside this evening as the 
pressure gradient weakens and also due to the loss of diurnal 
heating and mixing. High pressure continues to build across the 
central Appalachians to our south, but will nose its way 
northward across our area overnight. This will keep dry weather 
conditions and mostly clear conditions overnight, although there 
could be some patchy cloud cover at times. 

With the light winds, mostly clear skies, temperatures will radiate 
quite easily tonight. Temperatures will drop into the low to mid 30s 
everywhere, except the higher elevations which will drop into the 
upper 20s and coastal areas which may only be upper 30s or low 40s. 
We have upgraded a portion of the frost advisory to a freeze warning 
across portions of eastern Pennsylvania as well as portions of 
central/southern New Jersey, especially portions of The Pine 
Barrens. The rest of the frost advisory remains the same. We did not 
expand the advisory southward for the remainder of the Delmarva as 
temperatures may not get low enough for widespread areas of frost, 
although there will be some patchy frost for some areas. 


Short term /6 am Monday morning through 6 PM Monday/... 
high pressure continue to build to our south on Monday, then 
offshore by the afternoon. A return flow will develop across the 
area, which will allow temperatures to warm a few degrees from 
Sunday. Dry weather continues to be expected as low precipitable water values will 
remain across the area and now strong short wave/vorticity impulses 
are expected. Winds will become gusty around 15-20 mph during the 
afternoon for some areas, but it will not be as windy as Sunday. 


Long term /Monday night through Sunday/... 
Monday night...the high moves offshore and to the northeast of the 
area. As the high pulls away, a weak warm front may develop and push 
northward through the region overnight. It doesn't look like much on 
the models with no precipitation associated with it. 

Tuesday...the cold front arrives on Tuesday. Models continue to show 
a clipper-like system moving out of Canada and across the Great 
Lakes before reaching our area on Tuesday. It's a pretty fast moving 
system and the front quickly makes its way through the region. Still 
not seeing much moisture with the frontal passage and it could very 
well end up being dry. However, with another strong upper level 
trough crossing the region, I am inclined to continue the mention of 
some slight chance to chance pops across areas to the north and west 
of the I-80 corridor as a recent similar front was progged to be 
mostly dry and ended up being a fairly robust system moving through. 

Wednesday through Friday...strong surface high pressure builds into 
our area on Wednesday and persists through the end of the work week. 
We should remain nice and dry through the period. The bigger story 
is the return of colder air as it dips down from the north and 
settles over the eastern US through Friday. Windiest day looks to be 
Wednesday as the front pulls away from the area but it doesn't look 
nearly as windy as Sunday was. 

Saturday and Sunday...models are continuing to show the potential 
for a strong coastal system to move up the eastern Seaboard, 
bringing wind, rain, and potentially some snow (mainly higher 
elevations). One thing the models do not show is a good cold 
pool, which would help give more confidence to snow in the 
forecast area. So it may end up just being a cold rainstorm. 
Many of the details still need to worked out as the system 
develops and the track will play a crucial role as it has been 
moving close to and away from the coast over the past several 
model runs. 


Aviation /22z Sunday through Friday/... 
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg, 
kmiv, kacy and surrounding areas. 

Tonight...VFR conditions will continue through tonight. Northwest 
winds may still occasionally gust 15-20 knots early this 
evening before dropping off by late evening. Winds will become 
light and variable for some locations overnight. Otherwise, 
winds will become more west or southwest overnight around 5 

Monday...VFR conditions continue through Monday. Winds will become 
more southwesterly through the day around 5-10 knots. Some gusts 
around 15-20 knots are possible for some area during the 


Monday night and Tuesday...mainly VFR conditions expected. Light 
winds on Monday night, then west to northwest winds around 10 to 15 
knots with higher gusts possible on Tuesday. Showers possible at 
krdg/kabe with lower ceilings/visibilities possible. 

Wednesday...mainly VFR conditions expected. Northwest winds around 
10 to 15 knots with gusts around 25 knots possible. 

Wednesday night through Friday...VFR conditions expected. Light 
northwest to west winds overnight with speeds around 5 to 10 knots 
during the day. 


6 PM...Gale Warning has been allowed to expire as winds have 
dropped below criteria but a Small Craft Advisory is now in 
effect until midnight on the Delaware Bay and 3 am over the 
ocean waters. Once the Small Craft Advisory ends overnight, 
conditions will remain below advisory levels after that through 
the day Monday. 


Monday night through Thursday...winds start to pick up Monday night 
and may start to approach 25 knots. A cold front will cross the 
waters on Tuesday with a strong northwest flow behind it. Winds will 
increase starting on Tuesday and gusts above 25 knots will then 
continue through Thursday before starting to subside Thursday 
evening. A Small Craft Advisory will likely be needed for much 
of this period. 

Friday...sub-advisory conditions are expected on the area waters. 


Phi watches/warnings/advisories... 
PA...freeze warning from midnight tonight to 9 am EDT Monday for 
Frost advisory from midnight tonight to 9 am EDT Monday for 
New Jersey...freeze warning from midnight tonight to 9 am EDT Monday for 
Frost advisory from midnight tonight to 9 am EDT Monday for 
Delaware...frost advisory from midnight tonight to 9 am EDT Monday for 
Maryland...frost advisory from midnight tonight to 9 am EDT Monday for 
Marine...Small Craft Advisory until 3 am EDT Monday for anz450>455. 
Small Craft Advisory until midnight EDT tonight for anz430-431. 


near term...fitzsimmons/Robertson 

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