Area forecast discussion 
National Weather Service Mount Holly New Jersey 
309 PM EDT Thursday Jun 30 2016 


Synopsis... 
weak high pressure will continue to move offshore overnight. A cold 
front, attached to low pressure over Canada, will cross the area 
later Friday and Friday night. High pressure will build in for the 
weekend and persist into the Holiday. A warm front may begin to 
push into the region next Monday night and into Tuesday. 


&& 


Near term /until 6 am Friday morning/... 
a very nice Summer afternoon continues in progress. Scattered 
cumulus-stratocumulus. Southwest wind gusting 15 mph this 
with southeast sea breezes progressing slowly inland along the 
coasts as you see on Dix/dox/tphl radars and the observed wind 
shift/temps. 


Tonight...isolated showers and thunderstorms should begin to move 
into the southeast portion of our region, mainly after midnight. 
Weak instability burst. Pwat increases to 1.6" by 12z Fri phl 
south (up from the near 1 inch of today). Fog or stratus may 
develop toward dawn Friday. Light south wind. 


Forecast basis: 50 50 blend of 12z/30 GFS/NAM MOS but probability of precipitation raised 
se of the njt and Delaware tonight for an instability burst shower or 
garden variety thunderstorm in the 03z-09z time frame. 


Confidence: average. Doubts about how much fog tonight and whether 
it can rain tonight. 


&& 


Short term /6 am Friday morning through 6 PM Friday/... 
Friday...mixed clouds and sun, warm and more humid. Chance of 
showers/isolated thunderstorms during the morning. The primary 
thunderstorm event should develop eastward near and south of the 
Mason-Dixon line late in the afternoon with what I think is decent 
potential for scattered severe thunderstorms arriving Delmarva 
sometime after 5pm. That is where modeled MLCAPE is 1400+j, 
multi-model tt50, ki pooled 34+ and 0-6km bulk shear is 35-45 kt. 
South to southwest wind. 


12z/30 UK/ggem and ec override on the almost non existent afternoon 
NAM qpf, even tho the NAM instability pooling looks correct. 


Mid 80s continues to look good for Max temps much of the area 
Friday. Its possible we'll see some 88's Philadelphia southwestward 
since 850 warms to 15c by 12z. Guidance Max temps may be biased 
low by modeled morning qpf. 


Forecast basis: 50 50 blend of 12z/30 GFS/NAM MOS but probability of precipitation raised to 
likely Delmarva because of ec/ggem?Uk qpf and modeled instability 
fields. 


Confidence: above average. 


&& 


Long term /Friday night through Thursday/... 
the last of the showers and thunderstorms associated with the 
eastward moving cold front will be across the region Friday 
evening. The arrival of the cooler and drier air will cause pops to 
decrease from west to east overnight. 


The upcoming Holiday weekend looks great with high pressure 
building in Sat and remaining in control of the weather thru 
Monday. We will begin to show some increase in pops Monday, with 
some slgt chcs or small chc pops across the Delmarva and se PA by 
Mon afternoon. It shouldn't be enough to hinder any outdoor 
activities for that day. The air will be pleasantly dry on Sat, 
then some increase in humidity by the 4th. Temperatures will be 
near normal with highs in the low/mid 80s in most areas. 


The operational models are indicating a disturbance approaching 
from the south/southwest Monday night and lasting into Tue. It 
appears that a warm front and humid air will crease a round of 
showers/tstms for (mostly) the srn parts of the fcst areas. We 
will carry chc pops in the fcst attm. Details will be sorted out 
as the time frame draws nearer. Temperatures again near normal, or 
maybe a degree or two above. It will likely be rather humid as 
well. We will continue with a dry and seasonably mild fcst for 
Wed-Thu next week. 


&& 


Aviation /19z Thursday through Tuesday/... 
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg, 
kmiv, kacy and surrounding areas. 


Rest of today...VFR sct clouds aoa 6000 ft. Winds becoming south 
to southwest with southeasterly sea breezes. Confidence: well 
above average. 


Tonight...VFR to start but MVFR or IFR conditions in St/fog/haze 
possible after 06z/1. Isolated showers or thunderstorms possible 
03z-09z se of the njt and Delaware. For now, chances are too small to 
include in the tafs, but MVFR conditions will be possible if any 
showers or storms move over a taf site. Light southerly wind. 
Confidence: average since there is uncertainty regarding extent of 
any showers and St/fog development late tonight. 


Friday...becoming VFR sct-bkn aoa 4000 ft after any early morning 
IFR/MVFR lifts by 15z. Brief MVFR or IFR conditions possible in 
showers and thunderstorms, especially late day. Thinking that 
scattered severe thunderstorms will be developing eastward across 
the Delmarva into southern New Jersey sometime after 21z/1. South to 
southwest wind. Confidence: above average due to multi-model 
consensus overriding the dry 12z/30 NAM afternoon qpf. 


Outlook... 


Friday night...VFR sct-bkn aoa 4000 ft with sct showers and 
thunderstorms ending by 06z/2 with possible MVFR fog where it 
rains late Friday afternoon/evening. 


Saturday...mainly VFR conditions expected. West to northwest wind 
around 10 knots or less. 


Sunday...mainly VFR conditions expected. North to northwest winds 
becoming west to southwest. 


Monday...mainly VFR conditions expected. Showers and thunderstorms 
possible. 


Monday night and Tue...sct showers and thunderstorms especially 
S/SW. 


&& 


Marine... 
winds and seas should remain below Small Craft Advisory criteria tonight through 
Friday. A few gusts to 22 kt are possible on the coastal waters 
late this afternoon as the sea breeze ramps up, but should stay 
below 25 kt. 


Rip currents...remainder of today. Low risk may border on low end 
of moderate during late afternoon if a strong and more onshore 
wind develops along ocean and Monmouth County shores. 


Water temperatures were around 4 to 5 degrees above normal for 
late June...mid 60s to lower 70s throughout the de and New Jersey beaches 
with exceptions. The 1130z/30 (730am edt) satellite interpretation 
of water temps found a cooler pocket of water at the outermost 
Oceanside entrance to de Bay (lower 60s) midway between Cape May 
and Lewes and possibly also near Barnegat. 


From this time forward through September 30 we will be issuing a 
day 2 srf 1 line outlook for the media by 330 PM in the marine 
section of this afd. This will better support media early evening 
broadcasts while permitting our srf to run our day 1 forecast 
through sunset. We have an overwhelming number of fatalities 
occurring near the evening dinner hour, after beach patrols 
depart and its still quite warm. For safety awareness purposes our 
day2 will continue issuing after sunset when presumably more 
beachgoers are out of the water. 


Rip current outlook for Friday...the probable risk for the 
formation of dangerous rip currents tomorrow is low. 


Friday may border on moderate risk during the afternoon depending 
on the strength of any onshore flow during the afternoon, 
especially New Jersey. 


Outlook... 


Friday night through Tuesday...sub-sca conditions most of the 
time. Sct thunderstorms with higher winds and seas Fri evening and again 
Monday night/Tue. 


Rip currents...projecting a solid low for Saturday with a 3 ft 
7sec se swell but an offshore wind. Sunday-Monday-Tuesday projecting 
a low enhanced or possibly low end of a moderate risk where the 
new moon tends to accentuate tidal fluctuations and thereby increases 
current strength. The Sunday-Tuesday confidence projection is 
average. In other words, caution is advised when using a projection 
this far in advance, since a 1 foot difference in wave height 
expectation and/or a significant change in onshore wind can easily 
change the potential for dangerous rip current formation. 


The Atlantic Basin continues quiet for awhile so that bodes well 
for continuing the low risk, or possibly moderate risk for the 
formation of dangerous rip currents. 


Most fatalities from rip currents occur at unguarded beaches. The 
vast majority of fatalities are on low-moderate risk days which 
means there is a lack of awareness of the dangers of swimming at 
unguarded areas, or near jetties and piers. 


&& 


Phi watches/warnings/advisories... 
PA...none. 
New Jersey...none. 
Delaware...none. 
Maryland...none. 
Marine...none. 


&& 


$$ 
Synopsis...O'Hara 
near term...drag 
short term...drag 
long term...O'Hara 
aviation...drag/O'Hara/meola 
marine...drag/O'Hara 



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