Friday, July 20, 2018, 8:17 PM EDT
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Area Forecast Discussion
Valid At
Wed, Dec 31, 7:00pm EST
FXUS61 KCTP 202357
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
757 PM EDT Fri Jul 20 2018

.SYNOPSIS...
The recent stretch of pleasant and conformable weather across
central PA will come to an end this weekend, as the pattern 
turns decidedly unsettled, muggy and rather wet through next 
week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Enjoy and take advantage of the dry weather late this afternoon
and evening; changes are afoot.

North-south line of convection has developed as expected near/along
the I-79 corridor in WPA. Hires model consensus still suggests 
this line may drift eastward and clip the border counties 
adjacent to WFO PBZ. However, this is low probability with the 
majority -if not all- of central PA remaining dry through early
tonight.

Based on the latest hires model blends/ensemble means, there is
high confidence in showers spreading northward from the 
Delmarva/Chesapeake Bay region into south central/southeast PA 
early Saturday morning. An increasingly moist, southeasterly 
low level flow will also help to bring low clouds into much of 
the area.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Hybrid coastal low will track north along the mid Atlantic 
coast from eastern NC across the Delmarva on Saturday and 
approach southern New England by Sunday morning. This low will 
eventually be absorbed by the anomalous deep-layer cyclone that 
is expected to move slowly southeastward into the Ohio Valley. 

Confidence has increased significantly in a period of heavy rain
spreading northward across the eastern 1/3 of the CWA later
Saturday afternoon into Saturday night. The 12Z HREF mean shows
a cyclonically  curved, 50+kt LLJ drawing deep moisture inland 
ahead of the hybrid low, with PWs reaching 1.5 to 2.5 inches 
over southeast PA. There is definitely a short-duration flash 
flood risk given the impressive PWs, strong lift and low level 
moisture transport, but limiting factors include dry antecedent
conditions, high FFG and low CAPE. 1-2 inch amounts are likely 
with localized higher amounts possible. Despite high confidence 
in a period of heavy rain, decided to hold off on FF watch given
aforementioned factors and preference toward a more short-fused
issuance. Added heavy rain/ff threat in the HWO. 

Clouds will hold daytime temps in the low to mid 70s, and it
will feel more humid and muggy.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
By 12z Sunday, compact coastal low will be sliding north of the
area. But very gradually filling inverted low will edge toward
western PA while continuing to channeling tropical-like 
moisture into the region - keeping unsettled weather ongoing
through much of next week - peaking in the afternoons. Best
daily chances for tstorms shifts to western/central sections
Tue/Wed before returning eastward Thu as a cold frontal boundary
finally pushes across the state. 

Temperatures will be below normal Sun with thicker cloud cover 
and moist SE/E flow, then highs return closer to normal for 
next week while lows look to remain on the muggy side.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions across the region this evening. Banded showers
moving south to north over western Pennsylvania. Expect VFR 
conditions to continue into Saturday morning, followed by
lowering conditions during Saturday as low clouds and showers 
develop across the airspace.

Low VFR to MVFR ceilings are probable Saturday into Saturday 
night, with some pockets of IFR Saturday night into early 
Sunday. 

Showers are expected to spread northward from the Delmarva/Chesapeake
Bay region into the south central/southeast airspace early Saturday
morning. Expect a period of moderate to heavy rain later Saturday
afternoon into Saturday night across the eastern airspace. 

Unsettled weather with showers and isolated thunderstorms to
continue into mid week.

.Outlook... 

Sat...VFR start early, then conditions lowering to MVFR in all
areas except VCTY KBFD. 

Sun-Wed...Frequent showers/isolated T'storms with associated 
MVFR/IFR restrictions.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Steinbugl
LONG TERM...RXR
AVIATION...Jung/Steinbugl

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