Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 242155
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
555 PM EDT Wed May 24 2017

.SYNOPSIS...
A storm over the TN valley will deepen and slide over PA on
Thursday and up the New England coast Friday. Rain tonight and
Thursday morning will be followed by scattered showers through
Friday night. Saturday may be the best day of the weekend. The
second half of the Memorial Day weekend looks wet with another
storm system moving through the Great Lakes.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Low clouds have clogged up the skies in the southwest on deep
ESE flow. Diurnal cu are expanding across the rest of the area,
and will put a halt to our warming. These cu will likely just
turn to a lower deck of stratus. The light rain over PBZs area
will continue to stream over Warren Co for another hour or so.
But, a break will then occur until the short wave trough over
KY lifts and sends the showers currently over the Hatfields and
McCoys up toward the Laurels.

Will leave out the mention of thunder for tonight, but there may
be a rumble. It is going to be pretty stable with all the low
clouds. Forecast precip amounts remain on track with the 0.75-1
inch numbers advertised for a while. Recent runs of the
numerical guidance incl SREF show a slight uptick to a
general/widespread 1 inch with 1.2 on the high end. The end of
the steadier rain will be crossing the Mason-Dixon line around
sunrise.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
The rain will lift up northward through the morning. However,
it looks to stay cloudy for another few hours. The southerly
flow is not all that strong and may not help to scour out the
low clouds very efficiently. Showers may again develop - esp if
there will be breaks develop in the south. These would then
rotate north in the aftn. But, for most folks there will be a
brief break of just cloudy during the morning in the south and
midday central and elsewhere. Again, if the low clouds hang
around too long, the arrival of the upper energy will not line
up with sun/instability. May be able to make some points on
MOS by keeping temps down a notch or two in the south. The sky
cover forecast for Thurs is pretty bleak, so we will hold maxes
below guidance a bit.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
The strong upper trough will consolidate low pressure at the
surface over PA producing a rainy Thursday night before lifting
it up the New England coast Friday. Broad cyclonic/northwest
flow with additional shortwaves rotating around the departing
upper low will keep showers in the fcst on Friday before precip
winds down Friday night/AM Saturday.

A lower-amplitude mid level flow pattern in the wake of the
departing closed upper low will feature rising heights/weak
ridging aloft into the weekend. The pattern will evolve into a
broadly cyclonic flow regime by early next week with upper low
spinning between the Great Lakes and Hudson Bay into midweek.

There is still some uncertainty regarding the location and
timing of shortwave impulses that could be a factor for
convection on Saturday. Model and ensemble guidance still
favoring locations to the south/west of Central PA so a dry
start to the holiday weekend may be in store for the area.

Model blend maintains the highest POPs on Sunday with a risk for
thunderstorms as well as a frontal system slides through. Another
round of showers (storms SE) possible for Memorial Day, with sct
showers poss lingering Tue into Wed as the parade of shortwaves
around the trough continues into midweek.

&&

.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...

SE flow has brought MVFR ceilings into my SWRN terminals.

Regional radar shows a growing area of rain racing north out of
the Virginias. Continuity and the HRRR show the rain moving into
SWRN PA by sundown, continuing to overspread the region during
the evening and into the wee hours of Thursday.

Expect widespread MVFR/IFR to spread northward with the rain
with all terminals seeing conditions lower between about
03-06Z.

IFR conditions will continue into the morning in the south and
perhaps well into the afternoon in the north. Breaks associated
with the dry slot will develop in the S in the morning as the
steady rain pulls away to the north. This will set the stage for
some modest instability to develop leading to the small chance
for a thunderstorm in the afternoon.

.OUTLOOK...

Fri...Scattered showers with MVFR ceilings, mainly over western
terminals.

Sat...Mainly VFR with scattered rain showers.

Sun...Reduced conditions with scattered showers/thunderstorms
associated with a cold front.

Mon...Mainly VFR with scattered showers/thunderstorms.

&&

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

&&

$$
SYNOPSIS...Dangelo/Steinbugl
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...RXR/Steinbugl
AVIATION...Dangelo/La Corte



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