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452
FXUS61 KCTP 021305
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
905 AM EDT Thu May 2 2024

.SYNOPSIS...
-Warm/dry weather with lower humidity continues for today and
 most or all of Friday

-Trending unsettled into the weekend with some periods of rain
 and thunderstorms Sat/Sun

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Tranquil conditions with mainly clear skies cover the entire
forecast area early this morning. Surface T/Td spreads of
several deg F or more are negating any notable valley fog
development.

Temps to start the day will be close to 10 degrees above climo
in the warm advection regime ahead of a weak/dry cold front
front that was sliding across the NW Mtns of PA at 09Z.

Daybreak readings will range from 45F to 50F throughout the
higher rural valleys of Central PA, to the mid and upper 50s
across the Lower Susq Valley.

The aforementioned weak cold front will bring primarily a few to
several deg F drop in sfc dewpoints today, yielding another
excellent vsby day with abundant sunshine. This frontal
boundary will settle just south of the Mason Dixon Line by this
afternoon as the associated shortwave passes off the New England
Coast and upper level ridging sharpens and crests over PA
tonight.

Vertical mixing of model 850mb temps in the 12-14C range will
equate to highs ranging from the mid 70s over the N Mtns, to
the mid 80s in the Southern Valleys, which are 10-15 degrees
higher than what we normally see for early May.

A nearly east/west band of low level convergence and higher
humidity is depicted via the latest HREF near the Mason/Dixon
line this afternoon yielding MU CAPE values of a few to several
hundred j/kg.

A weak capping inversion and very dry air above 800mb suggests
any convection is very unlikely there.

The very dry air above the weak inversion aloft supports
undercutting NBM dewpoints this afternoon over the central and
northern part of the forecast area. We continued to employ a
blend of the NBM and the much lower numbers obtained from the
MixedDewpoint Tool.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
Sfc and upper level ridge of high pressure will remain over PA
for most or all of the daylight hours Friday. Clouds will
increase across the Western part of the CWA later Friday
afternoon, bringing the chance of a few showers near and to the
west of the RT 219 corridor after 21Z Friday.

Southeasterly flow will develop across much of the CWA Friday
as the center of sfc high pressure exits stage right off the Mid
Atlantic Coast. This will lead to cooler daytime highs - mainly
in the mid to upper 70s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
A frontal boundary will slowly make it`s way eastward from the
Midwest across the Commonwealth this weekend, accompanied by
showers and storms. The best chc of wet weather will be across
western PA Fri night, before expanding eastward Saturday into
Sunday.

Looking to the first half of next week, the front should pull
east of the region on Monday, taking the widespread shower/storm
activity with it. Tuesday into Wednesday, a warm front
approaching from the Ohio Valley should bring an increasing chc
of showers/storms.

&&

.AVIATION /13Z THURSDAY THROUGH MONDAY/...
There will be some high and mid-level clouds passing overhead
this morning as a weak area of low pressure passes to our north
and pushes a weak/dry cold front south across the Mason Dixon
Line. An upper ridge will build overhead through the rest of the
day, producing a clear afternoon. Sfc winds will become W to NW,
and could gust 15-20 kts by aftn. Tranquil weather will persist
through tonight with diminishing winds.

Outlook...

Fri...VFR with increasing high clouds.

Fri evening - Sat AM...Scattered SHRA/TSRA developing from west
to east w/ reductions possible.

Sat PM-Sun...Widespread restrictions across the central and
western mountains due to low cigs. SHRA likely with a chance of
TSRA.

Mon...AM fog/clouds poss. PM -SHRA possible areawide.

&&

.CLIMATE...
-- Changed Discussion --
Near-record highs are forecast for some locations in south
central PA this afternoon. The daily records are listed below.

Harrisburg88 in 1913
Altoona87 in 1954
State College86 in 1938
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Lambert/Dangelo
NEAR TERM...Lambert/Fitzgerald
SHORT TERM...Lambert/Fitzgerald
LONG TERM...Gartner/Evanego
AVIATION...Evanego/Colbert
CLIMATE...Steinbugl