Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCTP 241105
Area Forecast Discussion
National Weather Service State College PA
705 AM EDT SUN JUL 24 2016
Pennsylvania will remain on the northern edge of the subtropical
ridge into the upcoming week. A cold front sliding southeast
across the state monday afternoon and evening will bring the best
chance of widespread light to moderate rainfall amounts from
showers and scattered, potentially strong thunderstorms.
However, most of the time today, and again Tuesday through
Thursday will be fair, very warm and humid, but rain free.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --Variable amounts of high clouds were spilling southeast from the
glakes region above an area of surface high pressure, centered
over the Alleghenies of western PA.
11z temps ranged from the mid to upr 50s in the north (and
perennial cold valleys in central PA), to the mid and upper 60s
in the southern valleys.
PWATS across nearly all of the CWA are much more comfortable that
24 hours ago, and generally around 0.75 inch, while 1.5 inch PWAT
air is not too far south of the PA/MD border (and the PA/Ohio
border) along and sw of a surface warm front.
This front will buckle to the north and into western Penn late
today into tonight, as a weak short wave and 40-50 kt upper
jetlet slides east from the Ohio Valley.
Partly to mostly sunny skies will occur this afternoon.Mentioned
20-40 pops for a few showers/isolated to scattered tsra (a few of
which could be on the strong side) along the front that will be
advancing back to the north with decent low-level convergence
along it, and a higher cape/EHI environment being advected in from
the West and WNW.
Highs this afternoon should be 3-4 deg cooler than yesterday in
most locations. Maxes will be mainly in the upper 80s across the
mountains, but will again soar into the l-m 90s elsewhere
throughout Central PA and the Susquehanna River Valley.
-- End Changed Discussion --
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
Mugginess will be on the gradual increase tonight as a warm front
drifts back north and brings PWAT values close to 2 inches across
much of the state by 12z Monday.
A cluster of TSRA likely approaching from eastern Ohio/Western PA
was accounted for by 20-40 POPs for now. A few of the storms could
still be on the strong side as they drift ESE at around 30 kts
(climbing up and over the Allegheny Plateau and encountering the
greater llvl moisture/and cape of over 1500 j/kg.
.LONG TERM /MONDAY THROUGH SATURDAY/...
Big story in the extended fcst is the expected heat wave lasting
into early in the upcoming week, as the axis of the subtropical
ridge briefly shifts from the plains to the northeast conus.
Anomalous upper lvl ridging building over PA should bring hot and
mainly dry wx this weekend, as warm temps aloft suppress
convection. Next chance of shra/tsra for most of the area comes
Monday ahead of shortwave working across the Great Lakes. However,
any rainfall Monday is likely to do little to stem the dry pattern
we have been in.
Heat indices around 100F appear possible by Monday across the
Susq Valley, as higher dewpoints are advected into the area ahead
of potential convection. Overnight lows are also a concern as the
area doesn`t cool off at night through the weekend with Southern
PA lows in the 70s with highest readings Monday morning. Some
modest cooling appears likely by Tue/Wed of next week behind weak
cold front. However, temps still likely to remain somewhat abv
normal within a generally zonal flow.
Midweek weather looks dry again, with just low pops for isolated
tstms. Fri looks to be the next higher chance for tstm impacts
areawide as another cool front progged to move through.
.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
Some fog starting to form over locations where it rained yesterday -
only LNS has gone to IFR at this point. The dewpoints have dropped
off into the 50s over many locations except the MDT/LNS where m60s
hang in there -despite some decrease/drying in the last few hours.
T/Td spread still wide enough to preclude fog at most other sites.
Other than patchy lower/VFR clouds, no other restrictions are seen
at 08z. With the air drying very slightly, it may be difficult for
any more sites to develop fog - especially IFR fog.
After any fog burns off, the wind will be light and variable today.
The high pressure will be attacked as a short-wave trough moves into
PA from the NW late today. This forcing could combine with the
increase in swrly llvl flow to generate sct SHRA/TSRA late this aftn
- but more likely not until this evening - over the west. Have
included PROB30 groups for TSRA close to the western terminals
starting close to sunset.
Scattered convection may continue into the night and will spread to
the east a bit before dissipating for the most part. A cold front
will across the Great Lakes tonight and through PA on Monday. Thus,
additional SHRA/TSRA are expected through Monday evening, and
perhaps into very early Tues morning. High pressure returns for mid-
MON...Scattered restrictions possible in SHRA/TSRA.
TUE-WED...AM fog poss. Otherwise VFR.
THU...Mainly VFR. SCT PM SHRA/TSRA.
Record high in both IPT and MDT for today is 96F.
Current high temp forecast for both locations is 94F.
considering the maxes of the past few days...the very dry soil
and likely lack of thick high clouds today...we could easily tie
or jump nudge about those records later this afternoon.