Area Forecast Discussion
Issued by NWS State College, PA-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCTP 210034
Area Forecast Discussion
National Weather Service State College PA
834 PM EDT SAT AUG 20 2016
Warm and humid weather will continue through Sunday. A cold front
will push through the region Sunday, followed by a cooler airmass
with much lower humidity. The drier and cooler air will make it
very comfortable for much of the upcoming week. The next
significant chance for rain won`t arrive late Thursday or Friday.
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A few scattered thunderstorms continue across the higher terrain
of the west and north. Meso models show these making the usual
diurnal fade with the loss of heating, before new activity
upstream begins to approach around or shortly after midnight.
It will be another warm and muggy overnight as higher dewpoints
upstream advect in ahead of the approaching cold front.
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
a fairly sharp, but progressive nrn stream upper trough
will become located across the Lower Great Lakes region by 00Z
Monday. Decent height falls, instability and anomalously high (2
inch plus) PWATs will lead to favorable conditions for frequent
showers and embedded (mainly sub-severe) TSRA on Sunday.
SPC has maintained their MRGL risk in place for the eastern half
of PA Sunday, and model consensus timing of the cfropa through the
central mtns of PA (along with widespread cloud cover with only
limited breaks) during the mid afternoon hours agrees with this
placement and category for SVR threat.
There still is sufficient llvl speed shear and veering of the
vert wind profile across the SE third of the CWA Sunday afternoon
to bring the threat for at least transient mesos in any strong/svr
storms. Small pockets of EHI in the 1.5-2.5 m2/s2 range will be
highly dependent on seeing some decent breaks in the otherwise
widespread cloud cover within the region of mdtly strong uvvel
associated with the RE region of a potent swrly upper jet max.
Maintained basin avg rainfall of about 0.5 - 0.75 inch across the
SE and a little over one inch across portions of the NW mtns.
However...the high PWAT air will bring the chc for some pinpoint 2
inch amounts in places that see training TSRA. This should keep
any flood threat quite minimal, but still as noted by the previous
shift - a gully may get washed, but nothing more than nuisance
Timing of the exit of the storms seems to be pretty solid at
before noon in the NW and ~sunset in the far eastern zones.
Therefore, it may get pretty nice and only a little breezy in the
late afternoon across the western part of the area.
The cool air and cyclonic flow in the wake of the front may
generate some showers off the lakes later in the afternoon and Sun
night. Temps get pretty cool Sun night with lots of 50s and l60s.
This will make the requisite valley fog - but the drying before
sunset will keep the fog from being too widespread and keep it
mainly in the valleys and in the east where they probably won`t
have a chance to dry out before it clears and cools in the
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
The upper level trough will be mainly through the region by
tomorrow night with only lingering shower adn thunderstorms
possible through the first half of the overnight period. As the
trough lifts to the northeast expect that a mid level ridge and
weak flow aloft will move into the region. Cooler, drier air will
advect into the region bringing a period of precipitation free
weather through most of next week. The next period of active
weather will come as an upper level trough moves into the region
Thursday night into Friday. A front with +1 to 2 anomalous PWATS
progress through Friday. That should correspond with a passing but
possibly weakening cold front. Dry air should be possible behind
it for next weekend.
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --Scattered, diurnally-driven shra/tsra are dying out over the
Allegheny Mtns as sun sets this evening. A brief vis reduction
remains possible at KBFD and KJST through arnd 02Z. Elsewhere, VFR
flying conds will persist through the late evening hours.
A cold front will push east into the region late tonight and
Sunday, bringing deteriorating flying conds. An increasingly
moist southerly flow preceding the front will be accompanied by
sct showers and cigs falling into the MVFR category across much of
Central Pa btwn 07Z-11Z. The upslope flow into the northern mtns
could result in IFR cigs at KBFD by arnd dawn. Further east,
mclear skies and light wind could result in fog toward dawn across
southeast Pa. Latest model data suggests IFR vsbys are possible at
KLNS arnd dawn.
Improving conds are expected over the western half of the state by
Sunday aftn, as a drier westerly flow arrives behind departing
cold front. Over the eastern half of the state, MVFR reductions in
showers could persist well into the afternoon until passage of
front. Also, a few stronger tstorms could form on the front,
possibly affecting KIPT, KMDT and KLNS during the afternoon.
There is high confidence of VFR conds over most of Central Pa
Sunday evening, with the exception of KBFD, where a second batch
of -shra could arrive with passage of upper level trough.
Mon...No sig wx expected.
Tue-Wed...Patchy AM fog possible.
Thu...Isold pm tsra impacts possible w mtns.
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The KCCX radar remains down for preventative maintenance, panel
replacement and radome painting.
The radar is expected to be running on Sunday, but may need to be
taken off line again Monday to finish the work.
NEAR TERM...La Corte/Lambert