FXUS61 KCTP 210211
Area Forecast Discussion
National Weather Service State College PA
1011 PM EDT Mon May 20 2019
A cold front has pushed to the southeast and will allow high
pressure to build into the region for Tuesday and Wednesday.
Pennsylvania will be on the northern periphery of a building
subtropical ridge later this week.
.NEAR TERM /UNTIL 8 AM TUESDAY MORNING/...
Dry, cooler air continues to slide across the area. Clouds will
be the trouble in the forecast overnight. Will keep the sky
cover grid high for the next 6-9 hours in the Alleghenies where
upslope, cold air advection and strong/lowering subsidence keeps
the moisture rising and trapped/little mixing. However, the
dryness of the air on the whole and the crashing of the
inversion should allow for a decrease in coverage toward
sunrise. Earlier tweaks in temps okay.
Still pretty breezy as the dry air pushes in from the west.
The threat of showers/storms has ended across the SE as the
front has cleared them out. Secondary boundary (seen easily on
CCX and BGM radars) with more-northerly wind behind it is
inching southward thru the nrn mtns. Cloud shield is solid over
the far NW and this shield is expected to slide E/SE. The edge
of the ovc coverage will likely not get far past AOO/UNV/IPT,
but much of the night could be cloudy in the NW half/third of
the area under the steep subsidence inversion. This would keep
it a little milder than going mins, but we will only nudge them
a deg for now.
.SHORT TERM /8 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
High pressure and associated low-pwat air mass will build into
the region from the Grt Lks Tuesday, resulting in a high
confidence forecast of fair and cool weather. Ensemble mean
850mb temps support highs from only the low 60s over the
northern mountains, to around 70F across the Susq Valley.
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
High pressure will likely result in another day of fair weather
Wednesday. However, can't rule out a late day shower over the
western counties associated with an approaching warm front.
00Z NAEFS indicates Pennsylvania will be on the northern
periphery of a building subtropical ridge late this week into
next weekend. Shortwaves riding over the top of the ridge will
bring back the daily chance of convection. However, bulk of med
range guidance supports a brief period of fair weather Friday,
as drier air builds in behind a Thursday PM cold front.
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
The cold front continues to exit the region leaving only a few
forecast questions over the period. The first will be the
continuation of MVFR cigs over the NW MTNS. Due to the gusty
upslope flow these cigs should continue overnight before the
drying NW air filters down tomorrow morning between 11Z to 14Z.
The next issue is the timing of the gusty winds to end. Expect
a few hours after sunset, between 00Z to 02Z the cooling SFC
temperatures will allow for the inversion to form which will cut
off the stronger upper level winds. However, the persistent
northwesterly flow will continue overnight with around 10 to
15kt winds at all TAF sites. VFR conditions will dominate the
weather pattern tomorrow.
Thu-Fri...Isolated to scattered restrictions possible from
potential showers and thunderstorms.
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