Area Forecast Discussion
Issued by NWS State College, PA
FXUS61 KCTP 261142
Area Forecast Discussion
National Weather Service State College PA
742 AM EDT FRI AUG 26 2016
A large ridge of high pressure at the surface and aloft will build
over the Mid Atlantic Region through the upcoming weekend,
bringing a string of warm and dry days. A weak front will try to
push southeast across the state Sunday night into Monday morning
and could be accompanied by a shower or thunderstorm. Another
period of warmer than normal and dry days will follow for Monday,
Tuesday, and possibly Wednesday.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Last vestige of convection (just ahead of a weak pre-frontal
trough) were exiting our far SE zones at 09z.
Plenty of convective debris mid/high level cloud cover across the
Susq Valley and points east (and quite extensive strato cu across
the nrn and wrn mtns of PA), will combine with high sfc dewpoints
in the upper 60s to lower 70s, and light wind across the central
two-thirds of the CWA to bring a warm/muggy start to the day
Expect to see just some patchy fog through the mid morning hours
in areas that received some of the heavier rain Thursday evening
(which is across the NW Mtns and Laurel Highlands).
Temps will struggle to dip into the mid 60s across the mtns...
and will start out in the 70-75F range throughout the Susq Valley.
For later this morning and this afternoon...PWATs that were close
to 2 inches last evening and early today...will decrease to less
than 1.5 inches across much of the state...but will still linger
close to 1.75 inches right along the Mason-Dixon line. There...sfc
based cape should climb to 1300 j/kg or higher between 18-23Z
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Ridging during the day today will maintain quite warm
temperatures aloft (plus 7-9C) Combine this with a lack of
noticeable, organized Theta-E convergence and minimal mesoscale
upward Vertical Velocity, and we`ll see a great limitation to the
threat of convection. Slightly less surface moisture will make
things feel more comfortable, though temperatures will once again
top out well above average.
Sfc high will slide right over the region tonight, resulting in a
fair and mild night. Will have to watch for the possibility of
patchy valley fog over the northern mtns late.
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A weak cold front will bring the chance for a few showers or
thunderstorms late Sunday into Monday morning. Otherwise,
Medium Range Guidance is in good agreement in keeping an
anomalous ridge aloft in place over the region Sunday...into the
early days of next week. This will assure we remain warmer than
normal with daytime highs in the mid to upper 80s, low to mid 90s
over southeastern areas, at least into Tuesday.
By mid week week, weak troughing rippling through southern Canada
and the Great Lakes is made to erode the northern portion of the
northeastern ridge a bit, but only to the extent that upper
heights and temperatures fall back closer to normal values.
The NAEFS and GEFS end up carving out a weak mean trough by the
end of the week, but once again heights and temps are forecast to
be near seasonal norms so it should remain quite pleasant with
the biggest chance being a break in the humidity.
Chances for rain will be generally limited to scattered diurnal
convection each day, but with warm air aloft the chances should
remain small in the absence of well defined forcing. There is a
period later Sunday into Monday morning as we come under the
northern edge of the subtropical ridge and a weak cold front
approaches, which could be the first hints at the development of a
more significant MCS upstream. But with such a strong ridge aloft
it`s hard to be confident at this range.
Main item of difference is the tropical system the ECMWF blows
up over the southeastern Gulf of Mexico early next week that the
GFS doesn`t do much with at all. Both model suites agree with
the northern stream trough mentioned above to be enough to keep
any possible tropical developments well south of the local area.
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Patchy low cigs and fog will improve to VFR by mid morning. VFR
continues through tonight with some local fog impacts possible
early Saturday morning.
Sun...scattered TS northwest 1/2 airspace.
Mon-Tue...low chance of TS.
LONG TERM...La Corte/Lambert