Area Forecast Discussion
Issued by NWS State College, PA
FXUS61 KCTP 251914
Area Forecast Discussion
National Weather Service State College PA
314 PM EDT WED MAY 25 2016
A ridge of high pressure over Pennsylvania this afternoon will
slide east and set up shop across the western Atlantic over the
next several days. A southerly flow on the west side of this high
will transport increasing moisture north from the gulf coast
region. A few weak upper level disturbances will move east from
the Ohio Valley and interact with this moisture to spark
scattered afternoon and early evening showers and thunderstorms
both Thursday and Friday. The noticeably more summer-like pattern
will continue through at least the first half of the upcoming
holiday weekend. Cooler and showery weather may arrive for
.NEAR TERM /THROUGH TONIGHT/...
Moisture increasing in the mid levels (above a rather warm/dry
near sfc air with dewpoints in the mid 40s to around 50F) is
combining with a thin veil of cirrus to create a light hazy
appearance to am otherwise splendid late spring afternoon.
19Z temps are within a deg or two of their fcst highs in the u70s
to mid 80s.
A west to southwest breeze of 7-10kts with minor gusts into the
mid and upper teens...will lighten up tonight as it backs to the
sw then south by daybreak.
A deck of bkn-ovc alto cu over central and wrn Ohio (based between
8-15 kft agl) will move into our western zones around or shortly
before midnight...then across central PA and the Susq Valley late
tonight. Temps should reach their lows in many locations just
prior to the cloud cover spreading in (or the T curve should at
least flatten out late tonight).
Temps will dip into the low-mid 50s across the nrn mtns...and
settle into the u50s to l60s elsewhere.
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
A generally thick area of alto cu clouds should move across the
fcst area Thursday morning and linger through the midday hours
across the east before breaking a bit during the several hours of
peak heating. A weak upper shortwave and subtle llvl trough/wind
shift will slide ENE across the region Thursday afternoon and
Evening. The amount...intensity and location of showers and
isolated to sctd TSRA will depend highly on the amt of llvl
heating we can achieve through the cloud cover. In addition...the
presence of a weak mid-level capping inversion should limit
Latest Oper and ENS guidance points twd a few to svrl hour period
of high chc/low likely pops for convection between 20Z thur and
01z Friday with tapered pops on either side of this time period.
Mean QPF will be around one tenth of an inch...with obviously
higher and lower pinpoint amounts around and outside of the
anticipated small convective clusters.
High temps Thursday afternoon should be a few deg F lower in most
places due to the cloud cover.
After the scattered evening convection wanes...a mild and somewhat
muggy night will follow with mins between 58-65F.
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
The large scale pattern has a decidedly summertime look and feel
to it through Memorial Day weekend and into next week with light
winds aloft and a prevailing ridge across the northeast CONUS.
Temperatures will average above normal with the core of the `hot`
weather front-loaded Friday-Sunday before trending modestly toward
late May/early June climatology. Precipitation risk early in the
period should be characterized by diurnal convection with the
highest probs occurring during peak afternoon heating, augmented
at times perhaps by weak disturbances drifting through aloft. Max
POP may be centered on or around Memorial Day as weak shortwave
suppresses heights as it passes by to the north and some interaction
takes place with `tropical` system migrating toward the southeast
U.S. coast. Latest NHC forecast this area of disturbed weather has
a 50% chance of development within the next 5 days.
.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
High pressure will provide the region with a warm and sunny rest
of today with just some mainly thin high-level cirrus and
cirrostratus. VFR conditions will prevail.
West to southwest winds of 7-10kts with gusts in the 14-18kt range
will diminish quickly this evening...and become nearly calm later
tonight. Increasing BKN-OVC mid level cloud deck based between
8-15kft agl will drift into our western PA TAF sites later tonight
and over the SUSQ Valley during the late night and morning hours
Thursday. A few light showers could accompany this influx of
warmer/moist mid level air.
The low-level flow will become south to southwesterly late
Thursday morning and afternoon. There could be a few showers and
thunderstorms late Thursday afternoon/Thursday evening. Not
totally sold on this...as the mid and upper wave potentially
triggering the convection will be weakening as it approaches, and
dewpoints are relatively low to begin with (and have to come up a
lot higher) for any appreciable convection to fire. Somewhat a
better chance for scattered afternoon shra/tsra on Friday.
Fri-Sun...Isold...mainly pm tsra impacts possible.