Area Forecast Discussion
Issued by NWS State College, PA
FXUS61 KCTP 271202
Area Forecast Discussion
National Weather Service State College PA
802 AM EDT FRI MAY 27 2016
A ridge of high pressure over the western Atlantic will bring warm
and increasingly humid conditions to the region into the holiday
weekend. Cooler and showery weather may arrive for Memorial Day.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Radar mosaic at 11Z showing isold showers across northeast Pa
along axis of southerly ll jet. This feature and assoc shower
threat is progged to weaken and lift out of the area later this
morning, so will end mention of showers by arnd 12z.
After a warm and tranquil morning, diurnal heating of moist
airmass should yield sct pm, pulse-type convection. NCAR ensemble
data indicating CAPEs surging to arnd 2000 J/kg, which could
support locally isold strong wgusts/hail in best cells. However,
wind fields and deep lyr shear are weak, indicating organized svr
wx is unlikely.
Although aftn Pops are blw 50 pct, what rain does fall could be
locally heavy, due to slow storm motion and high PWATs.
Convection-allowing mdls show this potential with local amts in
excess of 2 inches possible.
Mdl 850mb temps close to 16C are supportive of max temps today
ranging from the l80s ovr the highest terrain, to nr 90F over
the Susq Valley.
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Diurnally-driven convection should fall apart with loss of heating
this evening. Partly cloudy skies and light wind could yield
patchy fog tonight where ground is wet from pm showers.
High dewpoints will lead to another very warm night with min temps
in the mid 60s over much of the area.
Subtropical ridge builds nwrd into Pa on Sat with 500mb height
anomalies reaching 2SD across southeast Pa. The assoc warm temps
aloft should suppress convection across the se counties Sat aftn.
However, sct diurnal tsra again appear likely across the nw half
of the state. Thermodynamic/kinematic profiles appear similar to
Friday, with moderate CAPE and weak shear suggesting pulse-type
convection and low risk of organized svr wx.
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Summertime upper level ridge over the Mid Atlantic and Northeast
states is forecast to peak around 29/00z with above normal
heights returning to normal by early next week. Temperatures
should follow a similar trajectory with positive temp departures
trending modestly lower/toward climatology into the first week of
June. The tropical disturbance /Invest AL912016/ approaching the
Southeast U.S. coast will add additional moisture to an already
humid/unstable airmass in place through Memorial day weekend. Some
interaction between the tropical disturbance and mid latitude
trough crossing the Central Appalachians likely favors the
greatest pcpn risk/potential pcpn coverage Sunday night into Memorial
Day (Monday) with a decreasing chance for rain into Tuesday.
Deterministic and ensemble guidance are in broad agreement in a
dry period of weather from Tuesday into Wednesday before pcpn risk
gradually increases into the second half of next week. Heights are
forecast to rise a bit around the end of the period before the
large scale pattern slowly shifts toward a western ridge/eastern
trough configuration by June 5th as depicted by the 27/00z NAEFS
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Ridge of high pressure remains in control keeping a summertime
weather pattern in place.
After a breif bout with cig/vsby reductions over the nw mtns and
se...VFR conditions will dominate much of the remainder of the
day. Though enough moisture/cape in place to generate sct
pulse-type thunderstorms with locally gusty winds in mid/late
afternoon across mainly eastern half of cwa. Did mention late-day
VCTS in Susq Valley in TAFS.
Vsby reductions to MVFR more likely tonight with humidity
increasing...with a few areas of IFR fog mainly confined to places
that receive rain today.
Sat...Early am low cigs/vsby possible. Isold pm tsra impacts.
Sun...Sct pm tsra impacts possible...mainly nw half.
Mon...Sct pm tsra impacts possible...mainly se half.
Tue...No sig wx.