Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 170913
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
513 AM EDT Tue Jul 17 2018

.SYNOPSIS...
Very warm and humid conditions will persist across much of
the Central Pennsylvania and the Susquehanna Valley before a
cold front sweeps southeast through the region. The front will
be preceded, and accompanied by more numerous showers and
thunderstorms. A few of the storms across the Susquehanna River
Valley this afternoon could produce strong, gusty winds and
locally very heavy rain in a short time period of time.
Noticeably cooler and drier weather will follow for the rest of
this week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Most of the overnight has been quite tranquil and muggy with
just a few isolated showers and thunderstorms drifting NE across
the northern and western mtns of the state.

An approaching cold front, increasing diffluence aloft, and a
NE/SW 925-850 mb theta-e ridge extending across Central and NW
PA to support expanding coverage of showers and TSRA this
morning.

Warm temps aloft (about 8-9C at 700 mb) and the lack of
significant forcing further across the SE half of the CWA will
keep POPs fairly minimal until the predawn hours of Tuesday.

We`ll have to deal with one last muggy early morning before we
exit this latest, anomalous warm spell. Given the high sfc
dewpoints in the mid 60s to low 70s, and extensive cloud cover,
min temps early today will once again vary from the upper 60s
to low 70s.

The cold frontal boundary will be slicing across the northwest
Mtns between will be slicing across the northwest mountains
between 11-13Z, and then gradually drift SE and likely bisect
the commonwealth from NE to SW around 16-18Z. The front will
reach our far SE zones around 21-22Z.

High PWAT air, increasing deep layer shear (0-3KM Bulk Shear
of 20-30 kt) and the cold front may lead to a few strong to
potentially severe thunderstorms across the SE half of the CWA,
and will be highly dependent on the amount of sunshine/cape that
can develop.

SPC`s and WPC`s outlooks for SVR and Excessive Rain are in the
MRGL category and limited to about the eastern third of our
CWA, where 2.0 PWATS will persist longest today ahead of the
cold front, and mdt deep layer shear will be present to better
organize storm structure and promote some localized bowing
echoes or line segments invof of mid level jet features
impinging on the back side of the TSRA.

Max temps today will be highest in the SE, but most places
won`t depart by any more than 3-4F from from their normals.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Drier air and building pressure behind the cold front tonight
into Wednesday will aid in clearing things out. High temps
Wednesday will be trimmed by about 5 degrees compared to today
(Tuesday).

The most notable and welcome change to most will be that
sharply lower dewpoints will make humidity levels become
much more comfortable.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
High pressure over PA Wednesday night will bring the coolest
morning of the week before it slided east off the coast on
Thursday. Flow aloft will shift from northwest to southwest and
surface winds will turn southeast. GFS hints at a marine layer
moving into lower Susq Thursday night and a return of higher dew
points may bring some patchy morning fog.

Next system slowly approaches by late Friday but stalls over the
Great Lakes as inverted trough develops on top of it. This
system will slowly work eastward into the Northeast over the
weekend bringing a return of unsettled weather. A weak low
center trying to form on the coastal front off the Carolinas
Saturday progged to move north to just of the Delmarva for
Sun/Mon, enhancing shower/tstm threat for eastern half of CWA.

&&

.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
The approach of a cold front will be preceded by
sct-numerous showers and a few thunderstorms early today across
the Central and NW Mtns of the state.

The cold front will reach KERI around sunrise and then slow a
little as it should take most of the day to get thru KLNS. But,
BFD should be dry aft 15Z and UNV/JST/AOO may be dry by 18Z.
Some storms with gusty winds and heavy rain are expected, mainly
in IPT, MDT and LNS where peak heating will meet up with
CFROPA. IFR is poss in any of the storms.

Drier and less humid conditions start Tues morning in the NW and
evening in the SE and last for the rest of the week.

.Outlook...

Wed-Fri...AM valley fog N, otherwise, no sig wx expected.

Sat...SHRA/TSRA poss vcty warm front.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...Dangelo/Lambert
NEAR TERM...Dangelo/Lambert
SHORT TERM...Lambert
LONG TERM...Lambert/RXR
AVIATION...Dangelo/Gartner



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