Area Forecast Discussion
Issued by NWS State College, PA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KCTP 221958
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
358 PM EDT Thu Jun 22 2017

.SYNOPSIS...
A warm front will move through the region today, bringing a
return to warmer and much more humid conditions this afternoon
right through Friday night. A cold front will push east across
the region during the morning or early afternoon hours Saturday,
followed by drier and cooler air with comfortable humidity that
will last through much of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
An area of showers and thunderstorms extends from east of BUF
down into NERN Ohio. The HRRR takes this ESE across the area
mainly north of I-80 through late afternoon before depicting it
as becoming more scattered and disorganized.

Dewpoints have surged into the mid and upper 60s rather quickly
with the approach and passage of the diffuse warm front. We
will stay in the soupy airmass for at least the next 36-48
hours before drier air returns to the region.

SPC has much of the northern portion of the region under a
Marginal Risk. Instability in the area of the Marginal Risk is
limited at best as of mid day, but model guidance does show the
development of at least moderate CAPE and shear over much of
the western part of the state as the afternoon warms up, and
with dewpoints climbing this looks reasonable.

RAP depicts 0-1km EHIs between 1 and 1.5 m2/s2 across much of
the NW part of my CWA into the evening, so the potential exists
for stronger storms to rotate. SPC addressed the convection
developing over the area and this tendency for rotation, but at
this time a watch is not likely.

The biggest threat over the next 36-48 hours will be for heavy
flooding rains as we see an almost classic set up for a PRE
event developing over the NERN US. Any localized heavy showers
and thunderstorms today will lay the groundwork/lower FFG values
and additional and potentially training convection that will
occur Friday through Friday night as moisture from Tropical
Storm Cindy surges into the NE US.

Moisture will continue to increase ahead of the remnants of TS
Cindy that are surging NE out of the Gulf States. PWATs are
forecast to increase to between 1-4 sigma by daybreak Friday and
continue into Saturday morning.

By late tonight rain and embedded heavy thunderstorms should be
overspreading my southern zones. Any decision on Flood Watches
will be made by later shifts.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
*Heavy rain and short-term flooding risk Friday-Friday night.

A significant influx of deep tropical moisture (PW 1.50-2"+)
associated with the remnants of TS Cindy will combine with an
approaching northern stream trough and cold front to bring an
elevated risk of heavy rainfall and potential flooding to
portions of central PA. The deep moisture will focus along/ahead
of an emerging frontal zone and interact with the westerlies
aloft and weak instability to support the heavy rain/FF risk.
The area that appears to be most susceptible/at greatest risk
would be over SW PA (southwest Alleghenies/Laurel Highlands)
where a multi-model blend incorporating HIRES models/CAMs has
been fairly consistent with location of max QPF. Enhanced
terrain lift will also be a factor over a region that has the
lowest short-term FFG in the CWA. Updated WPC D2 ERO shows a
MDT risk for excessive rain over SW PA clipping Somerset Co. with
SLGT risk encompassing the rest of the area. We will continue
to highlight +RA/FF risk via HWO at this time - later shifts
will likely consider a FF watch at shorter ranges with increasing
confidence. Expect some consolidation of pcpn along the frontal
boundary as it pushes southeast across the area Friday night
with max POPs generally shifting from west to east by the 06-12z
Saturday period.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
From a large scale perspective, the medium range forecast will
feature a seasonably strong/amplified upper trough settling over
the Northeast U.S into next week. The theme continues to be
above avg confidence in the pattern but low confidence in the
details.

Expect moisture/rainfall associated with the remnants of TS
Cindy to exit the area by Saturday afternoon. Drier, low PW
air arrives behind the cold front with decreasing clouds and
lowering humidity providing a nice start to the weekend. An
extended period of comfortable, low-humidity conditions with
temperatures near to below late June climatology are expected
to last through the early part of next week. A few cool nights
early next week with min temps 40-55F.

Precipitation opportunities will be modulated by shortwave
impulses reflecting weak surface fronts/troughs which have low
predictability at this range. Any pcpn would be generally
scattered in nature and on the light side given below normal
moisture levels for late June. The 22/12z GEFS shows PW values
remaining below average through midweek which would tend to
favor mainly dry wx.

Temperatures should stay on the cooler side of climo through
midweek as the upper level trough shifts east of the area.
Differences continue with the trough evolution later in the
week with the GFS initially more amplified before building SE
U.S. ridge. The EC generally maintains a mean trough over the
Northeast CONUS into the second half of next week.


&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
Widespread VFR exists as of 18Z.

An area of showers/thunderstorms is dropping ESE through the
northern mountains. BFD will be the most likely to experience
brief reductions as the convection affects the airfield.
Elsewhere VFR will continue into the evening with hit and miss
showers and storms causing localized reductions.

There will be a better chance for more widespread IFR
conditions to develop tonight and tomorrow as rain and embedded
thunderstorms from the remnants of TS Cindy overspreads the
region.


.OUTLOOK...

Sat-Sun...Mainly VFR

Mon-Tue...Mainly VFR. Chc SHRA/TSRA.

&&

.EQUIPMENT...
KCCX radar will be offline for approximately 4 days starting
Saturday, June 24th for technicians to install the first of 4
major service-life extension upgrades. The work on the radar has
been scheduled to minimize potential impacts to operations and
will be delayed if hazardous weather is forecast.

&&

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

&&

$$
SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...Steinbugl
LONG TERM...Steinbugl
AVIATION...La Corte
EQUIPMENT...Steinbugl



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.