Flood Watch 2, NWS State College, PA

743 
WGUS61 KCTP 290144
FFACTP

FLOOD WATCH
NATIONAL WEATHER SERVICE STATE COLLEGE PA
944 PM EDT THU JUL 28 2016


PAZ036-056-057-059-063>066-290245-
/O.CAN.KCTP.FA.A.0002.000000T0000Z-160729T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
FRANKLIN-PERRY-DAUPHIN-LEBANON-CUMBERLAND-ADAMS-YORK-LANCASTER-
INCLUDING THE CITIES OF...CHAMBERSBURG...NEWPORT...HARRISBURG...
HERSHEY...LEBANON...CARLISLE...GETTYSBURG...YORK...LANCASTER
944 PM EDT THU JUL 28 2016

...FLOOD WATCH IS CANCELLED...

THE FLOOD WATCH HAS BEEN CANCELLED. PERIODS OF RAIN WILL FALL OVER
THE REGION TONIGHT INTO FRIDAY MORNING. HOWEVER, THE RISK OF
FLOODING HAS DIMINISHED. 

$$

Area Forecast Discussion
National Weather Service State College PA
113 PM EDT THU JUL 28 2016

.SYNOPSIS...
The stalled surface front over the Mason Dixon line will move
northward today and tonight as a disturbance approaches from the
Ohio and mid Tennessee River Valleys. This will produce a soaking
rain over portions of central and south central PA tonight into
Friday morning. Behind this system slightly cooler air aloft
moves over the region to usher in the weekend. But the ridge may
begin to build to our west again early next week.

&&

.NEAR TERM /UNTIL 11 PM THIS EVENING/...

Updated all grids again. Difficulty making gridded temperatures.
Nearly all guidance cannot handle the slow rise in temperatures
and the depth of the mid clouds blocking the sun. Pretty hard to
correctly produce meaningful grids. Better where the HRRR has rain
in southwest. But HRRR had really high temperatures today. Not
going to happen.

Now convection has broken out in the southeast along with the
remnant MCS from Ohio now tracking across southwestern
Pennsylvania. The more intense convective cores have stayed south
of the Mason-Dixon line. But rain in Somerset county and west will
move east-northeast across south-central Pennsylvania this
afternoon and evening.

Expect more showers to develop in southern PA in the warmer air
and closer to the boundary. Each HRRR run has different scenarios
with evolution and the GFS has the heavy rain axis relatively deep
into the cooler air.

Lots of uncertainty but from this afternoon on any lumbering
convective core has the potential to produce locally heavy
rainfall cannot rule out 1-2 inches in 1 hour later this afternoon
and into this evening.

Our grids show the blended QPF with the 15Z HRRRV1 QPF overlaidfor
some convective texture. Our QPF is higher in
southern/southeastern PA with HRRR based isolated maximum in
western Schuylkill county.

The GFS still is wetter well north of the CAMS.

&&

.SHORT TERM /11 PM THIS EVENING THROUGH 6 PM FRIDAY/...

The rain with embedded heavy showers and storms will continue to
over take the region. We kept lowest PoPs and QPF in northwest.
Best chance of rain is clearly south and southeast.

The GFS rainfall is quite impressive but likely too far north and
west based on the CAMS. Things should wind down overnight and
early AM.

Not as hot Friday and the threat of heavy rain drops off fast in
AM and the PoPs will lower as the day goes on.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
In the medium to long-range period...conditions slowly revert to
near normal in temp and precip as several chunks of short wave
energy in the westerly flow aloft helps to carve out a mean 500 mb
trough axis over the Glakes and Ohio Valley region during the Thu-
Fri timeframe.

The peak in unsettled weather (with perhaps some periods of down-
right rainy conditions) occurs Thursday night and Friday as a
well-defined wave of sfc-850 mb low pressure lifts ENE out of the
Ohio Valley and heads across the I-95 Megalopolis.

Followed a blend of EC/GEFS/superblend and NBM guidance for that
particular 24-36 hour period to arrive at likely pops for rain and
scattered TSRA. Some uncertainty in timing and areal coverage of
the convection led us to undercut the NBM by 10-20 percent for
now, recognizing issues with large scale model convective
parameterization schemes (and subsequent exaggeration of the areal
coverage and broader qpf amounts) means that we'll likely see more
concentrated areas/bands of heavy convection, compared to the
model depicted, larger cold season stratiform look to the precip
shield.

Portions of Southern and Central PA...close to the track of the
1006-1008 mb sfc low will likely see some localized heavy 1-2
inch,12-24 hour rainfall amounts by Friday afternoon...with even
the potential for some pinpoint heavier amounts from embedded
TSRA, as a tongue of 2 inch pwat air lifts north and wraps
cyclonically into sern PA and the Lower Susq Valley.

For later Friday through the upcoming weekend, a large area of
high pressure (1020-1024 mb) near the border of southern Quebec
and Ontario will try to push drier air south into the Mid Atlantic
Region.

Another...apparently weaker wave of low pressure at the sfc and
aloft lifts NE out of the Ohio Valley over the weekend and brings
an enhanced chc for showers. Slight diffs in timing/location exist
between the EC/GEFS and NBM guidance. However...the target period
for the best chc of showers and isolated to sctd TSRA appears to
be late Sat into Sunday.

Afterward, heights begin to rise from the southwest, accompanied
by a ridge of surface high pressure building east into PA with
mainly dry conditions and a rebound in temps for early next week.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
12Z TAFS sent.

Minor updates for showers and rain coming into southwestern areas.

Earlier discussion below.

Main change was to back off on fog, given slight breeze in some
spots, and dewpoints not that high.

Isolated showers still across the far south.

Clouds will be on the increase today. Most of the day still
looks dry with VFR conditions.

Showers and storms will overspread the area from south to
north late today into early Friday. MVFR and IFR conditions
will develop overnight. Some improvement on Friday, as weak
low moves east of the area.

OUTLOOK...

FRI...Some restrictions in SHRA/TSRA and patchy fog...mainly
early.
SAT-MON...Wide range of conditions expected with a chance
of showers and storms.

&&

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

&&

SYNOPSIS...DeVoir
NEAR TERM...Grumm
SHORT TERM...Grumm
LONG TERM...Lambert/Gartner
AVIATION...Grumm

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE STATE COLLEGE PA
801 AM EDT THU JUL 28 2016

PAZ004>006-010-011-037-291215-
WARREN-MCKEAN-POTTER-ELK-CAMERON-TIOGA-
801 AM EDT THU JUL 28 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA.

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

PAZ012-017>019-024>028-033>036-041-042-045-046-049>053-056>059-
063>066-291215-
NORTHERN CLINTON-CLEARFIELD-NORTHERN CENTRE-SOUTHERN CENTRE-CAMBRIA-
BLAIR-HUNTINGDON-MIFFLIN-JUNIATA-SOMERSET-BEDFORD-FULTON-FRANKLIN-
NORTHERN LYCOMING-SULLIVAN-SOUTHERN CLINTON-SOUTHERN LYCOMING-UNION-
SNYDER-MONTOUR-NORTHUMBERLAND-COLUMBIA-PERRY-DAUPHIN-SCHUYLKILL-
LEBANON-CUMBERLAND-ADAMS-YORK-LANCASTER-
801 AM EDT THU JUL 28 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA.

.DAY ONE...TODAY AND TONIGHT.

THERE IS POTENTIAL FOR MODERATE TO HEAVY RAINFALL LATER THIS
AFTERNOON AND OVERNIGHT. THE HIGHEST POTENTIAL FOR SOME FLOODING
WOULD BE IN THE MORE SOUTHERN AREAS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.