Flash Flood Warning 9, NWS State College, PA

Area Forecast Discussion
National Weather Service State College PA
650 AM EDT Fri Aug 9 2024

.SYNOPSIS...
The remnants of Tropical Storm Debby will lift north across the
area today bringing widespread heavy rainfall. Heavy rain will
exit the region by tonight, with drier conditions prevailing
over the weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
...1045Z Update...
As expected, SPC TOR Watch #616 in effect for E/SE third of our
forecast area. Environment becoming more favorable after 11z for
isold tornadoes as turbulent flow associated with Debby's
remnants lift north of the Mason Dixon line. Persistent band
that extended from the Chesapeake to the Lycoming Valley
produced localized damage near Harrisburg between 5:30 AM and
5:45 AM, as torrential rainfall was arriving and Flash Flood
warning was issued. Reports of trees down around that time
suggest potential wet microburst, but tor cannot be ruled out
given weak rotation being tracked at the time (radar operator
had TOR Warning worked up but the circulation dissipated at the
next scan. A similar environment will be in place throughout the
morning.

...Previous discussion....
Main focus this morning on locally heavy rain bands arriving
into SC Mountains and Laurel Highlands, and faster progression
of rain from south to north across central PA later today.
Heaviest rainfall will come between 12z and 16z, with heavy rain
decreasing from south to north thereafter. An isolated tornado
or two will be possible during that same timeframe over my
southeast counties as 0-1km EHI maximizes this morning.

Additional westward shift to heavy rain axis puts eastern
portions of Elk and McKean Counties under the gun to reach their
1- and 3-hr FFG later this morning, and earlier collaboration
with BUF added them to Flash Flood Watch valid 10z to 18z for
those two counties. Additionally, we accelerated the ending
time of heavier rainfall for the remainder of central PA
counties, and adjusted the Flood Watch end time accordingly,
running through 22z (vs 06z tonight).

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Back edge of Debby's rainfall should be exiting to the east by
late afternoon, with a nice evening in store for many thanks to
her acceleration. Sfc ridging from the Ohio Valley will deliver
much lower dewpoints into central PA tonight, with a pleasant
day expected on Saturday with highs ranging from the lower 70s
north to the lower 80s southeast.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Upper level troughing over PA throughout weekend and into the
middle of next week continues to support temperatures running a
few degrees below normal. Surface ridging and low-pwat air
should result in mainly dry weather with plenty of sunshine
through Monday over most of the region. However, the air mass
crossing the Grt Lks will be cool enough to support some lake
effect cloud cover and perhaps a few showers over the northern
tier on Sunday and Monday.

The only synoptic forcing in place will be weak lingering
troughing over Pennsylvania, which could support isolated
diurnally- driven convection across the northern tier on Tuesday
through Thursday. Moderating surface temps/dewpoints could
provide for pleasant days towards the end of next week.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Continued very high confidence (80-90%) in poor flying
conditions overnight and much of Friday across central PA
airspace, as heavy rain from remnants of TS Debby and associated low
ceilings bring solid IFR restrictions.

Added LLWS for a time overnight for marginal shear conds at
most airfields.

The best chance for embedded thunderstorms will be from about 15z
through 21z Friday in the Lower Susquehanna Valley, so we did
add a VCTS group for KMDT and KLNS.

E-SE surface winds will slowly increase overnight, and become
gusty on Friday (up to 20-25 kt), especially at KLNS and KMDT.
KBFD and KJST should see a wind shift to W late in the day.

Late day improvement is most likely (50-70% chance) at KBFD and
KJST, with less confidence elsewhere.

Outlook...

Sat..Trending VFR with time, with gusty wind 20-25kt from ~270
degrees.

Sun...VFR/no sig wx.

Mon-Tue...PM Scattered SHRA/TSRA across N PA.

&&

.HYDROLOGY...
The remnants of Tropical Storm Debby will begin to accelerate
towards central Pennsylvania, but will still bring heavy
rainfall beginning late this evening and continuing through
Friday. The heaviest rainfall is expected to begin overnight
(~12am across the southern tier to ~2am northern tier) with
rainfall rates of 1-3"/hr in the heaviest showers/isolated
thunderstorms. Heavy rainfall will continue throughout much of
the day before rainfall begins to exit quickly to the east by
Saturday evening. Current Event-Total QPF of 3-5" and localized
amounts up to 7" along the Alleghenies have been fairly
consistent in model guidance outside of some shifting in the
track of the remnant low.

Recent rainfall has allowed for relatively low FFG values
across central portions of the CWA. The Flood Watch was expanded
this cycle where some guidance has signaled for heavier
rainfall. Impacts from the rainfall will continue into the
weekend, where the Susquehanna and Juniata basins will begin to
rise towards minor flood stage.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 2 PM EDT this afternoon for PAZ005-010.
Flood Watch until 6 PM EDT this evening for PAZ006-011-012-
017>019-024>028-033>037-041-042-045-046-049>053-056>059-
063>066.

&&

SYNOPSIS...Lambert/DeVoir/Fitzgerald/Martin
NEAR TERM...Jurewicz/Lambert/DeVoir/Fitzgerald/Martin
SHORT TERM...Lambert/DeVoir/Fitzgerald/Banghoff/Martin
LONG TERM...NPB/Bowen
AVIATION...Jurewicz/Gartner
HYDROLOGY...NPB

Hazardous Weather Outlook
National Weather Service State College PA
624 AM EDT Fri Aug 9 2024

PAZ004-101030-
Warren-
624 AM EDT Fri Aug 9 2024

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...Today and tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

PAZ005-010-101030-
McKean-Elk-
624 AM EDT Fri Aug 9 2024

...FLOOD WATCH IN EFFECT UNTIL 2 PM EDT THIS AFTERNOON...

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...Today and tonight.

Please listen to NOAA Weather Radio or go to
weather.gov/StateCollege on the internet for more
information about the following hazards.

   Flood Watch.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

PAZ028-041-042-046-049>053-056>059-063>066-101030-
Juniata-Northern Lycoming-Sullivan-Southern Lycoming-Union-Snyder-
Montour-Northumberland-Columbia-Perry-Dauphin-Schuylkill-Lebanon-
Cumberland-Adams-York-Lancaster-
624 AM EDT Fri Aug 9 2024

...FLOOD WATCH NOW IN EFFECT THROUGH THIS AFTERNOON...
...TORNADO WATCH 616 IN EFFECT UNTIL 2 PM EDT THIS AFTERNOON...

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...Today and tonight.

Please listen to NOAA Weather Radio or go to
weather.gov/StateCollege on the internet for more
information about the following hazards.

   Flood Watch.
   Tornado Watch.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

PAZ006-011-012-017>019-024>027-033>037-045-101030-
Potter-Cameron-Northern Clinton-Clearfield-Northern Centre-
Southern Centre-Cambria-Blair-Huntingdon-Mifflin-Somerset-Bedford-
Fulton-Franklin-Tioga-Southern Clinton-
624 AM EDT Fri Aug 9 2024

...FLOOD WATCH NOW IN EFFECT THROUGH THIS AFTERNOON...

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...Today and tonight.

Please listen to NOAA Weather Radio or go to
weather.gov/StateCollege on the internet for more
information about the following hazards.

   Flood Watch.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

Special Weather Statement
National Weather Service State College PA
605 AM EDT Fri Aug 9 2024

PAZ049-050-052-091030-
Union PA-Northumberland PA-Snyder PA-
605 AM EDT Fri Aug 9 2024

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN NORTHUMBERLAND...
EASTERN SNYDER AND EASTERN UNION COUNTIES THROUGH 630 AM EDT...

At 604 AM EDT, Doppler radar was tracking a strong thunderstorm over
Selinsgrove, moving north at 40 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Milton, Lewisburg, Selinsgrove, Mifflinburg, Winfield, Watsontown,
Linntown, Hummels Wharf, Middleburg, New Columbia, Montandon,
Kreamer, Port Trevorton, Penns Creek, Richfield, Mount Pleasant
Mills, Kratzerville, Allenwood, Paxtonville, and Vicksburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Very heavy rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4067 7691 4069 7711 4108 7704 4109 7698
      4112 7697 4110 7675
TIME...MOT...LOC 1004Z 191DEG 36KT 4083 7695

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

Beaty/DeVoir

Special Weather Statement
National Weather Service State College PA
628 AM EDT Fri Aug 9 2024

PAZ046-049-050-052-091100-
Southern Lycoming PA-Union PA-Northumberland PA-Snyder PA-
628 AM EDT Fri Aug 9 2024

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN NORTHUMBERLAND...
NORTHEASTERN SNYDER...SOUTH CENTRAL LYCOMING AND EASTERN UNION
COUNTIES THROUGH 700 AM EDT...

At 627 AM EDT, Doppler radar was tracking a strong thunderstorm over
Lewisburg, moving north at 35 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Williamsport, Milton, Lewisburg, Montoursville, Winfield, Muncy,
Watsontown, Montgomery, Linntown, Duboistown, New Columbia,
Montandon, Kratzerville, Allenwood, Vicksburg, Elimsport, Spruce Run
Reservoir, Delaware Run, South Williamsport, and West Milton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Very heavy rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

A Tornado Watch remains in effect until 200 PM EDT for central and
north central Pennsylvania.

&&

LAT...LON 4086 7685 4087 7702 4129 7704 4126 7674
TIME...MOT...LOC 1027Z 187DEG 31KT 4094 7693

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

Beaty

Preliminary Local Storm Report
National Weather Service State College PA
657 AM EDT Fri Aug 9 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0545 AM     Tstm Wnd Dmg     Harrisburg              40.28N 76.88W
08/09/2024                   Dauphin            PA   911 Call Center

            Multiple trees down, some on a house.

&&

GAD