Flash Flood Warning 7, NWS State College, PA

167 
WGUS71 KCTP 090556
FFSCTP

Flash Flood Statement
National Weather Service State College PA
156 AM EDT Fri Aug 9 2024

PAC009-057-090715-
/O.CON.KCTP.FF.W.0007.000000T0000Z-240809T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Bedford PA-Fulton PA-
156 AM EDT Fri Aug 9 2024

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 315 AM EDT EARLY THIS 
MORNING FOR SOUTHEASTERN BEDFORD AND FULTON COUNTIES...

At 156 AM EDT, Doppler radar and automated rain gauges indicated 
that heavy rain was falling across the warned area. Between 1.5 and 
4 inches of rain have fallen. The expected rainfall rate is 1 to 2 
inches in 1 hour. Flash flooding is ongoing or expected to begin 
shortly.

HAZARD...Flash flooding caused by heavy rain.

SOURCE...Radar and automated gauges.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Breezewood, Warfordsburg, Clearville, Everett, McConnellsburg, 
  Harrisonville, Big Cove Tannery, Crystal Springs, Waterfall, Wells 
  Tannery, Fort Littleton, Needmore, Valley-Hi, Locust Grove, 
  Saluvia, Sideling Hill Rest Area, Barnes Gap, Inglesmith and 
  Rainsburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 4003 7845 4017 7814 4013 7808 4010 7793
      4006 7786 4000 7792 3983 7800 3972 7810
      3972 7860

FLASH FLOOD...RADAR AND GAUGE INDICATED
EXPECTED RAINFALL RATE...1-2 INCHES IN 1 HOUR

$$

Jurewicz

Area Forecast Discussion
National Weather Service State College PA
1054 PM EDT Thu Aug 8 2024

.SYNOPSIS...
A frontal boundary will slowly lift northward overnight and
early Friday. The remnants of Tropical Storm Debby will lift
north across the area on Friday, as it merges with a cold front
approaching from the west. Drier conditions will prevail for
the weekend.

&&

.NEAR TERM /THROUGH FRIDAY/...
845 pm update... Narrow, but transitory moderate-heavy rain
bands continue to form over southern PA this evening, near and
just north of a stationary front, and also just ahead of Debby's
main rainfall shield. Only patchy light rain and drizzle is
present at this time north of I-80.

As Debby's remnant circulation moves northward overnight, steady
moderate-heavy rainfall will overspread the southern PA counties
first, then reach the northern tier towards daybreak.

As a truly tropical environment spreads into the Commonwealth
during the night, temperatures and dew points may actually nudge
upward a bit, especially south of US-22/I-78.

The upward trend in temperatures/low-level moisture will likely
continue to fuel some destabilization from south-north and
embedded convective elements, especially after midnight. This,
combined with strengthening low-level shear/enlarging
hodographs, could pose the threat for isolated tornadoes towards
daybreak, especially for the Middle and Lower Susquehanna
Valleys. We'll be watching this potential with a keen eye,
along with obviously the heavy rain/hydro threats.

No real changes in the overall forecast philosophy in terms of
Debby's rainfall totals, with a solid swath of 3-5" and locally
higher amounts in a band from south-central up through northeast
PA. There are some growing signals in some of our high-
resolution guidance for narrow bands of very heavy rainfall in
parts of the Susquehanna Valley as well, likely via narrow
spiral rain bands on the eastern side of Debby's circulation
center. Hence, one of the reasons that we expanded the Flood
Watch eastward through the Lower Susquehanna Valley and into the
western edge of the Poconos.

Previous discussion... Did think about expanding flood watch
into the east more, given how wet it has been, but QPF lower
there, held river fcst down for now. Some showers overnight and
so far today, but these are weaker now and lifting northward.
The 00Z EC has an interesting QPF max well north of the PA
border. The showers lifting north across our area at the current
time might find more heating to the north, then to our south.

Adjusted temperatures and dewpoints a bit, but overall these
fields are good, in line with frontal system slowly lifting
north and west.

SPC upgraded day 1 to push marginal into far south central
PA late tonight. Main change was to up POPS later tonight,
as timing of the system is a bit faster now.

&&

.SHORT TERM /FRIDAY NIGHT/...
9 pm update... The latest model guidance is trending faster
with the back edge of Debby's steady rainfall late Friday
afternoon, and even some potential late day clearing near and
west of I-99. We largely followed these trends in our gridded
fields.

Previous discussion...
As noted earlier, I looked over expected southeast flow and
high dewpoints across eastern areas for Friday. Our grids in
line with current guidance. Some support to see a small shift of
the outlook for storms on Friday a bit to the west, if track of
system remains close to the current track.

New discussion.

Anyway, SPC did upgrade the area a bit further west, and also
now a slight risk into eastern areas.

Main change to Friday was to end the widespread showers and
storms a bit faster now, than earlier fcst.

Still looks like the accelerating remnants of Debby will track
from near KHGR to near KAVP during Friday afternoon.

Main change to the QPF so far was to keep amts about the same,
but make the area a bit on the narrow side. Still expect
most areas to see 3 to 4 inches, with locally higher amts.
Will adjust more as needed, WPC call here shortly.

Still a bit early, but the combination of low to mid 70
dewpoints and strong southeast flow at low levels would
support strong to severe storms, and perhaps a short lived
tornado, if one gets some dry air aloft and some heating. Main
threat for storms would be across the Susquehanna Vly, where
there would be more time for heating. Also working on dewpoints
in the mid 70s.

&&

.LONG TERM /SATURDAY 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 parts of
Warren, McKean, and Potter counties.

Moderating surface temps/dewpoints could provide for pleasant
days towards the end of next week. 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.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
00z update... Very high confidence (80-90%) in deteriorating
flight conditions later tonight and much of Friday throughout
Central PA, as heavy rain and low ceilings bring solid IFR
restrictions.

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 from 2 AM EDT Friday through late Friday night for
PAZ006-011-012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066.

&&

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

Hazardous Weather Outlook
National Weather Service State College PA
1017 PM EDT Thu Aug 8 2024

PAZ004-005-010-100230-
Warren-McKean-Elk-
1017 PM EDT Thu Aug 8 2024

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...Tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

PAZ006-011-012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066-100230-
Potter-Cameron-Northern Clinton-Clearfield-Northern Centre-
Southern Centre-Cambria-Blair-Huntingdon-Mifflin-Juniata-Somerset-
Bedford-Fulton-Franklin-Tioga-Northern Lycoming-Sullivan-
Southern Clinton-Southern Lycoming-Union-Snyder-Montour-
Northumberland-Columbia-Perry-Dauphin-Schuylkill-Lebanon-Cumberland-
Adams-York-Lancaster-
1017 PM EDT Thu Aug 8 2024

...FLOOD WATCH IN EFFECT FROM 2 AM EDT FRIDAY THROUGH LATE FRIDAY
NIGHT...

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...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...Friday through Wednesday.

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

   Flood Watch.

The remnants of Tropical Storm Debby will drift north across
South-Central Pennsylvania and the Susquehanna Valley on Friday,
bringing the likelihood for widespread heavy rainfall of 2 to 4
inches, with locally higher amounts possible.

This heavy rainfall could lead to flooding of poor drainage areas,
small streams and possibly even some points along the larger rivers
Friday into Saturday.

There is also a chance for fast moving strong to severe
thunderstorms
on Friday, with the potential for a brief tornado.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.