844
FXUS61 KCTP 081138
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
638 AM EST Fri Nov 8 2024

.SYNOPSIS...
* Breezy and dry and unseasonably warm today
* Elevated to critical risk of wildfire spread today in south
  central and southeastern Pennsylvania
* Frontal system moves through later Sun and Sun night, bringing
  0.40-0.70" rain; next chance for rain on 11/14

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Valley fog has developed over the NW and has started to creep S
and a little E. A very low stratus deck has also begun to form
over the NW, too. That will keep temps steady or rising for the
rest of the night. The fog should dissipate everywhere this
morning, but the clouds in the NW will likely be stubborn to get
rid of. It may then re-form or just lift into a sct-bkn strato
cu deck. But, the majority of the area will be mostly to fully
sunny. The west wind should be gusting into the 20s, and may
touch 30 MPH as a dry cold front drops down across wrn NY and
into far nrn PA late in the day. Read more in the fire wx
section on the trouble this wind will cause today. Going maxes
should hold just fine with downslope helping the SE to get close
to 70F, and even the highest hill tops of the Alleghenies
having a 40% chc to get to 60F. However, cold advection at 8H
will keep mixing down more- shallow in the north than south this
aftn, thus giving the 60% chc to stay in the u50s (which is
still pretty nice for Nov).

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
A shortwave trough diving across southern Ontario/Quebec will
push a moisture-starved cold front across Central PA late this
evening and early tonight. 8H temps drop below 0C over the NE
half of the state, and clear sky will help sfc temps drop into
the 20s N, and 30s S of I-80. The wind and RH only rising to
80-85% by morning will keep fog at bay for the most part. But,
there still could be a couple of patches, mainly in the NW
toward sunrise as the wind slackens a little there.

Another sunny day is in store for Saturday under strong, but
migratory high pressure. Any low clouds in the N in the AM will
go away. Maxes will be quite a bit cooler on Sat vs Fri - esp
in the SE where the temps will be 10-15F cooler in the aftn. No
downslope help there. Dry wx holds Saturday night, as the high
pressure dome continues to migrate eastward along the Mid
Atlantic coast. The wind turns around to the S overnight in the
west, and keep temps a little milder (m30s) there than the east
(l30s).

NBM data continues to support a very high probability (>80%) of
much needed rain spreading west to east later Sunday into
Sunday night associated with strong warm/moisture advection via
LLJ downstream of a stacked low pressure system tracking
eastward from the North-Central Plains into the Great Lakes. A
plume of +2-3SD pwat (1-1.2") overrunning an approaching warm
front supports high POPs in the aftn W and perhaps even into the
east in the early evening. The GFS is about 5-7hrs faster with
the rain arrival and exit vs the NAM. The good news is that
some much-needed rainfall will occur for the whole area. SOme
members of the SREF, GEFS and NBM do get close to an inch for
spots here and there, but the consensus is closer to half an
inch for most of the CWA. With the recent/record dryness,
hedging bets slightly lower is probably a good move. WPC puts
0.70" in wrn PA, and just 0.40" in the central mtns.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Medium range guidance all track a weakening upper low north of
PA Sunday night, pushing an associated cold front through the
region. Showers should taper off from west to east overnight,
as drier air works in behind the exiting front. Most likely rain
totals by Monday morning based on latest ensembles is between
0.33 and 0.50 inches.

Generally fair and mild conditions appear likely Monday, as
large scale subsidence overspreads PA behind the departing
remnant upper low. There may be enough low level instability to
produce a few lingering showers over the N Mtns, but most
locations should be dry with a mix of sun and cumulus based on
model RH profiles. A secondary, moisture-starved cold front is
progged to push southeast across the state Monday evening,
perhaps accompanied by a few showers over the NW Mtns.

Fair and seasonable conditions currently look likely Tuesday
and Wednesday, as upper level ridging builds toward the area
from the Midwest. The next chance of rain comes Wed night into
Thursday, as the upper flow pattern across North America becomes
more amplified. There is remains considerable model agreement
that a cold front will be approaching from the Midwest by Wed
PM. However, there remains plenty of uncertainty with regard to
the exact timing of the fropa in Central PA or whether moisture
from the remnants of Rafael train north ahead of the front or
not. The latest EPS plumes still indicate some chance of a
significant (1 inch+) rainfall, but most members indicate only
modest rain totals owing to a lack of a tropical connection.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
LIFR conditions are currently present at BFD as fog has made
way into the airfield with an influx of low-level moisture. As
sunrise approaches the airfield, expect fog to begin mixing out
quickly with the bulk of model guidance outlining a brief
visibility improvement but retaining the low-level cloud deck
for +1hr. Given the general spread of guidance, have opted to
split the difference with higher confidence on resolution closer
to the 14Z Friday window. After fog mixes out, expect generally
clear skies throughout the afternoon hours. Recent model
guidance has outlined a lower-level cloud deck making way into
BFD in the 22Z Friday to 06Z Saturday timeframe as winds begin
to take on a NW`ly component.

Elsewhere, VFR conditions are present and expect these
conditions to continue with very high (~100%) confidence. Breezy
to gusty westerly winds are expected throughout the
afternoon/evening hours. Recent model guidance has ramped up
LLWS concerns at BFD in the 15-19Z window as wind increases in
the lower levels, thus have included mentions in the 12Z TAF
package with moderate (~50-60%) confidence. There will also be
some concerns of meeting LLWS criteria at UNV in the 15-18Z
window; however, confidence here remains lower (~20-30%) so have
opted to keep mentions out of the 12Z TAF at this time.

Outlook...

Sat-Sun...Patchy AM valley fog possible, mainly north.
Otherwise, predominantly VFR.

Sun(late)-Mon...Widespread rain showers with restrictions
possible.

Tue...Lingering SHRA NW early; otherwise, VFR w/ no sig wx.

&&

.FIRE WEATHER...
Critical fire weather conditions are expected over south central
PA today. Any fires that develop may spread very quickly and
become difficult to contain. The wind will be gusting to between
20 & 30 mph from the west, minimum RH will be below 30%, and
fuels are sufficiently dry. The worst conditions will be along
and SE of I-81 (the lower Susq and far south-cent mtns).

Low humidity is again expected on Saturday with no rise in fuel
moisture, but the wind will decrease due to high pressure moving
over the Commonwealth.

A widespread 0.40"-0.70" of rain is expected on Sunday and
Sunday night as a frontal system moves through the state from
west to east.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch until 6 PM EST this evening for PAZ019-
025>028-034-049>053-058.
Red Flag Warning until 6 PM EST this evening for PAZ035-036-
056-057-059-063>066.

&&

$$

SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Fitzgerald
AVIATION...NPB
FIRE WEATHER...Dangelo/Steinbugl/Banghoff