-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 221115
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
715 AM EDT Mon Apr 22 2024

.SYNOPSIS...
-Warmer start to the week with low humidity & areas of frost
-Light rain arrives late Tuesday and lasts through Wednesday
-Renewed frost/freeze risk Thursday and Friday morning

&&

.NEAR TERM /THROUGH TONIGHT/...
Chilly/frosty morning with daybreak readings from the mid 20s
in the normally colder northern valleys to the low and mid 30s
across the Lower Susq Valley. A Freeze Warning and Frost
Advisory continues until 8AM for the Ridge/Valley Region and
Middle to Lower Susquehanna Valley.

Plenty of sunshine expected today with ridging sfc and aloft.
Temps should climb quickly in the dry (low dewpoint) air this
morning with noticeably warmer readings this afternoon in the
mid 50s to low 60s.

Deep mixing heights 6-8kft combined with a northwest breeze and
very dry air above a weak inversion supports undercutting NBM
dewpoints resulting in low humidity this afternoon (see fire wx
section for more info).

Conditions remain favorable for radiational cooling particularly
early tonight in the decoupled central and southeastern valleys.
Expect areas of frost to form with low temps in the low to mid
30s. We will let the current frost/freeze headline expire and
allow the dayshift to post the next headline for tonight. High
clouds increase after midnight and could offset the diurnal
cooling a bit, but probably not enough to prevent another frosty
morning Tuesday.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Return southwest flow on the backside of high pressure sliding
off the Eastern Seaboard will result in a breezy and warmer day
on Tuesday. There are still some fire wx concerns especially
given an increase in wind speeds (see fire wx section). Tuesday
should be the warmest day of the week with maxT 60-70F.

All guidance then points to light rain and a subsequent cool
down associated with a cold front passage Tuesday night into
Wednesday. The moisture return ahead of the front is rather
unimpressive (pw <1 inch), but strong forcing ahead of a potent
upper level shortwave supports a measurable rainfall. The
latest multi model ensemble blend produces most likely rainfall
amounts ranging from around 0.05 inches over the Lower Susq
Valley, to 0.25 to 0.50 inches over the NW Alleghenies.

Potential frost/freeze conditions for late Wednesday night into
early Thursday morning as skies clear and abnormally dry air
arrives beneath seasonably strong sfc high. The renewed
frost/freeze risk will continue to be highlighted in the HWO.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
It appears there will be another chance of a frost/freeze Thu
and Fri AM, as Canadian High Pressure builds over the region.
Those with agricultural interests should keep an eye on the
forecast for the end of next week.

The next chance of rain will come Friday night into Saturday
associated with low pressure lifting into the Grt Lks and the
associated warm front approaching PA. Both the EPS and GEFS
indicate the warm front will lift north of the region by Sunday,
resulting in markedly warmer and more humid conditions with
scattered PM convection possible. Mean progged 850mb temps south
of the warm front are around 12C, supportive of highs in the
75-80F range.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
VFR conds will prevail through 00Z Tuesday with high (> 90%)
confidence. Winds will increase slightly towards 5-10kts
sustained with gusts up to 15kts late Monday afternoon into the
evening hours at 300-320.

Outlook...

Tue...Slight chance of evening showers/cig reductions NW Mtns.

Wed...Showers move in west-to-east from rain early, continues
throughout the day. TSRA possible SW late PM.

Thu...Clearing as high pressure builds into the area.

Fri...Mainly dry, but increasing clouds late.
-- End Changed Discussion --

&&

.FIRE WEATHER...
Marginal fire wx conditions to start the week. MinRH 15-25%
across most of the area this afternoon with wind gusts from the
northwest gusting 15-20 mph at times. The wind will increase
Tuesday with gusts 20-30 mph from the south/southwest. MinRH
should increase by 5-10%, but still bottom near or below 30%
over particularly over south central PA. The low humidity and
breezy conditions Monday & Tuesday could result in an elevated
risk of wildfire spread.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Freeze Warning until 8 AM EDT this morning for PAZ019-025>028-
034>036-045-046-049>053.
Frost Advisory until 8 AM EDT this morning for PAZ056-057-059-
063>066.

&&

$$

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