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057
FXUS61 KCTP 040740
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
340 AM EDT Tue Jun 4 2024

.SYNOPSIS...
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*Warmest day of the week Tuesday with a stray shower possible
*Cloudy and humid with showers and a thunderstorm Wed-Thu
*Cooler/more comfortable stretch Fri-Sun with passing showers
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&&

.NEAR TERM /THROUGH TONIGHT/...
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Patchy fog in the valleys early this morning; otherwise mostly
sunny and very warm today (warmest day of the week) with highs
in the 80-90F range or +5-15 degrees above early June climo.

580dm ridge over CPA should help to maintain dry wx in most
locations this afternoon and evening. However, strong diurnal
heating may be enough to break through a weak capping inversion
and trigger isolated PM convection. Latest HREF suggests the
best chance of a stray pulse type shower/t-storm will be along
the southern tier ridges into WV/MD panhandle where pwats ramp
to 1-1.3 in.

An increasingly moist (higher pwats & dewpoints) southeast flow
ahead of an upstream warm front over the Ohio Valley will send
POPs on a upward trend from late tonight into Wednesday morning.
Expect a muggy overnight with fairly uniform min temps in the
60-65F range (+10-15F above climo) with low stratus and patchy
fog developing over the majority of CPA/east of the Allegheny
Front by daybreak.
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&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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Latest suite of medium range guidance expands coverage of
showers Wednesday morning through Wednesday afternoon with max
POPs occurring Wednesday night into early Thursday morning. The
best instability/chance for t-storms is over the southwestern
zones where a conditional late day severe wx threat is possible.
PWs climb to 1.25-2.00 inches by 00Z Thu which favors potential
for locally heavy rainfall amounts -- WPC has maintained a MRGL
ERO over the entire forecast area for the day 2 period.

Model consensus shows QPF max shifting to the east Thursday
morning as the frontal system moves across PA. The remainder of
Thursday should feature scattered showers/PM t-storm as upper
low and cooler temps aloft begin to impinge on the area. Most of
this activity will be diurnally driven with little to no precip
expected Thursday night.

Persistent low clouds and southeast wind favor cooler max temps
Wednesday (5-10 deg lower than today) with highs in the 70-80F
range. Post frontal westerly/downslope flow along with breaks
of sun in the dry slot should push temps back up on Thursday
with highs peaking in the mid 80s in the Lower Susq Valley.
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&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The main weather feature for Central PA through next weekend
will be a slow-moving upper low, tracking from the eastern
Great Lakes across southern Ontario and Quebec. As a result, at
least hit and miss showers and possible thunderstorms are
expected on a daily basis, with diurnally more numerous coverage
anticipated in the afternoon and early evening hours,
particularly for the northern tier of the Commonwealth.

Current indications are that by early next week, the upper low
should begin to fill and drift northeast, with showers and
storms becoming less prevalent over time.

Temperatures are likely to average somewhat below climatology
for early to mid-June, with daily highs in the upper 60s and
70s, and overnight lows in the 50s to lower 60s.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
For the 06Z TAF package, not a lot of change. I did back off
on fog a bit, as dewpoints fcst to fall off a bit overnight,
as temperatures edge down a bit more.

Earlier discussion below.

VFR conditions are expected to continue through 06Z Tuesday
with very high (> 90%) confidence. The main concern overnight
will be radiation valley fog across central PA with localized
impacts at the various airfields. Both GLAMP and HREF guidance
continue to suggest BFD/AOO/UNV/IPT have the highest probs of
fuel-alternate restrictions with sub-MVFR conds after 06Z
Tuesday. Have continued to keep IFR and a period of LIFR conds
in the 06Z-12Z Tuesday range with moderate-to-high (60-70%)
confidence, with mainly timing adjustments from previous
forecasts.

Outside of these airfields, MVFR conds seem like the most
likely prevailing condition at JST in the 08Z-12Z timeframe with
VCFG in the valleys surrounding the terminal. A brief (1-2hr)
period of high-end IFR to low-end MVFR conds remains possible
around 09Z, but confidence in LIFR conds have lowered from
previous cycles (30-40%) with recent GLAMP guidance suggesting a
MVFR-to-IFR outcome during this timeframe. Recent GLAMP
guidance has also suggested a period of MVFR vsbys across the
LSQ airfields (MDT/LNS) in the 10Z-11Z timeframe. Low (< 30%)
confidence has kept mentions of MVFR conds out at this time as a
light breeze lingering around overnight could bring lower
probabilities of sub-VFR conditions.

After sunrise, conditions are expected to gradually improve
with VFR conditions prevailing area-wide after 15z Tuesday. Some
model guidance has started to suggest scattered -SHRA across
the southern tier around 18Z Tuesday, but lower (< 30%)
confidence in coverage and timing keeps any mentions out of the
00Z TAF package.

Outlook...

Wed-Thu...More numerous showers and thunderstorms, with at
least brief restrictions.

Fri-Sat...Hit and miss afternoon showers and thunderstorms with
brief restrictions, otherwise mostly VFR.

&&

.CLIMATE...
Prelim May and Spring 2024 Temperature & Precipitation Rankings

Harrisburg: T12th warmest; 76th driest May
 T3rd warmest; 33rd wettest Spring

Williamsport: 9th warmest; 22nd wettest May
4th warmest; 11th wettest Spring

Altoona: 9th warmest; 13th wettest May
2nd warmest; 3rd wettest Spring

Bradford: 4th warmest; 36th driest May
Warmest; 21st wettest Spring

&&

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

&&

$$

SYNOPSIS...Steinbugl/Banghoff
NEAR TERM...Fitzgerald/Steinbugl
SHORT TERM...Fitzgerald/Steinbugl/Banghoff
LONG TERM...Jurewicz/Fitzgerald
AVIATION...Jurewicz/Martin/NPB
CLIMATE...Steinbugl