Area Forecast Discussion Issued by NWS State College, PA
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FXUS61 KCTP 291129
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
729 AM EDT Fri Mar 29 2024
.SYNOPSIS...
High pressure will briefly build into Pennsylvania today into
tonight, then a weak area of low pressure approaching from the
midwest will pass across the state Saturday. A more significant
low is likely to track eastward across Pennsylvania early next
week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Large scale subsidence and low-pwat air behind the exiting
east coast trough will result in mainly sunny, breezy and
seasonable weather later today. Mixing down model 850mb temps
of around -1C to -4C translates to expected highs ranging from
the mid 40s over the N Mtns, to the mid 50s across the Lower
Susq Valley. Bufkit soundings also support wgusts several knots
above NBM guidance this afternoon and dewpoints a few degrees
below, due to fairly deep mixing. Higher fuel moistures should
limit the risk of wildfire spread, despite expected wind gusts
of 25-30kts and RH falling to around 30pct.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
Surface ridging should build into the state tonight, resulting
in fair weather and diminishing winds. Focus then shifts to a
weak area of low pressure lifting out of the midwest states.
This feature is progged to track across the Lower Grt Lks
Saturday, with the attendant warm front spreading rain into
Central PA. Latest ensemble plumes indicate rain should fall
primarily during the afternoon hours, with likely totals by
evening ranging from around 0.33 inches over the NW Mtns, to
around 0.10 inches over the Lower Susq Valley. It`s hard to see
temps rebounding as much as the NBM depicts Saturday across the
NW counties, given thickening clouds and arriving rain ahead of
the advancing warm front. Have therefore blended in the much
cooler GFS/NAM surface temps.
Model consensus tracks the surface low along the southern tier
of NY state Sat night, with a trailing cold front sweeping south
of PA by dawn. The bulk of the rain should have ended by 00Z
Sunday, as the mid level shortwave and bulk of the large scale forcing
will have shifted east of the area by then. However, a bit of
drizzle could accompany the advancing warm front in the evening
and a few lingering showers are possible with the cold front
passage overnight. A mild and dry day is expected to round out
the weekend on Sunday with ridging nosing in from the Grt Lks.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Sunday looks dry to start as a west-to-east oriented boundary
sags south of the Mason-Dixon Line. A wave of low pressure along
that boundary will lift back into Pennsylvania early next week,
bringing widespread rainfall Sunday night through Tuesday.
Zonal flow aloft often promotes seasonable temperatures, but
rain and clouds will likely result in temperatures trending a
bit below average for the start of April with highs in the upper
40s to low 50s.
For the second half of the week, ensemble guidance depicts a
deepening low pressure system moving into the northeast and
bombing out off the New England coast. This system is likely to
bring ample precipitation and strong winds. Current temperature
profiles indicate some snow potential at higher elevations in
the northern mountains and Laurels, but details remain highly
uncertain.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
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Moderate-to-high (60-70%) confidence in VFR conds prevailing
across central PA through 12Z Saturday. The main uncertainty
with regards to the forecast will be the lower clouds across SW
PA for the next couple of hours. Coverage is the main point of
uncertainty, with borderline MVFR/VFR cigs that could drop
JST/AOO to MVFR thresholds if thickening of the cloud deck
occurs. The bulk of near-term guidance does outline a low cloud
deck dipping southward from NY in the late morning to early
afternoon hours. Elsewhere, SKC/SCT high- level clouds are
expected to prevail for a majority of the forecast area.
The main concern in the next 24 hours aviation-wise will be
with respect to gusty winds (sustained 15-20 kts with gusts up
to 30 kts) at 290-330 after through the evening hours. Some
concern for LLWS criteria being met after 03Z Saturday through
the end of the forecast period at airfields along the southern
ridges due to a localized enhancement of the LLJ. The 12Z TAF
package outlines this potential for AOO/JST/UNV which outline
higher (60-70%) confidence for these thresholds being met, while
keeping mentions out of MDT/LNS due to relatively lower
(30-40%) confidence at this time.
Outlook...
Sat...Rain moves in from W early AM, restrictions possible.
Sun...Lingering rain across mainly SW PA early, rain moves in
and becomes areawide later in the day.
Mon-Tue...Widespread rain continues with some potential for TSRA
Tuesday afternoon into the evening.-- End Changed Discussion --
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Banghoff
AVIATION...NPB