575
FXUS61 KPBZ 161748
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
148 PM EDT Wed Apr 16 2025

.SYNOPSIS...
Dry weather today through Thursday. Frost Advisory out
for Thursday morning. Rain chances rise slightly Thursday night
with a warm front. Thunderstorms are possible this weekend with
a crossing cold front.

&&

.NEAR TERM /UNTIL 2 AM THURSDAY MORNING/...
KEY MESSAGES:

- Clouds to dissipate and winds to subside this afternoon
- Clear, calm and cold overnight
- Frost Advisory tonight for areas south of Pittsburgh
-------------------------------------------------------------------

Skies have begun to scatter south of I-80 with increasing low-
to-mid level subsidence as surface high pressure filters in and
500mb heights rise as the upper-level trough is shunted
eastward.

Gusty WNW winds continue through this afternoon at a much lower
clip than Tuesday and begin to decline this evening as the
pressure gradient relaxes with the building high.

High temperatures are expected to be around 10 degrees below average
owing to our continued northwest flow. Clear skies and calm winds
tonight open the door for efficient radiational cooling across the
area and the possibility of frost development. Probabilities for
temperatures to drop below freezing are largely above 80% areawide
and near 100% north of Pittsburgh and along the ridges. A Frost
Advisory continues for the areas where the growing season has begun
(most areas near and south of I-70).

&&

.SHORT TERM /2 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
KEY MESSAGES:

- Gradual warming Thursday before bigger warmup Friday
- Dry until shower chances return Thursday night and Friday
- Marginal Risk of storms Friday night
-------------------------------------------------------------------

High pressure continues dry weather on Thursday. 500mb height
rises and warm advection support a temperature recovery towards
normal. A subtle shortwave trough looks to traverse and slightly
flatten the ridge as it drags a surface warm front north
Thursday night into Friday. Shower chances return as this wave
crosses, but limited deep layer moisture precludes widespread
rain chances. Dry weather returns Friday afternoon as the wave
and front exit north.

Warm advection and largely clear skies are expected to result in a
surge in high temperatures 10 to 15 degrees above average on Friday.
NBM 25th percentile cloud cover (a reasonable clearer solution) has
skies clear across much of the region and NBM 75th percentile cloud
cover (a reasonable cloudier solution) still has skies largely less
than 50% cloud cover, with the clearest areas south of I-70. NBM
probabilities of temperatures greater than 80 degrees are largely
above 60% south of I-70 and even see some 40-60% probabilities sneak
into downtown Pittsburgh.

Another shortwave advances out of the Midwest region Friday night,
dragging a surface cold front eastward. Shower chances increase
again, mainly late, as this wave and front approach. There exists a
chance to see some thunderstorms along and ahead of this front, but
any thunderstorm risk would likely be late Friday night. SPC has
included some of our far western counties in a Marginal Risk for
severe weather Friday/Friday night, with hail and damaging wind the
most likely threats. LREF joint probabilities of CAPE (250 J/kg) and
Shear (30 KTS) remain largely in the 20-30% range with the axis of
best severe ingredients far to our west across the OH/IN border,
near SPCs Slight Risk.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
KEY MESSAGES:

- Showers and possible thunderstorms Saturday
- Periodic shower chances continue through early next week
- Above average temperatures through much of the period
-------------------------------------------------------------------

Ensembles continue to indicate the initial shortwave and surface
front crosses the area on Saturday with showers and storms. Time of
day looks to be a much bigger help to the severe threat on Saturday
as the front could be crossing the region during peak diurnal
heating, allowing for more potent storm production along and ahead
of it. Uncertainty in exact placement still exists this far away but
our same joint probability from the LREF shows an axis of elevated
probabilities between 40-60% south and east of Pittsburgh,
coinciding with the center of SPCs Day 4 Risk polygon.

Differences in the upper-air pattern begin to tick up from the end
of this weekend well into next week. Most ensembles favor upper
ridging across the area on the day Sunday pushing our surface
boundary to the south bringing cooler conditions Sunday. Heading
into next week, clustered ensembles seem to indicate a flatter, more
progressive but active pattern with near-daily chances to see
measurable rain as upper-level waves cross the region.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
With northwest flow, MVFR to VFR stratocu will continue through
dusk. A building ridge to the west has eroding a majority of the
cu field for ZZV, MGW, HLG, and LBE; VFR conditions are likely
to continue through the TAF period. FKL/DUJ will likely
experience MVFR cigs through 20Z to 23Z.

Winds will remain gusty (20-25kts) with enhanced vertical wind
profile.

Outlook...
Dry weather continues on Thursday with building high pressure
before another round of precipitation and restriction potential
returns later on Friday and into the weekend.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Frost Advisory from midnight tonight to 9 AM EDT Thursday for
     PAZ029-031-075.
OH...Frost Advisory from midnight tonight to 9 AM EDT Thursday for
     OHZ057>059-068-069.
WV...Frost Advisory from midnight tonight to 9 AM EDT Thursday for
     WVZ003-004-012-021-509>511.

&&

$$

SYNOPSIS...AK
NEAR TERM...AK
SHORT TERM...AK
LONG TERM...AK
AVIATION...Hefferan