470
FXUS61 KPBZ 091912
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
312 PM EDT Sun Mar 9 2025

.SYNOPSIS...
There is high confidence in above normal temperature through the
week with minimal rain chances. Low pressure passage this
weekend will promote widespread rain and a downward trend in
temperature.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
KEY MESSAGES:

- Quiet weather with temperatures warming above seasonal
  levels.
- Marginal fire weather conditions possible through 7pm with low
  humidity and occasional gusty wind.

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Quick 3pm update...
Lowered dewpoint forecast for most points across the region has
diurnal mixing has been fairly effective in lowering readings
and creating upper 20 to lower 30 humidity values. Marginal read
and brevity of these conditions for the rest of the afternoon
should preclude fire weather concerns, but caution on outdoor
fire activity may be advised given the presence of low RH and
gusty wind.

Rest of the discussion...

Abundant insolation outside of patchy diurnal CU and wave
clouds east of I-76 will support area temperature that is about
5-10 degrees above the daily average. Breezy west southwest wind
aided by boundary layer mixing will weaken overnight.

Residual SW flow and rising heights will temper the effects of
radiational cooling overnight when skies are expected to remain
clear. Look for morning lows to end up around 5 degrees above
the daily average.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
KEY MESSAGES:

- Dry weather and warming temperatures continue under building
  high pressure.
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Height rises and increasingly southwest flow ahead of a
northern stream shortwave low will foster dry conditions and
rising temperature Monday into Tuesday. Minimal moisture
advection Monday into early Tuesday will ensure abundant
sunshine that may drive area temperature above ensemble guidance
means (as prior cold weather creates a cold bias-correction).
Look for temperatures to be 10-15 degrees above normal Monday.

The eastward advancement of the northern stream shortwave trough
will push a decaying but dry cold front into the region Tuesday
afternoon through the overnight period. Timing of the frontal
passage and the efficiency of warm advection ahead of the
boundary is creating a bit more uncertainty in afternoon
temperature peaks, mainly northwest of Pittsburgh. To account
for these uncertainties and the general cool bias in ensemble
data, forecast trends closer to the mean NW of Pittsburgh and
gradually trends towards the 90th percentile temperatures SE of
Pittsburgh.

Cold advection is expected behind the cold front as it stalls
near the I-70 corridor overnight. There is some uncertainty in
its exact positioning as well as the potential presence of mid-
level clouds, but the general setup favors greater cooling for
locations north of the boundary and less for areas to the south.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
KEY MESSAGES:

- While temperature rises may stall Wednesday, warming will
  resume through the start of the weekend.
- Strong low pressure system likely to bring widespread rain and
  falling temperature, with more uncertainty in other hazards.
-------------------------------------------------------------------

Wednesday is favored to remain dry with greater confidence that
surface high pressure translating across the region will
suppress precipitation activity. That said, potential subtle
shortwave movement within gradually rising heights aloft may
lift the stalled boundary northward as a warm front and
introduce enough forcing for rain showers to develop. This is
out of the scope of most global models but bears monitoring when
higher-res models reach the forecast period. The timing of the
warm front lifting and potential for mid-level clouds also
creates variable daytime maximum, notably SW of Pittsburgh. Even
the most pessimistic scenarios suggest above normal temperature
will continue; the story of rising temperature through the week
would just be stalled.

Height rises amid eastern CONUS ridge building ahead of a
deepening central CONUS closed low is highly likely to return
the rising temperature theme through Saturday. Ensembles suggest
the potential for weak shortwave movement prior to the
developing ridging to generate low probability afternoon rain
showers Thursday; otherwise dry conditions will prevail until
the low approaches starting Saturday. Ensemble temperature
spreads are fairly low for the end of the week period, giving
greater confidence in the region seeing highs 20+ degrees above
the daily average. 70+ degree temperature probabilities are
currently around 40-60% and 60-90% around/south of Pittsburgh
Thursday and Friday, respectively, and there is potential for
higher rises if insolation/warm advection is maximized.

High confidence also exists in the deep, negatively closed low
lifting NW of the region to begin impact the Upper Ohio River
Valley Saturday. Rounds of showers, at times heavy, and gusty
wind are favored through the weekend but early analysis suggests
that any severe threat will be very correlated to the ability to
destabilize (low CAPE, high shear environment) and latest
ensembles trended more pessimistic in that outcome occurring.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
VFR conditions are forecast with high confidence through the
period. Patches of diurnal cumulus have developed, but these
will remain mostly in the 4500 to 5000 foot range. A few
mountain wave clouds have also formed int the LBE vicinity.
All of these clouds are forecast to dissipate by evening. Also
by evening, gusty west-to-southwest wind of 15 to 25 knots will
diminish to under 10 knots.

A mostly clear sky and generally light surface wind will then
dominate the forecast through Monday afternoon. The lone issue:
areas north of I-80 may get brushed by a 40-45 knot low-level
jet overnight, providing a period of low level wind shear that
should resolve by sunrise.

Outlook... VFR conditions are likely into Tuesday under high
pressure. However, wind gusts will likely increase during the
day on Tuesday with a strong pressure gradient and deep mixing
under dry conditions; winds will prevail from the
west/southwest.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.

&&

$$

SYNOPSIS...Frazier
NEAR TERM...Frazier
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...CL