113
FXUS61 KPBZ 300010
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
810 PM EDT Wed May 29 2024

.SYNOPSIS...
Scattered showers and thunderstorms will dissipate this evening.
Dry weather returns Thursday through Saturday as high pressure
builds with cooler than average temperatures. An unsettled but
warmer pattern looks to take hold by late weekend into next
week.

&&

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

- Scattered showers and thunderstorms expected through the
  evening hours.
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For the evening update...PoPs have been changed to represent
latest radar data and hires model data through the evening
hours. Back edge of the activity is finally starting to make
its way southward through the region on the western flank of the
exiting upper low. Expect with the best forcing leaving the
area, and the slow loss of sunlight, the rain should decrease
in coverage and intensity. Overnight lows were also refreshed
with the latest blended guidance.

Previous discussion...
Exiting of the upper level trough axis to the east will see
surface high pressure and subsidence build during the evening
and overnight hours. The expectation is for decaying convective
activity and clearing skies after daytime heating is lost.
Probability for pockets of fog, favoring river valley locations,
will increase toward daybreak with hi res ensemble favoring
south and east of Pittsburgh.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
KEY MESSAGES:

- Dry weather expected to close out the week.
- Temperatures remain below average.
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The upper trough will finally begin to make its exit on Thursday.
High pressure will build as one final shortwave traverses the area
in northerly flow aloft, but associated subsidence and increasing
mid-level dry air will keep the area rain-free and mixing will erode
residual cloud cover below a sinking inversion save for the ridges
where low level moisture may be a bit slower to clear. Cool air will
overspread the area with ensemble mean 850 mb temperature ranging
from 3-6C supporting highs in the mid 60s, about 10 degrees below
average, and a northerly gradient breeze through the day as the high
builds in. Lows will bring a bit of a chill to the air with 40s
expected and even a 40% probability of less than 40 mainly for the
higher elevations and north of I-80.

There is slight timing difference with the departure of the trough
lending the chance for slightly cooler highs than forecast on
Friday, but overall dry weather continues to close out the week with
high confidence. Temperature will begin to moderate some with rising
heights and with a dry atmosphere and sunny skies, adjusted NBM dew
points down a bit and highs up a touch to account for mixing bias.

&&

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

- Shower and thunderstorm chances increase late Saturday into early
  next week.
- Temperatures rebound back toward normal by Saturday.
-------------------------------------------------------------------

Upper level clouds increase on Saturday as ensembles eject an upper
wave out of the Plains. Uncertainty comes into play with variations
in strength and timing of the wave with some showing a flatter, more
progressive solution and others a more amplified, slower solution.
Temperatures will rebound Saturday as southerly flow on the backside
of the departing high promotes warm, moist advection.

Thereafter, the overall pattern trends toward weak westerlies aloft
through early next week. Embedded shortwaves may offer periodic
shower/thunderstorm chances but will be much more dependent on
convective evolution to the west to determine
timing/coverage/probability of occurrence for the forecast area.
There is higher confidence that broad height rises should enable
further warming areawide, making low to mid 80 values more likely by
Tuesday.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Scattered showers and isolated thunderstorms will continue to
diminish this evening with waning instability, and as a
shortwave trough completes its passage. Occasional MVFR
restrictions are expected this evening as the showers move
through.

Dry advection and a light north wind should keep fog
coverage confined to the valleys and fog prone airports
overnight and early Thursday morning. Included fog at these
ports, though limited the visibility to MVFR with uncertainty
and lower confidence in fog formation.

VFR is expected with mainly clear skies and a NNW wind at 5-10
kt on Thursday as surface high pressure builds across the
region.

.Outlook...
VFR is expected through Saturday under high pressure.
Restriction potential returns late Saturday and Sunday with
crossing low pressure.

&&

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

&&

$$

SYNOPSIS...MLB
NEAR TERM...MLB
SHORT TERM...MLB
LONG TERM...Frazier/MLB
AVIATION...WM