-- Discussion containing changed information from previous version are highlighted. --
069
FXUS61 KPBZ 292316 AAB
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
716 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/...
-- Changed Discussion --
KEY MESSAGES:

- Scattered showers and thunderstorms expected through the
  evening hours.
-------------------------------------------------------------------

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.
-- End Changed Discussion --

&&

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

- Dry weather expected to close out the week.
- Temperatures remain below average.
-------------------------------------------------------------------

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 /23Z WEDNESDAY THROUGH MONDAY/...
An upper low passing through the region is supporting scattered
to numerous slow-moving showers and thunderstorms across the
area this afternoon. These are bringing periods of heavy rain
and lightning to area terminals as well as restrictions to
cigs/vis. Expect the convection to continue throughout the
remainder of the day, tapering off from west to east after 00Z.
High pressure builds into the area in the wake of the low
overnight into Thursday, bringing VFR conditions and light
north to northwest flow thereafter through the remainder of the
TAF period.

.Outlook...
High pressure remains in place through the end of the week,
resulting in areawide VFR through that time. Some restriction
potential returns Saturday night into Sunday as showers and
thunderstorms return with the next disturbance.

&&

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

&&

$$

SYNOPSIS...MLB
NEAR TERM...MLB
SHORT TERM...MLB
LONG TERM...Frazier/MLB
AVIATION...Cermak/Shallenberger