Monday, April 24, 2017, 10:47 PM EDT
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Area Forecast Discussion
Valid At
Wed, Dec 31, 7:00pm EST
FXUS61 KPBZ 250152 AAC

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
952 PM EDT Mon Apr 24 2017

Low pressure tracking along the East Coast should result in 
periodic rain chances mainly east of I-79 early in the week. 
Dry and warm weather is expected with mid-week high pressure.


Forecast soundings along the ridges indicate a strong inversion
just above ridge-top level coupled with ely wind around 20-25
kt. These conditions may be conducive to development of a
mountain wave that could provide strong wind gusts overnight
/especially 03-09UTC timeframe/ along and in the wrn lee of the
mountains. A broad collection of hi-res models and ensembles 
also provide a coherent signal for this possibility. As such, 
wind grids overnight were manipulated to enhance wind speed and 
gusts in these focused locations. No wind headline appears
necessary at this time, but wind speed should be monitored.

An update was made to PoPs to reflect current radar data,
focused primarily in the nern and sern zones. Coverage trend is
downward, but slower to decrease than the previous forecast.
Previous discussion follows...

Latest satellite imagery showing the cloud shield has made very
little northward advancement. These clouds will slowly creep 
northward this afternoon as the southeastern CONUS low turns the
corner and moves northeast. Rain chances will ramp back up this
afternoon across the Ridges as mid-level dry air evacuates and 
moisture begins to advect back in from the Mid- Atlantic. Away 
from the high terrain, a lack of organized ascent will 
necessitate only slight rain chances through the night.

The upper low will track along the coast Tuesday, keeping us on
along the northwestern periphery of the system. Rain chances
will remain best confined to the higher elevations, but a weak 
area of deformation could spill rain west, closer to Pittsburgh
during the day Tuesday. 

Temperatures tonight will be above seasonal averages with
uniform cloud cover. Another west to east gradient of high
temperatures is expected Tuesday as cool air advects into the 
eastern zones, under overcast skies.


The upper-level low will finally move out of the region Wednesday 
morning as a ridge of high pressure builds over the Ohio Valley. 
This will bring tranquil weather back to the local area for 
Wednesday and Wednesday night. Strong southerly flow through the mid-
levels will establish as heights build Wednesday. This and 
relatively cloud-free skies will lead to strong warming, with 
temperatures topping out around 15 degrees above average. 
Highs in the low 80s should be common.


Ridging is progged to shift east early in the period as a trough
advances out of the Midwest, returning rain chances to the
forecast. Gradually increasing heights and SW upper flow are 
expected through the weekend in response to a deepening wrn 
CONUS trough. Embedded shortwaves in the SW flow should result
in periodic shower/thunderstorm chances from late week through
the weekend. Temperatures are expected to average 10-20 degrees
above seasonal levels.


VFR conditions will generally prevail through much of the
overnight period, with deeper moisture confined to the ridges 
in southeasterly flow. Some very light precip has been reported 
west of the terrain but this should not promote more than brief 
visibility restrictions, if any. Some stronger wind gusts may
continue through 09z, mainly at LBE, as low level winds 
increase at or just below the strengthening inversion.

Ceilings should generally stay around 5kft, but some lower cigs
are possible in the easternmost TAF locations Tuesday afternoon,
with deeper moisture spilling over the terrain.

The next chance for general restrictions is expected with mid
week low pressure.






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