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NWS Area Weather Forecast Discussion
County Warning Area [CWA]: PBZ
Regional NWS Weather Office: Pittsburgh, PA

FXUS61 KPBZ 210800

Area Forecast Discussion
National Weather Service Pittsburgh PA
400 AM EDT Sun Jul 21 2019

Warm, humid conditions will continue today with afternoon/evening
storm chances. Frontal passage will bring rain throughout the day
Monday, followed by cooler, drier weather for much of next week.


Tricky forecast again today. A cool front will drop across the
northern half of the region this morning. Its southward progression
will be influenced by a strong shortwave trough over the upper
midwest, which will work to further depress upper level heights. By
the afternoon, the boundary will pretty much split the region in half
and become the focal point for late afternoon storm development. It
appears that the initiation of the convection will be due to the
increased low-level moisture convergence along the front and also
further destabilization of the atmosphere with daytime heating. Upper
level support will be lacking, but forecast soundings show very
little inhibition above 1000ft and surface based capes above
3000j/kg. Shear will be marginal, but with that amount of
instability, updrafts should have no problem strengthening. With
surface dewpoints once again in the 70s, flooding will be a big
concern, particularly with the zonal flow aloft, which may promote
storms to train along the stalled boundary.


Main shortwave trough will dig into south-central Ohio late this
evening and this energy will work to drag the surface boundary
southward. It is possible evening convection briefly intensifies as
it gets a boost from the aforementioned upper level energy. At some
point late tonight, the surface boundary will stall over the
southern half of the region, Convective activity will wane overnight
as the atmosphere quickly stabilizes.

Monday is looking rather wet as a surface low will develop over
central Ohio during the morning, and drifts eastward along the
stalled front. At this point, only isolated convection is expected on
Monday, as the very unstable air will have been shunted well south
of the region, and a large cloud shield will blanket the region.

It will still be humid on Monday, but temperatures will be
noticeably cooler.

Impressive shortwave trough will dig into the upper midwest Monday
evening and shift eastward overnight. This energy will push the front
southeastward, and it will reach the mid-atlantic region by early
Tuesday morning. Showers will end from NW to SE Monday night. Cooler
and much less humid air will spread across the region behind the
exiting rain.

Tuesday will see a decrease in cloud cover and much more comfortable


Seasonal or even slightly below seasonal temperatures are expected
across the area through much of next week. Temperatures will rebound
by the weekend as southerly flow returns and high pressure slides
off the Atlantic coast. Ensembles and blended guidance are showing a
dry long term.


General VFR forecast, with the exception being at KFKL and KDUJ,
where pre-dawn MVFR fog is expected to develop.

Storms should regenerate this afternoon along a quasi-stationary
frontal boundary. A modestly-organized squall line appears possible
that could affect most terminals during the afternoon/evening.

Widespread restrictions will be possible Monday with the passage of
a cold front.





Forecast Discussion from: NOAA-NWS Script developed by: El Dorado Weather