Sunrise 6:20 AM   Sunset 8:28 PM Moonrise 3:53 AM   Moonset 4:45 PM

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FXUS61 KPBZ 050756 AFDPBZ

Area Forecast Discussion National Weather Service Pittsburgh PA 356 AM EDT Sun May 5 2024

SYNOPSIS
Intermittent rain and a few storms are possible today.
Temperatures will moderate as southerly flow returns. A break in the widespread rain is possible Monday.

NEAR TERM /UNTIL 6 PM THIS EVENING/
KEY MESSAGES:

- Showers continue today.
- Strong afternoon thunderstorms possible with the passage of a cold front.
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A weak shortwave trough will move across the Upper Ohio Valley today. This wave will weaken and push the east coast ridge out over the Atlantic. A surface cold front, trailing the upper wave, will cross the region today, reaching the eastern edge of the forecast area by early evening. The main moisture plume, that has been parked over the region for the last couple of days, will drift eastward with another weak shortwave behind the exiting ridge. This decrease in deep moisture, and loss of upper level support, should allow for a brief respite in the widespread showers. As the aforementioned cold front moves eastward across Ohio early this afternoon, showers and a few storms will redevelop and accompany the boundary as it clears the rest of the forecast area. SPC continues to advertise a marginal risk for severe storms today. The main driver in this assessment is the rapid destabilization of the atmosphere ahead of the front. However, latest model data continues to show a weak sheared environment, which will work against updraft enhancement, and plenty of cloud cover that will hinder day time heating. Additionally, weak warm air advection aloft may also work to cap the atmosphere. There could be some breaks in the cloud cover this afternoon with the warm advection, but will there be enough time to further destabilize the atmosphere?

With the surface flow veering to the south then southwest, and the warm air advection aloft, temperatures will again rise above seasonal averages.

SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/
KEY MESSAGES:

- Break in the rain possible Monday for a large portion of the region.
- Temperatures remain above normal Monday.

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A shortwave trough will dig into portions of the Upper Midwest Monday morning. This will promote modest height rises over the region. Weak cold air advection behind today's cold front will spread somewhat drier air over the area. This should allow for a break in the rain and some decrease in cloud cover Monday afternoon. A weak shortwave moving eastward around the main trough, could bring the risk for isolated to scattered showers over locations mainly south of I-70.

Temperatures will cool a bit on Monday, but still remain above normal.

Lots of uncertainty on Tuesday that will depend on the path of a weakening shortwave trough and the crossing of a surface warm front. If the trough digs further south, rainfall coverage would be more focused on the southern half of the forecast area as the surface boundary would not make as much headway to the north. If the wave shifts further north and the warm front does as well, then the showers would do the same. Further complicating Tuesday is the speed of the wave. A faster exit could cause modest 500mb height rises during the afternoon.
Latest blended guidance is leaning toward a more northerly and slower track of the wave, so will ride with that solution.

Temperatures will warm once again on Tuesday.

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
KEY MESSAGES:

- Rain chances continue through the week but more uncertainty lends to lower confidence.
- Temperatures favored to remain above normal.
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An active weather pattern will remain in place for our region, with decent daily precipitation chances through Friday. Deep- layer shear will increase as well behind the departing ridge, so severe weather chances will need to be monitored as well.

AVIATION /08Z SUNDAY THROUGH THURSDAY/
Waves of showers will continue on and off through the morning as weak shortwaves traverse the upper flow. Meager warm advection aloft and light southeasterly winds have promoted some lifting to VFR early this morning, primarily for PIT and areas south. This may begin to fill in again with MVFR/IFR ceilings closer to sunrise, but uncertainty remains high.

Height rises and diurnal heating will lift area cigs by 15Z and will result in a brief lull from convective activity. The passage of a shortwave and associated weak surface cold front will then create scattered thunderstorm coverage primarily after 19Z - lingering into the early overnight.

Outlook
A moist boundary layer behind the frontal passage and evening thunderstorms Sunday night likely will lead to widespread MVFR/IFR restrictions. Some improvements are expected Monday with influence of high pressure to the north, but shortwave movement across the TN River Valley may maintain some restriction/precipitation chances for southern terminals.

The rest of the week will remain active with varying periods of precipitation and restrictions amid low pressure passage.

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

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