FXUS61 KPBZ 041755

AFDPBZ



Area Forecast Discussion

National Weather Service Pittsburgh PA

155 PM EDT Mon May 4 2026



.WHAT HAS CHANGED...

No significant changes were made to the forecast.



&&



.KEY MESSAGES...

1) Shower and thunderstorm chances increase this evening and

tonight



2) Active weather pattern expected through the weekend



3) Frost possible Thursday night



&&



.DISCUSSION...

KEY MESSAGE 1... 

The latest mesoanalysis shows diurnal instability beginning to 

increase in the warm sector across the Midwest and Lower Ohio 

Valley regions. Low surface dew points continue to hinder 

destabilization, though expect some moist advection later this 

afternoon and evening in SW flow and an approaching low level 

jet. ML CAPE is still expected to be limited across the Upper 

Ohio Valley region (generally less than 750 j/kg,) though jet 

ascent and a crossing shortwave should spark scattered showers 

and thunderstorms late this afternoon into tonight. There is a 

brief window late this afternoon and early evening for strong 

storms with 30-35 kt of shear on the nose of the jet, though 

this potential should wane this evening as the limited 

instability diminishes. 



Elevated instability and the crossing shortwave should still 

maintain some showers/storms overnight. 



KEY MESSAGE 2... 

The focus will shift to an approaching cold front on Tuesday, 

as it sinks slowly south toward the region. The flow aloft is 

nearly parallel to the front, so expect only a slow 

progression. Shower/storm chances will increase from the NW 

through the day, but should mainly be confined north of PIT 

most of the day. Shear and instability is expected to be even 

more limited than today, with ML CAPE less than 500 j/kg and 

limited shear. Warm air aloft should also limit buoyancy, 

limiting any severe weather potential. More widespread showers 

and embedded thunderstorms are expected Tuesday evening into 

Wednesday as the front slowly drops south across the region. 



A wave of low pressure is progged to track along the front on 

Wednesday as it stalls across the Ohio Valley and central PA, 

maintaining more showers and isolated thunderstorms. It should 

turn much cooler north of the front Wednesday, with highs 

around 10 degrees below average. The front should progresses 

further out of the region Thursday as the flow turns more WNW, 

though it should still be in close enough proximity to maintain

shower chances. 



The Upper Ohio Valley region is then progged to be under a 

broad upper trough through the weekend. A series of shortwaves 

rotating through the trough will then keep periodic shower 

chances in the forecast. 



KEY MESSAGE 3... 

There is some potential for frost Thursday night, though this 

will be highly dependent on the amount of cloud cover in place 

and the resulting radiational cooling.



&&



.AVIATION /18Z MONDAY THROUGH SATURDAY/...

Scattered to broken mid-level cloud decks continue to move

across the region this afternoon along with breezy southwest

winds gusting to 20-25 knots. Scattered showers and possibly a

few thunderstorms develop this evening along the nose of a 

modest low- level jet characterized by 925mb-850mb flow around 

40-45 knots. There is still uncertainty regarding which 

terminals, if any, see impacts from the isolated evening

convection. The most consistent hi-res model signal has been a 

cluster moving west to east across northern WV and another 

somewhere in the vicinity or north of PIT/BVI. Still, due to 

the coverage uncertainty, opted to maintain PROB30s in TAFs.

However, increasing signals in guidance that MUCAPE will trend 

near 500 J/kg during evening hours provided enough confidence 

to introduce thunder in this TAF cycle. The most likely timing

for the evening thunderstorms will be 22z-02z.



As the low-level jet overspreadsthe area tonight, there will 

be a LLWS risk at any terminals that are able to decouple 

enough for surface gusts to subside. Shower activity lingers 

overnight as well, but likely shifts northward and remains 

mostly over northeast OH and northwest PA, with the greatest 

chance for impacts at FKL.





Outlook... 

A few thunderstorms are possible on Tuesday. More widespread 

restrictions in showers and thunderstorms are likely Tuesday 

night into Wednesday as a wave of low pressure tracks along an

advancing cold front.



&&



.PBZ WATCHES/WARNINGS/ADVISORIES...

PA...None.

OH...None.

WV...None.



&&



$$



DISCUSSION...WM

AVIATION...Cermak