568
FXUS61 KPBZ 230555
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
155 AM EDT WED JUL 23 2025
SYNOPSIS
INCREASINGLY HOT AND HUMID WEATHER IS EXPECTED THROUGH LATE
WEEK. DRY WEATHER WILL CONTINUE TODAY AND THURSDAY UNDER HIGH
PRESSURE, BEFORE SHOWER AND THUNDERSTORM CHANCES INCREASE
FRIDAY THROUGH THE WEEKEND AS A COLD FRONT APPROACHES, AND
STALLS ACROSS THE REGION.
NEAR TERM /THROUGH TODAY/
KEY MESSAGES:
- WARMER WITH INCREASING HUMIDITY TODAY
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SURFACE HIGH PRESSURE WILL REMAIN CENTERED ACROSS NEW ENGLAND
TODAY. SURFACE WIND WILL VEER TO THE SOUTH ACROSS THE UPPER
OHIO VALLEY REGION TODAY, AS 500MB HEIGHTS BUILD TO 593-594DM.
THIS SHOULD RESULT IN HIGH TEMPERATURES IN THE UPPER 80S TO
NEAR 90 FOR MUCH OF THE AREA SOUTH OF I-80 AND OUTSIDE OF THE
RIDGES. AN INCREASE IN DEW POINTS IS ALSO EXPECTED WITH THE
VEERING FLOW. HEAT INDEX VALUES ARE EXPECTED TO PEAK IN THE
UPPER 80S TO LOWER 90S ACROSS THIS SAME AREA.
SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/
KEY MESSAGES:
- HOT AND HUMID THURSDAY
- SHOWERS AND THUNDERSTORMS RETURN FRIDAY/FRIDAY NIGHT
- LOCALLY HEAVY RAINFALL POSSIBLE FRIDAY
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THE 500MB RIDGE IS EXPECTED TO BUILD FURTHER ACROSS THE REGION
ON THURSDAY, WITH 500MB HEIGHTS PROGGED TO REACH 594-595DM. AT
THE SAME TIME, 850MB TEMPERATURES ARE EXPECTED TO REACH 20-21
DEG C. THIS SHOULD RESULT IN THE HOTTEST DAY OF THE WEEK, WITH
MOST LOCATIONS OUTSIDE OF THE HIGHER TERRAIN REACHING THE LOWER
90S. INCREASINGLY MOIST SOUTHERLY FLOW SHOULD RESULT IN A
GRADUAL RISE IN THE DEW POINTS AS WELL. THE COMBINATION OF HEAT
AND HUMIDITY SHOULD RESULT IN HEAT INDEX VALUES IN THE MID TO
UPPER 90S FOR MOST AREAS OUTSIDE OF THE RIDGES. SOME OF THE
RIVER VALLEY/URBAN LOCATIONS COULD SEE HEAT INDICES APPROACHING
100.
THE RIDGE IS PROGGED TO BREAK DOWN AND SHIFT SOUTHWARD THURSDAY
NIGHT, AS A SHORTWAVE TROUGH AND ASSOCIATED SURFACE COLD FRONT
APPROACH FROM THE MIDWEST. MODEL ENSEMBLES INDICATE A ML CAPE
RANGING FROM 1500-2000 J/KG BY FRIDAY AFTERNOON, AS THE INITIAL
SHORTWAVE CROSSES THE UPPER OHIO VALLEY REGION, AND THE SURFACE
FRONT DROPS SLOWLY SOUTHWARD. SOME SEVERE WEATHER POTENTIAL IS
EXPECTED FRIDAY, THOUGH SHEAR WILL BE MARGINAL.
PWATS ARE ALSO EXPECTED TO INCREASE, RANGING FROM 1.8 TO 2
INCHES. FLOW ALOFT IS EXPECTED TO MODESTLY INCREASE, THOUGH
WITH WESTERLY FLOW ALOFT, AND A W-E ORIENTED SURFACE BOUNDARY,
TRAINING WILL BE POSSIBLE. THE UPPER OHIO VALLEY REGION IS
CURRENTLY UNDER A MARGINAL RISK FOR EXCESSIVE RAINFALL.
THE HIGHEST HEAT INDEX VALUES ARE EXPECTED SOUTH OF I 70 ON
FRIDAY, AND WILL BE HIGHLY DEPENDENT ON CONVECTION AND CLOUD
COVER.
SOME DECREASING TREND IN THE CONVECTION IS EXPECTED FRIDAY
NIGHT WITH WANING INSTABILITY, THOUGH ANOTHER DISTURBANCE IN
THE FLOW ALOFT COULD MAINTAIN SHOWERS AND A FEW THUNDERSTORMS
THROUGH THE OVERNIGHT HOURS.
LONG TERM /SATURDAY THROUGH TUESDAY/
KEY MESSAGES:
- PERIODIC SHOWERS AND THUNDERSTORM CHANCES THROUGH THE WEEKEND
- MAINLY DRY MONDAY
- ADDITIONAL SHOWERS/STORMS TUESDAY
- WARM AND HUMID THROUGH THE PERIOD
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THE SURFACE BOUNDARY IS EXPECTED TO REMAIN ACROSS THE UPPER
OHIO VALLEY REGION ON SATURDAY, AS ANOTHER SHORTWAVE TROUGH
TRACKS ALONG IT. SHOWERS AND THUNDERSTORMS ARE EXPECTED AT
TIMES, WITH THE GREATEST COVERAGE DURING THE AFTERNOON AND
EVENING HOURS.
THE FLOW ALOFT IS EXPECTED TO VEER TO THE NW FOLLOWING THE
PASSAGE OF THE SHORTWAVE SATURDAY NIGHT INTO SUNDAY. THIS
SHOULD PUSH THE SURFACE FRONT BACK SOUTH AS A COLD FRONT. MODEL
ENSEMBLES THEN INDICATE SHORTWAVE RIDGING WILL BUILD ACROSS THE
UPPER OHIO VALLEY REGION, WITH MAINLY DRY WEATHER RETURNING
SUNDAY NIGHT AND MONDAY.
A TROUGH EMBEDDED IN NW FLOW ALOFT IS EXPECTED TO APPROACH AND
CROSS THE REGION ON TUESDAY, RETURNING SHOWER AND THUNDERSTORM
CHANCES TO THE FORECAST. OUTSIDE OF THE PRECIPITATION CHANCES,
A GENERALLY WARM AND HUMID PATTERN WILL CONTINUE THROUGH THE
LONG TERM PERIOD.
AVIATION /06Z WEDNESDAY THROUGH SUNDAY/
HIGH PRESSURE AND AN OVERALL DRY COLUMN LEAD TO CONTINUED HIGH
CONFIDENCE IN VFR CONDITIONS THROUGH 06Z THURSDAY. WITH WARMER
TEMPERATURES AND STILL LOW DEWPOINTS, VALLEY FOG IS LESS LIKELY
THROUGH DAWN AND IS NOT EXPECTED TO IMPACT TERMINALS. SOME
CUMULUS SHOULD BEGIN TO FORM LATE MORNING AS MOISTURE BEGINS TO
INCREASE MARGINALLY. WIND WILL REMAIN LIGHT, BUT WILL TAKE ON
MORE OF A SOUTHERLY COMPONENT. THE DRYING CONTINUES TONIGHT AS
VALLEY FOG ISN'T EXPECTED TO BE AN ISSUE. EXPECT VFR
CONDITIONS.
OUTLOOK...
HIGH CONFIDENCE IN VFR AND DRY WEATHER CONTINUING THROUGH
THURSDAY. RAIN CHANCES (AND ASSOCIATED RESTRICTIONS) RETURN TO
THE FORECAST FRIDAY THROUGH THE WEEKEND.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...WM
NEAR TERM...WM
SHORT TERM...WM
LONG TERM...WM
AVIATION...CL/SHALLENBERGER
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