556
FXUS61 KPBZ 151713
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
113 PM EDT FRI MAY 15 2026
WHAT HAS CHANGED
NO NOTABLE CHANGES WITH CONTINUED MESSAGE OF ABOVE-NORMAL
TEMPERATURES AND PERIODIC RAIN CHANCES.
KEY MESSAGES
1) TEMPERATURES WARM TO WELL ABOVE-NORMAL BY EARLY NEXT WEEK
PROMPTING SOME IMPACTS TO THE HEAT SENSITIVE POPULATION
2) THUNDERSTORMS WITH NON-ZERO SEVERE THREAT EXISTS ON SATURDAY AS
WELL AS THE MIDDLE OF NEXT WEEK WITH UNRESOLVED DETAILS AT THIS
TIME
DISCUSSION
KEY MESSAGE 1...
HEIGHTS WILL RISE INTO THE WEEKEND AS FLAT RIDGING ESTABLISHES
OVERHEAD WHICH WILL RESULT IN THE BEGINNING OF A NOTABLE WARMUP INTO
THE MIDDLE OF NEXT WEEK. HIGHS OVER THE WEEKEND WILL QUICKLY JUMP
ABOVE CLIMATOLOGICAL NORMALS AND CONTINUE IN THAT DIRECTION WITH THE
WARMEST DAYS COMING MONDAY AND TUESDAY. BY THEN, EAST COAST
RIDGING WILL AMPLIFY IN RESPONSE TO A DIGGING TROUGH OUT WEST
WITH TEMPERATURES BY MONDAY AND TUESDAY APPROACHING 15 DEGREES
ABOVE NORMAL. 500 MB HEIGHTS ARE PROGGED TO REACH RIGHT AROUND
588 DAM WITH ONLY +/- 1 TO 2 DAM OF SPREAD IN THE DISTRIBUTION.
850 MB TEMPERATURES SURGE TO 18C WITH A 90+% CHANCE ON MONDAY
AND 70-90% CHANCE ON TUESDAY. WHILE THIS POINTS TOWARD AN
ABNORMAL WARMUP FOR MID TO LATE MAY, NBM RUNS CONTINUE TO BIAS
CORRECT MUCH TOO HIGH ON BOTH MAXT AND MINT WITH THE SUGGESTION
OF MID 90S FOR HIGHS AND LOW TO MID 70S FOR LOWS BOTH MONDAY AND
TUESDAY. THE 850 MB TEMPERATURE RULE, ASSUMING THAT THE
POTENTIAL IS MAXIMIZED WITH A CLEAR SKY DAY, WITH ~18C AT 850 MB
RESULTS IN MAXTS AROUND 85F. EVALUATION OF GLOBAL ENSEMBLE
DISTRIBUTION, AS WELL AS DETERMINISTIC AND ENSEMBLE AI GUIDANCE,
SUPPORTS MID TO UPPER 80S WITH THE 2/3 OR GREATER OF THE
DISTRIBUTION CLUSTERED BETWEEN 85-90F BOTH DAYS. A TAIL EXTENDS
WARMER ON BOTH DAYS, LIKELY DRIVEN BY THE SMALL MEMBERSHIP WITH
SLIGHTLY HIGHER 850 MB TEMPERATURES/500 MB HEIGHT OUTLIERS.
SIMILARLY, A TAIL EXTENDS COOLER, MAINLY ON TUESDAY, LIKELY
DRIVEN BY SOLUTIONS WITH MORE CLOUD COVER AND PRECIPITATION. SO,
WHILE LOW 90S AREN'T OUT OF THE QUESTION, AND MOST LIKELY SOUTH
OF PITTSBURGH, THE MORE LIKELY OUTCOME SITS IN THE MID TO UPPER
80S WITH A CONDITIONALLY COOLER DAY ON TUESDAY.
IT'S STILL WORTH NOTING THAT WITH THIS BEING THE FIRST NOTABLE
WARMUP WITH SEVERAL DAYS OF TEMPERATURES WELL ABOVE NORMAL,
THOSE WHO ARE MOST SUSCEPTIBLE TO HEAT WILL WANT TO TAKE PROPER
PRECAUTION. EVEN THOSE WHO AREN'T MAY STILL FEEL EFFECTS WITH
PROLONGED PERIODS OUTDOORS AS THE BODY WORKS ON ACCUSTOMING TO
WARMER TEMPERATURES.
KEY MESSAGE 2...
THE PREVIOUSLY MENTIONED PATTERN SHIFT WILL LIKELY ALSO CREATE TWO
MAIN PERIODS OF THUNDERSTORMS THAT OFFER NON-ZERO SEVERE RISKS:
SATURDAY AFTERNOON AND EVENING, AND SOMEWHERE IN THE TUESDAY TO
WEDNESDAY RANGE.
FOR SATURDAY, WEAK SHORTWAVE MOVEMENT WITHIN ZONAL FLOW ATOP THE
BUILDING SOUTHEAST CONUS RIDGE IS LIKELY TO GENERATE A THUNDERSTORM
COMPLEX NEAR THE IA/WI BORDER THAT TRAVELS TOWARD THE UPPER OHIO
RIVER VALLEY. LATEST GUIDANCE CONTINUES TO SUGGEST LITTLE WILL BE
LEFT OF THIS INITIAL COMPLEX AS IT REACHES EASTERN OH LATE SATURDAY
MORNING IN AN UNFAVORABLE ENVIRONMENT, BUT IT COULD AIDE IN RE-
DEVELOPMENT AMID AN INCREASINGLY WARM, MOIST ENVIRONMENT WITH A
NORTHWARD-LIFTING WARM FRONT. THE MOST LIKELY SCENARIO UNDER THIS
PREMISE FAVORS SCATTERED TO LOCALLY NUMEROUS SUB-SEVERE
SHOWERS/THUNDERSTORMS FORMING NEAR THE I-77 CORRIDOR AND TRAVELING
EAST THROUGH THE EVENING AS WEAK SHEAR (20-25KTS), LOWER CAPE (LESS
THAN 1000 J/KG), AND WARM MID-LEVELS KEEP ACTIVITY MILD. BUT, IF
SURFACE HEATING IS MAXIMIZED IN CONJUNCTION WITH LOW 60S DEWPOINTS,
ENOUGH BUOYANCY COULD LEND TO A LOWER-END HAIL AND DAMAGING WIND
THREAT (WITH SLIGHT HIGHER PROBABILITY FOR HAIL). CONFIDENCE IS LOW
GIVEN ENVIRONMENTAL STATE WILL BE HEAVILY INFLUENCED BY THAT DECAY
STORM COMPLEX, AND CAMS NOTORIOUSLY STRUGGLE TO RESOLVE DECAYING
MCSS. CONFIDENCE IN EITHER SCENARIO MAY NOT MANIFEST UNTIL WE CAN
SEE HOW THE COMPLEX MAINTAINS INTO THE OVERNIGHT HOURS FRIDAY NIGHT.
FOR TUESDAY/WEDNESDAY, SHORTWAVE MOVEMENT WITHIN SOUTHWEST FLOW IS
FAVORED BY ENSEMBLES THAT SHUNTS THE RIDGE SE AND CREATES ENOUGH
ASCENT WITH SURFACE LOW PASSAGE FOR WIDESPREAD SHOWERS AND
THUNDERSTORMS. TIMING AND DEPTH OF THE SHORTWAVE CREATES VARIANCES
IN WHEN THE AREA OF CONVECTION REACHES THE UPPER OHIO RIVER VALLEY,
RESULTING IN LARGE SPREADS IN ENVIRONMENTAL PARAMETERS USED TO
ASSESS SEVERE RISKS. THIS INCLUDES LARGE RANGES FOR INSTABILITY, MID-
LEVEL FORCING, AND UNCERTAINTIES IN FEATURES LIKE MID-LEVEL WARM
NOSES OR PRE-CONVECTION CLOUD COVER LIMITING HEATING/DESTABILIZATION.
THUS, IT IS BEST TO REMAIN COGNIZANT OF THIS PERIOD LIKELY
FEATURING SHOWERS/THUNDERSTORMS AND MONITOR TRENDS INTO THE
START OF NEXT WEEK TO LEARN WHAT DEGREE SEVERE HAZARDS MAY BE IN
PLAY OR NOT.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
AREAWIDE VFR BEGINS THE TAF PERIOD AND CONTINUES WITH HIGH
CONFIDENCE THROUGH 12Z TOMORROW.
TODAY WILL BE DOMINATED BY MAINLY HIGH CLOUDS, WITH WARM
ADVECTION AND A WEAK SHORTWAVE THIS EVENING. LIGHT WESTERLY
WINDS WILL CONTINUE TO BACK TOWARDS THE SOUTHWEST BY TONIGHT.
CLOUDS THICKEN AND LOWER OVERNIGHT AHEAD OF OUR NEXT SHOT AT
RAIN COMING IN THE FORM OF DISSIPATING THUNDERSTORMS NEAR MIDDAY
ON SATURDAY. AT THIS TIME, THESE SHOWERS HAVE BEEN INCLUDED IN
PROB30 GROUPS NEAR THE TAIL END OF THE CURRENT TAF PERIOD FOR
OUR WESTERN PORTS BUT HAVE BEEN INCLUDED AS PREVAILING FOR ZZV
WITH HIGHER CONFIDENCE OF OCCURRENCE FURTHER WEST.
OUTLOOK...
RESTRICTIONS AND RAIN CHANCES RETURN SATURDAY AFTERNOON INTO
SUNDAY WITH SOME SHOWER AND THUNDERSTORM CHANCES, ESPECIALLY
SATURDAY NIGHT. VFR RETURNS EARLY NEXT WEEK.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...FRAZIER/MLB
AVIATION...CL/AK
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