660
FXUS61 KPBZ 311821
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
121 PM EST SAT JAN 31 2026
WHAT HAS CHANGED
- COLD WEATHER ADVISORY UPGRADED TO EXTREME COLD WARNING THROUGH
11AM FOR PORTIONS OF THE AREA TONIGHT GIVEN TEMPERATURE CLOUD
COVER TRENDS. LOCALIZED TEMPERATURES/WIND CHILLS AS LOW AS 20
TO 30 BELOW POSSIBLE.
- NEW EXTREME COLD WARNING FOR EASTERN TUCKER FROM 7PM SATURDAY
TO 1PM SUNDAY WITH WIND CHILLS AS LOW AS 25 BELOW POSSIBLE
SUNDAY MORNING.
- NEW COLD WEATHER ADVISORY FOR ALL OTHER COUNTIES, SAVE
MERCER/VENANGO/FOREST, FROM 7PM SATURDAY TO 11AM SUNDAY WITH
WIND CHILLS AS LOW AS 5 TO 15 BELOW.
- AIR QUALITY ALERT FOR THE LIBERTY/CLAIRTON AREA IN ALLEGHENY
COUNTY UNTIL 10 PM THIS EVENING.
KEY MESSAGES
1) COLD AND LIGHT SNOW CHANCES THROUGH TODAY AND TONIGHT.
2) PROLONGED COLD AND PERIODIC SNOW CHANCES THROUGH NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...
EXPECT SOME LOW LEVEL CLOUD COVER TO PERSIST AS THE COLD AIR
REMAINS IN PLACE ACROSS THE AREA. EXPECT A THIN CIRRUS LAYER TO
REMAIN OVERHEAD AS WELL. THIS LOW LEVEL CLOUD COVER IS
SPECIFICALLY IN THE DGZ ALLOWING FOR INSTANCES OF LIGHT SNOW
ACROSS THE AREA AND THROUGH THE COMING DAY. THE OVERNIGHT PERIOD
WILL FEATURE CONTINUED INSTANCES OF LIGHT SNOW. GIVEN THE CLOUD
COVER, THE COLD HEADLINES WON'T QUITE AS IMPACTFUL.
TONIGHT WILL CARRY THE NEXT, AND LIKELY LAST, ROUND OF COLD
WEATHER HEADLINES FOR MOST. CLOUD COVER WILL POSE MORE
UNCERTAINTY IN TRUE RADIATIVE COOLING, THROUGH WIND GUSTS MAY
BE SLIGHTLY STRONGER IN WRAP-AROUND FLOW FROM A NOR-EASTER
PASSING TO THE EAST. MOST LIKELY WIND CHILLS SIT IN THE 5 TO 15
BELOW RANGE OVERNIGHT, PRIMARILY FOR THE HILLTOPS. LOWER VALUES
OF DOWN TO 15 TO 25 BELOW ZERO ARE POSSIBLE FOR THE RIDGES OF
PA AND WV.
SUNDAY, HIGHS MAY ACTUALLY ESCAPE THE TEENS INTO THE 20S FOR
SOME. SUNDAY NIGHT, MINIMUM WIND CHILLS ARE ACTUALLY FAVORED TO
BE WARMER THAN CRITERIA FOR MOST, SAVE EASTERN TUCKER COUNTY.
FOR THE REST OF THE WEEK FORECAST WIND CHILLS AT NIGHT ARE
MOSTLY ABOVE COLD WEATHER ADVISORY CRITERIA, AND WARMER HIGHS
ARE FORECAST. NONETHELESS, THE INTER-QUARTILE RANGE ON THE
HIGHS IS STILL ENTIRELY BELOW AVERAGE AND SHOWS A 75% CHANCE OF
SUB- FREEZING TEMPERATURES EACH DAY IN PITTSBURGH. THE CPC
HIGHLIGHTS CONTINUED CHANCES OF BELOW NORMAL TEMPERATURES,
SIGNALING A SLIGHT TO MODERATE CHANCE OF MUCH BELOW NORMAL
TEMPERATURES IN THE FEBRUARY 7TH TO FEBRUARY 10TH PERIOD. RIVER
ICE GROWTH IS EXPECTED TO CONTINUE OR REMAIN STEADY ACCORDINGLY.
KEY MESSAGE 2...
LONGWAVE TROUGHING IS FAVORED TO PERSIST OVER EASTERN NORTH
AMERICA THROUGHOUT THE UPCOMING WEEK. THIS WILL SUPPORT THE
CONTINUATION OF COLD TEMPERATURES, WITH EVEN THE WARMEST DAYS
APPEARING TO BARELY REACH OR EXCEED FREEZING. IN FACT, THE
LATEST NBM PROBABILITIES SUGGEST ONLY A 20-40 PERCENT CHANCE OF
REACHING 32 DEGREES ON TUESDAY (FOCUSED SOUTH OF I-70) AND A
30-60% CHANCE ON FRIDAY (HIGHEST IN EASTERN OH AND THE MON
VALLEY). GIVEN THE FACT THAT THE AVERAGE HIGH TEMPERATURE THIS
TIME OF YEAR IS THE UPPER 30S, THERE IS MEDIUM TO HIGH
CONFIDENCE IN MOST OF THE WEEK REMAINING COLDER THAN SEASONAL
NORMS.
MEANWHILE, A FEW GLANCING BLOWS FROM QUICK-MOVING SHORTWAVE
TROUGHS COULD BRING LOW-END CHANCES FOR SOME LIGHT SNOW SHOWERS
TO THE AREA MONDAY THROUGH WEDNESDAY, BUT POPS CURRENTLY TOP OUT
IN THE 20-30 PERCENT RANGE ANY GIVEN DAY AS A LACK OF DEEP-
LAYER MOISTURE KEEPS RATES LIGHT WITH MINIMAL ACCUMULATION. THE
LATEST NBM SUGGESTS ONLY A 10-20% CHANCE FOR AT LEAST 0.1" OF
SNOW ON MONDAY MAINLY IN THE RIDGES AND ALONG A MERCER-LATROBE
CORRIDOR, FOLLOWED BY HIGHER PROBABILITIES (UP TO 40%) IN THE
RIDGES AND MON VALLEY SOUTHEAST OF PITTSBURGH LATE TUESDAY AS
SURFACE LOW PRESSURE PASSES SOUTH OF THE AREA. STILL, GIVEN HOW
COLD THE GROUND IS WITH THE RECENT STRETCH OF BITTER COLD, ANY
SNOW THAT DOES FALL WILL STICK TO UNTREATED SURFACES AND COULD
CAUSE ROADS TO BECOME SLICK.
RIGHT NOW THE BETTER CHANCE FOR NOTABLE SNOWFALL ACCUMULATION
APPEARS TO BE WITH THE SYSTEM AT THE END OF THE WEEK. BY THEN, A
DEEPENING UPPER LOW IS FORECAST TO SWING SOUTHEASTWARD FROM
CENTRAL CANADA INTO SOUTHERN ONTARIO, BRINGING STRONGER SYNOPTIC
ASCENT TO THE OHIO VALLEY AS A SURFACE LOW MOVES ACROSS LOWER
ONTARIO AND THE LOWER GREAT LAKES. THE SOURCE LOCATION AND
TRAJECTORY OF THIS LOW WOULD MAKE IT DIFFICULT TO ESTABLISH A
NOTABLE "WARM" SECTOR, HENCE TEMPERATURE FORECASTS REMAINING
NEAR OR BARELY ABOVE FREEZING ON FRIDAY AND A PREVAILING PTYPE
OF SNOW, EVEN AS WINDS SHIFT OUT OF THE SOUTH OR SOUTHWEST. AS
FOR SNOWFALL AMOUNTS, LATEST LONG- RANGE ENSEMBLE INTERQUARTILES
FAVOR SUB- ADVISORY SNOWFALL (LESS THAN 3 INCHES) ACROSS
LOWLAND AREAS AND HIGHER AMOUNTS (3 TO 6 INCHES) IN THE RIDGES,
HOWEVER THESE NUMBERS SHOULD ALL BE TAKEN WITH A HEAPING
TABLESPOON OF SALT THIS FAR OUT. WHAT APPEARS MORE LIKELY WITH
THE FRIDAY SYSTEM IS A REINFORCING SHOT OF THE CRISP NORTHERN
CANADIAN AIR WE'VE GROWN TO LOVE (OR HATE) OVER THE PAST WEEK,
WITH ENSEMBLES SHOWING LOW TEMPERATURES DROPPING BACK TO NEAR OR
BELOW ZERO NEXT WEEKEND.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
KEY MESSAGES...
1) MVFR/IFR CIG RESTRICTIONS CONTINUE TODAY
2) PASSING DISTURBANCE MAY RETURN SNOW ON TUESDAY
------------------------------------------------------------
A LOW-LEVEL CLOUD DECK WILL REMAIN IN PLACE THROUGH TODAY AND
INTO TONIGHT. THIS WILL HOVER BETWEEN VFR AND MVFR THROUGH THE
DAY BUT INTO THE EVENING THE CIGS WILL LIKELY FALL TO MVFR/IFR
THROUGH THE EVENING AND OVERNIGHT. WINDS WILL MAINLY BE LIGHT
AND VARIABLE THROUGH THE PERIOD. THE COLD AIR IN PLACE AND LOW
CIGS WILL ALLOW FOR INSTANCES OF LIGHT SNOW TO FALL THROUGH THE
PERIOD. IN MOST CASES, THE VIS FROM SNOW WILL BE MAINLY VFR BUT
A FEW INSTANCES OF MVFR CIGS ARE POSSIBLE.
OUTLOOK... LONG-RANGE MODELS SUGGEST A DISTURBANCE DEVELOPING
TUESDAY INTO WEDNESDAY THAT WILL LIKELY CREATE WIDESPREAD
RESTRICTIONS WITH SNOW. PROBABILITY OF MEASURABLE SNOW (0.1")
RANGES FROM 20-50% ACROSS THE REGION; HIGHER PROBABILITIES NOTED
SOUTH OF PIT.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...COLD WEATHER ADVISORY FROM 7 PM THIS EVENING TO 11 AM EST
SUNDAY FOR PAZ013>016-020>022-029-031-073>078.
AIR QUALITY ALERT UNTIL 10 PM EST THIS EVENING FOR PAZ021.
OH...COLD WEATHER ADVISORY FROM 7 PM THIS EVENING TO 11 AM EST
SUNDAY FOR OHZ039>041-048>050-057>059-068-069.
WV...COLD WEATHER ADVISORY FROM 7 PM THIS EVENING TO 11 AM EST
SUNDAY FOR WVZ001>004-012-021-509>513.
EXTREME COLD WARNING FROM 7 PM THIS EVENING TO 1 PM EST SUNDAY
FOR WVZ514.
DISCUSSION...CERMAK/SHALLENBERGER
AVIATION...SHALLENBERGER
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