853
FXUS61 KPBZ 200905
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
405 AM EST TUE JAN 20 2026
WHAT HAS CHANGED
WIND ADVISORY HAS EXPIRED. BETTER CONFIDENCE IN A PROLONGED COLD
EVENT FRIDAY THROUGH THE WEEKEND
KEY MESSAGES
1) COLD WEATHER ADVISORY AND EXTREME COLD WARNING CONTINUES THROUGH
THE MORNING.
2) RAIN AND SNOW RETURN WEDNESDAY THROUGH THURSDAY WITH A
PASSING TROUGH AND ASSOCIATED FRONT.
3) CONSECUTIVE COLD MEAN DAILY TEMPERATURES LATER THIS WEEK AND
THROUGH THE WEEKEND COULD NEGATIVELY IMPACT REGIONAL INFRASTRUCTURE,
SUCH AS FROZEN PIPES, AND PUTTING A STRAIN ON THE ENERGY GRID.
DISCUSSION
KEY MESSAGE 1... COLD WEATHER ADVISORY AND EXTREME COLD WARNING
CONTINUES THROUGH THE MORNING.
THE COLD WEATHER ADVISORY AND EXTREME COLD WARNING (FOR EASTERN
TUCKER COUNTY) REMAINS IN EFFECT.
COLD TEMPERATURES AND A STILL-TIGHT PRESSURE GRADIENT WILL
RESULT IN SUB-ZERO APPARENT TEMPERATURES THIS MORNING. EVEN
FOR SHELTERED VALLEYS THAT WILL NOT SEE ANY PERIODIC ELEVATED
WIND SPEEDS, WITH A CLEAR SKY, AND DEWPOINTS AROUND -5F ON
AVERAGE, TEMPERATURES WILL CRATER THIS MORNING WITH STRONG
RADIATIONAL COOLING. 40% OF TOP ANALOGS SHOW MINTS <0F, WHICH IS
CLOSE TO LATEST ENSEMBLE GUIDANCE.
WE WILL SEE A SLIGHT WARM-UP TODAY, BUT NOT MUCH WITH CONTINUED
COLD ADVECTION AND ELEVATED WIND SPEEDS. COMPARING OBSERVATIONS
OVER THE PAST SEVERAL HOURS AND MODEL GUIDANCE, 10TH PERCENTILE
NBM GUIDANCE APPEARS TO BE PERFORMING BEST UNDER THE CURRENT
SETUP, WHICH SHOWS DAYTIME HIGHS AROUND 5 DEGREES BELOW STRAIGHT
NBM VALUES ACROSS THE REGION TODAY. IF THE HOURLY GUIDANCE
CONTINUES TO REMAIN CLOSE TO THE 10TH PERCENTILE AS WE GO
FURTHER INTO THE MORNING, DAYTIME HIGHS MAY NEED TO BE ADJUSTED
LOWER THAN CURRENTLY FORECAST. THERE WILL BE LIMITED CLOUD
COVERAGE, BUT SOLAR INSOLATION IS LIMITED THIS TIME OF YEAR. A
LOCAL STUDY DONE IN 2001 BY THE OFFICE GIVES A DAYTIME HIGH OF
PGH OF 14F WHEN H850 TEMPERATURE IS -20F (WHERE MODEL GUIDANCE
PEGS IT) UNDER LIMITED CLOUD COVERAGE.
IN ANY CASE, MOST LOCATIONS WILL NOT RISE ABOVE NEGATIVE WIND
CHILL TERRITORY UNTIL THE AFTERNOON.
KEY MESSAGE 2... RAIN AND SNOW RETURN WEDNESDAY THROUGH THURSDAY WITH A
PASSING TROUGH AND ASSOCIATED FRONT.
ANOTHER TROUGH AND ASSOCIATED FRONT WITHIN THE NORTHWEST FLOW
WILL CROSS THE GREAT LAKES ON WEDNESDAY INTO WEDNESDAY NIGHT,
BRINGING ANOTHER ROUND OF SNOW NORTH OF I-80, AND A COMBO OF RAIN
AND SNOW FARTHER SOUTH OF I-80 WITH WARM ADVECTION AHEAD OF THE
FRONT. 1 TO 4 INCHES WILL BE POSSIBLE ACROSS NORTHERN COUNTIES
(HIGHER VALUES FROM SOUTH TO NORTH), MAINLY ALONG AND NORTH OF
I-80. OVERALL GUIDANCE HAS TRENDED LOWER WITH AMOUNTS, BUT
ADVISORY LEVELS ARE STILL POSSIBLE SO HAVE MAINTAINED MENTION
OF THAT IN THE HWO.
ANOTHER CONSIDERATION IS FOR AREAS THAT SEE RAIN DURING THE DAY
ON WEDNESDAY WHERE SURFACE TEMPERATURES MAY STILL BE BELOW
FREEZING GIVEN PREVIOUS COLD TEMPERATURES. THIS WILL NEED TO BE
MONITORED.
KEY MESSAGE 3... CONSECUTIVE COLD MEAN DAILY TEMPERATURES LATER
THIS WEEK AND THROUGH THE WEEKEND COULD NEGATIVELY IMPACT
REGIONAL INFRASTRUCTURE, SUCH AS FROZEN PIPES, AND PUTTING A
STRAIN ON THE ENERGY GRID.
MODEL GUIDANCE CONTINUES TO SIGNAL A RELATIVELY LONG PERIOD OF
WELL BELOW NORMAL TEMPERATURES FROM FRIDAY TO MONDAY, POSSIBLY
AS FAR OUT AS TUESDAY. EMPIRICAL DATA SUGGESTS INFRASTRUCTURE
PROBLEMS (FROZEN PIPES, ETC), START TO OCCUR AFTER THE MEAN
DAILY TEMPERATURE RUNS -12F BELOW NORMAL FOR 48 HOURS OR MORE.
FOR THIS TIME OF YEAR IN THE PGH AREA THIS IS APPROXIMATELY A
DAILY MEAN TEMPERATURE OF 15F. CALCULATING THE DAILY MEAN FROM
THE CURRENT FORECAST, IT WILL BE AROUND THAT VALUE (GIVE OR TAKE
A COUPLE DEGREES FRIDAY UNTIL NEXT TUESDAY. A LOT CAN CHANGE
BEING THAT FAR OUT, BUT IT WILL BE MONITORED.
ADDITIONALLY, WE MAY SEE RELATIVELY FAST ICE FORMATION ON AREA
RIVERS GIVEN THE AVERAGE DAILY TEMPERATURES THAT ARE FORECAST.
AVIATION /09Z TUESDAY THROUGH SATURDAY/
KEY MESSAGES...
1) GUSTY WEST WIND TO 20KTS AFTER SUNRISE, RELAXING THIS EVENING
2) VFR FOR ALL BUT FKL/DUJ THIS MORNING, ALL TERMINALS BY THIS
AFTERNOON
------------------------------------------------------------
POST-FRONTAL STRATOCU HAS BEEN VERY SPARSE GIVEN DRY CONDITIONS.
MAINLY CLEAR CONDITIONS PERSIST FOR ALL BUT FKL/DUJ WHERE
STRATOCU STRUGGLED TO FORM, BUT HAS SINCE ERODED. GUIDANCE STILL
INDICATES MVFR CIGS FOR FKL/DUJ WILL FORM CLOSER TO SUNRISE,
BUT CONFIDENCE IN THIS IS LOW. MVFR BECOMES MORE LIKELY AFTER
SUNRISE, ERODING THROUGH THE EARLY AFTERNOON. ELSEWHERE, VFR IS
EXPECTED THROUGH THE PERIOD.
WESTERLY WIND REMAINS STOUT OVERNIGHT, THOUGH HAVE DROPPED THE
GUSTS WITH THIS PACKAGE. GUSTS TO AROUND 20 KTS SHOULD RETURN
AFTER SUNRISE WITH DEEPER MIXING, GRADUALLY DIMINISHING THIS
AFTERNOON AS THE GRADIENT SLACKENS.
OUTLOOK...
RESTRICTIONS AND SNOW RETURN WEDNESDAY AND THURSDAY WITH THE
APPROACH AND PASSAGE OF A COLD FRONT. CIG RESTRICTIONS ARE STILL
POSSIBLE FRIDAY AND SATURDAY UNDER COLD NW FLOW AND BROAD UPPER
TROUGHING.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...COLD WEATHER ADVISORY UNTIL NOON EST TODAY FOR PAZ007>009-
013>016-020>022-029-031-073>078.
OH...COLD WEATHER ADVISORY UNTIL NOON EST TODAY FOR OHZ039>041-
048>050-057>059-068-069.
WV...COLD WEATHER ADVISORY UNTIL NOON EST TODAY FOR WVZ001>004-012-
021-509>513.
EXTREME COLD WARNING UNTIL NOON EST TODAY FOR WVZ514.
DISCUSSION...88
AVIATION...WM/RACKLEY
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