396
FXUS61 KPBZ 201941
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
241 PM EST MON JAN 20 2025
SYNOPSIS
POTENTIALLY DANGEROUS SUB FREEZING WIND CHILLS IS EXPECTED
THROUGH WEDNESDAY; COLD WEATHER ADVISORY/EXTREME COLD WARNINGS
REMAINS IN EFFECT ACROSS THE REGION.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- VERY LIGHT SNOW THROUGH THIS EVENING.
- COLD WEATHER ADVISORY/EXTREME COLD WARNING IN EFFECT
RESIDUAL MOISTURE FROM AN EXITING LOW, SOUTH AND EAST OF
PITTSBURGH, HAS CREATE AREAS OF LINGERING CLOUD COVERAGE AND
LIGHT SNOW SHOWERS. ISOLATED AREAS COULD MEASURE A TRACE TO 0.1
INCHES OF SNOW WITHIN THE LOWER ELEVATIONS DUE TO GRAVITY WAVE
ACTIVITY; HIGHER TERRAIN COULD MEASURE A HALF INCH DUE TO
UPSLOPING
TEMPERATURES WILL STRUGGLE TO REACH THE LOW TO MID-TEENS TODAY
DESPITE THE SUNSHINE AS AN ARCTIC AIRMASS CONTINUES TO ADVANCE
INTO THE OHIO RIVER VALLEY FROM THE WEST. WITH WIND GUST RANGE
FROM 20 TO 25MPH, EXPECTED WIND CHILL VALUES TO RANGE FROM
-5F TO -15F FOR THE LOWER ELEVATIONS THROUGH THIS EVENING; -15F TO
-30F IN THE HIGHER TERRAIN. THEREFORE, COLD WEATHER HEADLINES
WILL CONTINUE TO REMAIN IN EFFECT.
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SHORT TERM /TUESDAY THROUGH WEDNESDAY/
KEY MESSAGES:
- ARCTIC OUTBREAK WITH DANGEROUSLY COLD TEMPERATURES AND WIND CHILLS.
- EXTREME COLD WARNING FOR RIDGES AND ADVISORY FOR LOWLANDS IN
EFFECT.
- A PASSING SHORTWAVE COULD IMPACT THE TUES AFTERNOON/EVENING
COMMUTE
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EXTREME COLD THROUGH WEDNESDAY MORNING...
CONFIDENCE IS HIGH THAT A POTENTIALLY DANGEROUS COLD
WEATHER OUTBREAK IS EXPECTED TO CONTINUE INTO THE SHORT TERM
PERIOD AS AN ARCTIC AIRMASS LINGERS ACROSS THE GREAT LAKES/OHIO
RIVER VALLEY REGION.
LONG AND SHORT RANGE MODELS (NAEFS AND GEFS) HAVE CLIMATOLOGICAL
ANOMALIES RANGING WITHIN THE -3.5C TO -4.0C STANDARD DEVIATION
FOR THE UPPER-LVL TEMPS (850MB/700MB/500MB) AND HIGHLIGHTING
THAT RETURN INTERVAL OF THIS COLD OUTBREAK IS A 1 IN EVERY 10
YEAR OCCURRENCE, WHICH IS RARE. THE COLDEST TIME PERIOD IS
EXPECTED TO BE LATE TUESDAY INTO WEDNESDAY MORNING AS AN
EMBEDDED SHORTWAVE TRACKS THROUGH THE DAKOTAS AND ADVANCES THE
COLDEST AIR ALOFT, WHICH IS CURRENTLY IN THE MIDWEST, TOWARDS
THE EAST COAST. RECORD LOWS AND RECORD LOMAX TEMPS COULD BE TIED
OR BROKEN AT A NUMBER OF CLIMATE SITES TOMORROW INTO WEDNESDAY.
THE POTENTIAL FOR UPGRADING TO A EXTREME COLD WARNING ACROSS THE
REGION IS BELOW 50% FOR EARLY WEDNESDAY. THE SPREAD OF THE
APPARENT TEMPERATURES FOR THE LATEST RUN OF THE ENSEMBLES THAT
COVER THE 25TH TO 75TH PERCENTILE IS 6 DEGREES (BETWEEN -17F TO
-23F). A POTENTIAL OUTCOME IS THAT A STRONG SFC HIGH BUILDS OVER
THE REGION (POTENTIALLY AS HIGH AS 1040MB) AND MEASURED TEMPS
COULD RANGE FROM -15F TO -18F BUT WITH VERY LITTLE WIND.
HISTORICALLY, THESE ARE THE NOTED IMPACTS ACROSS OUR REGION WITH
A COLD WEATHER OUTBREAK THIS SEVERE: UNPROTECTED PIPES CAN
FREEZE AND BURST. PROLONGED EXPOSURE TO THE COLD MAY LEAD TO
HYPOTHERMIA. FROSTBITE CAN OCCUR IN AS LITTLE AS 30 MINUTES FOR
EXPOSED SKIN.
WE ADVISE CHECKING IN ROUTINELY WITH VULNERABLE FRIENDS AND
FAMILY. EXTREME CARE IS ENCOURAGED FOR THE PROTECTION OF PETS
AND ANIMALS. RESCHEDULING ANY EVENTS, ESPECIALLY THOSE TAKING
PLACE OUTDOORS, IS ALSO ENCOURAGED.
ALONG WITH COLD WEATHER, A POTENTIAL SHORTWAVE IS EXPECTED TO
CROSS THE REGION TUESDAY AFTERNOON AND INCREASE THE THREAT OF
HAZARDOUS TRAVEL DUE TO SNOW. SNOWFALL AMOUNTS ARE EXPECTED TO
STAY BELOW ADVISORY CRITERIA (LIKELY 0.5 TO 1.0 INCHES IN
ISOLATED AREAS; A TRACE TO 0.5 ELSEWHERE). HOWEVER, BRIEF
PERIODS OF LOW VISIBILITY FROM HEAVY SNOW CAN'T BE RULED OUT.
THE 0-3KM CAPE VALUES RANGE FROM 25J/KG TO 50J/KG ALONG THE
TROUGH AXIS. HI-RES GUIDANCE ALSO HAS SOME NOTED POTENTIAL
STRONGER BANDS (REFLECTIVITY ON THE RADAR COULD MEASURE 20DBZ TO
30DBZ AT TIMES) BETWEEN 3PM TO 6PM (INCLUDING PITTSBURGH). IF
MODELS REMAIN CONSISTENT WITH THIS POTENTIAL OUTCOME, SHORT-
FUSED SPECIAL WEATHER STATEMENTS AND/OR SNOW SQUALL WARNINGS MAY
BE NEEDED TO HIGHLIGHT THE THREAT.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
KEY MESSAGES:
- CONFIDENCE IS HIGH THAT VERY EXTREMELY COLD TEMPERATURES WILL
EXIT THE REGION WEDNESDAY. HOWEVER, BELOW AVERAGE TEMPS ARE
EXPECTED TO LINGER.
- NEAR NORMAL TEMPS AND WIDESPREAD PRECIP MAY RETURN SUNDAY INTO
MONDAY
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A RIDGE AXIS IS EXPECTED TO DRIFT OVER THE OHIO RIVER VALLEY
EARLY WEDNESDAY. THE RETURN OF WARM SOUTHWEST FLOW WILL LIKELY END
THE THREAT FOR EXTREME COLD CONDITIONS ACROSS PORTIONS OF THE
REGION BY MID-DAY. OVERNIGHT LOWS/WIND CHILLS LATE WEDNESDAY
INTO EARLY THURSDAY MAY PROMPT A COLD WEATHER ADVISORY FOR
FORECAST ZONES WITHIN THE RIDGES (TUCKER/PRESTON), BUT THE
POTENTIAL OF -10F WIND CHILL VALUES FOR THE LOWER TERRAIN IS
LOW (LESS THAN 10% BASED ON NUMEROUS LONG RANGE ENSEMBLES).
MODELS HAVE BEEN CONSISTENT THAT WIDESPREAD PRECIPITATION MAY
RETURN ON SUNDAY. PROBABILITY OF MEASURABLE PRECIPITATION
WITHIN A 24 HOUR TIME PERIOD IS 60% TO 75%, HIGHER VALUES NOTED
ALONG THE RIDGES. IF TEMPERATURES TREND COLDER, THERE IS A 10%
CHANCE OF SNOW AMOUNTS ALONG THE RIDGES REACH OR EXCEEDING THE
WINTER WEATHER ADVISORY CRITERIA. IF WARM AIR LINGERS, SNOW
RATIOS COULD TREND DOWN (DECREASING SNOW AMOUNTS TOTALS) AND A
RAIN/SNOW/WINTRY MIX MAY OCCUR IN PORTIONS OF OUR REGION.
AVIATION /19Z MONDAY THROUGH SATURDAY/
STEEP LAPSE RATES AND ENOUGH BOUNDARY LAYER MOISTURE MAY ALLOW
FOR SCATTERED TO BROKEN HIGH MVFR TO LOW VFR CIGS AND GENERALLY
SPOTTY LIGHT SNOW SHOWERS THIS AFTERNOON. THAT DEEP MIXING PLUS
RESIDUAL SURFACE PRESSURE GRADIENTS ARE ALSO LEADING TO GUSTS
BETWEEN 15-25KTS THAT WILL TAPER OFF AFTER SUNSET. CONFIDENCE
REMAINS HIGH (90% PROBABILITY) FOR CONTINUED DRY ADVECTION AND
SUBSIDENCE TO END AREA SNOW SHOWERS AND ERODE STRATOCU FROM WEST
TO EAST.
LIGHT WIND AND VFR IS EXPECTED OVERNIGHT. A WEAK BUT REINFORCING
SHOT OF COLD AIR TUESDAY TETHERED TO AN UPPER LEVEL SHORTWAVE
SHOULD RESULT IN MVFR CIGS (60-80% PROBABILITY). HI-RES MODELS
ALSO INDICATE POTENTIAL FOR SCATTERED SNOW SHOWERS; DUE TO WEAK
INSTABILITY AND THE COLD AIR MASS, THESE SHOWERS MAY BRIEFLY BUT
QUICKLY REDUCE VSBYS TO 1 MILE OR LESS AND CREATE A QUICK
COATING ON ALL SURFACES.
OUTLOOK...
DEVELOPMENT OF STRONG SURFACE HIGH PRESSURE FROM THE WEST WILL
RETURN VFR (NEAR 100% PROBABILITY) TO ALL SITES BY WEDNESDAY.
RESTRICTION AND PRECIPITATION CHANCES INCREASE FRIDAY WITH THE
LIKELY APPROACH/PASSAGE OF THE NEXT UPPER LEVEL TROUGH.
CLIMATE
A PERIOD OF ANOMALOUSLY COLD WEATHER IS EXPECTED TO PASS MONDAY
THROUGH WEDNESDAY THAT WILL CHALLENGE MANY STANDING JANUARY
TEMPERATURE RECORDS. ATTACHED BELOW ARE THE STANDING
CLIMATOLOGY FOR LOCAL SITES. PITTSBURGH HAS A FULL RECORD,
WHILE OTHER SITES ARE PARTIAL RECORDS AND MAY NOT BE FULLY
REFLECTIVE OF HISTORICAL TEMPERATURES:
JANUARY 20TH: HIGH MINIMUM LOW MINIMUM
PITTSBURGH, PA 1F (1985) -18F (1985)
WHEELING, WV 13F (1940) -1F (1940)
MORGANTOWN, WV 3F (1985) -17F (1985)
NEW PHILADELPHIA, OH -3F (1994) -22F (1994)
ZANESVILLE, OH -2F (1985) -17F (1985)
DUBOIS, PA -2F (1985) -19F (1985)
JANUARY 21ST: HIGH MINIMUM LOW MINIMUM
PITTSBURGH, PA 5F (1984) -18F (1985)
WHEELING, WV 12F (2000) -2F (1924)
MORGANTOWN, WV 2F (1985) -18F (1985)
NEW PHILADELPHIA, OH -8F (1985) -19F (1985)
ZANESVILLE, OH 7F (1985) -22F (1984)
DUBOIS, PA 0F (1985) -22F (1985)
JANUARY 22ND: HIGH MINIMUM LOW MINIMUM
PITTSBURGH, PA 10F (1961) -14F (1936)
WHEELING, WV 11F (2014) -4F (2014)
MORGANTOWN, WV 11F (2014) -5F (1984)
NEW PHILADELPHIA, OH 5F (1984) -15F (1994)
ZANESVILLE, OH 13F (2014) -11F (2011)
DUBOIS, PA 8F (2013) -11F (1984)
BELOW IS THE LOWEST DAILY HIGH AND DAILY LOW TEMPERATURES OF THE
21ST CENTURY. THIS ENCOMPASSES ALL DAYS OF ALL MONTHS RUNNING
FROM JANUARY 2000 TO PRESENT:
HIGH MINIMUM LOW MINIMUM
PITTSBURGH, PA 4F (01/07/2014) -10F (01/17/2009)
(02/20/2015)
WHEELING, WV 5F (01/07/2014) -10F (01/07/2014)
MORGANTOWN, WV 7F (01/07/2014) -9F (01/28/2014)
(01/28/2014) (01/29/2014)
NEW PHILADELPHIA, OH 6F (01/16/2009) -18F (01/28/2014)
(01/28/2014)
(02/15/2015)
ZANESVILLE, OH 6F (01/28/2014) -20F (01/29/2014)
DUBOIS, PA 0F (01/07/2014) -17F (02/16/2015)
IN ADDITION, PITTSBURGH HAS NOT SEEN A DAYTIME HIGH BELOW 4F
SINCE JANUARY OF 1994. PITTSBURGH HAS ALSO HAS NOT SEEN 2
CONSECUTIVE DAYS OF HIGH TEMPERATURES LESS THAN 10F SINCE
JANUARY OF 1997. IF YOU EXTEND THIS STATISTIC TO 3 DAYS, YOU
WOULD HAVE TO GO BACK TO FEBRUARY 1899.
THE LAST TIME PITTSBURGH'S MINIMUM TEMPERATURE WAS LESS THAN OR
EQUAL TO -5F WAS DECEMBER 2022. LAST TIME IT WAS BELOW OR EQUAL
TO -10F WAS FEBRUARY 2015. FOR 2 CONSECUTIVE DAYS OF LOWS LESS
THAN OR EQUAL -10F, YOU WOULD HAVE TO GO BACK TO JANUARY OF
1994.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...COLD WEATHER ADVISORY UNTIL 1 PM EST WEDNESDAY FOR PAZ007>009-
013>016-020>022-029-031-073-075-077.
EXTREME COLD WARNING UNTIL 1 PM EST WEDNESDAY FOR PAZ074-076-
078.
OH...COLD WEATHER ADVISORY UNTIL 1 PM EST WEDNESDAY FOR OHZ039>041-
048>050-057>059-068-069.
WV...COLD WEATHER ADVISORY UNTIL 1 PM EST WEDNESDAY FOR WVZ001>004-
012-021-509>511.
EXTREME COLD WARNING UNTIL 1 PM EST WEDNESDAY FOR WVZ512>514.
SYNOPSIS...HEFFERAN
NEAR TERM...HEFFERAN
SHORT TERM...HEFFERAN
LONG TERM...HEFFERAN
AVIATION...FRAZIER
CLIMATE...
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