135
FXUS61 KPBZ 200102
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
802 PM EST SUN JAN 19 2025
SYNOPSIS
HEAVY BANDED SNOW ACROSS THE LAUREL HIGHLANDS WILL SHIFT EAST OF
THE AREA THIS AFTERNOON, WITH SCATTERED MOSTLY LIGHT SNOW
SHOWERS CONTINUING THROUGH MONDAY MORNING. DRY WEATHER AND
EXTREME COLD WILL GRIP THE REGION THROUGH WEDNESDAY BEFORE
TEMPERATURE MODERATES AT THE END OF THE WEEK.
NEAR TERM /THROUGH MONDAY/
KEY MESSAGES:
- TRANSITION TO SCATTERED SNOW SHOWERS EXPECTED INTO EARLY
MONDAY MORNING WITH AN ARCTIC FRONT PASSAGE.
- COMBINATION OF COLD AIR AND GUSTY WIND WILL CREATE NEGATIVE
WIND CHILLS MONDAY.
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THE CURRENT 00Z SOUNDING ALLUDES THE THE HEAVILY ANTICIPATED
ARCTIC FRONTAL PASSING OVERNIGHT TONIGHT, WITH A TROPOPAUSE OF
500MB WITH DRY STRATOSPHERIC AIR ABOVE THAT. AN ADIABATIC,
NEARLY SATURATED LAYER IS OBSERVED FROM THE SURFACE TO ROUGHLY
800MB, WHICH HAS BEEN RESPONSIBLE FOR THE CONVECTIVE SNOW DURING
THE EARLY OVERNIGHT HOURS TONIGHT. THE FORCING FOR SNOW HAS
MOSTLY BEEN THE STARK SURFACE CONVERGENCE AS THE COLD AIR
BULLIES IS WAY IN ALONG THE FRONT. THE FRONTAL PASSAGE WILL
CROSS TONIGHT, LEADING TO DRAMATIC DROPS IN TEMPERATURES. THE
MOST LIKELY PASSAGE TIME WILL BE ROUGHLY 9PM FOR ZANESVILLE, 1AM
FOR WHEELING, 3AM FOR PITTSBURGH AND MORGANTOWN, 5AM FOR
LATROBE, AND 7AM FOR DUBOIS.
FLOW IS EXPECTED TO BE PROGRESSIVE ENOUGH TO RESULT IN MINIMAL
TOTALS. LESS THAN 1" OF ADDITIONAL SNOW MAY BE POSSIBLE ALONG
THE FRONT ON IN DRY, FLUFFY, HIGH- RATIO CONVECTIVE SNOW.
VISIBILITY MAY DROP AS LOW AS 1/2 MI, BUT EVEN LOWER
VISIBILITIES ARE POSSIBLE IN BLOWING SNOW. OBSERVATIONS IN OHIO
INDICATE WINDS GUSTING AS HIGH AS 20MPH TO 30MPH ALONG AND
BEHIND THE FRONTAL PASSAGE. WEBCAMS SHOW SNOW-COVERED ROADS.
PROBABILITIES OF LOW-VISIBILITY SNOW WITH ADDITIONAL
ACCUMULATIONS REMAIN HIGHEST IN THE I-80 CORRIDOR, BUT LOW
VISIBILITY SHOWERS REMAIN POSSIBLE ANYWHERE WITHIN THE REGION,
PARTICULARITY ALONG AND BEHIND THE FRONTAL PASSAGE. WITH
TEMPERATURES DROPPING INTO THE 10S, SNOW WILL EASILY BE ABLE TO
STICK TO ROADS AND WATER MAY REFREEZE, MAKING TRAVEL SLICK ON
UNTREATED AND TREATED ROADS. MOTORISTS SHOULD BE PREPARED FOR
CHANGEABLE VISIBILITY AND ROAD CONDITIONS IF TRAVELING
OVERNIGHT. CHANGES IN VISIBILITY AND SLICK ROADS WITH SNOW
SHOWERS MAY LEAD TO ACCIDENTS. A SPS IS OUT TO HIGHLIGHT THIS,
AND WINTER WEATHER ADVISORIES / WINTER STORM WARNINGS REMAIN IN
PLACE ACCORDINGLY.
.. PREVIOUS DISCUSSION ..
STEEPENING LAPSE RATES AND ENOUGH OPEN LAKE WATERS (WITH
FETCHES FROM BOTH LAKE MICHIGAN AND LAKE ERIE) IS EXPECTED TO
CREATE SCATTERED SNOW SHOWERS THIS EVENING THROUGH EARLY MONDAY
MORNING. HI-RES MODEL GUIDANCE SHOWS LARGE VARIATIONS IN LAKE
ENHANCED BANDS AND THE INFLUENCE OF VORT ADVECTION WITHIN NW
FLOW ALOFT, MAKING IT DIFFICULT TO PINPOINT ADDITIONAL SNOW
ACCUMULATIONS. ON AVERAGE, LOWLAND AREAS SHOULD SEE LESS THAN 1"
(90% PROBABILITY) OF ADDITIONAL ACCUMULATION DESPITE ~20:1 SLRS
DUE TO THE TRANSIENT NATURE OF THE SHOWERS AND A FAIRLY RAPID
BACKING OF BOUNDARY LAYER WINDS TO THE WEST. OROGRAPHIC LIFT IS
EXPECTED TO AID SLIGHTLY HIGHER ACCUMULATIONS FOR THE WARNED
TERRAIN LOCATIONS, BUT SNOWFALL MAY BE SPOTTY WITH RATES
GENERALLY LESS 0.5"/HR.
THE AFOREMENTIONED COLD ADVECTION WILL ALSO COMBINE WITH BREEZY
WIND FROM DEEPER MIXING TO CREATE NEGATIVE WIND CHILLS BY THE
MONDAY MORNING COMMUTE. THOUGH INCREASING SUBSIDENCE AND DRY
ADVECTION WILL CLEAR CLOUDS AND END SNOW BY MONDAY AFTERNOON,
LITTLE DIURNAL HEATING WILL KEEP DAYTIME AIR TEMPERATURE NEAR OR
BELOW 10 DEGREES AND NEGATIVE WIND CHILLS.
SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/
KEY MESSAGES:
- ARCTIC OUTBREAK WITH DANGEROUSLY COLD TEMPERATURES AND WIND CHILLS.
- EXTREME COLD WARNING FOR RIDGES AND ADVISORY FOR LOWLANDS ISSUED.
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EXTREME COLD MONDAY NIGHT THROUGH WEDNESDAY MORNING...
DANGEROUSLY COLD TEMPERATURES ARE EXPECTED THROUGHOUT THE SHORT TERM
PERIOD AS AN ANOMALOUSLY DEEP TROUGH OVER EASTERN NORTH AMERICA
OPENS THE DOOR FOR ARCTIC AIR TO MAKE ITS WAY FROM NORTHERN CANADA
INTO THE EASTERN CONUS. LOCALLY, TEMPERATURES WILL HOVER 20 TO 25
DEGREES BELOW NORMAL FOR THIS TIME OF YEAR, WITH TUESDAY MORNING
STARTING OUT NEAR OR SLIGHTLY BELOW ZERO, INCREASING TO THE UPPER
SINGLE DIGITS TO LOW TEENS TUESDAY AFTERNOON, AND THEN PLUMMETING TO
AROUND -10 DEGREES TUESDAY NIGHT. EXTREME COLD WARNINGS ARE IN
EFFECT FOR THE RIDGES OF SOUTHWEST PA AND NORTHERN WV WHERE WIND
CHILLS WILL PERIODICALLY DIP TO -20 TO -25 DEGREES. A COLD WEATHER
ADVISORY IS IN EFFECT FOR THE REST OF THE AREA WITH WIND CHILLS IN
THE -10 TO -20 DEGREE RANGE. HOWEVER, WE WILL NEED TO MONITOR TRENDS
FOR LOW TEMPERATURES AND WIND CHILLS TUESDAY NIGHT INTO EARLY
WEDNESDAY MORNING WHEN SOME LOWLAND AREAS COULD EXCEED EXTREME COLD
WARNING CRITERIA (-20 DEGREES SOUTH OF I-80, -25 DEGREES NORTH OF
THE INTERSTATE) AND UPGRADES MAY BE NEEDED. FLURRIES WILL BE
POSSIBLE DURING THE DAY TUESDAY IF THERE IS ENOUGH LOW-LEVEL
MOISTURE, THOUGH WITH LITTLE TO NO ACCUMULATION.
WE RECOMMEND BEGINNING TO PREPARE FOR THESE COLD CONDITIONS NOW.
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. CHECK IN ROUTINELY WITH VULNERABLE FRIENDS
AND FAMILY. BRING MOVABLE PLANTS INDOORS. EXTREME CARE IS ENCOURAGED
FOR THE PROTECTION OF PETS AND ANIMALS. RESCHEDULING ANY EVENTS,
ESPECIALLY THOSE TAKING PLACE OUTDOORS, IS ALSO ENCOURAGED.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
KEY MESSAGES:
- THERE WILL BE SOME WARMING BY THE END OF THE WEEK BUT
TEMPERATURES REMAIN BELOW NORMAL THROUGH AT LEAST SATURDAY.
- PRECIPITATION CHANCES MAY INCREASE FRIDAY INTO THE WEEKEND AS
ANOTHER UPPER TROUGH APPROACHES FROM THE WEST.
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VERY COLD TEMPERATURES HANG ON THROUGH WEDNESDAY NIGHT, WITH
HIGHS WEDNESDAY AFTERNOON IN THE UPPER SINGLE DIGITS TO LOW
TEENS AND NIGHTTIME LOWS IN THE LOWER SINGLE DIGITS TO NEAR
ZERO (WIND CHILLS NEAR OR SLIGHTLY BELOW ZERO). GRADUAL WARMING
IS EXPECTED THEREAFTER TO CLOSE THE WEEK AS GLOBAL ENSEMBLES
ARE IN FAIR AGREEMENT THAT THE EASTERN CONUS TROUGH DEPARTS AND
WE SEE WEAK HEIGHT RISES IN RESPONSE TO ANOTHER UPSTREAM TROUGH
DIGGING INTO THE CENTRAL CONUS. TEMPERATURES REBOUND INTO THE
20S FRIDAY AND 30S NEXT WEEKEND. DEPENDING ON THE EVENTUAL
PROGRESSION OF THE UPSTREAM TROUGH, THIS WARMING COULD ALSO BE
ACCOMPANIED BY A ROUND OF INCREASING PRECIP CHANCES.
AVIATION /01Z MONDAY THROUGH FRIDAY/
IFR TO LIFR CONDITIONS ARE EXPECTED AS A BAND OF MODERATE SNOW
TRACKS ACROSS THE REGION THIS EVENING UNDER A CROSSING VORTICITY
MAXIMUM. ANOTHER BROKEN BAND OF SNOW WAS MOVING EAST ACROSS OH
ON THE LEADING EDGE OF STRONG COLD ADVECTION, AND THIS WILL ALSO
RESULT IN BRIEF REDUCTIONS TO IFR AS IT CROSSES THE AREA.
OUTSIDE OF THESE SNOW BANDS, EXPECT MVFR/OCNL IFR CONDITIONS IN
AREAS OF SNOW SHOWERS IN COLD NW FLOW AND BROAD UPPER TROUGHING.
THE SNOW SHOULD GRADUALLY TAPER OFF LATER TONIGHT AS THE
BOUNDARY LAYER FLOW CONTINUES TO BACK, AND MOISTURE IN THE
DENDRITIC REGION DECREASES. MVFR CIGS ARE EXPECTED TO CONTINUE
WITH A STEEP LOW LEVEL LAPSE RATE, AND MOISTURE BELOW A
TEMPERATURE INVERSION ALOFT. THESE CIGS WILL CONTINUE INTO
MONDAY BEFORE PARTIAL CLEARING TAKES PLACE FROM SW-NE LATER IN
THE DAY AND EVENING AS HIGH PRESSURE BEGINS TO BRIEFLY BUILD
IN. GUSTY W WIND AROUND 20KT IS ALSO EXPECTED LATE TONIGHT AND
MONDAY, WITH MIXING AND A TIGHT SURFACE PRESSURE GRADIENT.
OUTLOOK...
VFR IS EXPECTED TO RETURN MONDAY EVENING AS HIGH PRESSURE BUILDS
IN. A REINFORCING TROUGH RETURNS MVFR CIG RESTRICTION POTENTIAL
TUESDAY, BEFORE VFR RETURNS WEDNESDAY UNDER HIGH PRESSURE. SNOW
SHOWER AND RESTRICTION POTENTIAL RETURNS WITH A FRIDAY COLD
FRONT.
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 FROM 1 AM MONDAY TO 1 PM EST WEDNESDAY
FOR PAZ007>009-013>016-020>022-029-031-073-075-077.
WINTER WEATHER ADVISORY UNTIL 9 AM EST MONDAY FOR PAZ031-073-
075-078.
WINTER STORM WARNING UNTIL 9 AM EST MONDAY FOR PAZ074-076.
EXTREME COLD WARNING FROM 1 AM MONDAY TO 1 PM EST WEDNESDAY
FOR PAZ074-076-078.
OH...COLD WEATHER ADVISORY FROM 1 AM MONDAY TO 1 PM EST WEDNESDAY
FOR OHZ039>041-048>050-057>059-068-069.
WV...COLD WEATHER ADVISORY FROM 1 AM MONDAY TO 1 PM EST WEDNESDAY
FOR WVZ001>004-012-021-509>511.
WINTER WEATHER ADVISORY UNTIL 9 AM EST MONDAY FOR WVZ012-021-
509.
WINTER STORM WARNING UNTIL 9 AM EST MONDAY FOR WVZ510>514.
EXTREME COLD WARNING FROM 1 AM MONDAY TO 1 PM EST WEDNESDAY
FOR WVZ512>514.
SYNOPSIS...FRAZIER
NEAR TERM...MILCAREK
SHORT TERM...CERMAK/SHALLENBERGER
LONG TERM...CERMAK/SHALLENBERGER/LUPO
AVIATION...WM
CLIMATE...MILCAREK
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