998
FXUS61 KPBZ 180916
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
416 AM EST SAT JAN 18 2025
SYNOPSIS
RAIN AND SNOW RETURNS TODAY. IMPACTFUL SNOW POSSIBLE FOR THE
HIGHER TERRAIN OF WEST VIRGINIA THIS SUNDAY AND SUNDAY NIGHT,
FOLLOWED BY AN EXTREME COLD OUTBREAK NEXT MONDAY THROUGH
WEDNESDAY. A WARMING TREND IS EXPECTED BY AT LEAST THURSDAY OF
NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- RAIN AND SNOW CHANCES INCREASE OVERNIGHT
- SLIGHT CHANCE OF FREEZING RAIN AT ONSET
- RAIN CONTINUES TODAY, A MIX OF SNOW AND RAIN NORTH OF
PIT/RIDGES
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CURRENT TRENDS SHOWS PRECIPITATION MOVING INTO THE REGION THIS
MORNING. WITH STILL SOME LINGERING 10 TO 15 DEGREE DEW POINT
DEPRESSIONS ACROSS THE AREA. THIS IS EFFECTIVELY KEEPING PRECIP
FROM REACHING THE SURFACE WHILE AIR TEMPERATURES WARM AND
EVENTUALLY, THE ROAD TEMPERATURES. THIS WILL KEEP FZRA LESS OF A
POTENTIAL AND EVEN THE NBM PROBS ARE GIVING A LESS THAN 10%
PROBABILITY OF ANY ACCRUAL OF ICE.
THE LOWER ATMOSPHERE WILL FINALLY BEGIN TO SATURATE BY 12Z WITH
RAIN AND SNOW TO THE NORTH, AND SNOW OVER THE RIDGES PRETTY MUCH
AT ONSET. ANY MIX IN THE SOUTHERN LOWER ELEVATIONS SHOULD
CHANGE TO RAIN SOUTH OF RT 422 BY MID MORNING, WITH SNOW MIXED
WITH RAIN TO THE NORTH. SNOW ACCUMULATION TO THE NORTH SHOULD BE
LIMITED TO LESS THAN AN INCH WITH TEMPERATURES ABOVE FREEZING.
ACCUMULATION OVER THE RIDGES WILL BEGIN BY THIS AFTERNOON. THIS
WILL UNFOLD AS A SURFACE COLD FRONT WILL THEN APPROACH AND
CROSS THE REGION LATE SATURDAY AFTERNOON, CONTINUING THE PRECIP
CHANCES.
SHORT TERM /SUNDAY THROUGH MONDAY/
KEY MESSAGES:
- SLOW COLD FRONT PASSAGE WITH ANOTHER DISTURBANCE RIDING ALONG
THE HIGH TERRAIN.
- WINTER STORM WARNINGS GO INTO EFFECT FOR WV RIDGES.
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AS THE FRONT DIPS ACROSS THE AREA, TEMPERATURES ARE EXPECTED TO
VERY GRADUALLY DECREASE ACROSS THE AREA THROUGH THE PERIOD. THIS
WILL MEAN THAT ALL SNOW WILL BE THE PREDOMINANT PRECIPITATION
TYPE FOR TONIGHT.
THERE HAS BEEN INCREASING CONFIDENCE IN AN IMPACTFUL WINTER
SYSTEM FOR THE WEST VIRGINIA RIDGES AS ANOTHER CYCLONE DEVELOPS
AND MOVES UP THE FRONT, SHOVELING MOISTURE BACK INTO THE COLD
SECTOR OF THE LOW FOR THE HIGH TERRAIN.
FOR NOW, MOST OF THIS SNOW IS EXPECTED TO START TONIGHT WITH
THE HIGHEST RATES SUNDAY MORNING, FOLLOWED BY OROGRAPHIC
ENHANCEMENT IN NORTHWEST FLOW SUNDAY INTO SUNDAY NIGHT. THE
HIGHEST QPF WILL LIKELY FALL IN A DEFORMATION ZONE. CONFIDENCE
IN THERE THIS SETS UP IS QUITE LOW, WITH SOME GUIDANCE PUSHING
INTO THE LOWLANDS A BUT, AND SOME WELL EAST OF THE FORECAST
AREA. BECAUSE MODELS POORLY CAPTURE THIS, TOTALS MAY BE OVERDONE
OUTSIDE OF THE ZONE, AND UNDERDONE WITHIN THE ZONE. FOR
AWARENESS, A WATCH WAS HOISTED FOR THE WV RIDGES WHERE
OROGRAPHIC INFLUENCE IS THE HIGHEST, AND THE HIGHEST
PROBABILITIES (30% TO 50%) OF HEAVY SNOW ARE FORECAST. FROM
START TO END, SNOWFALL RATIOS WILL GO FROM ALMOST 10:1 TO 20:1
AS TEMPERATURES COOL, BECOMING AS LOW AS THE SINGLE DIGITS
MONDAY MORNING. MORE ON THE EXTREME COLD IS INCLUDED IN THE LONG
TERM. FOR THE WORST- CASE SCENARIO (90TH PERCENTILE), 6"+ IS
POSSIBLE FOR THE RIDGES AND 3"+ FOR THE LOWLANDS. ON THE LOW
SIDE, LOW END ADVISORIES OR EVEN LESS THAN 3" ARE POSSIBLE FOR
THE RIDGES, DEPENDING ON STORM TRACK.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
KEY MESSAGES:
- SNOW SHOWERS CONTINUE ON SUNDAY AND MONDAY IN NORTHWEST FLOW.
- ARCTIC OUTBREAK WITH DANGEROUSLY COLD TEMPERATURES AND WIND
CHILLS LIKELY NEXT WEEK.
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EXTREME COLD MONDAY THROUGH WEDNESDAY...
CONFIDENCE HAS INCREASED ENOUGH ON DANGEROUS COLD WITH
SIGNIFICANT IMPACTS TO ISSUE AN EXTREME COLD WATCH. EXTREMELY
LOW TEMPERATURES AND WIND CHILL TEMPERATURES ARE EXPECTED TO
IMPACT THE REGION MONDAY THROUGH WEDNESDAY. ARCTIC AIR WILL DIP
DOWN OUT OF FAR NORTHERN CANADA ACROSS THE EASTERN UNITED STATES
BEGINNING SUNDAY NIGHT.
THE COLD IMPACTS THROUGH AT LEAST WEDNESDAY MORNING REMAIN HIGH
CONFIDENCE. THERE IS HIGH AGREEMENT AMONG ENSEMBLE CLUSTERS OF
THE 500MB HEIGHT AND TEMPERATURE TRENDS OF DEEP TROUGHING ACROSS
THE EASTERN CONUS, DIPPING TEMPERATURES AS LOW AS 35 DEGREES
BELOW NORMAL. LONG-RANGE GUIDANCE (NAEFS) HAS 850MB AND 700MB
TEMPERATURES EARLY NEXT WEEK NEAR THE 1ST PERCENTILE
(TEMPERATURES THIS TIME OF YEAR ARE WARMER THAN THIS 99% OF THE
TIME).
CONFIDENCE HAS INCREASED THAT THE COLDEST DAYTIME HIGH OF THE
PERIOD MAY BE MONDAY (MIDDLE SINGLE DIGITS) WITH THE INITIAL
INTRUSION OR ARCTIC AIR, BUT CLEAR SKIES AND THE POTENTIAL FOR
DECOUPLING AND COLD AIR DRAINAGE OVERNIGHT MEAN THAT THE COLDEST
MORNING MAY BE TUESDAY AND WEDNESDAY MORNING. GIVEN THE COMPLEX
TERRAIN AND MICRO-METEOROLOGICAL COLD AIR DRAINAGE PROCESSES,
LOW TEMPERATURES WILL LIKELY BE VARIABLE ACROSS THE AREA WITH
THE COLDEST POCKETS IN SHELTERED VALLEYS. EXPOSED RIDGE TOPS
MAY BE A BIT WARMER, BUT ALSO EXPOSED TO THE WIND. ALL IN ALL,
LOW TEMPERATURES IN THE HIGH NEGATIVE SINGLE DIGITS AND LOW
NEGATIVE TEENS WITH WIND CHILLS AS LOW AS -25F FOR THE LOWLANDS
AND -30F FOR THE RIDGES.
FORECAST CONFIDENCE DECREASES WEDNESDAY, WITH GEFS DOMINATED
ENSEMBLES SHOWING A BRIEF BOUT OF SHORTWAVE REJOINING BRINGING
TEMPERATURES UP TO THE HIGH 10S, WHILE THE EURO ENSEMBLES HOLD
COLDER WITH CONTINUED HIGHS IN THE SINGLE DIGITS. UNDER THE
SURFACE HIGH, EFFICIENT RADIATIVE COOLING IS STILL EXPECTED TO
DROP WIND CHILL TEMPERATURES CLOSE TO ADVISORY CRITERIA THURSDAY
MORNING. EVEN WITH THE BIMODAL SOLUTION, THE WATCH EXTENDS
THROUGH 15Z TO ACCOUNT FOR ONE MODE AND ALSO THE CUMULATIVE
IMPACTS OF THE EXTREME COLD TO THIS POINT.
THE TIME TO BEGIN PREPARING IS 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. IT
IS ENCOURAGED TO BRING MOVABLE PLANTS INDOORS. EXTREME CARE IS
ENCOURAGED FOR THE PROTECTION OF PETS AND ANIMALS. RESCHEDULING ANY
EVENTS, ESPECIALLY OUTDOOR EVENTS, IS ENCOURAGED.
BY THE END OF NEXT WEEK (THURSDAY, FRIDAY, SATURDAY), THERE IS
STILL HIGH CONFIDENCE THAT RIDGING BUILDS IN AND WARMS HIGH
TEMPERATURES INTO THE LOW 30S AND UPPER 20S WITH LOWS IN THE LOW
20S TO UPPER 10S, WHICH IS STILL A HARE BELOW AVERAGE.
AVIATION /08Z SATURDAY THROUGH WEDNESDAY/
VFR CONDITIONS ARE EXPECTED TO CONTINUE FOR THE BULK OF THE
NIGHT, ALTHOUGH CLOUDS WILL THICKEN AND LOWER WITH TIME AS
MOISTURE ALOFT INCREASES ON SOUTHWEST FLOW. A 40 KNOT LOW-LEVEL
JET ABOVE A SURFACE-BASED INVERSION WILL INTRODUCE LOW-LEVEL
SHEAR CONCERNS THROUGH AROUND 12Z.
PRECIPITATION RETURNS IN EASTERN OHIO BY 09Z AND WILL OVERSPREAD
THE REGION BY MID-MORNING AHEAD OF AN ADVANCING COLD FRONT. HREF
PROBABILITIES SHOW HIGH CONFIDENCE IN AREAWIDE MVFR CONDITIONS
BY 13Z, AND THEN IFR AT MOST TERMINALS BY 16-17Z. MGW MAY BE A
HOLDOUT FOR A BIT WITH LOW-LEVEL SOUTHEAST DOWNSLOPE FLOW, BUT
EVEN THAT AIRPORT IS LIKELY TO SINK TO THE IFR THRESHOLD DURING
THE AFTERNOON. PRECIP TYPE MAY BEGIN BRIEFLY AS SNOW OR A
RAIN/SNOW MIX NORTH OF PIT, BUT ALL RAIN IS EXPECTED BY MIDDAY
WITH MODERATE CONFIDENCE.
THE COLD FRONT SWEEPS ACROSS THE REGION AFTER 18Z, WITH SOME
REDUCTION IN PRECIPITATION COVERAGE, BUT MAINLY IFR CEILINGS ARE
EXPECTED TO LINGER THROUGH SUNSET. LINGERING PRECIPITATION IS
EXPECTED TO CHANGE BACK TO SNOW FROM WEST TO EAST AFTER 21Z OR
SO, DIMINISHING THROUGH THE EVENING.
WIND WILL VEER WITH TIME THROUGH THE TAF PERIOD, FROM S/SE
INITIALLY, TO SW DURING THE SATURDAY DAYLIGHT HOURS, AND FINALLY
TO W AND NW BEHIND THE FRONT.
OUTLOOK...
RESTRICTIONS ARE POSSIBLE IN SNOW THROUGH SUNDAY. A STRONG
ARCTIC FRONT WILL BRING BITTER COLD TEMPERATURES NEAR OR BELOW
ZERO MONDAY MORNING THROUGH WEDNESDAY NIGHT.
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...EXTREME COLD WATCH FROM LATE SUNDAY NIGHT THROUGH THURSDAY
MORNING FOR PAZ007>009-013>016-020>022-029-031-073>078.
OH...EXTREME COLD WATCH FROM LATE SUNDAY NIGHT THROUGH THURSDAY
MORNING FOR OHZ039>041-048>050-057>059-068-069.
WV...EXTREME COLD WATCH FROM LATE SUNDAY NIGHT THROUGH THURSDAY
MORNING FOR WVZ001>004-012-021-509>514.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING
FOR WVZ512>514.
SYNOPSIS...WM/MILCAREK
NEAR TERM...SHALLENBERGER
SHORT TERM...MILCAREK/SHALLENBERGER
LONG TERM...MILCAREK/SHALLENBERGER
AVIATION...RACKLEY/CL
CLIMATE...MILCAREK
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