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Area Forecast Discussion
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000
FXUS61 KPBZ 240947
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
431 AM EST MON NOV 24 2014

.SYNOPSIS...
GUSTY WINDS TODAY WILL BE FOLLOWED BY A COLD FRONT AND A RETURN
TO MUCH COLDER CONDITIONS FOR THE REMAINDER OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
A FAIRLY STARK DRY SLOT IS EVIDENT ON SATELLITE IMAGERY
FOLLOWING THE SPRAWLING UPPER LOW THAT IS MOVING INTO THE CENTRAL
GREAT LAKES EARLY THIS MORNING. WIND GUSTS HAVE MANAGED TO MIX
DOWN IN THE SUBSIDENCE IN THIS FEATURE VIA A FAIRLY DISCERNIBLE
TROPOPAUSE FOLD OVERNIGHT ON THE ORDER OF 20-30 KTS. LUCKILY
ENOUGH...THE BEST SUBSIDENCE AND DEEPEST PV PENETRATION INTO THE
LOWER ATMOSPHERE HAS ALREADY CROSSED OUR AREA...SO FOR THE
MOMENT...WIND GUSTS HAVE TEMPORARILY PEAKED WITHOUT INCIDENT
ACROSS THE AREA.  

YET ANOTHER UPPER LOW IS POISED TO TRAVERSE THE CENTRAL GREAT
LAKES BY AFTERNOON. THE UPPER PV FIELD WILL AGAIN BE CONTORTED BY
THIS FEATURE AS YET ANOTHER INTRUSION OF HIGH PV AIR IS SET TO
DROP THE DYNAMIC TROPOPAUSE GREATLY BY AFTERNOON OVER CENTRAL AND
NORTHERN OHIO. THIS IS WELL DEPICTED ON MODEL CROSS SECTIONS VIA
A VERY DEEP TROPOPAUSE FOLD THAT IS PULLING THE 1.5 PVU SURFACE
DOWN TOWARD AND BELOW 600 MB ON MOST GUIDANCE. SUBSIDENCE BRINGING
THIS FEATURE DOWNWARD COMBINED WITH 55-70 KTS OF AVAILABLE
MOMENTUM WILL LIKELY ALLOW FOR WIND GUSTS IN EXCESS OF 60 MPH IN
PORTIONS OF CENTRAL AND NORTHERN OHIO. HOWEVER...FARTHER TO THE
SOUTH AN EAST ACROSS EASTERN OHIO AND THE REMAINDER OF OUR
FORECAST AREA...A WEAKER FIELD OF MOMENTUM AND LESS POTENT
MECHANISM FOR DOWNWARD MOMENTUM TRANSFER SEEM LIKELY TO ALLOW FOR
OUR GUSTS TO TOP OUT AROUND 50 MPH. THIS PUTS US JUST A BIT SHY OF
THE CRITERIA FOR A HIGH WIND WARNING...WHICH JIVES VERY WELL WITH
THE PREVIOUS FORECAST. AS SUCH...WIND ADVISORIES WILL CONTINUE FOR
ALL PORTIONS OF THE AREA. IF ANYWHERE IS TO OVERACHIEVE AN
ADVISORY...IT WILL LIKELY BE OUR WESTERNMOST OHIO COUNTIES OR EVEN
MERCER COUNTY AS THE HIGHEST AVAILABLE MOMENTUM VALUES ARE IN THE
AFOREMENTIONED AREAS DURING MID-AFTERNOON.

WINDS WILL LIKELY TAKE A WHILE TO SLOWLY TAPER OFF THIS EVENING
WITH SOME LESSER GUSTS CONTINUING INTO THE OVERNIGHT PERIOD.
HOWEVER...THE BIGGER STORY WILL LIKELY BE THE THERMAL ROLLER
COASTER. WITH EXTREMELY STRONG MIXING AND SUBSIDENCE THIS
AFTERNOON ALONG WITH 850 MB TEMPERATURES ON THE ORDER OF +8 TO
+10C WITH A FULLY MIXED BOUNDARY LAYER...SOME 70S WILL CERTAINLY
BE POSSIBLE SOUTH AND EAST OF PITTSBURGH...PARTICULARLY WITH A FEW
SUN BREAKS. HOWEVER...A COLD FRONT RIPS THROUGH IN ASSOCIATION
WITH THE STRONGEST WIND GUSTS LATE IN THE AFTERNOON. THIS WILL
DROP 850 MB TEMPERATURES INTO THE -4 TO -8C RANGE BY THE OVERNIGHT
HOURS. THIS WILL LIKELY DROP SURFACE TEMPERATURES AROUND 35
DEGREES FROM TODAY'S HIGHS TO TONIGHT'S LOWS AND RETURN US TO OUR
RECENT COLDER THAN NORMAL TEMPERATURES AFTER A VERY WARM MONDAY.
FRIES 

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
TUES MORNING FLOW REMAINS FROM THE SW...BUT A STOUT INVERSION 
PROGGED AT H85 WILL HOLD LLVL MOISTURE IN THROUGH AT LEAST MIDDAY. 
THIS WILL KEEP CLOUDS HOLDING STEADY THROUGH THE DAY. H85 TEMPS IN 
THE -4C TO -6C RANGE STEEPENS LAPSE RATES IN THE BL ENOUGH TO 
GENERATE SOME LIGHT SHOWER ACTIVITY. KEEPING POPS MAINLY ALONG AND 
NORTH OF I-80 DURING THIS TIMEFRAME. 

BRIEF RESPITE FROM DISTURBED WEATHER TUES EVENING...BUT THE NEXT 
SYSTEM ARRIVES WEDS MORNING...WITH THE POTENTIAL TO DISRUPT HOLIDAY 
TRAVEL...ESPECIALLY FOR THOSE HEADED EAST. A DEVELOPING COASTAL LOW WILL 
TRACK NORTH THROUGH THE MID-ATLANTIC WEDS WITH THE WRN EXTENT OF THE 
PRECIPITATION SHIELD REACHING SOMEWHERE BETWEEN THE ERN SLOPES OF 
THE APPALACHIANS TO THE OHIO VALLEY. EXACT PLACEMENT AND AMOUNTS OF 
PRECIPITATION DEPEND ON THE INTERACTION WITH A CLIPPER-TYPE 
SYSTEM MOVING OUT OF THE NRN PLAINS. ATTM MODEL SOLNS STILL VARY 
GREATLY WITH THE NAM BRINGING THE PLAINS SHORTWAVE IN  
QUICKER...ULTIMATELY PUSHING THE COASTAL LOW EAST OF THE 
AREA....HOLDING ALL PRECIPITATION ASSOCIATED WITH IT OUT OF OUR 
RIDGES. THE 00Z ECMWF IS ON THE OPPOSITE END OF THE SPECTRUM 
ALLOWING THE LOW TO TRACK FURTHER WEST WITH PRECIPITATION SPREADING 
WEST TO AT LEAST THE OHIO BORDER. WITH THIS MUCH SPREAD...DECIDED TO 
HOLD ONTO THE SREF AS GUIDANCE...WHICH IS A DECENT COMPROMISE. POPS 
WERE EXPANDED WESTWARD...HOWEVER...TO SHOW AT LEAST A CHANCE OF 
PRECIPITATION GETTING WEST OF THE RIDGES. 

COMPLICATING MATTERS FOR THE MID-WEEK SYSTEM WILL BE TEMPS HOVERING 
NEAR OR ABOVE FREEZING FOR LOCATIONS RECEIVING PRECIPITATION. 
ATTM...OPTED FOR A MAV/MOS BLEND FOR HIGHS WEDS...AND APPLIED A 
LIBERAL RAIN/SNOW DELINEATION...GIVEN THE FAIRLY COLD AIR ALOFT AND 
A RELATIVELY SHALLOW WARM LAYER NEAR THE SFC. ALL TOLD...THROUGH 
EARLY THANKSGIVING MORNING...BETWEEN THE COASTAL LOW AND THE 
CLIPPER...HAVE LIGHT SNOW ACCUMULATIONS FOR THE RIDGES AND LITTLE TO 
NO SNOW ACCUMULATION ACROSS THE LOWER ELEVATIONS WEST. FOR 
REFERENCE...THE GFS...WHICH HOLDS A SIMILAR TRACK TO THE 00Z ECMWF 
MODEL MENTIONED ABOVE...GENERATES AROUND 6" IN THE HIGHEST 
ELEVATIONS THROUGH WEDS NIGHT. 
TAX

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
NORTHWEST FLOW AND REMNANT MOISTURE FROM THE EXITING MID-WEEK SYSTEM 
WILL PRODUCE SNOW SHOWERS THANKSGIVING NIGHT...ENHANCED JUST 
DOWNWIND OF LAKE ERIE AND IN THE UPSLOPE REGIONS OF OUR SE RIDGES. 
THESE SHOWERS SHOULD QUICKLY TAPER OFF EARLY FRI...HOWEVER...AS 
SUBSIDENCE OCCURS WITH HIGH PRESSURE MOVING IN FROM THE WEST. THIS 
WILL EFFECTIVELY LOWER INVERSION HEIGHTS AND CHOKE OUT THE REMAINING 
BL MOISTURE BY LATE FRI MORNING.

FROM THAT POINT THE EXTENDED PERIOD GETS A LITTLE TRICKY AS MODEL 
GUIDANCE DIVERGES GREATLY. PRIMARILY STUCK CLOSE TO WPC GUIDANCE 
BASED HEAVILY ON THE OPERATIONAL GFS. THIS BRIEFLY HOLDS THE SFC 
HIGH OVER THE AREA INTO THE EARLY PART OF THE WEEKEND BEFORE AN 
UPPER TROF PROPELS A SFC LOW PRESSURE SYSTEM THROUGH THE NRN GREAT 
LAKES. THE ASSOCIATED MOISTURE-STARVED COLD FRONT WILL STREAM ACROSS 
THE FORECAST AREA SUN RESULTING IN SOME SHOWERS. RAISED TEMPS AHEAD 
OF THE FRONT WHICH MEANS THAT RAIN AND RAIN/SNOW COME INTO 
PLAY...BUT ANY QPF ASSOCIATED LOOKS LIGHT. 
TAX

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
AREA OF STRATIFORM RAIN WITH MAINLY VFR CONDITIONS ADVANCING
TOWARD ONLY THE MOST NORTHERN TAF SITES AT THIS HOUR. A LARGE
SCALE DRY SLOT FOLLOWS IT WITH WINDS GUSTING AND TURNING A BIT
MORE SOUTHERLY. BEHIND THIS DRY SLOT...STRATUS IS ADVANCING
NORTHEASTWARD AND WILL LIKELY COME OVER MOST SITES IN THE WITHIN
THE NEXT FEW HOURS. GUSTY SOUTH TO SOUTHWEST WINDS WILL FOLLOW BY
AFTERNOON AS STRATUS SCOURS OUT. WIND GUSTS OVER 40 KTS WILL BE
POSSIBLE AT ALL SITES. FRIES


OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/...
POSSIBLE RESTRICTIONS IN SNOW SHOWERS LATE WEDNESDAY THROUGH
THURSDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WIND ADVISORY FROM 11 AM THIS MORNING TO 10 PM EST THIS 
     EVENING FOR MDZ001.
OH...WIND ADVISORY FROM 11 AM THIS MORNING TO 10 PM EST THIS 
     EVENING FOR OHZ039>041-048>050-057>059-068-069.
PA...WIND ADVISORY FROM 11 AM THIS MORNING TO 10 PM EST THIS 
     EVENING FOR PAZ007>009-013>016-020>023-029-031-073>076.
WV...WIND ADVISORY FROM 11 AM THIS MORNING TO 10 PM EST THIS 
     EVENING FOR WVZ001>004-012-021>023-041.

&&

$$









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