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Area Forecast Discussion
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000
FXUS61 KPBZ 011115
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
615 AM EST SUN FEB 1 2015

.SYNOPSIS...
LOW PRESSURE WILL BRING WINTRY WEATHER SUNDAY INTO MONDAY WITH
COLD TEMPERATURES FOR TUESDAY MORNING. ANOTHER COLD FRONT FOR THE
WEDNESDAY NIGHT WILL REINFORCE COLD AIR FOR THE LATTER PART OF
THE WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
WARMER TREND IN THE MODELS CONTINUES.  SURFACE LOW TRACKS INTO THE 
OHIO VALLEY LATER TODAY...AND THEN ENE INTO THE CWA BY 12Z MONDAY.  
INITIAL LIGHT BAND OF PRECIP THIS MORNING WILL MAINLY BE IN THE FORM 
OF SNOW.  BEST ACCUMULATION OF AN INCH OR TWO WILL BE SEEN ACROSS 
THE WESTERN CWA.  THIS BAND LIFTS OUT BY THIS AFTERNOON...WITH A DRY 
SLOT THEN ENTERING THE CWA FROM THE SOUTHWEST.  THIS MAY REDUCE 
PRECIP TO DRIZZLE FOR A TIME AS IT ROTATES ACROSS THROUGH THE EARLY 
EVENING.  FIRST OF TWO LOW LEVEL WARM PUNCHES ALSO ARRIVES...WITH 
AREAS SOUTH OF I-70 TURNING TO LIQUID BY 00Z. 

SECOND WARM PUNCH ACCOMPANIES APPROACH OF H850 LOW TONIGHT...WHICH
WILL TRACK ACROSS NORTHERN OHIO TO ERIE BY 12Z MONDAY.  INCREASING 
SW FLOW WILL BRING A RENEWED FEED OF MOISTURE...AND ALSO THE H850 
ZERO LINE TO JUST SOUTH OF I-80.  THUS...SNOW WILL MIX WITH RAIN AND 
FREEZING RAIN...BEFORE TURNING TO ALL RAIN FOR THE MAJORITY OF THE 
CWA BY 06Z MONDAY. SURFACE LOW PASSES NEAR OR JUST SOUTH OF PIT LATE 
TONIGHT...WHICH WILL TURN WINDS TO MORE OF A WESTERLY COMPONENT AND 
START TO BRING COLDER AIR BACK IN.  EXPECT MOST OF OHIO TO TURN BACK 
TO SNOW BY 12Z MONDAY...WITH REST OF CWA FOLLOWING IN QUICK ORDER 
LATER MONDAY MORNING.  POPS DECREASE AS WELL WITH DEEPER MOISTURE 
BEING SHUNTED OFF TO THE EAST.

AFTER COLLABORATION...ELECTED TO DOWNGRADE COLUMBIANA AND BEAVER
COUNTIES TO AN ADVISORY...AND LEFT ALL OTHER HEADLINES INTACT FOR 
NOW.  WILL NOT BE SURPRISED IF A FURTHER NORTHWARD MOVEMENT OF 
WARNINGS/ADVISORIES IS NEEDED LATER TODAY DEPENDING ON EVENTUAL 
STRENGTH OF WARM SURGE.  FOREST/VENANGO/MERCER STILL PICTURED AS 
REMAINING MOSTLY SNOW...ALTHOUGH A BRIEF MIX WILL STILL BE POSSIBLE 
TONIGHT.  WINTRY MIX AND RAIN WILL HOLD BACK ACCUMULATIONS SOUTH OF 
THERE. CL

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/...
DRY SLOT WILL BEGIN PUSHING EAST OF THE CWA LINE BY MON MORNING AS 
WE TRANSITION TO COLD ADVECTION IN THE WAKE OF THE LOW. 12Z MON 
MARKS A GOOD TRANSITION POINT IN THE SYSTEM AS MOST PRECIP WILL HAVE 
FULLY CHANGED OVER TO SNOW AS THE SFC LOW MOVES EAST THROUGH PA. 
STRATIFORM SNOW WILL STILL BE PRESENT THROUGH MID-MORNING AS THE 
MID-LEVEL DEFORMATION BAND EVIDENT ON THE LATEST NAM SWINGS 
THROUGH...DESPITE A STOUT 500MB JET THAT WILL INJECT DRY AIR INTO 
AXIS OF THE UPPER LOW. COPIOUS MOISTURE STILL EXISTS FROM THE SFC TO 
700MB AND REMAINS THROUGH THE EARLY EVENING AS THE BOTTOM DROPS OUT 
ON THE MID-LEVEL TEMPS. 

VERY STRONG CAA WILL BRING 850MB TEMPS DOWN NEARLY 20C IN THE MATTER 
OF 12HRS. THE DENDRITIC GROWTH ZONE WILL DROP LIKE AN ANCHOR TO THE 
SFC ALLOWING EVERY BIT OF MOISTURE TO PRECIPITATE OUT IN THE FORM OF 
SNOW. RAPID COOLING OF THE MID-LEVELS WILL TRANSLATE TO THE SFC 
CAUSING ADDITIONAL PROBLEMS AS SFC TEMPS ARE EXPECTED TO DECREASE 
THROUGH THE DAY. THIS WILL MEAN THAT UNTREATED PAVEMENT SURFACES 
COULD SEE FLASH FREEZING...AND THAT SLICK SPOTS COULD EXIST EVEN IN 
THE ABSENCE OF EARLIER HEAVY SNOW OR MIXED PRECIPITATION.

SNOW SHOWERS IN COLD AIR BEHIND THE UPPER LOW COULD PRODUCE AROUND 
AN INCH OF FLUFFY ACCUMULATION ACROSS MUCH OF THE LOWLAND 
COUNTIES...WITH A LITTLE MORE IN THE RIDGES OF PA/MD/WV AND UP 
NORTH. EXPECTING FLUFFY SNOW SHOWERS TO FINALLY TAPER DOWN TO 
FLURRIES AND THEN FULLY CEASE BY MIDNIGHT MON AS THE MOISTURE DRIES 
UP. TEMPERATURE FORECAST TUES MORNING IS TRICKY...AS SOON AS THE 
COLD AIR ARRIVES...ITS GONE AND WAA BEGINS TO KICK IN BY DAY BREAK 
TUES. WILL REMAIN BELOW GUIDANCE TUES MORNING AS WE DECOUPLE UNDER 
HIGH PRESSURE WITH CLEARING SKIES AND A LINGERING SNOWPACK. CALM 
SFC WINDS MAY PRECLUDE THE NEED FOR A WIND CHILL ADVISORY ALONG THE 
NORTH TUES MORNING...BUT IT WILL BE DOWNRIGHT COLD REGARDLESS.
TAX

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THE TEMPORARY EXODUS OF HIGH PRESSURE MARKS THE BEGINNING OF THE 
EXTENDED AS A WEAK LOW MOVES THROUGH THE SRN GREAT LAKES BY 
MID-WEEK. THIS RELATIVELY DRY SYSTEM SHOULD PRODUCE LIGHT SNOW ALONG 
THE NRN PERIPHERY OF THE CWA WEDS INTO THURS...BUT JUST AS 
IMPORTANT...THE TRAILING COLD FRONT WILL REINFORCE THE UPPER LEVEL 
TROF AS COLD AIR POURS IN TOWARDS THE END OF THE WEEK. HIGH PRESSURE 
WILL ENSURE A DRY START TO THE WEEKEND...BUT ANOTHER LOW IS POISED 
TO IMPACT THE AREA BY NEXT SUN.
TAX

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
INITIAL BAND OF LIGHT SNOW IN PLACE...WITH MOSTLY MVFR CIG AND
IFR VSBY. FKL/DUJ WILL BEGIN TO SNOW SOON. EXPECT THIS BAND TO
LIFT OUT BY MIDDAY. A DRY SLOT MAY IMPACT THE AREA THIS
AFTERNOON...LEADING TO SEVERAL HOURS OF VFR CONDTIONS FOR MANY
TERMINALS. FKL/DUJ SHOULD REMAIN IN THE SNOW FOR THE MOST PARTY
WITH LOW MVFR/IFR. LOW CONFIDENCE FORECAST FOR THE AFTERNOON.
RENEWED MOISTURE PUSH TONIGHT AS SURFACE LOW APPROACHES...WITH ALL
SITES EXPECTED TO DROP DOWN TO IFR AND PERHAPS LIFR. FKL/DUJ WILL
CONTINUE WITH SNOW...WHILE OTHER SITES CHANGE TO RAIN OR HAVE A
PERIOD OF WINTRY MIX. DID NOT INCLUDE ICY PRECIP TYPES
YET...HOPING FOR MORE CLARITY IN FUTURE FORECASTS. COLDER AIR
RETURNS TO ZZV JUST BEFORE THE END OF THE TAF PERIOD...WITH RAIN
CHANGING BACK TO SNOW. CL


OUTLOOK.../MONDAY THROUGH THURSDAY/...
WIDESPREAD RESTRICTIONS CAN BE EXPECTED INTO MONDAY AS A LOW
PRESSURE SYSTEM CROSSES THE REGION. NEXT CHANCE FOR WIDESPREAD
RESTRICTIONS WILL BE WITH A WEDNESDAY COLD FRONT.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...WINTER WEATHER ADVISORY UNTIL NOON EST MONDAY FOR OHZ039>041-
     048>050-057>059.
PA...WINTER WEATHER ADVISORY UNTIL NOON EST MONDAY FOR PAZ020-021-
     029-073-074.
     WINTER STORM WARNING UNTIL NOON EST MONDAY FOR PAZ007>009-
     013>016-022-023.
WV...WINTER WEATHER ADVISORY UNTIL NOON EST MONDAY FOR WVZ001>003.

&&

$$






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