-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 111147
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
747 AM EDT TUE MAR 11 2014

.SYNOPSIS...
-- Changed Discussion --
LOW PRESSURE WILL TRACK ACROSS THE UPPER OHIO VALLEY REGION TONIGHT
INTO WEDNESDAY EVENING BRINGING RAIN...SNOW...GUSTY WINDS...AND MUCH
COLDER TEMPERATURES.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
SFC RIDGING SHOULD KEEP DRY WEA ACRS THE RGN TDA...THOUGH MD AND
HIGH LVL CLDS WL INCR THRU THE DAY. TEMPS ARE STARTING OUT
WARM...WITH HIGHS 10-15 ABV AVG EXPD.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
00Z NAM SURFACE LOW TRACK IS ABOUT 100 MILES NORTHWEST OF GFS/ECMWF
CONSENSUS...AND HAVE THEREFORE NOT USED THE NAM IN THIS FORECAST.
STATIONARY FRONT WILL BE DRAPED ACROSS THE REGION THIS
EVENING...WITH MAJORITY OF PRECIPITATION REMAINING FARTHER TO THE
NORTH. PRECIP WILL NOT BEGIN IN EARNEST UNTIL AFTER
MIDNIGHT...WITH BULK OCCURRING WEDNESDAY MORNING. WITH RECENT
MODELS HAVING TRENDED SLIGHTLY FARTHER TO THE NORTHWEST...HAVE
ALSO INCHED UP OVERNIGHT TEMPERATURES AS WELL...ESPECIALLY WITH
SOUTHERLY WINDS CONTINUING THROUGH THE TIME PERIOD. STILL EXPECT
THAT ALL PRECIPITATION WILL START AS RAIN...WITH MIX POSSIBLE
ACROSS THE NORTH LATE TONIGHT AND INTO WEDNESDAY MORNING. THINK
THAT CHANGEOVER TO SNOW MAY NOT OCCUR UNTIL WEDNESDAY AFTERNOON IN
MOST LOCATIONS...ALTHOUGH ONE FLY IN THE OINTMENT IS THAT MODELS
ARE ALSO SHOWING A DRY SLOT PUNCHING INTO THE REGION DURING THE
AFTERNOON HOURS AS WELL. THIS COULD CUT DOWN ON SNOW
ACCUMULATION...AS PRECIPITATION MAY ACTUALLY TRANSITION TO
FREEZING DRIZZLE FOR A COUPLE OF HOURS WITH WARM CLOUD TOP
TEMPERATURES.

ONE UNEXPECTED THREAT MAY BE OF SEVERE WEATHER...ALTHOUGH THE THREAT
APPEARS LIMITED RIGHT NOW. THE SURFACE LOW SHOULD PASS NEAR
MORGANTOWN WEDNESDAY AFTERNOON...AND HIGH-RESOLUTION MODELS INDICATE
THAT THERE COULD BE A LINE OF THUNDERSTORMS EXTENDING SOUTH ALONG
THE COLD FRONT. ALTHOUGH BUOYANCY WILL BE LIMITED...MODERATE
LOW-LEVEL LAPSE RATES AND WIND SHEAR COULD ALLOW FOR SOME
THUNDERSTORMS ACROSS THE SOUTHERN MOST PORTIONS OF THE FORECAST
AREA.

BY LATE AFTERNOON COLD AIR WILL COME ROARING INTO THE
REGION...TURNING ALL PRECIPITATION TO SNOW. CANNOT RULE OUT THE
POSSIBILITY OF A FLASH FREEZE WITH RAINFALL FROM EARLIER IN THE DAY
FREEZING IN PLACE WITH THE RUSH OF COLD AIR. IN ADDITION...VERY
STRONG WINDS UP TO 40 MPH ARE ALSO EXPECTED...AND CANNOT RULE OUT
THE POSSIBILITY OF A WIND ADVISORY BEING NEEDED. TEMPERATURES WILL
PLUMMET WEDNESDAY NIGHT WITH LOWS DROPPING INTO THE SINGLE DIGITS
NEARLY EVERYWHERE. WIND CHILLS WILL APPROACH ADVISORY CRITERIA OF
-10 THURSDAY MORNING NORTH AND SOUTHEAST OF PITTSBURGH.

FOR MOST OF THE FORECAST AREA...DID NOT CHANGE MUCH WHEN IT COMES TO
SNOW TOTALS...ALTHOUGH A LOT OF UNCERTAINTY REMAINS. AT THIS POINT
IT APPEARS THAT THE BULK OF THE PRECIPITATION WILL FALL DURING
WEDNESDAY MORNING WHEN TEMPERATURES WILL SUPPORT RAIN. ALTHOUGH
WEDNESDAY AFTERNOON WOULD BE THE PRIMARY TIME FOR ANY HEAVIER
SNOWFALL...POTENTIAL FOR DRY SLOT AND FREEZING DRIZZLE LIMITS HOW
HIGH TO GO WITH SNOW TOTALS. IN ADDITION...LIQUID PRECIPITATION
EQUIVALENTS SEEM A BIT HIGH CONSIDERING ECMWF/GFS BOTH SHOW AN
OPEN WAVE AT 500MB AND 700MB LOW CLOSING OFF AS THE SYSTEM
DEPARTS. DID BUMP UP SNOWFALL AMOUNTS NORTH OF INTERSTATE 80
DURING AFTERNOON HOURS. UPSLOPE SNOW POTENTIAL WILL BE THE BEST
WEDNESDAY EVENING...BUT INVERSION HEIGHTS WILL DROP QUICKLY AFTER
MIDNIGHT. CURRENT FORECAST THINKING IS STILL 1 TO 3 INCHES OF SNOW
FOR MOST LOCATIONS...WITH 3 TO 6 INCHES POSSIBLE NORTH OF US 422.
THIS WOULD REMAIN BELOW WARNING CRITERIA...AND WITH THERE STILL
BEING A LOT OF UNCERTAINTY...DID NOT FEEL THE NEED TO ISSUE A
WINTER STORM WATCH FOR THE NORTHERN COUNTIES.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
BY THURSDAY MORNING SNOW SHOULD BE LIMITED MOSTLY TO UPSLOPE OR LAKE
EFFECT SNOW...ALTHOUGH ADDITIONAL ACCUMULATION SHOULD BE LIMITED BY
LOW INVERSION HEIGHTS. EVEN AS HIGH PRESSURE RIDGE MOVES IN AND
SKIES CLEAR OUT...TEMPERATURES WILL STILL END UP SOME 20 TO 30
DEGREES BELOW NORMAL. INCREASING CLOUDINESS THURSDAY NIGHT WILL ACT
AS A BIT OF A THERMAL BLANKET AND PREVENT AS COLD A NIGHT AS
WEDNESDAY NIGHT...BUT LOWS FROM THE UPPER SINGLE DIGITS TO THE MID
TEENS WILL REMAIN WELL BELOW NORMAL.

STRONG WAA WILL BRING TEMPS BACK TO NEAR NORMAL FRIDAY...AND THE
WEEKEND WILL START RELATIVELY DRY UNDER HIGH PRESSURE. ANOTHER
COLD FRONT WILL PUSH OUT OF THE GREAT LAKES SAT USHERING IN COLDER
TEMPS AND MIXED PRECIPITATION CHANCES. ALTHOUGH INCONSISTENCIES IN
THE GUIDANCE EXISTS DAY 5 ON...ATTM HIGH PRESSURE LOOKS TO RETURN
FOR THE EARLY PART OF NEXT WEEK. KEPT POP CHCS LOWER THROUGH THIS
PERIOD.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS WILL CONTINUE TODAY UNDER HIGH PRESSURE. WINDS WILL
CONTINUE TO DECREASE BOTH AT THE SFC AND IN THE LOW LEVELS THIS
MORNING...SO LLWS THREAT WILL ALSO DECREASE. EXPECTING MOSTLY HIGH
CLOUDS TODAY THAT WILL THICKEN IN ADVANCE OF THE MID-WEEK SYSTEM.
MVFR CIGS SHOULD BE COMMON WITH RAIN SHOWERS BEGINNING TOWARDS
DAYBREAK WEDS.

.OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/...
RSTRNS ARE PSBL FRI NGT INTO SAT WITH A CROSSING CDFNT.

&&

.HYDROLOGY...
THROUGH WEDNESDAY...THE BREEZY COMBINATION OF WARMTH WITH INCRSG
DEWPOINTS FOLLOWED BY RAIN WL ELIMINATE ANY RMNG SNOW IN THE
RIDGES. WITH THE QPF OF THE WEDNESDAY SYSTEM ON THE ORDER OF
THREE QUARTERS OF AN INCH...ANY FLOOD CONCERNS SHOULD BE
LOCALIZED WITH RISES ON STREAMS AND CREEKS EXPECTED.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$