-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 041923
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
223 PM EST WED MAR 4 2015

.SYNOPSIS...
RAIN AND MIXED PRECIPITATION WILL TURN TO SNOW ACROSS THE ENTIRE
REGION THIS EVENING...WITH SEVERAL INCHES OF SNOW EXPECTED INTO
NORTHERN WEST VIRGINIA. TEMPERATURES WILL BE UNSEASONABLY COLD
INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH THURSDAY/...
HAVE CLEARED ADDITIONAL COUNTIES FROM THE FLOOD WATCH WHERE
FLOODING IS NO LONGER OCCURRING OR EXPECTED AS ADDITIONAL PRECIP
WOULD BE MAINLY SNOW.

COLD AIR ABOVE THE SURFACE CONTINUES TO WORK INTO THE REGION WITH
SNOW REPORTS AT KHLG AND AT KPIT THE LAST COUPLE HOURS. EXPECT
SOME SLEET TO ALSO OCCUR THIS EVENING DURING THE TRANSITION TO
SNOW FROM PITTSBURGH SOUTH INTO THE RIDGES...WITH A BRIEF PERIOD
OF FREEZING RAIN IN THE RIDGES BEFORE PRECIP TURNS TO ALL SNOW.
NOT MUCH CHANGE TO PREVIOUS THINKING ON SNOW AMOUNTS BUT DID LOWER
AMOUNTS A BIT ACROSS THE NORTHERN TIER OF THE ADVISORY AS NEW
MODEL RUNS ARE JUST A BIT FARTHER SOUTH WITH CORE OF DEEP MOISTURE
AND LIFT. NO CHANGES TO PREVIOUS ADVISORIES OR WARNINGS...AS STILL
EXPECT UPPER LEVEL WAVE MOVING ALONG THE STRENGTHENING BAROCLINIC
ZONE TO PRODUCE SIGNIFICANT SNOW ACCUMULATIONS. ONLY CAVEAT IS IF
PRECIP STAYS A MIX OF SLEET ACROSS THE RIDGES LONGER THIS EVENING
AMOUNTS COULD BE HELD DOWN...BUT STILL IN WARNING RANGE.

SNOW WILL BEGIN TO TRANSITION EAST THURSDAY MORNING AND DIMINISH
BY AFTERNOON.

AREAS NORTH OF PITTSBURGH WILL SEE LESSER AMOUNTS AS DEEP MOISTURE
WILL BE LACKING. IMPRESSIVE PUSH OF COLD AIR TONIGHT INTO THURSDAY
WITH LOWS SINGLE DIGITS FAR NORTH TO NEAR 20 FAR SOUTH. LITTLE
TEMPERATURE RECOVERY DURING THE DAY THURSDAY AS CORE OF COLD AIR
AT 850MB TRANSITIONS ACROSS REGION.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
WEATHER PATTERN QUIETS DOWN FOR THE END OF THE WEEK AS A BROAD
AREA OF HIGH SURFACE PRESSURE PUSHES IN FROM THE WEST AND KICKS
OUT THE MID-WEEK SYSTEM. LINGERING LIGHT SNOW SHOWERS WILL
DISSIPATE QUICKLY THURS NIGHT AND SKIES WILL BEGIN CLEARING FROM
THE WEST. REMNANT SKY COVER WILL PLAY A BIG ROLE IN OVERNIGHT LOWS
HEADING INTO FRIDAY MORNING. WITH CALM WINDS AND THE PRESENCE OF A
FRESH SNOW PACK...FOR AT LEAST 1/2 OF THE CWA...ALL SIGNS POINT
TO DECOUPLING OF THE LOWER ATMOSPHERE AND TEMPERATURES BEGINNING
TO CRATER WELL BELOW AVERAGE. MET AND MAV GUIDANCE SHOW AT LEAST SOME
CLOUDS HOLDING IN DURING THE PRE-DAWN HOURS FRI...WHICH WOULD
DISRUPT EFFICIENT RADIATIONAL COOLING. THINK THIS ROUTE IS A BIT
CONSERVATIVE...AND HAVE HELD LOWS BELOW THOSE NUMBERS.

TEMPERATURES WILL WARM UP QUICKLY HEADING INTO THE WEEKEND WITH
DRIER AND CLEARER CONDITIONS EXPECTED. NEXT SYSTEM POISED TO
STREAM NORTH OF THE FORECAST AREA...EMBEDDED IN THE NORTHWEST
UPPER LEVEL FLOW. NAM/ECMWF SEEM TO HAVE THE BEST HANDLE ON THIS
RELATIVELY DRY SYSTEM...AND THEREFORE FOLLOWED THIS TO INTRODUCE
LIGHT SNOW SATURDAY EVENING.
TAX

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THE LONG TERM PERIOD LOOKS RELATIVELY QUIET WITH A PROGRESSIVE
PATTERN FEATURING PASSAGE OF A COUPLE OF SHORTWAVE TROUGHS. POPS
WERE FORECAST GENERALLY BELOW CHANCE CLIMO NUMBERS USING GFS
TIMING...BUT LONG TERM CONFIDENCE IS MINIMAL WITH DOUBTS ABOUT
TIMING AND MOISTURE SUPPLY. SEASONALLY COOL TEMPERATURES WERE
FORECAST VIA PERSISTENCE AND MOS.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
LOW MVFR/IFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE NIGHT AS
COPIOUS MOISTURE FLOWS NORTH AND GENERATES PRECIPITATION ALONG A
STATIONARY BOUNDARY. FOR TERMINALS NORTH AND WEST OF
LBE/MGW...SNOW WILL BE PRECIPITATION TYPE THROUGH THE DURATION OF
THE EVENT. AT LBE/MGW CURRENT RAIN WILL GRADUALLY TRANSITION TO
SNOW THIS EVENING AND REMAIN SNOW THROUGH THE NIGHT. MODERATE TO
HEAVY SNOW BANDING TONIGHT COULD RESULT IN LIFR
CONDITIONS...ESPECIALLY FOR SOUTHERN TERMINALS. FAR NORTHERN
TERMINALS SHOULD STAY OUT OF THE MODERATE SNOW...BUT MVFR/IFR
SHOULD HOLD THROUGH THE NIGHT. WITH LOW CIGS.

GRADUAL IMPROVEMENT AFTER DAYBREAK FROM WEST TO EAST.
TAX

.OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
RESTRICTIONS ARE POSSIBLE WITH A SATURDAY NIGHT/SUNDAY MORNING COLD
FRONT.

&&

.HYDROLOGY...
THE COMBINATION OF SNOW MELT AND DEVELOPING RAIN IS EXPECTED TO
CAUSE SIGNIFICANT RISES ON THE CHEAT... MONONGAHELA AND
YOUGHIOGHENY RIVER BASINS. THESE RISES WILL AID IN MOVING ICE INTO
AREAS WHERE ICE JAMS ARE KNOWN TO DEVELOP. THE RISES WILL MOST
LIKELY PERSIST THROUGH THURSDAY. CONFIDENCE IN RAIN AMOUNTS
REMAINS LOW...BUT THE BETTER CHANCE FOR MORE SIGNIFICANT
ACCUMULATION IS EXPECTED TO BE ALONG AND SOUTH OF A ZANESVILLE TO
LATROBE LINE.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...FLOOD WATCH UNTIL 7 PM EST THIS EVENING FOR MDZ001.
     WINTER STORM WARNING UNTIL 4 PM EST THURSDAY FOR MDZ001.
OH...WINTER WEATHER ADVISORY UNTIL 4 PM EST THURSDAY FOR OHZ049-050-
     057>059-068.
     FLOOD WATCH UNTIL 7 PM EST THIS EVENING FOR OHZ059-068-069.
     WINTER STORM WARNING UNTIL 4 PM EST THURSDAY FOR OHZ069.
PA...WINTER WEATHER ADVISORY UNTIL 4 PM EST THURSDAY FOR PAZ021-023-
     029-031-073>075.
     FLOOD WATCH UNTIL 7 PM EST THIS EVENING FOR PAZ029-031-073>076.
     WINTER STORM WARNING UNTIL 4 PM EST THURSDAY FOR PAZ076.
WV...WINTER WEATHER ADVISORY UNTIL 4 PM EST THURSDAY FOR WVZ001>004.
     FLOOD WATCH UNTIL 7 PM EST THIS EVENING FOR WVZ001>004-012-
     021>023-041.
     WINTER STORM WARNING UNTIL 4 PM EST THURSDAY FOR WVZ012-
     021>023-041.

&&

$$