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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 081505
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1005 AM EST SUN DEC 8 2013

.SYNOPSIS...
A WINTRY MIX WILL SLOWLY OVERSPREAD THE AREA TODAY AND TONIGHT BEFORE
CHANGING TO ALL RAIN MONDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MRNG UPDT TO INCR SNW ACCUMS ACRS TUCKER...GARRETT AND PRESTON
COUNTIES TO 2-4 INCHES AS A BAND OF HEAVIER SNW AFFECTS THAT RGN
THIS MRNG. STLT/RADAR TRENDS AND NR TERM MDL PROGS INDICATE THE
HEAVIEST PCPN SHOULD STAY JUST TO THE S OF OUR FCST AREA. NO OTHER
CHGS MADE ATTM.

PREVIOUS...RATHER COMPLICATED SETUP FOR TODAY. MOISTURE...ON THE
NORTHERN SIDE OF MID-ATLANTIC WARM FRONT...WILL SLOWLY SPREAD
NORTHWARD TODAY. ALL THE PRECIPITATION WILL BEGIN AS SNOW...AS
TEMPERATURES THROUGHOUT THE ENTIRE ATMOSPHERIC COLUMN REMAIN BELOW
0C. HOWEVER...AS THE FRONT APPROACHES...STRONG WAA ALOFT WILL
ENSUE. THIS WILL SETUP A SITUATION WHERE TEMPERATURES IN THE CLOUD
LAYER WILL BE WARMER THEN TEMPERATURES AT THE SURFACE. AS THESE
WARMER TEMPS ALOFT ENTER THE REGION A CHANGE IN PRECIP TYPE WILL
BEGIN TO OCCUR FROM SOUTH TO NORTH. THE TRANSITION WILL GO FROM
SNOW TO SLEET TO FREEZING RAIN. THERE ARE OTHER COMPLICATIONS AS
WELL. THE MODELS ARE SHOWING A PRONOUNCED MID-LEVEL DRY SLOT
DEVELOPING THIS AFTERNOON...ADDITIONALLY MOST OF THE UPPER LEVEL
ENERGY WILL SWING EASTWARD TOWARD THE COAST LATER THIS MORNING.
THIS WOULD INDICATE THAT EVEN THOUGH IT WILL BE PRECIPITATING AT
ALL LOCATIONS TODAY...THE AMOUNT THAT FALLS WILL BE LIGHT. THE
EXCEPTION TO THIS WOULD BE IN THE RIDGES AND AREAS JUST TO THE
WEST OF THE HIGHER ELEVATIONS...AS THEY WILL REMAIN AWAY FROM THE
INFLUENCES OF THE DRY SLOT THE LONGEST AND WILL TAP INTO MORE OF
THE MOISTURE BEFORE IT SHIFTS EASTWARD.

SO THE REAL PROBLEM ARISES BECAUSE TEMPS AT THE SURFACE WILL WORK
VERY HARD TO STAY BELOW FREEZING. MODELS ARE IN GOOD AGREEMENT
THAT IT WILL TAKE ALL DAY FOR SURFACE TEMPS IN THE FAR SOUTH TO
FINALLY RISE ABOVE 32.

HAVE ISSUED AN ADVISORY FOR SNOW...SLEET AND FREEZING RAIN FOR ALL
COUNTIES.

FIRST QUESTION WILL BE HOW MUCH SNOW. GENERALLY AN INCH OR LESS
LOOKS LIKE A GOOD PLACE TO START. WILL NUDGE THAT A BIT HIGHER
OVER COUNTIES NEAR THE MASON-DIXON LINE AND IN THE RIDGES.

WILL CONTINUE WITH PREVIOUS FORECAST OF KEEPING THE HIGHEST ICE
ACCUMULATIONS OVER THE RIDGES...WITH MUCH LIGHTER AMOUNTS IN THE
LOW LANDS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
EVENTUALLY THE TRANSITION WILL OVERSPREAD ENTIRE CWA. WILL CONTINUE
THE ADVISORY TONIGHT.

THE PRECIP THAT DOES FALL TONIGHT WILL CONTINUE TO BE LIGHT AS THE
AFOREMENTIONED DRY SLOT COVERS THE ENTIRE REGION. WITH THE LOSS OF
MOISTURE ALOFT AND THUS ICE CRYSTALS...IT MAY MEAN THAT RATHER
THEN LIGHT FREEZING RAIN...WE MAY SEE FREEZING DRIZZLE. INTENSITY
ASIDE...TEMPS WILL STILL BE BELOW 32...AND ANYTHING THAT DOES
FALL...WILL FREEZE WHEN IT CONTACTS THE GROUND.

MODELS CONTINUE TO BE IN GOOD AGREEMENT WITH TEMPS TONIGHT...
INDICATING IT WILL TAKE ALL NIGHT FOR THE WARMER SURFACE TEMPS TO
FINALLY REACH MY NORTHERN MOST COUNTIES.

BY MONDAY MORNING...EXPECT ALL LOCATIONS TO BE RAIN. COLD FRONT
WILL SWING THROUGH DURING THE MORNING...EVENTUALLY ENDING THE
SHOWERS.

CAA WILL FOLLOW THE EXITING FRONT LATER MONDAY.

A WEAK UPPER LEVEL DISTURBANCE WILL SWING THROUGH THE MID-ATLANTIC
STATES TUESDAY...BRINGING ANOTHER CHANCE FOR SNOW SHOWERS.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MUCH COLDER AIR WILL SETTLE IN FOR MOST OF THE LONG TERM...
ALTHOUGH IT DOES APPEAR THAT AN OVERALL DRY PATTERN WILL DEVELOP.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
IFR IN SNOW AT TIMES THIS AT KMGW IS WITH LEADING EDGE OF WARM
ADVECTION AND WILL SHIFT TOWARD THE SOUTHEAST RIDGES BY 17Z. BEHIND
THIS FIRST BATCH OF IFR IS A WIDER BAND OF SNOW AND SLEET ACROSS KY
AND WV LOOKS TO STAY SOUTH OF TERMINALS. ELSEWHERE ONLY PATCHY LIGHT
SNOW THIS MORNING SHOULD BECOME MORE WIDESPREAD WITH IFR CIGS
DEVELOPING ALL PORTS BY LATE AFTERNOON. BY SUNSET EXPECT PRECIP TO
TRANSITION TO FREEZING DRIZZLE WHICH WILL CONTINUE OVERNIGHT FROM
PITTSBURGH NORTH. TEMPERATURES WILL RISE TO ALLOW PLAIN RAIN AT KMGW
LATER THIS EVENING.

.OUTLOOK.../MONDAY THROUGH THURSDAY/...
PCPN IS EXPECTED TO CHANGE TO ALL LGT RAIN OR DZ BY DAYBREAK
MONDAY...BUT RESTRICTIONS INCLUDING IFR ARE UNTIL A STRNG CDFNT
SWEEPS THE REGION ON MONDAY NGT. GENERAL VFR EXPECTED INTO MID WEEK.
-- End Changed Discussion --

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY UNTIL 6 AM EST MONDAY FOR MDZ001.
OH...WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR OHZ039>041-
     048>050-057>059-068-069.
PA...WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR PAZ020-021-
     029-031-073-075.
     WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM EST
     MONDAY FOR PAZ007>009-013>016-022-023.
     WINTER WEATHER ADVISORY UNTIL 6 AM EST MONDAY FOR PAZ074-076.
WV...WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR WVZ001>004-
     012-021-022.
     WINTER WEATHER ADVISORY UNTIL 6 AM EST MONDAY FOR WVZ023-041.

&&

$$