-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 080638 AAC
AFDPBZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
138 AM EST SUN DEC 8 2013

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

&&

.NEAR TERM /THROUGH TODAY/...
-- Changed Discussion --
ONLY MINOR CHANGES TO OVERNIGHT PERIOD. INCREASED CLOUD COVER AND
ADJUSTED TEMPS TO LATEST GUIDANCE.

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.

WILL BE ISSUING AN ADVISORY FOR FREEZING RAIN WITH THE NEXT
ISSUANCE.

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.
-- End Changed Discussion --

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
-- Changed Discussion --
EVENTUALLY THE TRANSITION WILL OVERSPREAD MY ENTIRE CWA. WILL
NEED TO CONTINUE THE ADVISORY TONIGHT.

THE PRECIP THAT DOES FALL TONIGHT WILL CONTINUE TO BE LIGHT AS THE
AFOREMENTIONED DRY SLOW WILL COVER 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.
-- End Changed Discussion --


&&

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


&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
VFR WL PREVAIL TNGT WITH HIGH PRES SLIDING OVR THE REGION.
HOWEVER...DETERIORATION TO IFR CAN BE EXPECTED AFTR DAYBREAK AS
RAPIDLY ENCROACHING DISTURBANCE SHUNTS MSTR OVR THE UPR OH REGION.
SYSTEM PCPN IS EXPECTED TO BGN AS LGT SNOW...BUT ADVNG DRY SLOT IS
LIKELY TO SPPRT EVENTUAL FZDZ WITH SUFFCIENT WARM ADVCNT FOR -RA OVR
SRN TERMINALS.

.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.
-- End Changed Discussion --

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
MD...WINTER WEATHER ADVISORY FROM 6 AM THIS MORNING TO 6 AM EST
     MONDAY FOR MDZ001.
OH...NONE.
PA...NONE.
WV...WINTER WEATHER ADVISORY FROM 6 AM THIS MORNING TO 6 AM EST
     MONDAY FOR WVZ023-041.
-- End Changed Discussion --

&&

$$