FXUS61 KPBZ 301539
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1039 AM EST MON NOV 30 2009
.SYNOPSIS...
A COLD FRONT HAS EXITED THE REGION THIS MORNING WITH COLDER
TEMPERATURES MOVING ACROSS THE REGION. STEADY RAIN WILL END IN THE
SOUTH AND EAST THIS AFTERNOON FOLLOWED BY SNOW SHOWERS INTO TONIGHT
IN THE COLDER AIR. HIGH PRESSURE WILL PROVIDE A DRY PERIOD FROM
TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING. A LOW PRESSURE SYSTEM
WILL THEN AFFECT THE REGION FOR WEDNESDAY AFTERNOON THROUGH
THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
COLD FRONT NOW WELL SOUTH OF REGION WITH BACK EDGE OF RAIN SHOWERS
SLOWLY EXITING SOUTHEAST QUARTER OF CWA. UPDATE WAS FOR
TEMPERATURES AND POPS TO REFLECT CURRENT RADAR TRENDS AND
TEMPERATURES. WEAK SURFACE RIDGE BUILDS IN TONIGHT WITH SNOW
SHOWERS MAINLY NORTH AND RIDGES.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
COLD ADVECTION COUPLED WITH A SHORT WAVE IN THE 500H TROUGH WILL
LEAD TO SNOW SHOWER ACTIVITY TONIGHT INTO EARLY TUESDAY. THIS
UPPER TROUGH FLATTENS BY TUESDAY AFTERNOON...WITH SURFACE HIGH
PRESSURE BUILDING EAST. SURFACE RIDGING WILL HOLD INTO WEDNESDAY
MORNING. NORTHWARD ADVANCING MOISTURE AHEAD OF AN APPROACHING LOW
WILL THEN BRING RAIN CHANCES IN THE AFTERNOON. WAA AHEAD OF THIS
LOW SHOULD PUSH TEMPS ABOVE AVERAGE INTO THE 50S WEDNESDAY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
PRECIP SHIELD IN ADVANCE OF DEEPENING SURFACE LOW PROGGED TO BE
AROUND TN BY WEDNESDAY EVENING WILL OVERSPREAD THE AREA WEDNESDAY
NIGHT THEN SURFACE LOW MOVES THROUGH OHIO VALLEY THURSDAY. EXACT
TIMING AND PATH OF SURFACE LOW WILL HAVE A BIG IMPACT ON
PRECIPITATION TYPE THURSDAY WITH GFS FASTER TO MOVE SYSTEM NORTH AND
WRAP IN COLD AIR ACROSS REGION. ECMWF IS SLOWER WITH SYSTEM AND COLD
AIR BUT TOOK A MIDDLE OF THE ROAD APPROACH AS WITH EITHER SOLUTION
PRECIP WILL BE ALL SNOW BY LATER THURSDAY. MUCH UNCERTAINTY WILL
REMAIN WITH THIS STORM AND FUTURE FORECASTS WILL LIKELY CHANGE QUITE
A BIT. STRONG COLD ADVECTION BEHIND THIS SYSTEM INTO WEEKEND AND
STAYED CLOSE TO HPC SOLUTION WHICH IS NEARER THE 12Z ECMWF. SNOW
SHOWERS WILL REMAIN INTO THE WEEKEND AS QUITE COLD UPPER TROF OR
CLOSED LOW MOVES ACROSS THE OHIO VALLEY. KEPT TEMPERATURES WELL
BELOW NEW MEX MOS WHICH HAS FLIP FLOPPED FROM PAST COUPLE RUNS.
&&
.AVIATION /16Z MONDAY THROUGH FRIDAY/...
A COLD FRONT WILL PUSH ACROSS THE DISTRICT THIS MORNING. MVFR TO IFR
CEILINGS CAN BE EXPECTED IN THE FRONTAL ZONE AROUND DAYBREAK ALONG
WITH OCCASIONAL MVFR TO IFR VSBY IN SHOWERS. IN THE COLD ADVECTION
BEHIND FRONT CEILINGS WILL SLOWLY IMPROVE FROM WEST TO EAST IN THE
AFTERNOON. COLD NORTHWEST WINDS TONIGHT WILL BRING GENERAL MVFR
CEILINGS AND OCCASIONAL SNOW SHOWERS WITH BRIEF MVFR TO IFR VSBY IN
HEAVIER SNOW SHOWERS.
HIGH PRESSURE BUILDING INTO THE DISTRICT TUESDAY WILL BRING AN END
TO THE SNOW SHOWERS AND PROVIDE VFR CONDITIONS.
HIGH PRESSURE WILL CONTINUE VFR CONDITIONS INTO WEDNESDAY. A
STRONG STORM SYSTEM MOVING NORTHEAST FROM THE DEEP SOUTH WILL BRING
RESTRICTIONS IN MIXED PRECIPITATION LATER WEDNESDAY NIGHT AND
THURSDAY WITH SNOW SHOWERS FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
