FXUS61 KPBZ 290228
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
928 PM EST SAT NOV 28 2009
.SYNOPSIS...
A COLD FRONT COMING FROM WISCONSIN WILL BRING RAIN SHOWERS LATE SUNDAY
AND MONDAY WITH POSSIBLY LIGHT SNOW SHOWERS LATE MONDAY NIGHT.
&&
.NEAR TERM /THROUGH SUNDAY/...
BLEND OF RECENT SATELLITE AND SURFACE DATA ALONG WITH SREF MODEL
OUTPUT CONTINUES TO SHOW RELATIVELY CLOUD FREE CONDITIONS ACROSS
THE UPPER OHIO VALLEY TONIGHT AND SUNDAY MORNING. THEN AS A COLD
FRONTAL SYSTEM COMING FROM WISCONSIN GETS CLOSER...EXPECT INCREASING
CLOUDS FROM THE WEST AND POSSIBLY SHOWERS IN EAST CENTRAL OHIO BY
LATE SUNDAY AFTERNOON.
CONTINUED TO FORECAST TEMPERATURES COLDER THAN GFS AND NAM MOS
VALUES TONIGHT DUE TO THE EXPECTED INCREASED RADIATIONAL COOLING.
HOWEVER FOR DAYTIME SUNDAY WENT ALONG WITH THE IDEA OF PREFRONTAL
SOUTHWEST WINDS PROVIDING A DISTINCT WARM UP WITH HIGHS CLOSE TO
GFS MOS VALUES.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
JUDGING FROM RECENT SREF MODEL OUTPUT CONTINUE TO EXPECT BULK OF
THE COLD FRONTAL SHOWERS TO MOVE THROUGH THE UPPER OHIO VALLEY
LATE MONDAY NIGHT AND TUESDAY MORNING. POST SYSTEM NORTHWEST WINDS
MAY PROVIDE SUFFICIENT LAKE ENHANCED INSTABILITY TO MAINTAIN
SCATTERED RAIN SHOWERS MONDAY AFTERNOON AND EVENING...AND WITH
TEMPERATURES COOLING INTO THE LOWER 30S...PERHAPS SCATTERED SNOW
SHOWERS MONDAY NIGHT INTO TUESDAY MORNING.
FOR RAIN AMOUNTS...USED HPC IDEA FOR FRONTAL SHOWER BAND
PROVIDING 6-HOUR RAIN AMOUNTS NEAR 0.20-0.30 MONDAY MORNING.
BASED TEMPERATURES ON BLEND OF GFS AND NAM MOS VALUES WHICH
SUGGESTED SURFACE LAYER COLD ENOUGH FOR SNOW SHOWERS MONDAY NIGHT.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
INTERESTING PATTERN FOR MID TO LATE WEEK WITH SOUTHERN STREAM ENERGY
KICKING OUT IN ADVANCE OF NORTHERN STREAM TROF DIGGING INTO THE
GREAT LAKES. NOT THAT FAR OFF OF HPC PROGS ALTHOUGH DID GO A BIT
COLDER FOR THURSDAY AND BROUGHT THE PRECIP SWITCH OVER TO SNOW BY
LATE DAY. LATEST ECMWF AND GFS LOOKING COLDER FOR LATE WEEK INTO
NEXT WEEKEND AND WENT NEAR OR A BIT BELOW HPC GUIDANCE.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
EXPECT VFR INTO SUNDAY AFTERNOON. THE A COLD FRONTAL SYSTEM
COMING FROM WISCONSIN WILL BRING SUB-VFR CONDITIONS WITH
PRECIPITATION SUNDAY NIGHT INTO TUESDAY MORNING. MOST OF THIS TIME
EXPECT MVFR CONDITIONS...BUT THERE CAN BE PERIODS OF IFR WITH THE
BAND OF SHOWERS ACCOMPANYING THE COLD FRONTAL PASSAGE LATE SUNDAY
NIGHT AND MONDAY MORNING AND AGAIN WITH SCATTERED LAKE EFFECT AND
OROGRAPHICALLY-ENHANCED SNOW SHOWERS MONDAY NIGHT.
SURFACE WINDS WILL BE FROM THE SOUTH NEAR 5 KTS TONIGHT AND THEN
BECOME SOUTHWEST 10 TO 20 KTS DAYTIME SUNDAY.
AFTER VFR TUESDAY...THERE CAN BE ANOTHER PERIOD OF REDUCED
CONDITIONS WEDNESDAY AND THURSDAY DUE TO PRECIPITATION ASSOCIATED
WITH A LOW PRESSURE SYSTEM MOVING NORTHEASTWARD ALONG THE EAST COAST.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
