FXUS61 KPBZ 151903
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
203 PM EST TUE DEC 15 2009
.SYNOPSIS...
LOW PRESSURE WILL MOVE NORTHEAST TO EASTERN CANADA BY WEDNESDAY.
COLDER AIR...ALONG WITH SCATTERED LAKE ENHANCED AND UPLAND SNOW
SHOWERS WILL PREVAIL THROUGH MIDWEEK. DRY AND COLD CONDITIONS WILL
PREVAIL FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
COLDER AIR WILL CONTINUE TO WORK ACROSS THE REGION IN THE WAKE
OF A COLD FRONT. UPPER LEVEL LOW PRESSURE WILL CROSS THE GREAT
LAKES TONIGHT...EXITING INTO THE CANADIAN MARITIMES WEDNESDAY.
LAKE ENHANCED/UPSLOPE SNOW SHOWERS WILL DEVELOP TNGT...BUT WITH
DEEP MOISTURE LIMITED...WILL KEEP POPS SCATTERED WITH ACCUMULATIONS
AN INCH OR LESS. FOR PIT SOUTH...ANY SNOW SHOWERS WILL BE ISOLATED
IN COVERAGE WITH NO ACCUMS EXPECTED. SNOW SHOWERS WILL DIMINISH
WEDNESDAY AS HIGH PRESSURE BUILDS IN. TEMPERATURES 5-10 DEGREES
BELOW NORMAL WILL PREVAIL. EXPECT WEST WINDS 10-15 MPH WITH GUSTS
TO 25 MPH THROUGH EARLY THIS EVENING...DIMINISHING SOME OVERNIGHT
AND WEDNESDAY.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
HIGH PRESSURE WILL PREVAIL...WITH ANY RESIDUAL SNOW SHOWERS
ALONG THE I-80 CORRIDOR ENDING WEDNESDAY NIGHT. BELOW NORMAL
TEMPERATURES WILL CONTINUE...WITH ONLY A SLIGHT MODERATION FROM
WEDNESDAYS COLD READINGS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
BLEND OF GEFS AND ECMWF MODEL OUTPUT CONTINUE TO SHOW A COLD UPPER
LOW OVER EASTERN CANADA ROTATING A SHORT WAVE TROUGH SLOWLY THROUGH
THE GREAT LAKES THIS PERIOD. THIS SCENARIO WILL RESULT PERSISTENT
CLOUDS ACROSS THE UPPER OHIO VALLEY AND PERIODS OF INSTABILITY SNOW
SHOWERS ENHANCED BY LAKE AND MOUNTAIN EFFECTS WITH TEMPERATURES
GENERALLY 5-10 DEGF COLDER THAN NORMAL.
&&
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
JUDGING FROM RECENT SURFACE AND RADAR DATA...EXPECT POSTFRONTAL MVFR
STRATOCUMULUS TO LINGER ACROSS THE UPPER OHIO VALLEY INTO WEDNESDAY
AFTERNOON. THERE CAN BE BRIEF DETERIORATIONS TO IFR THROUGH TONIGHT
DURING SCATTERED LATE EFFECT SHOWERS. THE PRECIPITATION TYPE
CHANGING FROM MAINLY RAIN THIS AFTERNOON TO ALL SNOW TONIGHT.
SURFACE WINDS WILL BE FROM THE WEST AND NORTHWEST 10-15 KTS WITH
GUSTS TO 20-25 KTS THROUGH TONIGHT. WINDS WILL TURN MORE WESTERLY
10-15 KTS LATE TONIGHT AND WEDNESDAY.
RECENT NAM MODEL PROFILES SHOW THE MVFR STRATOCUMULUS EITHER LIFTING
TO VFR LEVEL MIDDAY WEDNESDAY AND THEN DISSIPATING BY EVENING.
ENSUING HIGH PRESSURE WILL THEN PROVIDE PREVALENT VFR FOR THE UPPER
OHIO VALLEY THURSDAY AND FRIDAY. THEN BLEND OF GEFS AND ECMWF MODEL
OUTPUT SHOW A COLD UPPER LOW OVER EASTERN CANADA ROTATING A SHORT
WAVE TROUGH SLOWLY THROUGH THE GREAT LAKES THIS WEEKEND. SUCH A
SCENARIO WOULD INDUCE SUBVFR STRATOCUMULUS AND INSTABILITY SNOW
SHOWERS ACROSS THE UPPER OHIO VALLEY FOR THE WEEKEND.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
