-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 181645
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1245 PM EDT TUE JUN 18 2013

.SYNOPSIS...
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP TODAY AS A COLD
FRONT SLIDES ACROSS THE UPPER OHIO VALLEY REGION.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
VERY SLOW MOVING CONVECTIVE ACTIVITY HAS DEVELOPED FROM
SOUTHEASTERN OHIO TOWARD WESTERN MARYLAND LATE THIS MORNING AND
EARLY AFTERNOON AHEAD OF A VERY SLOWLY SOUTHEASTWARD SAGGING
FRONTAL BOUNDARY...THE RIGHT ENTRANCE REGION OF A ROUGHLY 80 KT
UPPER JET STREAM....AND AHEAD OF A WEAK NORTHEASTERLY MOVING VORT
MAXIMA. WITH DECENT MOISTURE IN PLACE AS EVIDENCED BY DEWPOINTS IN
THE MID 60S AND SLOWLY MOVING BUT SIGNIFICANT SYNOPTIC FORCING
COMING INTO PLAY...THE STAGE HAS BEEN SET FOR RELATIVELY SLOWLY-
MOVING CONVECTIVE ACTIVITY ACROSS THE SOUTHERN TIER OF THE
FORECAST AREA THROUGH THE AFTERNOON. AT THE MOMENT...A FLOOD
ADVISORY HAS BEEN ISSUED FOR GARRET/TUCKER/PRESTON COUNTIES TO
COVER MINOR FLOODING ISSUES...BUT TRENDS WILL BE CONTINUOUSLY
MONITORED THROUGH THE AFTERNOON.

OTHERWISE...THE SURFACE FRONT ITSELF CURRENTLY LIES FROM ROUGHLY
COLUMBUS TO ALMOST PITTSBURGH TO NEAR DUBOIS. IN THE AREA BETWEEN
THE CURRENT CONVECTIVE BAND AND THE FRONT...SHOWERS AND
THUNDERSTORMS SHOULD SLOWLY DEVELOP THIS AFTERNOON. THEIR
DEVELOPMENT TO THIS POINT HAS BEEN SLOW DUE TO WEAK INSTABILITY
AND LATE ARRIVING SHEAR VALUES...HOWEVER THE FIRST CELLS ARE
POPPING IN COSHOCTON AND TUSCARAWS COUNTIES AT THE MOMENT...AND IT
WOULD SEEM THIS DEVELOPMENT SHOULD CONTINUE DOWN THE FRONTAL
BOUNDARY THROUGH THE DAY. INSTABILITY IS LIMITED DUE TO ONGOING
CLOUDINESS WITH MODEL SOUNDINGS INDICATING ONLY 500-800
J/KG...HOWEVER THE INCREASE IN SHEAR ALONG THE FRONT THROUGH THE
DAY SHOULD ALLOW FOR SOME DEVELOPMENT.

ANY SEVERE WEATHER TODAY SEEMS TO BE RELEGATED TO POINTS TO THE
WEST OF OUR AREA. ANY CLEARING EVIDENT ON VISIBLE IMAGERY SEEMS TO
STILL BE WEST OF COLUMBUS...WHICH SHOULD KEEP MOST OF OUR AREA
FROM BEING ANYTHING MORE THAN MARGINALLY UNSTABLE. AS SUCH...NO
SEVERE WEATHER SEEMS LIKELY AT THIS POINT.

HIGHS WERE DROPPED A BIT FROM PITTSBURGH TO THE SOUTH AND EAST AS
ONGOING CLOUDINESS AND PRECIPITATION SHOULD KEEP DIURNAL RISES IN
CHECK. FRIES
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
MODELS IN FAIR AGREEMENT WITH TIMING OF FRONT TO MOVE SOUTH OF THE
FORECAST AREA BY TONIGHT. HIGH PRESSURE WILL SETTLE OVER THE REGION AND
KEEP TEMPERATURES COOLER THAN NORMAL WEDNESDAY AND THURSDAY.
WARMER THAN AVERAGE TEMPERATURES WILL FOLLOW ON FRIDAY AS WARM AIR
ADVECTION FROM THE SOUTHWEST BEGINS TO PERSIST.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
WARM AND HUMID CONDITIONS ARE FORECAST INTO EARLY NXT WEEK AS BROAD
RIDGE IS STILL PROJECTED TO BLD OVR THE SRN AND ERN CONUS.  HAVE
USED THE WARMER MOS GUIDANCE ONCE AGAIN FOR THE PD GIVEN CONSISTENT
HT PROGS AS DEPICTED BY GFS AND ECMWF MDLS OVR THE PAST CPL OF DAYS.

CHC/NR CLIMO POPS WERE ALSO INCLUDED THROUGH THE WEEKEND GIVEN THE
INSTABILITY THAT WL ACCOMPANY THE WARMTH AND MSTR...WITH LIMITATIONS
IMPOSED BY MID LVL CAPPING AND DEPENDENCY ON SHRTWV SPPRT ACRS THE
NRN PERIPHERY OF THE RIDGE.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
GENL VFR IS ANTICIPATED THIS MRNG...BUT SCT SHWRS ARE EXPECTED TO
DVLP...AND BECOME MORE WIDESPREAD BY THIS AFTN AS A CDFNT SAGS
ACRS THE UPR OH VALLEY REGION. THE BTR CHC FOR TERMINAL EFFECTS WL
BE FOR PORTS S OF PIT AS HEATING/DESTABILIZATION MAY SPPRT MORE
WIDESPREAD SHWR AND TSTM DVLPMNT IN CONJUNCTION WITH FRONTAL
PROGRESS.

OUTLOOK.../TONIGHT THROUGH SATURDAY/...
RESTRNS ARE PSBL S OF PIT TNGT AS THE CDFNT EXITS...BUT BLDG HIGH
PRES IS EXPD TO PRODUCE GENL VFR FOR THE RMNDR OF THE WEEK.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$