Special Weather Statement, NWS Pittsburgh, PA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
734 PM EDT FRI AUG 3 2012

.SYNOPSIS...
HIGH PRESSURE WILL KEEP MOST OF THE AREA DRY FOR ONE MORE DAY.
SOUTHERLY FLOW AHEAD OF THE NEXT LOW PRESSURE SYSTEM WILL BRING
THE RETURN OF HUMID CONDITIONS AND CHANCES FOR THUNDERSTORMS
THROUGH THE WEEKEND.

&&

.NEAR TERM /THROUGH SATURDAY/...
A BIT OF AN ELEVATED WARM LAYER CONTINUES TO EXIST FROM COLUMBUS
TO PITTSBURGH TO DUBOIS AND NORTHWARD THIS EVENING. AS A
RESULT...NORTH OF THIS AXIS...CONVECTIVE UPDRAFTS SEEMS LIKE THEY
SHOULD BE LESS LIKELY TO SUSTAIN THEMSELVES. SOUTH OF THIS
LINE...SOME AMOUNT OF CONVECTION SEEMS A BIT MORE LIKELY.
INSTABILITY IS FAIRLY PLENTIFUL...HOWEVER ORGANIZATION VIA
VERTICAL SHEAR IS PARTICULARLY WEAK. HOWEVER...DECENT INSTABILITY
AND SOME OUTFLOW BOUNDARIES LITTERED ABOUT THE SOUTHERN AND
EASTERN PORTIONS OF THE FORECAST AREA HAVE ALLOWED FOR A FOCUSING
MECHANISM AROUND WHICH CONVECTIVE UPDRAFTS HAVE FORMED. AS A
RESULT...THE AREA OF ISOLATED SHOWERS/THUNDERSTORMS HAS BEEN
EXPANDED FOR THE EVENING HOURS...GENERALLY TO THE SOUTH AND EAST.
OTHERWISE...CONVECTIVE DEBRIS FROM AN ONGOING MCS TO OUR SOUTHEAST
WILL TRAVERSE THE SOUTHERN TIER OF THE FORECAST AREA
OVERNIGHT...WHILE THE NORTHERN ZONES UP ALONG I-80 SHOULD SEE A
FAIRLY CLEAR NIGHT. FRIES

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
MODELS ARE IN GOOD AGREEMENT THAT THE UPPER LEVEL TROUGH AND COLD
FRONT WILL CROSS OHIO MIDDAY. OUT AHEAD OF THE
FRONT...THUNDERSTORMS MAY BE ONGOING AS SHORTWAVE CROSSES OVER THE
GREAT LAKES. SPC CONTINUES TO CARRY A SLIGHT RISK OF SEVERE
STORMS FOR SUNDAY...AS HAS BEEN THE CASE FOR THE LAST 2 DAYS. STEEP
LOW LEVEL LAPSE RATES...30KTS 0-6KM SHEAR...AND OVER 1500J/KG OF
CAPE CONTINUE TO BE SUGGESTED BY THE MODELS. THIS IS SUFFICIENT TO
MAINTAIN ANY CELLS TO SEVERE LEVELS. THE ONLY LIMITING FACTOR
COULD BE THE CLOUD COVER FROM OVERNIGHT CONVECTION SATURDAY.
STILL...WITH SUCH GREAT MODEL CONFIDENCE WILL MAINTAIN THE LIKELY
POPS THROUGH LATE SUNDAY.

BOTH THE ECMWF AND GFS SUGGEST THE FRONT WILL SLOW AS IT REACHES
THE RIDGES OF WV...SO MAINTAINED CHANCE POPS IN THOSE LOCATIONS
MONDAY AFTERNOON. OTHERWISE HIGH PRESSURE WILL BUILD OVER MUCH OF
THE OHIO VALLEY MONDAY.

MAINTAINED TEMPERATURES NEAR MAV GUIDANCE THROUGH THE PERIOD.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
COLD FRONT WILL BE WELL EAST OF THE AREA MONDAY NIGHT WITH HIGH
PRESSURE BUILDING EAST ACROSS THE REGION INTO TUESDAY. A WEAK
SECONDARY COLD FRONT WILL CROSS REGION WEDNESDAY BUT FOR NOW ONLY
SLIGHT CHANCE POPS AS AVAILABLE MOISTURE AND UPPER LEVEL SUPPORT IN
DOUBT. TIMING OF NEXT FRONT AND RETURN OF DEEPER MOISTURE LATE WEEK
WILL BE DIFFICULT SO STAYED CLOSE TO HPC WITH A DRY FORECAST
THURSDAY AND CHANCE POPS FRIDAY. NEAR NORMAL TEMPERATURES MID WEEK
FOLLOWED BY SLIGHT ABOVE NORMAL TEMPERATURES LATE WEEK.

&&

.AVIATION /00Z FRIDAY THROUGH WEDNESDAY/...
WARM MOIST AIR WILL CONTINUE TO PUSH NORTHWARD AHEAD OF A MID-WEST COLD
FRONT. WIDELY SCATTERED SHOWERS AND STORMS WILL DIMINISH AFTER
SUNSET BUT STORMS WILL BE SCATTERED AGAIN BY LATER SATURDAY
AFTERNOON. SOME FOG TOWARD MORNING ESPECIALLY THOSE TERMINALS
THAT RECEIVED RAIN LATE TODAY LIKE LBE. SOUTHEAST WINDS WILL GO
VARIABLE AFTER SUNSET AND THEN CALM MANY LOCATIONS. SKIES
GENERALLY CLEAR TO SOME SCT CI ACROSS NORTHERN HALF CWA. INCREASE
IN MOISTURE FROM SOUTH OVERNIGHT AND SOME CONVECTIVE CLOUD DEBRIS
...MORE CLOUDS SOUTHERN HALF OF FORECAST AREA.

OUTLOOK...SATURDAY NIGHT THROUGH WEDNESDAY...
SOME SCATTERED STORMS STILL EARLY SATURDAY NIGHT. COLD FRONT
APPROACHES ON SUNDAY WITH RESTRICTIONS IN WIDESPREAD SHOWERS AND
STORMS. HIGH PRESSURE BUILDS ACROSS TERMINALS FOR MONDAY THROUGH
WEDNESDAY WITH GENERAL VFR CONDITIONS.

&&

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

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PITTSBURGH PA
357 AM EDT FRI AUG 3 2012

MDZ001-OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023-
029-031-073>076-WVZ001>004-012-021>023-041-040800-
GARRETT-TUSCARAWAS-CARROLL-COLUMBIANA-COSHOCTON-HARRISON-
JEFFERSON OH-MUSKINGUM-GUERNSEY-BELMONT-NOBLE-MONROE-MERCER-VENANGO-
FOREST-LAWRENCE-BUTLER-CLARION-JEFFERSON PA-BEAVER-ALLEGHENY-
ARMSTRONG-INDIANA-WASHINGTON-GREENE-WESTMORELAND-WESTMORELAND RIDGES-
FAYETTE-FAYETTE RIDGES-HANCOCK-BROOKE-OHIO-MARSHALL-WETZEL-MARION-
MONONGALIA-PRESTON-TUCKER-
357 AM EDT FRI AUG 3 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN MARYLAND...EAST
CENTRAL OHIO...NORTHWEST PENNSYLVANIA...SOUTHWEST
PENNSYLVANIA...WEST CENTRAL PENNSYLVANIA...NORTHERN WEST VIRGINIA
AND NORTHERN PANHANDLE OF WEST VIRGINIA.

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR SUNDAY
AFTERNOON INTO SUNDAY EVENING.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PITTSBURGH PA
658 PM EDT FRI AUG 3 2012

MDZ001-WVZ023-041-040015-
GARRETT MD-PRESTON WV-TUCKER WV-
658 PM EDT FRI AUG 3 2012

...THUNDERSTORMS WITH VERY HEAVY RAIN WILL AFFECT TUCKER COUNTY WEST
VIRGINIA...

AT 653 PM EDT...THUNDERSTORMS WERE ABOUT TO ENTER TUCKER COUNTY FROM
THE SOUTH. THEY WERE MOVING SLOWLY NORTH AT 15 MPH.

HEAVY RAIN WILL POND WATER ON ROADS AND QUICKLY FILL DITCHES AND
SMALL STREAMS.  INTENSE FREQUENT LIGHTNING CAN BE EXPECTED FROM
THESE STORMS. MOVE INDOORS WHEN A THUNDERSTORM APPROACHES. DO NOT
SEEK SHELTER UNDER TREES.

SOME LOCATIONS THAT WILL BE IMPACTED INCLUDE...
  THOMAS...           PARSONS...

PLEASE REPORT SIGNIFICANT WEATHER TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...877-633-6772.

LAT...LON 3897 7951 3903 7978 3908 7978 3913 7984
      3923 7981 3925 7986 3932 7990 3928 7935
      3919 7948 3919 7940 3922 7934 3920 7929
      3909 7935 3907 7929 3897 7933 3896 7935

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PITTSBURGH PA
828 PM EDT FRI AUG 3 2012

PAZ020-021-029-040115-
ALLEGHENY PA-BEAVER PA-WASHINGTON PA-
828 PM EDT FRI AUG 3 2012

...A THUNDERSTORM WILL AFFECT EXTREME SOUTHWESTERN
BEAVER...NORTHWESTERN WASHINGTON AND WEST CENTRAL ALLEGHENY
COUNTIES...

AT 824 PM EDT...A THUNDERSTORM WAS LOCATED 4 MILES NORTH OF
CLAYSVILLE...MOVING NORTH AT 20 MPH.

WIND GUSTS TO 50 MPH ARE POSSIBLE WITH THIS STORM.

SOME LOCATIONS THAT WILL BE IMPACTED INCLUDE...
  AVELLA...             BURGETTSTOWN...
  RACCOON CREEK STATE PARK...                 MOON...
  IMPERIAL...           FLORENCE...

THIS WILL IMPACT THE FOLLOWING HIGHWAYS...

I-376 BETWEEN MILE MARKERS 52 AND 55.
I-70 IN PENNSYLVANIA BETWEEN MILE MARKERS 3 AND 10.

PLEASE REPORT SIGNIFICANT WEATHER TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...877-633-6772.

LAT...LON 4051 8022 4011 8034 4012 8051 4019 8052
      4050 8052