Area Forecast Discussion
Issued by NWS Cleveland, OH

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000
FXUS61 KCLE 311132
AFDCLE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CLEVELAND OH
732 AM EDT FRI JUL 31 2015

.SYNOPSIS...
HIGH PRESSURE REMAINS OVER THE OHIO VALLEY WITH A TROUGH
OVER EASTERN CANADA. A WEAK FRONT WILL SINK SOUTH ACROSS THE AREA
THIS EVENING. HIGH PRESSURE WILL EXPAND OVER THE LOWER LAKES REGION
ON SATURDAY...SHIFTING TO THE EAST ON SUNDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
ONLY MINOR TWEAKS TO HOURLY TEMPS/DEWPOINTS OVER THE NEXT FEW
HOURS WITH THE EARLY MORNING UPDATE.

FORECAST CHALLENGE FOR TODAY REVOLVES AROUND CHANCES OF SHOWERS AND
THUNDERSTORMS FOR LATE AFTERNOON INTO THIS EVENING AS A WEAK FRONT
MOVES SOUTHEAST ACROSS THE AREA. THE AIRMASS IS STARTING OFF DRY
THIS MORNING AS EVIDENCED BY SURROUNDING 00Z SOUNDINGS AND LARGE
SWATH OF DRY AIR SEEN ON WATER VAPOR IMAGERY. WEAK SURFACE PRESSURE
FALLS ARE NOTED EARLY THIS MORNING ACROSS THE UPPER MIDWEST AHEAD OF
A SERIES OF SHORTWAVES SLIDING SOUTHEAST OUT OF CANADA. THIS WEAK
FRONT WILL APPROACH WESTERN LAKE ERIE AND NORTHWEST OHIO BY
21Z...PASSING EAST OF THE FORECAST AREA AFTER MIDNIGHT. MOISTURE
WILL TRY TO INCREASE AHEAD OF THE FRONT WITH DEWPOINTS SNEAKING UP
TO THE LOW 60S IN NW OHIO AND WEAK THETA-E ADVECTION UP TO AROUND
800MB. THE NAM IS MORE AGGRESSIVE WITH THE MOISTURE RETURN AND
CHANCES OF PRECIPITATION THIS AFTERNOON THAN MANY OF THE OTHER
DETERMINISTIC MODELS. HOWEVER MANY OF THE HIGHER RESOLUTION MODELS
ALSO SHOW A WIDELY SCATTERED LINE OF THUNDERSTORMS DEVELOPING
AHEAD OF THE FRONT. THUNDERSTORMS INITIATION LOOKS TIED TO TWO
MAIN AREAS OF SLIGHTLY HIGHER INSTABILITY...ONE NEAR FINDLAY IN
THE VICINITY OF THE FRONT AND THE OTHER ACROSS LAKE
ERIE...EVENTUALLY SPREADING INTO NW PA. HEIGHT FALLS ALOFT AND INCREASING
JET ENERGY WILL LIKELY PROVIDE THE ADDED BOOST TO SEE A FEW
THUNDERSTORMS DEVELOP AND HAVE 20-40 POPS IN THE FORECAST FOR MOST
AREAS THIS EVENING. BECAUSE OF THE INCREASING WIND FIELD...THE
STORM PREDICTION CENTER HAS PLACED MUCH OF THE AREA IN A MARGINAL
THREAT FOR SEVERE STORMS. THIS WILL BE CONDITIONAL OF COURSE ON
THUNDERSTORM INITIATION OCCURRING AND EVEN THEN EXPECT ONLY AN
ISOLATED THREAT OF A SEVERE STORM. HIGHS TODAY WILL BE NEAR
YESTERDAYS VALUES IN THE 82-86 DEGREE RANGE.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
ALTHOUGH THE FRONT WILL BE EAST OF THE AREA BY SATURDAY
MORNING...A WEAK THERMAL TROUGH IN THE VICINITY OF EASTERN LAKE
ERIE COULD RESULT IN SOME CLOUDS AND MOISTURE LINGERING IN THE NE
COUNTIES. WILL HOLD ONTO A SLIGHT CHANCE POP ON SATURDAY MORNING
IN NW PA...EXPANDING TO NORTHWEST OHIO BY AFTERNOON AHEAD OF
ANOTHER SHORTWAVE. TEMPERATURES ON SATURDAY WILL BE A LITTLE
COOLER IN THE UPPER 70S/LOW 80S.

SURFACE HIGH PRESSURE EXPANDS EASTWARD ON SATURDAY NIGHT AND SUNDAY
AHEAD OF THE NEXT TROUGH TO APPROACH FROM THE NORTHWEST. THIS
FEATURE DEVELOPS AHEAD OF A SLIGHTLY STRONGER UPPER LEVEL WAVE
DROPPING SOUTH ACROSS CANADA. BETTER MOISTURE ADVECTION IS EXPECTED
AHEAD OF THIS NEXT TROUGH WITH CHANCES OF SHOWERS AND THUNDERSTORMS
DEVELOPING SUNDAY AFTERNOON IN THE NORTH...AND EXPANDING TO ALL
AREAS FOR SUNDAY NIGHT AND MONDAY.  SEASONAL TEMPERATURES WILL
CONTINUE.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
THE MODELS LOOK SIMILAR THROUGH MID WEEK WITH THE FRONT
INITIALLY STALLING SOMEWHERE NEAR THE OHIO VALLEY. THIS MAKES FOR A
CHANCE FOR SOME OVER RUNNING SHOWERS...MAINLY ACROSS THE SOUTHERN
PORTION OF THE FORECAST AREA. STILL NOT A LOT OF CONFIDENCE ON THE
THREAT OF RAIN BUT WILL INCLUDE A SMALL CHANCE IN THE SOUTH. 850 MB
TEMPERATURES MAY GET COLD ENOUGH FOR LAKE EFFECT RAIN SHOWERS
ALTHOUGH THERE MAY BE ENOUGH SUBSIDENCE AND SHEAR THAT NOTHING
MATERIALIZES. IT IS WORTH A MENTION BY TUESDAY NIGHT INTO
WEDNESDAY.

THE MODELS REMAIN FAR APART BY NEXT THURSDAY WITH THE GFS
CONTINUING TO DRIVE THE FRONT WELL SOUTH OF THE AREA AND THE ECMWF
DEVELOPING ANOTHER OVER RUNNING WAVE THAT COULD AT LEAST CATCH THE
SOUTHERN PART OF THE FORECAST AREA. WILL CONTINUE TO FAVOR THE DRY
FORECAST...ONE WOULD EXPECT THE SURFACE HIGH TO BUILD SOUTH AT
SOME POINT GIVEN THE DEEPENING TROUGH ALOFT.

SHAVED OFF A DEGREE OR TWO ON FORECAST HIGH TEMPERATURES MID WEEK
GIVEN THE THREAT FOR CLOUDS AND SHOWERS AND THE COOL FLOW. TEMPS
COULD BE COOLER THAN FORECAST...ESPECIALLY IF IT WAS TO BE CLOUDY
AND RAINY BUT WITH THE DAYS SO LONG AND WARM IN EARLY AUGUST WILL
STAY WITHIN 10 DEGREES OF NORMAL FOR NOW.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
A CHUNK OF HIGH PRESSURE AT THE SURFACE WAS OVER THE OHIO VALLEY
SLIDING EAST. A WEAK COLD FRONT/TROUGH OVER THE NORTHERN GREAT
LAKES WILL DROP ACROSS THE AREA LATE THIS AFTERNOON AND EVENING.
WEST WINDS WILL GET A BIT GUSTY THIS AFTERNOON AHEAD OF THE
TROUGH. MOISTURE IS VERY LIMITED BUT THERE SHOULD BE SOME CAPE
DEVELOP IN THE HEATING OF THE DAY. AN INCREASE IN SHEAR IS
PROGGED. A FEW THUNDERSTORMS COULD POP UP. COVERAGE WILL LIKELY BE
SMALL BUT THE THREAT IS MENTIONED IN THE CURRENT TAF FORECASTS AS
"VICINITY" AND WILL CONTINUE WITH THAT FORECAST LATE THIS
AFTERNOON INTO TONIGHT.

OUTLOOK...NON VFR POSSIBLE SUNDAY AFTERNOON AND MONDAY IN
SHRA/TSRA.

&&

.MARINE...
WITH A RELATIVELY FAST FLOW ALOFT...EACH WEAK FRONT/TROUGH WILL
PRODUCE THE POSSIBILITY OF SMALL CRAFT ADVISORY CONDITIONS ON LAKE
ERIE...MAINLY THE EAST HALF OF THE LAKE SINCE THE FLOW IS WEST
SOUTHWEST. A WEAK TROUGH IS EXPECTED THIS EVENING AND WILL POST A
SMALL CRAFT ADVISORY FOR THE ERIE COUNTY PA LAKESHORE FROM EARLY
AFTERNOON INTO TONIGHT. THE MAJORITY OF THE WIND WILL BE OVER THE
EAST THIRD OF THE LAKE BUT 4 FOOT WAVES ARE CERTAINLY POSSIBLE
AT ERIE PA LATER TODAY INTO TONIGHT.

THE NEXT WEAK FRONT/TROUGH WILL BE LATER SUNDAY WITH A STRONGER COLD
FRONT ON MONDAY. BOTH OF THOSE SYSTEMS MAY WELL REQUIRE A SMALL
CRAFT ADVISORY...ESPECIALLY FOR THE EAST LAKESHORE.

HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN LAKES NEXT WEEK AND THE
FLOW WILL LIKELY VEER MORE FROM THE NORTH BY MID WEEK.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...BEACH HAZARDS STATEMENT FROM 2 PM EDT THIS AFTERNOON THROUGH
     LATE TONIGHT FOR PAZ001.
MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM EDT
     SATURDAY FOR LEZ149.

&&

$$
SYNOPSIS...KEC
NEAR TERM...KEC
SHORT TERM...KEC
LONG TERM...KOSARIK
AVIATION...KOSARIK
MARINE...KOSARIK


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