-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCLE 201356
AFDCLE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CLEVELAND OH
956 AM EDT MON MAY 20 2013

.SYNOPSIS...
AN UPPER RIDGE ACROSS THE AREA TODAY WILL MOVE EAST TONIGHT. A
WEAK WARM FRONT WILL MOVE ACROSS THE REGION TODAY. AN AREA OF LOW
PRESSURE OVER THE NORTHERN PLAINS WILL SLOWLY PROGRESS EASTWARD
ACROSS THE GREAT LAKES REGION THROUGH MID WEEK. THE AIRMASS WILL
BECOME INCREASINGLY MOIST AND UNSTABLE AS THIS FEATURE APPROACHES.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
A BROKEN LINE OF SHOWERS IS STARTING TO DEVELOP EXTENDING FROM
NORTH CENTRAL MICHIGAN TO WESTERN VIRGINIA. THE CU FIELD CONTINUES
TO DEVELOP ACROSS OUR WESTERN COUNTIES ALONG A NARROW CORRIDOR OF
THETA-E ADVECTION NEAR 850MB AND EXPECT AT LEAST SCATTERED
SHOWERS TO DEVELOP AND MOVE EAST. MU CAPES ARE NEAR 2000 J/KG WITH
STEEPENING MID-LEVEL LAPSE RATES APPROACHING 7 C/KM SO THUNDER
WILL ALSO BE POSSIBLE. EXPECT THE TREND THROUGH EARLY AFTERNOON TO BE FOR
THIS THETA-E RIDGE TO LIFT NORTH ACROSS LAKE ERIE SO ONLY CARRIED
THE CHANCE OF SHOWERS AND THUNDERSTORMS EAST TO ABOUT
CLEVELAND...WITH DECREASING CHANCES FOR SHOWERS AND THUNDERSTORMS
THROUGH THE AFTERNOON. LEANING TOWARDS THE GFS SOUNDING WHICH ARE
WARMER ALOFT THOUGH 700MB TODAY AND MORE IN LINE WITH THE 12Z ILN
SOUNDING...SUGGESTING WE WILL BE CAPPED FOR THE AFTERNOON. WE WILL
HAVE TO KEEP AN EYE ON THE RADAR THOUGH AS DEWPOINTS ARE ALREADY
IN THE UPPER 60S IN SOME AREAS.

PREVIOUS DISCUSSION...TODAY IS A TOUGH FORECAST. THE HRRR AND
RUC/RAP MODELS HAVE BEEN FORECASTING A NARROW BAND OF
SHOWERS/THUNDERSTORMS TO DEVELOP OVER EASTERN INDIANA EARLY THIS
MORNING AND THEN MOVE EAST. AT 3 AM EDT THE ILN 88D WAS INDICATING
A FINE LINE OVER SE INDIANA. AS EACH HOUR HAS GONE ON THE MODELS
ARE DELAYING THE DEVELOPMENT AND INTENSITY OF THE PRECIPITATION.
NOW THEY DON`T HAVE ANY PRECIPITATION DEVELOPING ON THIS LINE
UNTIL AROUND 8 OR 9 AM MAINLY FROM CLE SOUTH. SOME OF THE RADAR
FORECAST OUTPUT FROM SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY
MODELS ARE ALL OVER THE PLACE FOR TODAY...SOME WITH NO SHOWER OR
THUNDERSTORM DEVELOPMENT IN THE FORECAST AREA AND SOME WITH A
LITTLE DEVELOPMENT. THE 4KM WRF NMM MODEL HAS SOME ISOLATED
SHOWERS DEVELOPING. CONFIDENCE IS LOW IN THIS BECAUSE OF SO MUCH
RIDGING ALOFT...BUT WILL FORECAST A CHANCE OF SPRINKLES MAINLY
THIS AM AS THIS LINE MOVES THROUGH. WILL MONITOR THIS AND UPDATE
AS NEEDED.

ANY FOG THAT DEVELOPS THROUGH DAYBREAK SHOULD NOT BE SIGNIFICANT
ENOUGH TO BE MENTIONED IN THE ZONES/GRIDS.

NOT MUCH IN THE WAY OF CLOUDS ACROSS THE FORECAST AREA AT 4
AM...HOWEVER...THEY ARE EXPECTED TO DEVELOP THROUGH DAYBREAK.
PARTLY CLOUDY SHOULD HANDLE MOST OF TODAY.

OTHER THEN THIS NOT EXPECTING ANY SHOWERS AND THUNDERSTORMS TO
DEVELOP TODAY...THEY SHOULD HOLD OFF UNTIL AFTER 6 PM. NOT
EXPECTING MUCH OF A LAKE BREEZE AS THE GRADIENT WILL BE TOO
STRONG. ERIE MAY GET A LAKE BREEZE FOR A TIME THIS AFTERNOON. WENT
ON THE WARMER SIDE OF GUIDANCE FOR HIGHS BECAUSE OF AN INCREASING
SOUTHWEST FLOW AND WARMER AIR ALOFT.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
THE UPPER LOW AND SURFACE LOW NOW OVER THE NORTHERN PLAINS WILL
MOVE SLOWLY EAST AND BE OVER THE FORECAST AREA THURSDAY AND
THURSDAY NIGHT. IN THE MEANTIME THE CHALLENGE IS FIGURING OUT THE
SHOWER AND THUNDERSTORM CHANCES.

FOR TONIGHT THE UPPER RIDGE MOVES EAST AND WITH SOME MOISTURE AND A
WEAK IMPULSE MOVING THROUGH KEPT CHANCE POPS MAINLY OVER THE
NORTHERN PORTION OF THE FORECAST AREA. THE RADAR FORECAST FROM THE
4KM WRF NMM 00Z MODEL SEEMS REASONABLE WITH SOME THUNDERSTORMS
BRUSHING THE NORTHERN PORTION OF THE FORECAST AREA.

FOR TUESDAY CHANCE POPS MOST AREAS BUT DID CONTINUE LIKELY POPS
EXTREME NORTHWEST OHIO. ON THE EDGE ABOUT THAT BASED ON THE LACK
OF MOISTURE ALOFT. THE AIRMASS IS UNSTABLE. FOR TUESDAY NIGHT
AGAIN...CHANCE POPS AS THE AIRMASS IS BECOMING MORE MOIST AND
CONTINUED UNSTABLE. FOR WEDNESDAY INTO THURSDAY WITH THE FRONT
GETTING CLOSE WEDNESDAY AND THEN SAGGING THROUGH ON THURSDAY
LIKELY POPS AT TIMES LOOKS VERY GOOD. AS WE GET CLOSER WE WILL BE
ABLE TO PUT MORE RESOLUTION INTO THE FORECAST.

USED A BLEND OF GUIDANCE AND THE PREVIOUS FORECAST FOR THE HIGHS AND
LOWS. THE HIGHS TUESDAY AND WEDNESDAY ARE TRICKY IF WE GET TOO MUCH
CONVECTION AND CLOUDS THIS WILL HAVE A TREMENDOUS IMPACT ON THE
TEMPERATURES.

RAINFALL AMOUNTS ARE EXPECTED TO BE LESS THAN INCH FOR THIS
WEEK...EXCEPT LOCALLY HIGHER AMOUNTS IN SOME THUNDERSTORMS.

THE AIRMASS FOR TONIGHT WILL BE SOMEWHAT DRY ALOFT AND THIS WILL
LEAD TO POSSIBLE SIGNIFICANT DOWNDRAFTS AS PER THE DELTA THETA E...WILL
MENTION THAT IN THE HAZARDOUS WEATHER OUTLOOK. WILL ALSO MENTION
RISK OF SEVERE TUESDAY THROUGH WEDNESDAY NIGHT ESPECIALLY.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
LITTLE CHANGE IN THE EXTENDED.  BOTH GFS AND ECMWF MOVE HIGH
PRESSURE OVER THE AREA FRIDAY...WHICH LINGERS THROUGH THE WEEKEND.
EXTENDED LOOKS DRY WITH MORE SEASONAL TEMPS THROUGH THE WEEKEND.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/...
PATCHY MVFR BR WILL BURNOFF QUICKLY THIS MORNING. POTENTIAL EXISTS
FOR SCATTERED TSRA NW OH LATE THIS AFTERNOON AS CAPES APPROACH
3000 J/KG. CONFIDENCE IS STILL LOW AS TO EXACTLY WHERE AND WHEN
SCATTERED TSRA WILL DEVELOP AS STRONG RIDGE REMAINS OVERHEAD AND
SEE NO TRIGGER. MUCH BETTER CHANCE OF TSRA OVERNIGHT TONIGHT.


.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS OVERNIGHT THROUGH
THURSDAY.

&&

.MARINE...
PREDOMINATELY A SOUTH TO SOUTHEAST FLOW TODAY ALTHOUGH COULD SEE A
WEAK LAKE BREEZE EAST HALF FOR A FEW HOURS.  EXPECT SOUTHWEST FLOW
TO DEVELOP TOMORROW AHEAD OF NEXT SYSTEM.  MODELS IN GOOD AGREEMENT
PUSHING THE NEXT FRONT THROUGH ON THURSDAY.  WITH NORTH TO NORTHEAST
FLOW DEVELOPING BEHIND THE SYSTEM WILL APPROACH SMALL CRAFT ADVISORY
CRITERIA.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...KIELTYKA
NEAR TERM...KEC/KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB