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Area Forecast Discussion

000
FXUS63 KIWX 282329
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
729 PM EDT TUE JUL 28 2015

.SYNOPSIS...
ISSUED AT 311 PM EDT TUE JUL 28 2015

HIGH PRESSURE ACROSS THE GREAT LAKES WILL CONTINUE TO PROVIDE
WARM AND HUMID CONDITIONS. THIS HIGH WILL BEGIN TO SHIFT TO THE
EAST TONIGHT. INCREASING MOISTURE WILL BRING INCREASING CHANCES OF
SHOWERS AND THUNDERSTORMS LATE TONIGHT..AND A COLD FRONT WILL PASS
THROUGH WEDNESDAY PRODUCING ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS.
 
LOWS TONIGHT WILL BE NEAR 70. HIGHS ON WEDNESDAY WILL RANGE FROM 
LOWER 80S NEAR LAKE MICHIGAN TO UPPER 80S IN NORTHWEST OHIO. 

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 311 PM EDT TUE JUL 28 2015

QUIET WEATHER FOR TONIGHT. THREAT OF SHOWERS / THUNDERSTORMS EARLY 
WEDNESDAY AND AGAIN WEDNESDAY AFTERNOON. 

5H RIDGE OVER THE LOWER MISSISSIPPI RIVER VALLEY WILL MOVE LITTLE 
FOR THE NEAR TERM. UPR LEVEL TROF AND ASSOCIATED SURFACE LOW DEEPENS 
IN THE LEE OF THE CANADIAN ROCKIES OVERNIGHT...AND THIS IN TURN WILL 
FLATTEN THE RIDGE EVER SO SLIGHTLY BY DAYBREAK WEDNESDAY. 

OVERNIGHT...BOUNDARY LAYER MOISTURE AND INSTABILITY WILL INCREASE AHEAD
OF THE DECAYING SURFACE FRONT. CONVECTION OVER THE NORTHERN
PLAINS/UPPER MISSISSIPPI RIVER VALLEY WILL PUSH EASTWARD OVERNIGHT
AND EXPECT TO SEE THE REMNANTS SPREAD INTO THE WESTERN THIRD OF
THE FORECAST AREA EARLY DURING THE DAY.

CLOUD COVER WILL PLAY A BIG ROLE AS TO WHETHER OR NOT THE 
INSTABILITY CAN BE FULLY REALIZED AS THE WEAK FRONTAL BOUNDARY 
PUSHES THROUGH THE AREA DURING THE LATE AFTERNOON/EARLY EVENING. 
THIS LOOKS TO BE A SIMILAR SETUP TO FAVOR RAPID CONVECTIVE
DEVELOPMENT COMBINED WITH SHEAR ALONG THE FRONT...COULD NOT RULE
OUT FUNNEL/LAND SPOUT FORMATION. ADDITIONALLY...STORMS THAT DO
DEVELOP WILL BE VERY EFFICIENT RAIN PRODUCERS AND EXPECT THAT
THERE WILL BE ISOLATED RAINFALL REPORTS APPROACHING 0.75 TO 1.00
INCHES.

&&

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 311 PM EDT TUE JUL 28 2015
 

SURFACE COLD FRONT ASSOCIATED WITH WEAK SHORT WAVE ROTATING AROUND 
BASE OF LARGE UPPER LOW OVER CANADA WILL BE EXITING THE AREA AT 
BEGINNING OF PERIOD WEDNESDAY EVENING. NAM12 REMAINS ONE OF SLOWER 
MODELS WITH SECONDARY DEVELOPMENT ALONG 850MB MOISTURE GRADIENT WITH 
WEAK SHORT WAVE. MOST OTHER GUIDANCE ON AGREEMENT WITH FRONT AND 
PCPN CHANCES EXITING THE SOUTHEAST EARLY IN THE EVENING. WILL KEEP A 
SLIGHT CHANCE MENTION FOR CONTINUITY AT THIS TIME RANGE. 

HIGH PRESSURE THEN MOVES IN THROUGH FRIDAY. UPPER LEVEL RIDGE 
RETROGRADES AND BUILDS WEST WHILE NORTHWEST FLOW ALOFT DEVELOPS ONCE 
AGAIN OVER THE MIDWEST AND GREAT LAKES REGION. THIS SHOULD SET THE 
STAGE FOR NUMEROUS SMALL SCALE PERTURBATIONS WHICH WILL FLY THROUGH 
FROM TIME TO TIME. EXPECT MODEST TO STRONG INSTABILITY AT TIMES 
GIVEN STILL MOIST LOWER LEVELS AND COOLING ALOFT. A WEAK SHORT WAVE 
AND SFC FRONT INDICATED FOR FRIDAY NIGHT BUT POOR TIMING AND LACK OF 
STRONG MOISTURE RETURN INITIALLY SO WILL KEEP THIS PERIOD PCPN FREE 
FOR NOW. WILL CONTINUE WITH LOW POP CHANCES LATER IN THE WEEKEND 
INTO EARLY NEXT WEEK WITH SEVERAL MORE WEAK SHORT WAVES. CONFIDENCE 
IN TIMING LOW BUT WILL MAINTAIN CONTINUITY WITH PREVIOUS FORECAST 
AND SUPERBLEND INIT AND LATEST MODEL OUTPUT. 

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 727 PM EDT TUE JUL 28 2015

E-SE LOW LEVEL FLOW SHOULD GRDLY VEER TO SOUTHERLY OVERNIGHT AS 
CDFNT OVER WRN IA MOVES EAST TO NWRN INDIANA. THIS WILL RESULT IN A 
RETURN OF DEEP MOISTURE TO THE AREA BY LATE TONIGHT. AREAS OF MVFR 
BR/HZ PSBL ACROSS NRN INDIANA TOWARD DAYBREAK BUT DOUBT IT WILL
LOWER VSBYS BLO 6SM AT THE TERMINALS.

SOME CONVECTION WILL LIKELY ACCOMPANY AND/OR PRECEDE THE CDFNT AS IT 
MOVES ACROSS NRN INDIANA WED... BUT WIDE RANGE OF MODEL SOLUTIONS 
REMAINS WITH REGARD TO TIMING/INTENSITY/COVERAGE OF CONVECTION SO
FOR NOW STUCK WITH PREVIOUS TAF FOR WEDNESDAY... BUT CONFIDENCE IS
LOW. BY THIS TIME TOMORROW CDFNT SHOULD HAVE MOVE THROUGH THE AREA
WITH THREAT OF TS ENDING.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...LEWIS
SHORT TERM...LEWIS
LONG TERM...LASHLEY
AVIATION...JT

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