Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 190623
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
223 AM EDT TUE AUG 19 2014

.SYNOPSIS...
ISSUED AT 138 AM EDT TUE AUG 19 2014

LOW PRESSURE AND A SLOW MOVING COLD FRONT WILL APPROACH THE REGION
TODAY. AS IT DOES...THE CHANCES FOR SHOWERS AND THUNDERSTORMS
WILL INCREASE...STARTING THIS MORNING ACROSS WESTERN INDIANA AND
MICHIGAN AND SPREADING EAST BY MIDDAY. WIDESPREAD RAINFALL IS NOT
EXPECTED...HOWEVER ANY SHOWERS AND STORMS WILL BE CAPABLE OF
LOCALLY HEAVY RAIN. HIGHS TODAY WILL BE IN THE LOWER 80S.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 406 PM EDT MON AUG 18 2014

NEAR TERM FORECAST WILL INCLUDE ISOLATED SHOWERS/STORMS IN THE
VICINITY OF A LAKE BREEZE WHICH IS SLOWLY DRIFTING SE. MAIN THREAT
WOULD BE LOCALLY HEAVY RAIN WITH ANY ACTIVITY DISSIPATING TOWARDS
EVENING.

MODELS GENERALLY AGREE ON DEVELOPMENT OF SHOWERS AND THUNDERSTORMS
(SCATTERED TO POTENTIALLY NUMEROUS) ACROSS IOWA/WISCONSIN/MINNESOTA
WHERE UNSTABLE CONDITIONS WERE IN PLACE THIS AFTERNOON. THESE WILL
TRANSLATE EAST THIS EVENING INTO THE OVERNIGHT HOURS...WHICH IS
WHERE THE MODELS BEGIN TO HEAD DOWN THEIR OWN PATHS. MODELS VARY
ANYWHERE FROM LATE OVERNIGHT TO TUESDAY MORNING TO REMAINING HIGH
AND DRY TILL AFTERNOON. STILL SEEMS PLAUSIBLE THAT AT LEAST SOME
SHOWER/STORM ACTIVITY MOVES IN LATER TONIGHT OR FIRST THING
TUESDAY...POTENTIALLY IN A WEAKENING STATE. HOWEVER THE EFFECTS OF
THIS COULD SPELL ADDITIONAL CHALLENGES FOR REDEVELOPMENT AHEAD OF
THE MAIN FRONT AND WAVE TUES AFTERNOON INTO EVENING. NEW SPC DAY 2
OUTLOOK BRINGS A SLIGHT RISK OF SEVERE WEATHER INTO OUR SOUTHERN
AREAS (SOUTH OF ROUTE 24). WHILE NOT RULING THIS OUT...THIS WOULD BE
CONDITIONAL ON SUFFICIENT HEATING OCCURRING. OVERALL SHEAR WOULD
LIMIT ORGANIZATION AND BRING MORE "PULSEY" STORMS CAPABLE OF VERY
HEAVY RAIN AND ISOLATED HAIL/WIND THREAT. DO NOT PLAN ON ADDING TO
HWO AT THIS TIME.

TO FURTHER COMPLICATE THINGS...SOME FOG DEVELOPMENT IS POSSIBLE ONCE
AGAIN AHEAD OF ANY PRECIPITATION THAT MAY MOVE IN. NOT SURE IF WE
WILL SEE THE LARGER COVERAGE OF FOG OR EVEN DENSE FOG AT THIS POINT.
HAVE OPTED TO HOLD OFF ON INTRODUCING INTO GRIDS. TEMPERATURES WILL
FALL BACK INTO THE MIDDLE 60S TONIGHT. HIGHS TUESDAY WILL BE
DEPENDENT ON AMOUNT OF SKY COVER AND SHOWER/STORM ACTIVITY. IF TODAY
IS ANY INDICATION...ANY BREAKS WILL ALLOW FOR RAPID JUMPS IN
TEMPERATURES WHILE OTHER AREAS SLOWLY CREEP UP. WILL THEREFORE LEAVE
HIGHS ALONE.

&&

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 406 PM EDT MON AUG 18 2014

LOWER CONFIDENCE FORECAST HEADING INTO THE REST OF THE WEEK.
PRONOUNCED UPPER LOW WILL SLOWLY PUSH THROUGH THE CENTRAL GREAT
LAKES ON WEDNESDAY. MAIN CORE OF CVA/Q-VECTOR CONVERGENCE WILL PASS
JUST TO OUR NORTHEAST. SUSPECT AT LEAST THE SOUTHWEST PORTIONS OF
THE CWA WILL REMAIN DRY WITH JUST A LOW CHANCE IN THE
NORTHEAST...CLOSER TO THE VORTICITY LOBE. TEMPS WILL BE ON THE WARM
AND MUGGY SIDE WITH WEAK WARM/MOIST AIR ADVECTION SUPPORTING HIGHS
IN THE LOW TO MID 80S WITH DEWPOINTS NEAR 70F.

MORE CHALLENGING ASPECT OF THE FORECAST WILL BE THURSDAY INTO THE
WEEKEND. OLD FRONTAL BOUNDARY WILL BEGIN TO LIFT NORTH AGAIN IN
RESPONSE TO HIGH AMPLITUDE RIDGE AXIS BUILDING OVER THE GREAT LAKES.
TIMING AND EVOLUTION OF THIS FRONT HAVE BEEN DIFFICULT TO RESOLVE. A
FEW SUBTLE SHORTWAVES WILL RIDE OVER THIS EXPANDING LONGWAVE
RIDGE...MOST NOTABLY ON THURSDAY...AND WILL LIKELY ENHANCE PRECIP
CHANCES SOMEWHAT ALONG THE BAROCLINIC ZONE. DETAILS REMAIN VERY
MURKY AT THIS POINT THOUGH WITH GENERALLY WEAK FORCING AND
INCREASINGLY POOR MIDLEVEL LAPSE RATES. THURSDAY LOOKS TO BE THE
BEST CHANCE FOR RAIN GIVEN AT LEAST MODEST MIDLEVEL SUPPORT AND
DECENT INSTABILITY. THEREAFTER...MODELS SUGGEST CONVECTION PERSISTS
INTO FRIDAY AND PERHAPS THROUGH THE ENTIRE WEEKEND. HARD TO FIND
MUCH SUPPORT FOR THIS GIVEN BUILDING RIDGE BUT APPEARS TO BE ENOUGH
MOISTURE/INSTABILITY TO SUPPORT A FEW SCT THUNDERSTORMS FRIDAY AND
PERHAPS SATURDAY. KEPT SUNDAY AND MONDAY DRY FOR NOW THOUGH. TEMPS
WILL CONTINUE THE UPWARD TREND. DEPENDING ON TIMING/COVERAGE OF
CLOUDS AND PRECIP...UPPER 80S POSSIBLE FRIDAY AND SATURDAY WITH
LOWER 90S NOT OUT OF THE QUESTION ON SUNDAY IF WE SEE ENOUGH
INSOLATION. WILL LIKELY FEEL MUGGY AS WELL WITH DEWPOINTS HOLDING
AROUND 70F.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 138 AM EDT TUE AUG 19 2014

AN UPPER LEVEL LOW AND ASSOCIATED TROF WILL MOVE INTO THE UPPER
MIDWEST TODAY...AND PROVIDE A MORE FAVORABLE ENVIRONMENT FOR
THUNDERSTORMS OVER THE FORECAST AREA. BEFORE THIS...AREAS OF FOG
HAD ALREADY DEVELOPED OVER THE WESTERN PART OF THE AREA. THE FOGGY
CONDITIONS WILL IMPROVE EARLY THIS MORNING AS UPSTREAM CLOUDS
SPREAD OVER THE AREA AND AS LOW LEVEL FLOW INCREASES. RVR SENSORS
AT SBN INDICATE GROUND FOG IN THE AREA...SO CONDITIONS MAY DROP
BRIEFLY LOWER THAN INDICATED ON THE TAF. ADDED THUNDER TO SBN TAF
GIVEN MORE FAVORABLE ENVIRONMENT BY LATE TODAY.

&&

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

$$

SYNOPSIS...SKIPPER
SHORT TERM...FISHER
LONG TERM...AGD
AVIATION...SKIPPER


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