Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 011946
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
346 PM EDT TUE SEP 1 2015

.SYNOPSIS...
ISSUED AT 345 PM EDT TUE SEP 1 2015

SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE THROUGH THE
EVENING AND OVERNIGHT AS AN UPPER LEVEL DISTURBANCE MOVES THROUGH
THE AREA. ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS WILL THEN
BE POSSIBLE THROUGH THE END OF THE WEEK WITH HOT AND HUMID
CONDITIONS IN PLACE. HIGHS WILL BE MID TO UPPER 80S WITH LOWS IN
THE MID TO UPPER 60S.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 345 PM EDT TUE SEP 1 2015

PESKY COMPACT MIDLEVEL VORT MAX CONTINUES TO SWIRL ACROSS CENTRAL
INDIANA THIS AFTERNOON WITH LITTLE FORWARD MOMENTUM. DEWPOINTS IN
THE LOW 70S SUPPORTING SOME DECENT SBCAPE PER SPC/RAP MESOANALYSIS
DESPITE VERY POOR LAPSE RATES ALOFT. DPVA IN THE PRESENCE OF THIS
INSTABILITY IS GENERATING SOME SCT CONVECTION...WITH THE HIGHEST
COVERAGE IN OUR SOUTH CLOSER TO THE HEIGHT ANOMALY AND ALONG REMNANT
OUTFLOW FROM MORNING CONVECTION. EXPECT THIS ACTIVITY TO CONTINUE
THROUGH THE EVENING BUT SHOULD WANE WITH THE LOSS OF DAYTIME
HEATING.

MAIN LINE OF CONVECTION TO OUR W/SW THIS MORNING WAS ACTUALLY BEING
DRIVEN BY FOCUSED 305K ISENTROPIC UPGLIDE ON THE BACKSIDE OF
MIDLEVEL CIRCULATION. SOME OF THE LATEST MODELS (BOTH HI-RES AND
OTHERWISE) SHOW THIS AREA OF ENHANCED ASCENT AND MOISTURE
CONVERGENCE WITH 20-25 KT LLJ SETTING UP AGAIN OVER AT LEAST OUR
SOUTHEAST COUNTIES LATER TONIGHT...PROMPTING CONTINUED LOW CHANCE
POPS IN OUR EAST THROUGH TOMORROW. COVERAGE HIGHLY QUESTIONABLE
GIVEN WEAK FORCING AND INSTABILITY SO WILL MAINTAIN JUST SLIGHT
CHANCE POPS FOR NOW. NO SEVERE WEATHER EXPECTED WITH ANY OF THIS
ACTIVITY GIVEN LIMITED UPDRAFT POTENTIAL AND VIRTUALLY NO FLOW
ALOFT. COROLLARY TO THIS IS THAT ANY CONVECTION THAT DOES MANAGE TO
DEVELOP AND PERSIST WILL MOVE VERY SLOW AND COULD LEAD TO LOCALLY
HEAVY RAINFALL.

OTHER MAIN STORY WILL BE THE HEAT AND HUMIDITY. HIGHS TOMORROW
EXPECTED TO BE A FEW DEGREES WARMER THAN TODAY...APPROACHING 90F.
WITH DEWPOINTS IN THE LOW 70S ONCE AGAIN...HEAT INDICES WILL LIKELY
APPROACH THE MID 90S.

&&

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 345 PM EDT TUE SEP 1 2015

HOT AND HUMID CONDITIONS TO DOMINATE THE REGION THROUGH THE UPCOMING
HOLIDAY WEEKEND AND BEYOND WITH ONLY MINIMAL CHANCES FOR NEEDED
RAINFALL.

UPPER LEVEL RIDGING WILL CONTINUE TO INFLUENCE THE REGION INTO
FRIDAY WITH A SERIES OF WEAK DISTURBANCES RIDING ITS PERIPHERY. ONE
OF THESE IS POISED TO MOVE NE OUT OF PLAINS AND THEN DROP SE INTO
THE WESTERN GREAT LAKES THURSDAY AND LINGERING INTO FRIDAY. NAM/GFS
SOUNDINGS SUGGEST WE SHOULD BE UNCAPPED WITH AT LEAST LOW TO
MODERATE INSTABILITY AROUND. WILD CARD WILL BE AMOUNT OF SURFACE
CONVERGENCE ASSOCIATED WITH THIS FEATURE AND ITS ABILITY TO SPARK
ISOL TO MAYBE SCT CONVECTION. WILL BE KEEPING POPS SUBDUED FOR THE
TIME BEING IN THE SLGT CHC TO LOW CHC CATEGORY DURING THE
AFTERNOON/EVENING HOURS.

BY SATURDAY...MED RANGE MODELS ALL AGREE ON 588 DM OR HIGHER UPPER
LEVEL HEIGHTS NUDGING INTO THE REGION AND HOLDING TIGHT INTO MONDAY.
THIS WILL RESULT IN HIGHS WELL INTO THE 80S AND POSSIBLY AROUND 90
WITH HEAT INDICIES INTO THE 90S. DEEP LOW PRESSURE WILL MOVE INTO
THE WESTERN STATES SATURDAY AND MAKE AN ATTEMPT TO BREAK DOWN THE
RIDGE FOR THE START OF NEXT WEEK. ECMWF DOES SUGGEST A WEAK
DISTURBANCE WELL SOUTH OF THE MAIN UPPER LOW THAT COULD BRING AN
OUTSIDE CHANCE OF A AFTERNOON/EVENING SHOWER OR STORM TO THE AREA
TUESDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 138 PM EDT TUE SEP 1 2015

A FEW SHOWERS AND THUNDERSTORMS POSSIBLE THIS AFTERNOON...
PRIMARILY AT KFWA...AS A MIDLEVEL CIRCULATION PASSES THROUGH THE
AREA WITH MODERATE SURFACE BASED INSTABILITY. CONFIDENCE IN
COVERAGE AND TIMING IS NOT HIGH ENOUGH FOR INCLUSION IN THE TAF
THOUGH. CONVECTION WILL BE POSSIBLE AT KFWA AGAIN TONIGHT AS LLJ
RAMPS BACK UP BUT CONFIDENCE IS STILL NOT HIGH ENOUGH FOR ANY
MENTION IN THE TAF. OTHER CONCERN IS SOME PATCHY BR AROUND SUNRISE
BUT DENSE FOG NOT EXPECTED GIVEN MODEST SW SURFACE WINDS.

&&

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

$$

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


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