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Area Forecast Discussion

000
FXUS63 KIWX 012341
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
741 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 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 735 PM EDT TUE SEP 1 2015

ISOLATED THUNDERSTORMS HAVE AVOIDED BOTH TERMINALS THIS EVENING
AND THAT TREND APPEARS TO CONTINUE OVERNIGHT. DEWPOINTS IN THE LOW
70S LENDS SOME CONCERN FOR FOG POTENTIAL OVERNIGHT...BUT IT
APPEARS SW WINDS WILL BE JUST STRONG ENOUGH TO KEEP FOG
DEVELOPMENT AT BAY. THIS IS SUPPORTED BY LATEST RAP AND HRRR WHICH
KEEP VISIBILITIES P6SM ALL NIGHT. DECIDED TO KEEP TEMPO 4SM BR
MENTION IN THE TAF GIVEN THE AFOREMENTIONED MOIST LOW LEVEL
DEWPOINTS. OTHERWISE...A FEW SHOWERS AND THUNDERSTORMS ARE
POSSIBLE LATER TONIGHT ACROSS CENTRAL INDIANA AS THE LOW LEVEL JET
STRENGTHENS...BUT THESE SHOULD STAY SOUTH OF KFWA. SHOWERS AND
THUNDERSTORMS ON WEDNESDAY WILL LIKELY BE EVEN MORE WIDESPREAD
THAN TODAY...SO HAVE NOT INCLUDED ANY MENTION IN THIS TAF
ISSUANCE. 

&&

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

$$

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

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