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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KIWX 182346
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
746 PM EDT SAT MAY 18 2013

.SYNOPSIS...
ISSUED AT 443 PM EDT SAT MAY 18 2013

REMAINING PRECIP CHANCES WILL DIMINISH THIS EVENING MAKING FOR A
PARTLY CLOUDY NIGHT ACROSS THE AREA. A STALLED FRONTAL BOUNDARY
ACROSS THE REGION WILL BEGIN TO LIFT NORTHWARD AS A WARM FRONT
SUNDAY AND SUNDAY NIGHT. WARM CONDITIONS CAN BE EXPECTED SUNDAY
AND MONDAY IN ADVANCE OF A COLD FRONT AND UPPER LEVEL DISTURBANCE
THAT WILL BRING A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS TO THE
REGION MONDAY THROUGH WEDNESDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 259 PM EDT SAT MAY 18 2013

STATIONARY BOUNDARY SITUATED ACROSS SOUTHERN HALF OF THE AREA THIS
AFTERNOON...WITH DRY BOUNDARY LAYER CONDITIONS NORTH OF THE FRONT
AND HIGHER MOISTURE SOUTH. HIGH RES GUIDANCE CONTINUES TO INDICATE
ISOLATED CONVECTIVE DEVELOPMENT ALONG AND SOUTH OF THE FRONT THIS
AFTERNOON AS MID LVL IMPULSE TRACKS SOUTHEAST OUT OF SOUTHERN IL.
ALIGNED SLIGHT CHANCE POPS ALONG AND SOUTH OF SFC MOISTURE
GRADIENT...ROUGHLY ALONG AND SOUTH OF A LIMA TO ROCHESTER LINE...AND
WEST OF A ROCHESTER TO MICHIGAN CITY LINE. LIMITED SLIGHT CHANCE
THUNDER MENTION TO SOUTHWEST AREAS...WHERE SFC LI VALUES DIP TO -3
TO -4C THROUGH EARLY EVENING.

RAIN CHANCES QUICKLY DIMINISH AFTER 00Z...WITH DRY EASTERLY FLOW
ACROSS AREAS NORTH OF THE BOUNDARY. KEPT LOW TEMPS ABOUT THE SAME AS
PREVIOUS FCST...MAYBE A TOUCH LOWER IN NORTHEAST AREAS. FRONTAL
BOUNDARY WILL BEGIN TO PUSH NORTH THROUGH THE AREA EARLY SUNDAY
MORNING THROUGH THE AFTERNOON SUNDAY. WARM TEMPERATURES WITH HIGHER
DEWPOINTS EXPECTED ON SUNDAY. LEFT HIGHS THE SAME...WITH LOW TO
UPPER 80S ACROSS THE AREA...HIGHEST TEMPS NORTHEAST WHERE CLOUD
COVER SHOULD BE LIMITED.

KEPT POPS DRY TOMORROW ACROSS THE AREA. MODELS INDICATE SMALL PRECIP
CHANCES ACROSS SOUTHEAST AREAS TOMORROW AFTERNOON...HOWEVER FEEL
THAT LACK OF FORCING...AND MAIN MID LVL ENERGY WELL SOUTH OF THE
AREA ALONG THE OHIO RIVER VALLEY...WARRANTS A DRY SUNDAY FORECAST.

&&

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 259 PM EDT SAT MAY 18 2013

AMPLIFICATION OF THE MID-UPPER TROP PATTERN UNDERWAY AS STRONG JET
DYNAMICS MOVE ONSHORE IN THE WESTERN US TODAY. RESULT WILL HAVE
500MB RIDGING EXTENDING UP FROM THE TN VALLEY INTO THE GREAT LAKES
REGION TO BEGIN THE FCST PERIOD. WELL DEFINED QUASI-STATIONARY SFC
BOUNDARY ACROSS NORTH-CENTRAL INDIANA...AS EVIDENCED BY 20F DEWPOINT
GRADIENT ACROSS THE AREA THIS MORNING...WILL BECOME MORE DIFFUSE
WITH TIME AS FLOW BECOMES MORE SOUTHERLY AND NEW BAROCLINIC ZONE
ESTABLISHES OVER THE NORTHERN GREAT LAKES REGION. RESULT WILL HAVE
OUR AREA IN A MODERATELY UNSTABLE WARM SECTOR WITH CAPES GT
2000J/KG. THIS IS EXPECTED TO BE AIDED BY MID LEVEL FORCING ROUNDING
UP THROUGH THE EAST SIDE OF UPPER LEVEL LOW IN THE NORTH-CENTRAL
PLAINS AND LEND POTENTIAL FOR CONVECTION TO BECOME MARGINALLY SEVERE
BY MONDAY AFTERNOON. BUFKIT FCST SOUNDINGS SHOWING A FAIRLY
UNIDIRECTIONAL AND WEAKLY SHEARED ENVIRONMENT WHICH WILL SERVE AS A
LIMITING FACTOR. VERTICALLY STACKED PLAINS SYSTEM WILL THEN SLOWLY
WORK ACROSS THE AREA TUE-THU...BRINGING BEST PRECIP CHANCES WITH IT
DESPITE WEAKENING TRENDS AS IT MOVES THROUGH. MODELS OFFERING
VARYING SOLNS ON THE EXIT OF THIS SYSTEM. GFS HAS UPPER TROF MORE
DETACHED FROM THE MEAN FLOW AND THEREFORE A SLOWER SOLN...ALLOWING A
SFC FRONTAL WAVE TO DEVELOP AND MOVE UP THROUGH THE AREA. MEANWHILE
ECMWF INDICATES A BIT OF PHASING WITH THE NORTHERN STREAM AS HUDSON
BAY VORTEX DROPS DOWN THROUGH EASTERN ONTARIO AND ABSORBS THE
ORPHANED TROF INTO THE NORTHERN STREAM FLOW AND SHIFTS THE MEAN TROF
AXIS TOWARD THE EASTERN US. ALLBLEND SEEMS TO OFFER GOOD COMPROMISE
WITH LINGERING SMALL CHANCE INTO THURSDAY NIGHT BUT WILL TRIM BACK
FRIDAY TO KEEP FCST DRY. BARRING ANY DEBRIS CLOUD SHIELD FROM
NOCTURNAL CONVECTION SUNDAY NIGHT...LOW LEVEL THERMAL RIDGE MOVING
OVER THE AREA WOULD SUPPORT TEMPS MIXING DOWN TO NEAR 90....SO WILL
CONTINUE WITH GOING FCST OF U80S. COOLER CANADIAN AIRMASS BY THE END
OF THE WEEK WILL HAVE TEMPS MARKEDLY COOLER COMPARED TO MONDAY BUT
STILL ONLY SEASONABLY COOL FOR THIS TIME OF YEAR.

&&

.AVIATION...
-- Changed Discussion --
(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 737 PM EDT SAT MAY 18 2013

FRONTAL BOUNDARY STILL DRAPED JUST SOUTH OF THE AREA AND WILL
REMAIN THERE OR SHIFT SOMEWHAT SOUTH OVERNIGHT BEFORE MAKING A
FINAL PUSH NORTH DURING THE DAY SUNDAY. GUIDANCE STILL HINTING AT
SOME POTENTIAL LOW MVFR CIGS/VSBY LATER TONIGHT AT KFWA AND MAYBE
DURING SUN MORNING AT KSBN. HAVE CONTINUED WITH PREV FORECAST OF
SCT VFR CIGS AROUND 3KFT FOR A FEW HOURS BEFORE THREAT ENDS AS
FRONT PUSHES NORTH. HAVE SHIFTED WINDS MORE SOUTHERLY IN THE
AFTERNOON BUT STILL UNDER 10 KTS WITH NO CONVECTION EXPECTED ALONG
OR BEHIND THE FRONT.
-- End Changed Discussion --

&&

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

$$

SYNOPSIS...MARSILI/KG
SHORT TERM...NG
LONG TERM...JAL
AVIATION...FISHER


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