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000
FXUS63 KIWX 190638
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
238 AM EDT SUN MAY 19 2013

.SYNOPSIS...
ISSUED AT 215 AM EDT SUN MAY 19 2013

A WEAK UPPER LOW WILL EJECT NORTHEAST TODAY...WITH A SHOWER OR
THUNDERSTORM POSSIBLE OVER MAINLY OHIO. OTHERWISE...AN UPPER LEVEL
RIDGE WILL BUILD NORTHEAST ACROSS THE MIDWEST INTO THE OHIO VALLEY
REGION EARLY THIS WEEK. TEMPERATURES WILL BECOME HOT BY MONDAY WITH
HIGHS AROUND 90. AS THE UPPER LEVEL RIDGE BUILDS EAST...SHOWERS AND
THUNDERSTORMS WILL SPREAD EAST IN ADVANCE OF A COLD FRONT AND
UPPER LEVEL DISTURBANCE MONDAY THROUGH THURSDAY. RAINFALL AMOUNTS
SHOULD EXCEED AN INCH BY LATE IN THE WEEK.

&&

.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...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 230 AM EDT SUN MAY 19 2013

A TIGHT MOISTURE GRADIENT REMAINED OVER THE AREA FOR A THIRD
STRAIGHT NIGHT...WITH DEW POINTS JUST SOUTH OF THE TERMINALS IN
THE LOWER 60S. NORTH OF THE BOUNDARY...DEW POINTS WERE IN THE
40S. GIVEN SOME VFR CLOUDS OVER THE AREA...KEPT FOG OUT FOR NOW.
VPZ WITH A DEW PT OF 60F HAD SOME LIGHT FOG AT 06Z...BUT SFC
CONDITIONS WERE DRIER NORTHEAST. AFTERNOON CAPES OF NEAR 2000 J/KG
WOULD SUPPORT CONVECTION...BUT GIVEN LIGHT WIND FIELDS AND NOTHING
TO FORCE OR FOCUS CONVECTION...KEPT TAFS DRY WITH VFR CONDITIONS.

&&

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

$$

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


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