000
FXUS63 KIWX 131421
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1021 AM EDT MON MAY 13 2013

.SYNOPSIS...
ISSUED AT 1020 AM EDT MON MAY 13 2013

A RIDGE OF HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA
THIS AFTERNOON AND TONIGHT RESULTING IN CONTINUED DRY CONDITIONS
AND THE BEGINNING OF A MODERATING TEMPERATURE TREND. SOUTHERLY
FLOW WILL DEVELOP ACROSS THE REGION TONIGHT AS THIS HIGH SHIFTS
OFF TO THE EAST...ALLOWING FOR MUCH WARMER CONDITIONS ON TUESDAY
AND WEDNESDAY. A FRONTAL BOUNDARY WILL SLOW ACROSS THE AREA ON
WEDNESDAY...PROVIDING A CHANCE OF SHOWERS AND THUNDERSTORMS
WEDNESDAY AFTERNOON AND NIGHT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 355 AM EDT MON MAY 13 2013

WATER VAPOR IMAGERY EARLY THIS MORNING DEPICTS A WELL DEFINED VORT
MAX ACROSS CENTRAL LOWER MICHIGAN THAT WILL CONTINUE TO PROGRESS
SOUTHEAST INTO NORTHERN OHIO THIS MORNING. PERTURBED WIND FIELD WITH
THIS FEATURE APPEARS TO HAVE INDUCED LOW/MID LEVEL FRONTOGENETICAL
RESPONSE WITH A TIGHT PREEXISTING BAROCLINIC ZONE IN PLACE GIVEN
SYNOPTIC SETUP OF DEPARTING COLD POOL. PROGRESSION OF THE MI VORT
MAX SHOULD ALLOW ASSOCIATED FRONTOGENESIS TO ALSO SHIFT INTO OHIO
EARLY THIS MORNING. THIS MID DECK HAS BEEN A WILDCARD IN TERMS OF
FROST/FREEZE FORECAST AS APPROACH OF THIS MID DECK HAS ALLOWED TEMPS
TO CREEP BACK UP INTO THE MID 30S TO LOWER 40S. WITH DIMINISHING
CLOUDS EXPECTED THROUGH 12Z FROM NORTHWEST TO SOUTHEAST...A BRIEF
WINDOW OF CLEAR/PARTLY CLOUDY SKIES IS EXPECTED WHERE SHARP
RADIATIONAL DROPS IN TEMPS COULD OCCUR TO AT OR BELOW FREEZING IN
SPOTS.

OTHERWISE FOR TODAY...DIURNAL CU DEVELOPMENT WILL OCCUR AGAIN THIS
MORNING...PARTICULARLY ACROSS EASTERN THIRD OF THE AREA COINCIDENT
WITH POCKET OF STEEPER MID LEVEL LAPSE RATES ACCOMPANYING
AFOREMENTIONED MI VORT MAX. BACK TO THE WEST MAINLY FEW-SCT CU IS
EXPECTED. LARGE SCALE FLOW PATTERN WILL BEGIN TO UNDERGO
DEAMPLIFICATION TODAY AS ACTIVE EASTERN PACIFIC PATTERN SUPPRESSES
CENTRAL CONUS RIDGING. THIS WILL BE CONDUCIVE FOR EASTWARD
PROGRESSION OF HIGH CLOUDINESS INTO THE AREA LATE AFTERNOON/EVENING.
SOME MODERATION IN LOW LEVEL THERMAL PROFILES TODAY...ALTHOUGH
MIXING HEIGHTS LIKELY TO BE SLIGHTLY MORE LIMITED THAN YESTERDAY.
PREVIOUS FORECASTED HIGHS STILL APPEAR TO BE REASONABLE FROM THE MID
50S NORTH...TO NEAR 60 FAR SOUTHWEST. LOW LEVEL ANTICYCLONE SHOULD
ENHANCED DIVERGENT LOW LEVEL FLOW ACROSS LAKE MICHIGAN THIS
AFTERNOON PERHAPS ALLOWING FOR TEMPS TO DROP BACK INTO THE UPPER 40S
TO LOWER 50S THIS AFTERNOON FOR LAKESHORE AREAS.

FOR TONIGHT...WEAK SHORT WAVES PROGRESSING THROUGH DAMPENING UPPER
RIDGE WILL DROP INTO THE WESTERN GREAT LAKES WITH STRONG ISENTROPIC
UPGLIDE SETTING UP BY THE 06Z-12Z TIMEFRAME. 290-295K CONDENSATION
PRESSURE DEFICITS STILL APPEAR TO BE MORE AGGRESSIVELY LOWER JUST
NORTH OF LOCAL AREA OVERNIGHT. MAINTENANCE OF DRY SUBCLOUD LAYER
SUGGESTS MAINLY JUST A SPRINKLE POSSIBILITY ACROSS THE WEST LATE
TONIGHT. GIVEN LACK OF GOOD MID LEVEL FORCING WILL KEEP FORECAST DRY
AND LET DAY SHIFT ASSESS NEED FOR ANY LOW OVERNIGHT POPS ACROSS THE
WEST. MIN TEMPS LIKELY TO BE REACHED IN THE MID TO LATE EVENING MOST
LOCATIONS BEFORE LOW LEVEL WAA/THICKENING MID CLOUD ALLOW FOR A
STEADY OR SLOWLY RISING TEMPERATURE TREND OVERNIGHT.

&&

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 355 AM EDT MON MAY 13 2013

SIGNIFICANT WARMING TREND TUESDAY INTO WEDNESDAY AND CHANCES FOR
SHOWERS/STORMS LATER WEDNESDAY INTO WEDNESDAY NIGHT THE PRIMARY
FOCUS THIS PACKAGE...

A NORTHEAST PACIFIC UPPER LEVEL PV ANOMALY WILL TRANSLATE EAST TO
THE NORTHERN PLAINS/SOUTH-CENTRAL CANADA TUESDAY AND
ONTARIO/NORTHERN GREAT LAKES BY WEDNESDAY IN TRANSITION TO FLATTENED
PROGRESSIVE LONGWAVE PATTERN. THIS WILL ALLOW A WESTERN CONUS RIDGE
TO DE-AMPLIFY INTO THE CENTRAL US WITH STRONG WARM ADVECTION
ANTICIPATED TUESDAY WITH SFC WARM FRONTAL PASSAGE. MODELS STILL
ADVERTISING A MAINLY DRY FRONTAL PASSAGE LOCALLY WITH MORE
PRONOUNCED MOISTURE CONVERGENCE WITH NORTHEASTWARD LIFTING LOW LEVEL
BAROCLINIC ZONE SETTING UP NORTH INTO CENTRAL/NORTHERN MICHIGAN.

CAPPED WARM SECTOR WILL BUILD INTO THE ENTIRE AREA BY TUESDAY NIGHT
AND WEDNESDAY MORNING WITH TRAILING CDFNT DROPPING INTO THE AREA
WEDNESDAY AFTERNOON/EVENING. MODEST MID LEVEL LAPSE RATES, BUILDING
SURFACE BASED INSTABILITY, AND RELATIVELY TIGHT THETA-E GRADIENT
ALONG FRONT WARRANT POPS FOR CONVECTION LATER WEDNESDAY INTO
WEDNESDAY NIGHT. HELD THESE POPS IN THE LOW TO MID CHC CATEGORY AS
CAPPING INVERSION IMPRESSIVE TO START NEAR 850-800 MB WITH MODELS
LIKELY OVERDOING SFC DEWPOINTS/INSTABILITY AS WELL. IF CONVECTION
DOES FIRE LATER WEDNESDAY AFTN CANNOT RULE OUT AN ISOLATED WIND/HAIL
THREAT GIVEN POTENTIAL FOR 1000-1500 J/KG OF SBCAPE AND 30-40 KNOTS
OF DEEP LAYER SHEAR ON SOUTHERN FRINGE OF A CENTRAL GREAT LAKES MID
LVL SPEED MAX.

00Z MODEL SUITE CONTINUED THE TREND IN FORCING THE FRONTAL BOUNDARY
SOUTH OF THE AREA THURSDAY INTO FRIDAY IN RESPONSE TO MORE
IMPRESSIVE GREAT LAKES/NORTHEAST HEIGHT FALLS WITH MERGED SOUTHEAST
CANADA NEGATIVE HEIGHT ANOMALY. AS A RESULT LOWERED POPS
CONSIDERABLY (REMOVED ALTOGETHER IN MANY LOCATIONS) DURING THIS TIME
AS SFC HIGH BRIEFLY BUILDS INTO THE GREAT LAKES.

ECMWF/GFS ARE IN PRETTY GOOD AGREEMENT OVER THE WEEKEND AS AN UPPER
TROUGH EJECTS OUT OF THE WEST INTO THE HIGH PLAINS. THIS SHOULD AID
IN MIXING THE FRONT BACK NORTH INTO THE SOUTHERN GREAT LAKES WITH
INCREASING CHANCES FOR SHOWERS/STORMS. TEMPS THURSDAY THROUGH SUNDAY
ARE EXPECTED TO BE AT OR ABOVE NORMAL WITH POLAR JET NORTH OF THE
AREA.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 611 AM EDT MON MAY 13 2013

MID LEVEL CLOUDS WILL EXIT FAR NORTHEAST INDIANA EARLY THIS
MORNING...WITH JUST SOME SCT VFR DIURNAL CU EXPECTED TO REDEVELOP
ACROSS NORTHEAST INDIANA. OTHERWISE...JUST SOME CIRRUS EXPECTED TO
SPILL INTO THE AREA LATE AFTERNOON WITH GRADUALLY THICKENING AND
LOWERING MID CLOUD OVERNIGHT IN RESPONSE TO STRENGTHENING WARM
ADVECTION PATTERN. LIGHT WINDS EARLY THIS MORNING WILL INCREASE TO
10 TO 15 KNOTS BY MID MORNING AS MIXED LAYER DEVELOPS. SFC RIDGE
SHIFTING EAST OF THE AREA TONIGHT WILL ALLOW MODEST SOUTHEAST
GRADIENT TO DEVELOP LATE THAT SHOULD SUPPORT SOUTH SOUTHEAST WINDS
OF AROUND 10 KNOTS TOWARD THE END OF THE PERIOD. WARM ADVECTION
FORCING MAY ALLOW FOR SOME ISOLD-SCT LIGHT SHOWERS OR SPRINKLES
TOWARD THE END OF THE PERIOD...BUT WILL OMIT FOR 12Z TAFS WITH DRY
SUBCLOUD LAYER PERSISTING.


&&

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

$$

SYNOPSIS...MARSILI/KG
SHORT TERM...MARSILI
LONG TERM...STEINWEDEL
AVIATION...MARSILI


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