Special Weather Statement, NWS Northern Indiana

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
130 PM EDT FRI JUN 29 2012

.AVIATION... /18 UTC TAFS/
HIGH CONFIDENCE TSRA AT KSBN AIRFIELD NEXT TWO HOURS. WHILE LESSER
CONFIDENCE AT KFWA WITH REGARD TO EVENT MORPHOLOGY ATTM W/POTNL NRN
XTENT DECAY ANTICIPATED AND INCSRGLY FAVORED KLAF-KMIE INSTABILITY
AXIS FAVORING HIEST PROBABILITIES SOUTH OF KFWA LATER THIS
AFTN...THOUGH MAGNITUDE OF INSTABILITY INVOF KFWA NECESSITATING
SHORT 2HR PD /20-22 UTC/ TEMPO TSRA AS WELL. UPSTREAM SHORTWAVE ACRS
CNTL SD TIMED INTO NRN IL BYND 06 UTC. WITH FAVORABLE LLJ IMPINGING
UPON MODERATE INSTABILITY WILL OFFER VCTS LATE TONIGHT/TOWARD
DAYBREAK...THOUGH EXACT ONSET TIMING UNCERTAIN ATTM. AND WITH AT
LEAST A LOW POTNL FOR ADDNL/MULTIPLE CONVECTIVE COMPLEXES CONTG INTO
SAT AM...DO NOT FAVOR ANY FINER RESOLUTION BYND LAST VCTS/CB CHANGE
GROUP.

&&

.UPDATE...
RAPID/SIG UPDATE THIS AM TO ASSESS INCRSG TSRA/SVR RISK SPCLY FAR
SWRN CWA THIS AFTN...TRANSLATING EWD ALONG/SOUTH ROUTE 24...AND
ALONG/SOUTH ROUTE 30 IN ERN CWA LATER THIS EVENING. RICH 0-0.5KM
THETA-E LAID ACRS ERN IA/N CNTL IL INTO CNTL IN/XTRM SRN CWA WITH
XTRM MLCAPE OBSERVED/RAP PROGGED IN 4-6KJ/KG COINCIDENT WITH SRN
PERIPHERY OF HIR 40-50KT 0-6KM DLS. PROGGED SHEAR TO
MAINTAIN/SLGHTLY INCRS INTO AFTN AS CONFLUENCE WITHIN ML/UL DRIVES
ISOHYETAL SPEED INCRS/LENGTHENING HODOS. SHEAR MAGNITUDE OF
INSTABILITY ALONG WITH 1200-1400 J/KG DCAPE ALONG/SOUTH OF FNTL
BNDRY LAID ENHANCED BY EXTREME DIFFERENTIAL HEATING WITH CNTL
IL/IN INSOLATION AT 15 UTC INTO LWR 90S/MID TO UPR 70S. PRIME MCS
ACRS NRN IL DRIVEN BY WAA SHOULD EITHER LATCH UPON INSTABILITY
AXIS WELL SOUTH AND/OR BEGIN LYSIS AS IT ENCOUNTERS HIR MLCIN ACRS
NRN IN. FURTHER AND LKLY MORE PROBABLE INITIATION BY ERLY AFTN
ACRS FAR SWRN CWA/KLAF REGN AS MESOVORT NOTED IN NORTHEAST OF KBMI
SFC VORTICITY/BREAK IN SCCAS/ACCAS LN...MOVG EWD AT 40 KTS. OPTED
FOR COVERAGE TYPE/SVR WORDING ALONG SRN TIER CWA...TIERED WITH
LOW/SLGHT CHC PROBABILISTIC WORDING NORTH AND CONTD DRY NRN/NERN
CWA...PROVIDING CONSIDERABLY GREATER TEMPORAL/SPATIAL DETAIL THIS
AFTN/EVE. ONE OR MORE ADDNL CONVECTIVE SYSTEMS PSBL LATE TONIGHT
WESTERN HALF CWA DRIVEN BY VEERED/INCSG LLVL JETLET ACRS NRN IL
ALONG WITH ARRIVAL OF MORE SIG SD/NE SHORTWAVE ENERGY...SPREADING
EWD/CONTG INTO SAT...THOUGH A MORE COMPLETE 12 UTC MODEL SYNOPTIC
SIGNAL CONSIDERATION STILL NEEDED.

&&

.PREV DISCUSSION... /ISSUED 432 AM EDT FRI JUN 29 2012/

SHORT TERM... /TODAY THROUGH SATURDAY NIGHT/

.HOT AND HUMID CONDITIONS TO CONTINUE...

SULTRY CONDITIONS IN PLACE WITH TEMPERATURES IN THE MID 70S TO LOWER
80S ACROSS THE AREA AND DEWPTS IN THE 60S. BOUNDARY THAT AIDED
CONVECTION OVER THE PAST EVENING WAS SITUATED NEAR OR JUST SOUTH OF
THE FORECAST AREA. CHALLENGES ARE TWO FOLD...ONE BEING TEMPS/HEAT
INDICES AND TWO CONVECTIVE CHANCES.

A GOOD DEAL OF SUNSHINE SHOULD BE SEEN TODAY..ESPECIALLY IN SE
SECTIONS WHERE CONVECTIVE DEBRIS FROM UPSTREAM ACTIVITY SHOULD
EITHER BE KEPT AT A MINIMUM OR AT LEAST DELAYED UNTIL LATER
AFTERNOON. WITH THE WARM OVERNIGHT START...SHOULD NOT BE HARD FOR
MANY SPOTS TO JUMP 10 TO 20 DEGREES BEFORE NOON...WITH VALUES IN THE
LOW TO MID 90S WIDESPREAD. DEWPTS WILL LIKELY REMAIN IN THE MID TO
UPPER 60S...ALLOWING FOR HEAT INDICES TO CLIMB TO NEAR OR ABOVE
ADVISORY CRITERIA. RECORD HIGH AT SOUTH BEND SHOULD BE SAFE (102)
BUT FT WAYNE MAY BE AR RISK WITH VALUE OF 99. AFTER COORDINATION
HAVE OPTED TO GO WITH ADVISORY ROUGHLY ALONG AND EAST OF A
MONTICELLO TO WARSAW TO HILLSDALE LINE. THAT BEING SAID...THE SECOND
AREA OF CONCERN BELOW COULD CAUSE SOME ISSUES WITH ESPECIALLY
WESTERN/SW COUNTIES AND THE ADVISORY.

WATER VAPOR LOOP SHOWS 2 FEATURES OF INTEREST. FIRST WAS A COMPACT
WAVE MOVING INTO SW ND. THE OTHER A MCS IN EASTERN NEBRASKA THAT WAS
WORKING SLOWLY EASTWARD. MODELS EACH KEY IN ON THEIR OWN FEATURES OF
THESE ITEMS AND RUN THE GAMBIT WITH CONVECTIVE SCENARIOS FROM LATE
MORNING INTO THE OVERNIGHT HOURS. IN ADDITION...HI RES MODELS
DEVELOP CONVECTION ACROSS EASTERN IA BETWEEN NOW AND 12Z WHICH
TRACKS EAST INTO ILLINOIS. UNCERTAINTIES EXIST WHETHER THIS IS IN
RESPONSE TO DYING COMPLEX MOVING INTO WESTERN IOWA FROM NEBRASKA OR
FOCUSED LL WAA AND INFLOW. REGARDLESS NO IMMEDIATE SIGNS OF
DEVELOPMENT. HI RES MODELS HAVE A GENERAL WEAKENING TREND AS
ANYTHING MOVES EAST WITH MAIN FOCUS SHIFTING S OF THE AREA. SPC DAY1
OUTLOOK HAS PLACED ENTIRE AREA IN SLGT RISK. WITH EXPECTED TEMPS AND
DEWPTS AND AT LEAST SOMEWHAT MORE SUBDUED CAPPING...SEVERE THREAT
DOES EXIST IF ANY CONVECTION CAN DEVELOP. HAVE OPTED TO RUN WITH
SLGT CHC POPS ALL AREAS THROUGH THIS EVENING WITH CHC POPS IN SW
AREAS CLOSER TO LIKELY TRACK OF CONVECTION. WILL PASS ONTO DAY SHIFT
TO MONITOR TRENDS. NO MENTION OF SVR IN ZONES BUT WILL PLACE WORDING
IN HWO.

RICH LL THETA E AIR WILL REMAIN IN PLACE ACROSS THE REGION THROUGH
SATURDAY NIGHT. ADDITIONAL CHANCES FOR CONVECTION WILL EXIST BUT
TIMING OF THESE CHANCES AND LOCATIONS OF SUBTLE FEATURES REMAINS A
CHALLENGE...WARRANTING HOLDING OFF ON ANY CHANGES. ADDITIONAL HEAT
ADVISORIES COULD BE NEEDED SAT.

LONG TERM...SUNDAY THROUGH THURSDAY

A SHORT WAVE TROUGH EJECTING EASTWARD FROM LARGER SCALE UPPER TROUGH
MOVING ACROSS PACIFIC NORTHWEST THIS MORNING WILL BE THE MAIN
FEATURE OF INTEREST FOR SUNDAY...ACTING TO SUPPRESS MEAN UPPER
RIDGING ACROSS GREAT LAKES/OHIO RIVER VALLEY. DETERMINISTIC
SOLUTIONS ARE IN FAIRLY GOOD AGREEMENT ON THIS FEATURE...WHILE THE
GFS REMAINS THE STRONGEST IN AMPLITUDE. SOME CONCERN THAT THE GFS
MAY BE A BIT TOO AMPLIFIED WITH SOME POTENTIAL CONVECTIVE FEEDBACK
ISSUES ACROSS THE DAKOTAS ON SATURDAY. HOWEVER...PASSAGE OF THIS
SHORT WAVE SHOULD TEND TO ANCHOR A WEAK LOW LEVEL SYNOPTIC
CONFLUENCE ZONE/TROUGH FROM THE MID MS RIVER VALLEY ACROSS THE
SOUTHERN GREAT LAKES REGION THAT SHOULD ALLOW FOR A MODEST AXIS OF
LOW LEVEL MOISTURE TO RESIDE ACROSS THE REGION. CONVECTIVE POTENTIAL
ON SUNDAY WILL DEPEND SOMEWHAT ON EVOLUTION OF SATURDAY/SATURDAY
NIGHT CONVECTION AND HOW ANY RESIDUAL OUTFLOWS EFFECT SFC
BOUNDARY/LOCATION OF BEST LOW LEVEL MOISTURE. DID ADD SOME SLIGHT
CHANCE TSRA POPS FOR SUNDAY GIVEN THIS LARGER SCALE SUPPORT AND
POTENTIAL FOR SECONDARY WEAK SFC TROUGH TO ACCOMPANY THIS SHORT WAVE.

MON-THU PERIOD WILL BE CHARACTERIZED BY TRICKY NORTHWEST FLOW
PATTERN WITH A CONTINUED POTENTIAL FOR WEAK SHORT WAVES TO PROGRESS
DOWN THE UPPER RIDGE INTO THE SOUTHERN GREAT LAKES. SOME POTENTIAL
DURING THIS PERIOD OF ANOTHER LOW LEVEL ISENTROPIC LIFT/THETAE
ADVECTION SURGE THAT COULD OVERCOME CAPPING CONCERNS FOR CHANCES OF
CONVECTION...BUT WITH ONGOING DROUGHT/DRY SOILS...WEAK NATURE OF
THIS FORCING...AND SMALL SCALE OF THESE PERTURBATIONS MAKING IT
DIFFICULT TO TIME ENHANCED PERIODS OF POSITIVE THETAE
ADVECTION...WILL KEEP FORECAST DRY THROUGH THIS PERIOD. ABOVE NORMAL
TEMPERATURES TO CONTINUE THROUGH THE PERIOD AND WILL MAINTAIN HIGHS
IN THE LOWER TO MID 90S MORE INLINE WITH ECMWF MOS GUIDANCE...THAT
MAY NOT BE AS AFFECTED BY SPURIOUS CONVECTION OF THE OVERLY MOIST
GFS/MEX THROUGH MID WEEK. TOWARD THE END OF THE PERIOD...LATEST
TRENDS IN GFS ARE COMING MORE INLINE WITH ECMWF IDEA OF SOME
AMPLIFICATION OF CENTRAL CONUS RIDGE THAT SHOULD KEEP VERY HOT
CONDITIONS IN PLACE THROUGH THE END OF THIS FORECAST PERIOD.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
    INZ007>009-015>018-020-022>027-032>034.

MI...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR MIZ081.

OH...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
     OHZ001-002-004-005-015-016-024-025.

LM...NONE.
&&

SHORT TERM...FISHER
LONG TERM...MARSILI
AVIATION...MURPHY
UPDATE...MURPHY

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORTHERN INDIANA
309 PM EDT FRI JUN 29 2012

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0221 PM     TSTM WND DMG     2 W COLUMBIA CITY       41.16N  85.53W
06/29/2012                   WHITLEY            IN   AMATEUR RADIO

            TOP 40 FEET OF 100 FOOT RADIO TOWER BLOWN DOWN. ALSO
            SEPARATE REPORT OF TOP 2 SECTIONS OF 160 FOOT TOWER
            DOWN.

&&

BENTLEY

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