Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 261346
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
946 AM EDT SAT JUL 26 2014

.SYNOPSIS...
ISSUED AT 655 AM EDT SAT JUL 26 2014

PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS LATER TONIGHT AND
SUNDAY AS A FRONTAL BOUNDARY SETTLES INTO THE REGION. HIGHS ARE
EXPECTED TO REACH THE 80S TODAY AND SUNDAY. MUCH COOLER WEATHER
WILL RETURN EARLY NEXT WEEK AS AN UPPER TROUGH SETTLES IN.

&&

.UPDATE...
ISSUED AT 946 AM EDT SAT JUL 26 2014

FORECAST INTO THIS AFTERNOON IN PRETTY GOOD SHAPE WITH ONLY SOME
MINOR CHANGES MADE. SLOWLY INTRODUCED LOW 15-20 POPS FOR ISOLATED
SHOWERS/THUNDER INTO NORTHERN/EASTERN ZONES THIS AFTERNOON GIVEN
WEAK WAA/ISENTROPIC ASCENT AND BOUNDARY LAYER HEATING IN ADVANCE
OF A WARM FRONT AND STOUT (IA/NRN MO/WS IL) EML. THIS EML APPEARS
RATHER IMPRESSIVE ON 12Z DVN/ILX/OMX RAOBS WITH CONVECTIVE TEMPS
IN EXCESS OF 100F. THIS MAY DELAY PRIMARY CONVECTIVE COMPLEX
PROGGED TO POSSIBLY CLIP OUR SOUTHERN ZONES TO LATER TONIGHT WHEN
HEIGHT FALLS BEGIN TO OVERSPREAD THE FRONTAL BOUNDARY.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 451 AM EDT SAT JUL 26 2014

NOSE OF LOW LEVEL JET FOCUS COINCIDENT WITH EASTERN PERIPHERY OF
STOUT EML BEGINNING TO DRIVE CONVECTIVE DEVELOPMENT UPSTREAM IN ARC
STRETCHING FROM EASTERN IA-NWRN IL-FAR WCNTL IN. VEERING JETLET AND
STEERING FLOW SUGGESTS MAJORITY OF SHRA TO TARGET ONLY FAR SWRN/SRN
CWA THIS AM. LACK OF APPRECIABLE LOW LEVEL MOISTURE WITH EASTERN
EXTENT SHOULD PRECLUDE ALL BUT PERHAPS AN ISOLD TSRA WITH EASTERN
EXTENT INTO CWA. SMALL CHC TSRA POPS IN DEFERENCE TO SHORT MODEL
CONSENSUS AFFORDED ACROSS ERN CWA THIS AFTN AS RIDGE OF GREATER
1000-850MB THETA-E/MOISTURE FLUX CONVERGENCE ASSERTS INTO NERN
IN/NWRN OH. DIFFERENTIAL HEATING ALONG DECAYING AM SHRA AND
STRATO/ALTOCU LAYERS AND PRESENCE OF DIFFUSE WARM FRONTAL LIMB LENDS
CREDENCE TO TREND OF OUTCOME/SOLUTIONS SEEN WITH 3KM HIGH-RES RAPID
REFRESH RUC IN THIS REGARD. WEAK LOW AMPLITUDE RIDGING SHOULD ALLOW
LOW END MENTION TO SUFFICE THROUGH TODAY. BY FAR THE GREATER
CONVECTIVE CONCERN LIES UPSTREAM AS EXTREME SERN SASK VORTEX DRIVES
SEWD INTO NRN MN EARLY TONIGHT WITH 60-70KT MID TROPOSPHERIC FLOW
ALONG SOUTHERN PERIPHERY OF WAVE. STRONG MID/UPPER LEVEL KINEMATICS
TO IMPINGE ON AREA OF SIGNIFICANT MOISTENING/HEATING BENEATH
RESIDUAL EML TO OFFER STRONG 3500-5000 J/KG SBCAPE BY 00 UTC SUN.
THIS LARGE INSTABILITY POOL PRESENTS ELONGATED E-W FROM SWRN CWA TO
MO/IA BORDER AMID 40-50 KTS DEEP LAYER BULK SHEAR. DECENT POTENTIAL
FOR MULTIPLE EPISODIC EVENING/EARLY NIGHT SUPERCELLS TO DEVELOP
UPSTREAM ACROSS CENTRAL/NCENTRAL ILLINOIS TO TRACK INTO SRN HALF OF
CWA AND TRANSITION TOWARD STRONG/SEVERE QUASI-LINEAR SEGMENTS
THROUGH SOUTHERN HALF OF CWA IN STRONG PARALLEL STORM MOTION
VECTORING. MDPI GT 1 AND DECENT /1000-1250 J/KG/ CAPE WITHIN
M10-M30C HAIL PRODUCTION ZONE WITH FAVORABLE WETBULB ZERO HEIGHTS IN
10.5-11.5 RANGE SUGGESTIVE OF MULTIPLE DAMAGING WIND EVENTS/ISOLATED
LARGE HAIL RISKS. DIFFICULTY IN SHARP DEMARCATION OF POPS WITH
EXTREMELY SHARP INSTABILITY GRADIENT WITH ONLY SLIGHT CHC MENTION
WARRANTED FAR NRN CWA RAMPING TO SIGNIFICANT/SEVERE LIKELY
POPS/SEVERE MENTION GENERALLY ALONG/S OF ROUTE 30 IN 00-09 UTC
TIMEFRAME. SOME CONCERN FOR POTENTIAL BACKBUILDING/TRAILING
STRATIFORM CONVECTION IN 06-12 UTC TIMEFRAME AS STORM MOTION VECTORS
BACK DUE WESTERLY...ALONG/PARALLEL TO TRAILING POOL OF EXTREME
1000-850MB MIXING RATIO GTE 16 G/KG THAT REACHES BACK INTO WEST
CENTRAL IL. WILL ADDRESS TERTIARY FLOODING POTENTIAL IN HWO IN
ADDITION TO DMG WIND/HAIL CONCERNS.

&&

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 451 AM EDT SAT JUL 26 2014

A WELL DEFINED UPPER LEVEL DISTURBANCE OVER SOUTHERN SASKATCHEWAN
PROVENCE EARLY THIS MORNING WILL MOVE SOUTHEAST DOWN THE BACKSIDE OF
THE UPPER LEVEL RIDGE. AS THIS SYSTEM MOVES SOUTHEAST TOWARD THE
WESTERN GREAT LAKES REGION...VERY UNSTABLE AIR WILL EXTEND INTO
NORTHERN INDIANA AND NORTHWEST OHIO EARLY SUNDAY MORNING. HIGH
ENERGY HELICITY INDEX VALUES UP TO 4.0 TO 5.0 M2/S2 REFLECT THE
POTENTIAL FOR SUPERCELL ACTIVITY OVER THE SOUTHERN THIRD OF THE
FORECAST AREA EARLY SUNDAY MORNING. SEVERE WEATHER CHANCES LOOK BEST
IN THE MORNING OVER FAR SOUTH AND SOUTHEAST AREAS. CONCERN FOR
MAINLY DAMAGING WINDS EARLY GIVEN A FAVORABLE WIND PROFILE
SIGNATURE. SEVERE WEATHER CHANCES SHOULD DIMINISH BY EARLY AFTERNOON
AS COOLER AIR SPREADS OVER THE AREA BEHIND THE FRONT. FOR THE REST
OF THE PERIOD...SOME LINGERING SHOWERS ARE POSSIBLE TONIGHT AND
MONDAY AS A POST FRONTAL TROF MOVES ACROSS THE AREA. KEPT THE REST
OF THE PERIOD DRY AS THE UPPER LEVEL TROF REMAINS OVER THE AREA. 500
MB ANALOGS SUPPORT TEMPERATURES BELOW NORMAL THIS UPCOMING WORK WEEK
WITH A PERSISTENT NEGATIVE HEIGHT ANOMALY SOUTH OF HUDSON BAY.
PREFER THE COOLER GFS/MEAN/MEX VALUES GIVEN COOL 850 MB TEMPERATURES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 652 AM EDT SAT JUL 26 2014

AS UPSTREAM LOWER LEVEL JET VEERS SUSPECT NERN IL INTO WCNTL IN
SHRA/ISOLD TSRA TO WEAKEN WITH EWD PROGRESSION THIS MORNING. BETTER
CHANCES FOR CONVECTIVE DEVELOPMENT CONTINUE TO APPEAR JUST AFTER
DARK AS KS FRONTAL WAVE LIFTS INTO CNTL IL AMID LARGE/EXTREME
3500-5000 J/KG SBCAPE POOL. MINOR ADJUSTMENTS TO TEMPO TSRA
TIMING.


&&

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

$$

UPDATE...STEINWEDEL
SYNOPSIS...MURPHY
SHORT TERM...MURPHY
LONG TERM...SKIPPER
AVIATION...MURPHY


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