Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 260039
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
839 PM EDT FRI JUL 25 2014

.SYNOPSIS...
ISSUED AT 305 PM EDT FRI JUL 25 2014

PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS WILL RETURN LATER
TONIGHT INTO THIS WEEKEND AS A FRONTAL BOUNDARY SETTLES INTO THE
REGION. LOWS WILL GENERALLY BE IN THE 60S...WITH HIGHS EXPECTED TO
REACH THE 80S ON SATURDAY AND SUNDAY. MUCH COOLER WEATHER WILL
RETURN EARLY NEXT WEEK AS AN UPPER TROUGH SETTLES IN.

&&

.UPDATE...
ISSUED AT 800 PM EDT FRI JUL 25 2014

A WELL PRONOUNCED SHORT WAVE TRACKING ACROSS NORTHERN
INDIANA/SOUTHERN LOWER MICHIGAN THIS EVENING WILL EXIT THE AREA
LATE THIS EVENING. LIGHT RAIN/SPRINKLES HAVE EXPANDED IN COVERAGE
ACROSS SOUTHEAST LOWER MICHIGAN AHEAD OF THIS VORT MAX...BUT WITH
STRONGEST DPVA DEPARTING EAST OF THE AREA OVER THE NEXT FEW HOURS
WILL MAINTAIN JUST SLIGHT CHANCE -RW POPS. PROGRESSIVE AND LOWER
AMPLITUDE ADDITIONAL SHORT WAVES ARE EXPECTED TO SHIFT INTO THE
WESTERN GREAT LAKES REGION OVERNIGHT INTO EARLY SATURDAY WITH
WESTERLY LOW LEVEL JET HELPING TO ADVECT MORE SUBSTANTIAL LOW LEVEL
THETAE NOSE EASTWARD OVERNIGHT...PARTICULARLY ACROSS WESTERN HALF
OF THE AREA. INCREASED LOW LEVEL MOISTURE SHOULD ALLOW FOR
INCREASED DEPTH TO ELEVATED INSTABILITY PARTICULARLY AFTER 09Z.
THUS...HAVE MADE FEW IF ANY CHANGES TO PREVIOUS POPS WITH WEST TO
EAST GRADIENT SETTING UP OVERNIGHT...HIGHEST CHANCE ACROSS THE
WEST.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 305 PM EDT FRI JUL 25 2014

A WEAK SHORTWAVE NOW INTO SRN WI PER LATEST WATER VAPOR IMAGERY WILL
PROPAGATE SOUTHEAST THROUGH THE LOWER LAKES LATE THIS
AFTERNOON/EARLY EVENING. THIS TIMED WITH INITIAL 850-700MB THETA-E
SURGE/WEAK ISENTROPIC ASCENT MAY BE ENOUGH TO GENERATE A FEW
SPRINKLES/LIGHT SHOWERS INTO MAINLY OUR FAR NORTHWEST DURING THIS
TIME...ALTHOUGH KEPT POPS FOR MEASURABLE PCPN LOW GIVEN VERY
DRY/DEEP SUB-CLOUD LAYER.

CHANCES FOR SHOWERS/ELEVATED CONVECTION WILL INCREASE LATER TONIGHT
INTO SATURDAY MORNING AS LOW LEVEL THETA-E RIDGE FOLDS SOUTHEAST IN
ADVANCE OF AN UPPER MIDWEST LOW LEVEL TROUGH AXIS. THIS FEATURE WILL
EVENTUALLY BE FORCED INTO THE CENTRAL/LOWER LAKES ON THE LEADING
EDGE OF A STRENGTHENING NORTHERN PLAINS TO WESTERN GREAT LAKES
MID-UPPER JET STREAK. ASSOCIATED BOOST OF PRECIPITABLE WATER VALUES
TO GREATER THAN 1.6 INCHES WITHIN A MODEST 30 KT LLJ...AND ADDED
MOISTURE CONVERGENCE ALONG AN APPROACHING WARM FRONT SUPPORT
INHERITED MID CHC POPS...ALTHOUGH COVERAGE REMAINS IN QUESTION GIVEN
LACK OF HEIGHT FALLS/SUPPORT ALOFT. EXPECTED INCREASE IN MUCAPE TO
GREATER THAN 1000 J/KG AND 40 KTS OF DEEP LAYER SHEAR SUGGESTS A LOW
RISK FOR SVR HAIL INTO OUR FAR WESTERN ZONES SATURDAY MORNING.
OTHERWISE...TEMPERATURES WARM CLOSER TO NORMAL TONIGHT INTO SATURDAY.

SFC TROUGH/INSTABILITY GRADIENT LOOKS TO LAY OUT MORE WEST TO EAST
OVER CENTRAL/SOUTHERN PORTIONS OF THE FA BY MID-LATE AFTERNOON
SATURDAY...WITHIN THE SOUTHERN FRINGE OF STRONG MID-UPPER LEVEL JET
CORE. THE EASTWARD ADVANCEMENT OF A PLAINS EML OVER AN INCREASINGLY
JUICED BOUNDARY LAYER SHOULD YIELD SBCAPE VALUES IN EXCESS OF 3000
J/KG ALONG/SOUTH OF BOUNDARY IF HIGHS INTO THE LOW/MID 80S ARE
ATTAINED (DEPENDENT ON LINGERING CONVECTIVE CLOUD DEBRIS)...WITH
EXTREME INSTABILITY POSSIBLE INTO SOUTHWESTERN PORTIONS OF THE FA
WHERE WARM SECTOR MAY BECOME BRIEFLY ESTABLISHED. WITH 0-6 KM
SHEAR/FLOW PROGGED TO BE SUFFICIENT FOR UPSCALE GROWTH/ORGANIZATION
WILL HAVE TO CLOSELY MONITOR THE SEVERE WEATHER POTENTIAL (DISCRETE
SUPERCELLS DEVELOP ACROSS CENTRAL IL AND ROLE EAST INTO INDIANA AS A
MCS?) LATER SATURDAY AFTERNOON INTO SATURDAY EVENING...BEST CHANCES
SOUTH OF THE HWY 30 CORRIDOR IN INDIANA/OHIO.

&&

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 305 PM EDT FRI JUL 25 2014

POTENT SW TROUGH ALG THE BC/AB BORDER WILL DIG SEWD INTO THE WRN
LAKES THIS WEEKEND CONCURRENT W/DEEP MERIDONAL FLW AMPLIFICATION
ACRS NOAM. ACTIVE SFC FNTL ZONE/COMPOSITE OUTFLW BNDRY POSITION
STILL VRY UNCERTAIN AND POSES THE GREATEST QUANDARY THIS PD. HWVR
WOULD CERTAINLY PREFER TO SEE MORE SIG RIDGE AMPLIFICATION NEWD OF
UPR RIDGE CNTRD OVR THE SRN PLAINS TO JUSTIFY A MORE NWD FNTL/OUTFLW
POSITION THIS WEEKEND. REGARDLESS LOOSE MODEL CONSENSUS FVRS SRN
ZONES SAT EVENING AND ERN ZONES SUN FOR GREATER POP WEIGHTING HWVR
WILL REFRAIN FM ELUCIDATING LIKELY OR HIGHER POPS AT THIS RANGE.

THIS SYS WILL BECOME ABSORBED IN LARGER SCALE TROUGH AMPLIFICATION
THROUGH ERN CANADA OF WHICH WILL DRIVE ANOTHER UNSEASONABLY COOL
AIRMASS SWD ACRS THE ERN US. STRONGLY PREFER COOLER GUIDANCE TEMPS
MON-TUE BFR MODERATING BACK TWD NORMAL LT PD. OTRWS REMAINDER OF THE
PD BEYOND SUN XPCD TO BE DRY AS SIG THETA-E SINK DVLPS SWD INTO THE
OH VALLEY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 800 PM EDT FRI JUL 25 2014

A FAIRLY STRONG SHORT WAVE TRACKING ACROSS NORTHERN INDIANA HAS
STRUGGLED TO PRODUCE MEASURABLE PRECIPITATION WITH AN INITIALLY
DRY SUBCLOUD LAYER. STRONGEST FORCING WITH THIS WAVE IS ALREADY
SHIFTING INTO NORTHWEST OHIO AT 00Z...AND THUS EXPECTING TERMINALS
TO REMAIN DRY THROUGH THE REMAINDER OF THE EVENING AND INTO THE
EARLY PORTION OF THE OVERNIGHT HOURS. ADDITIONAL SMALL SCALE WAVES
ACROSS THE CENTRAL PLAINS/CORN BELT ARE EXPECTED TO SHIFT INTO THE
REGION OVERNIGHT. GRADUALLY VEERING LOW LEVEL FLOW WILL ALSO ALLOW
FOR STRONG LOW/MID LEVEL THETAE ADVECTION OVERNIGHT INTO EARLY
SUNDAY IN ASSOCIATION WITH WESTERLY LOW LEVEL JET. THIS WILL
RESULT IN SOME LOW CHANCE OF TSRA AT PARTICULARLY SOUTH BEND LATE
TONIGHT INTO EARLY SUNDAY BUT CONFIDENCE IS TOO LOW FOR INCLUSION
FOR 00Z TAFS AT THIS TIME. MODERATE TO STRONG INSTABILITY TO
DEVELOP FOR SATURDAY...PARTICULARLY SOUTH OF ROUTE 30. POTENTIAL OF
SCATTERED THUNDERSTORMS WILL EXIST SATURDAY AFTERNOON/EVENING IN
ASSOCIATION WITH WARM FRONTAL BOUNDARY TRACKING NORTHWARD...AND
HAVE INCLUDED VCTS MENTION AT KFWA AFTER 18Z.

&&

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

$$

UPDATE...MARSILI
SYNOPSIS...STEINWEDEL
SHORT TERM...STEINWEDEL
LONG TERM...T
AVIATION...MARSILI


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