Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 020536
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
136 AM EDT TUE SEP 2 2014

.SYNOPSIS...
ISSUED AT 130 AM EDT TUE SEP 2 2014

A COLD FRONT WILL PUSH SOUTH THROUGH THE AREA TONIGHT...KEEPING
THE BETTER CHANCE FOR RAINFALL ACROSS CENTRAL INDIAN. HIGH
PRESSURE WILL BUILD INTO THE AREA ON TUESDAY...PROVIDING DRY
CONDITIONS AND COOLER...LESS HUMID CONDITIONS THROUGH MIDWEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 320 PM EDT MON SEP 1 2014

CONVECTIVE ACTIVITY ONGOING ACROSS NORTHWEST THIRD OF CWA AS OF
1845Z AS REMNANT OUTFLOW BOUNDARY SLIDES EASTWARD ACROSS THE AREA
AHEAD OF LARGER SCALE FORCING. SEVERE THREAT HAS DIMINISHED FROM
THE EARLY MORNING HOURS AS EXTENSIVE CLOUD COVER HAS KEPT A
RELATIVELY STABILIZED ATMOSPHERE IN PLACE. CANNOT RULE OUT AN
ISOLATED STRONG TO SEVERE STORM THROUGH 00Z...WITH DAMAGING WINDS
THE MAIN THREAT...AS LATE AFTERNOON DESTABILIZATION YIELDING
1500-2000 J/KG SBCAPE EAST OF U.S. 31 AND 0-6KM BULK SHEAR OF
30-40 KTS ACROSS THE AREA. HOWEVER POOR MID LEVEL LAPSE RATES AND
LACK OF STRONG FORCING SHOULD LIMIT OVERALL ORGANIZATION.
COVERAGE WORDING REFLECTED IN THE FORECAST THROUGH 00Z.

ATTENTION TURNS TO THE POTENTIAL FOR HEAVY RAINFALL ACROSS
SOUTHERN PORTIONS OF THE AREA OVERNIGHT...AS LARGE SCALE NORTH
CENTRAL CONUS TROF SLIDES EAST TOWARDS THE GREAT LAKES AND SFC
COLD FRONT PUSHES SOUTHEAST THROUGH THE AREA. WIDE SPREAD OF
SOLUTIONS AMONG MODEL GUIDANCE WRT LOCATION/AXIS OF HEAVIEST
RAINFALL. AS SFC BOUNDARY SETTLES SOUTHEAST INTO THE FCST
AREA...S/W ENERGY EJECTING THROUGH THE LARGE SCALE TROF AND 120
KT UPPER JET EJECTING NORTHEAST THROUGH THE GREAT LAKES WILL
PROVIDE STRONG FORCING ACROSS THE REGION. HIGHER RES GUIDANCE
SUCH AS THE ARW-EAST...NMM-EAST AND 4KM SPC WRF...SUGGEST
AFTERNOON/EARLY EVENING CONVECTION REINFORCING THE FOCUS FOR
CONVECTIVE ACTIVITY SOUTH OF THE AREA OVERNIGHT...ROUGHLY FROM AN
EVANSVILLE TO COLUMBUS OH LINE. LOWER RES GUIDANCE SUCH AS THE
NAM/GFS/ECMWF PUTS THE FOCUS OF THE CONVECTION CLOSER TO THE MAIN
SYNOPTIC SFC FORCING...WITH THE HEAVIEST AXIS OF RAINFALL FROM
KIND TO KCLE. THIS SOLUTION WOULD PUT THE FAR SOUTHEAST
COUNTIES...FROM A MARION TO PAULDING LINE AND SOUTHWARD...AT RISK
FOR HEAVY RAINFALL AND LOCALIZED FLOODING AFTER MIDNIGHT INTO
EARLY TUESDAY MORNING. ALTHOUGH CONFIDENCE IS HIGH FOR HEAVIER
RAINFALL EVENT GIVEN RIGHT ENTRANCE REGION OF JET STREAK
OVERHEAD...PWAT VALUES IN TH 1.6-1.8 INCH RANGE...WARM CLOUD
DEPTHS AROUND 12KFT...LITTLE CLOUD LAYER SHEAR AND CLOUD LAYER
FLOW PARALLEL TO THE SFC BOUNDARY...UNCERTAINTIES WITH THE
LOCATION OF THE RAINFALL WILL PRECLUDE CATEGORICAL POPS OR
HEADLINES OVERNIGHT. WILL MAINTAIN A MENTION OF HEAVY RAINFALL
AND LOCALIZED FLOODING ROUGHLY ALONG AND SE OF THE U.S. 24
CORRIDOR. WILL CLOSELY MONITOR TRENDS TONIGHT AND ADJUST FORECAST
ACCORDINGLY.

AS FRONTAL WAVE PUSHES NORTHEAST OF THE AREA TUESDAY MORNING AND
SFC BOUNDARY SLIDES SOUTHEAST OF THE AREA...PRECIP CHANCES WILL
WANE FROM NW TO SE THROUGH THE DAY. POP TRENDS FOR THE TUESDAY
PERIOD STILL IN LINE FROM PREVIOUS FCST...SO NO MAJOR CHANGES WITH
THIS ISSUANCE. NO MAJOR CHANGES TO TEMPS TONIGHT AND TUESDAY.

&&

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 320 PM EDT MON SEP 1 2014

PERTURBED NRN STREAM FLW ACRS SRN CANADA OVERTOP FLAT CONUS
RIDGING WILL CONT THIS PD. HIGH PRES BLDS EWD OUT OF THE PLAINS
TO START THE PD TUE NIGHT IN WAKE OF LEAD SW LIFTING UP THROUGH
NRN QB. HWVR SHALLOW CAA WING GIVES WAY QUICKLY AS FLW BACKS
DURING THE DAY WED IN RESPONSE TO ANOTHER UPSTREAM VIGOROUS SYS
EJECTING EWD THROUGH SRN AB. THIS SYS WILL CONT TO STREAK EWD
THROUGH FRI AS ATTENDANT SFC BNDRY SAGS SWD INTO THE LWR LAKES/OH
VALLEY. HWVR AS HAS BEEN THE CASE W/MOST OF THESE SYS/S...HGT
FALLS ARE CONFINED WELL NORTH W/TRAILING SFC FNTL BNDRY WKNG
THROUGH TIME. AS SUCH AND IN REFLECTION OF MOST 12Z MED RANGE
MODEL GUIDANCE...NOTHING MORE THAN A LOW CHC POP WARRANTED LATE
WEEK.

BEYOND THAT SERN US/WRN ATL UPR RIDGE LOOKS TO FLATTEN FURTHER
W/SECONDARY SW AMPLIFYING THROUGH JAMES BAY NXT WEEKEND. THIS
WILL ALLOW A BIT COOLER CANADIAN AIRMASS TO DRIVE SEWD ACRS THE
LAKES/NEW ENGLAND W/SEASONABLY PLEASANT AND DRY WX XPCD.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 130 AM EDT TUE SEP 2 2014

PRIMARILY VFR MET CONDITIONS ANTICIPATED THROUGH THE FORECAST
PERIOD. AREA OF ELEVATED -RA ACRS NRN IL MAY PROVIDE KSBN SOME
SPRINKLES TOWARD DAYBREAK/COVERED WITH VCSH. ONLY NORTHERN FRINGE
OF LARGELY STRATIFORM RAIN SHIELD INTO KFWA EARLY THIS
MORNING...WITH BULK OF CONVECTION RIDING EWD THROUGH THE OHIO
VALLEY. MORE STEADY PRECIP COULD BRING PD OF HIGH END MVFR
CONDITIONS AROUND/FEW HOURS AFTER DAYBREAK. OTHERWISE INCREASING
DRY AIR ADVECTION LEADING TO ONLY SCT CU FIELD BY LATE
MORNING/AFTERNOON HOURS. SUBSEQUENT FORECASTS TO ADDRESS BR/FG
POTENTIAL NEAR SUNRISE WED.

&&

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

$$

SYNOPSIS...NG
SHORT TERM...NG
LONG TERM...T
AVIATION...MURPHY


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