Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 311406
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1006 AM EDT FRI JUL 31 2015

.SYNOPSIS...
ISSUED AT 953 AM EDT FRI JUL 31 2015

ISOLATED SHOWERS ARE EXPECTED NEAR LAKE MICHIGAN THIS MORNING AS
A WEAK DISTURBANCE APPROACHES THE AREA. OTHERWISE...EXPECT PARTLY
TO MOSTLY SUNNY SKIES THROUGH THE AFTERNOON. ADDITIONAL ISOLATED
TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED LATER TODAY.
HIGHS WILL BE IN THE 80S.

&&

.UPDATE...
ISSUED AT 953 AM EDT FRI JUL 31 2015

UPDATED FORECAST TO INCREASE CLOUD COVER AND INCLUDE A MENTION OF
ISOLATED SHOWERS ASSOCIATED WITH THE APPROACHING SHORTWAVE IN THE
WESTERN PORTIONS OF THE CWA. UPSTREAM OBSERVATIONS/WEBCAMS SHOW
SCT-BKN DECK OF CLOUDS MOVING ONSHORE IN BERRIEN/LAPORTE
COUNTIES AS OF 14Z. UNCERTAIN HOW MUCH OF UPSTREAM PRECIPITATION
WILL MAKE IT TO THE GROUND GIVEN DRIER AIR IN PLACE...SO KEPT
COVERAGE TO ISOLATED. AFTERNOON FORECAST OF SHOWERS/T-STORMS STILL
UNCERTAIN...HAVE KEPT GOING ISO-SCT COVERAGE FOR NOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM EDT FRI JUL 31 2015

DIFFICULT NR TERM OWING TO SEWD AMPLIFICATION OF
SEASONABLY STG SW OVR SWRN ONTARIO AS ATTENDANT SFC TROUGH CROSSES
THE SRN LAKES THIS AFTN. NARROW LL THETA-E RIDGING NOTED UPSTREAM IN
00Z RAOBS AND XPCD TO ADVT E/NE INTO THE AREA BY THIS AFTN. HWVR SIG
DIFFS NOTED AMG EVEN SHRT TERM GUIDANCE W/DEGREE OF BNDRY LYR
MOISTENING AND/OR DRYING THAT TAKES PLACE INTO THIS AFTN AND AS SUCH
WHETHER OR NOT CONVN INITIATES OR NOT IN AN OTRWS FVRBL SYNOPTIC
ENVIRONMENT AS DECENT HGT FALLS OVERSPREAD FNTL ZONE THIS AFTN.
REGARDLESS GIVEN OBSVD SFC CONDS UPSTREAM YDA WITHIN WELL MIXED
BNDRY LYR AND GENERAL WIDESPREAD UPR 50 TDS...CONSERVATIVE SFC BASED
CAPES SHLD APCH 1000 J/KG ACRS NRN IN/NW OH PRIOR TO FROPA AND WILL
ENTERTAIN USUALLY SUPERIOR 4KM SPC WRF IN NOTCHING A SWATH OF HIGHER
POPS MID-LT AFTN SOUTH OF HIGHWAY 6 ESP SW/SRN THIRD IN PROXIMITY TO
HIGHER XPCD LL THETA-E RTN.

&&

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 330 AM EDT FRI JUL 31 2015

THIS PERIOD WILL FEATURE A SOMEWHAT ACTIVE NORTHWEST FLOW REGIME
UNDER A QUASI-STATIONARY HUDSON BAY UPPER LOW THAT WILL SLOWLY PIVOT
SOUTHEAST. NUMEROUS SMALLER SCALE SHORTWAVES EMBEDDED IN THIS
CYCLONIC FLOW WILL SUPPORT SHOWER/STORM CHANCES FOR THE SECOND HALF
OF THE WEEKEND INTO MUCH OF NEXT WEEK...WITH TEMPERATURES TRENDING
BELOW NORMAL. AS EXPECTED MODELS STRUGGLING WITH THE
TIMING/AMPLITUDE OF THESE SMALLER SCALE FEATURES MAKING POPS A LOW
CONFIDENCE FCST IN ANY ONE PERIOD. MODELS CONTINUE TO KEY IN ON
LATER SATURDAY NIGHT/SUNDAY WITH INITIAL LOW LEVEL WAA
SURGE/CONVECTIVELY AIDED WAVE...AND LATER SUNDAY NIGHT/EARLY MONDAY
WITH A STRONGER SHORTWAVE TROUGH/CDFNT ROTATING THROUGH THE GREAT
LAKES FOR BEST SHOWER/STORM CHANCES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 646 AM EDT FRI JUL 31 2015

VFR CONDS XPCD THROUGH THE PD. WHILE SUGGESTION REMAINS IN EARLIER
00Z BASED GUIDANCE...SUBSEQUENT RUNS OF HRRR/RAP ALG W/06Z NAM HAVE
DECIDEDLY TRENDED HOSTILE TWD INITIATING CONVN ALG WK CDFNT CROSSING
THE TERMINALS THIS AFTN. AS SUCH AND IN LIGHT OF QUESTIONABLE MODEL
HANDLING OF CRITICAL BNDRY LYR MASS FLUX WILL DEFER POTENTIAL AFTN
TSRA INCLUSION AT KFWA TO 18Z ISSUANCE AS REACH OF LL THETA-E PLUME
AS SAMPLED IN 12Z RAOBS WILL BE INSTRUMENTAL AT NARROWING POTENTIAL
WINDOW OF OPPORTUNITY. OTRWS DECENT MIXING XPCD AGAIN THIS AFTN
W/WRLY SFC GUSTS AOA 20KTS BY MID AFTN.


&&

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

$$

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


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