Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 070446
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1246 AM EDT TUE JUL 7 2015

.SYNOPSIS...
ISSUED AT 703 PM EDT MON JUL 6 2015

A COLD FRONT OVER THE UPPER MIDWEST AND PLAINS WILL MOVE EAST
ACROSS OUR AREA OVERNIGHT INTO TUESDAY. SHOWERS AND A FEW
THUNDERSTORMS ARE EXPECTED TO ACCOMPANY THE FRONT AS IT MOVES
THROUGH THE AREA. LOWS TONIGHT WILL BE IN THE UPPER 60S AND LOWER
70S WITH HIGHS TOMORROW REMAINING IN THE 70S BEHIND THE FRONT.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 344 PM EDT MON JUL 6 2015

CONSOLIDATING POSITIVELY-TILTED LONGWAVE TROUGH EXTENDING FROM
HUDSON BAY CLOSED LOW CONTINUES TO SLOWLY PUSH EAST AND THE
ASSOCIATED COLD FRONT IS THE MAIN FEATURE OF NOTE FOR THIS SHORT
TERM FORECAST. BEST CVA FORCING PASSES WELL TO OUR NORTH BUT MODELS
STILL INDICATE DECENT MIDLEVEL HEIGHT FALLS GENERATING A HEALTHY (BY
JULY STANDARDS ANYWAY) STRIPE OF LOW LEVEL (925-850MB) CONVERGENCE
AND FRONTOGENESIS...AIDED TO SOME DEGREE BY NORTHERN LAKES UPPER JET
STREAK. THIS COMBINED WITH A STRONG...ALBEIT NARROW...SURGE OF DEEP
TROPOSPHERIC MOISTURE JUST AHEAD OF THE FRONT WILL SET THE STAGE FOR
NUMEROUS SHOWERS AND THUNDERSTORMS LATE TONIGHT INTO TOMORROW.

LATEST REGIONAL SURFACE OBS SHOW ACTUAL SURFACE BOUNDARY STILL WELL
UPSTREAM ACROSS CENTRAL IOWA AND WISCONSIN. THERE IS HOWEVER A LINE
OF CONVECTION MOVING THROUGH THE CHICAGO AREA ASSOCIATED WITH
PREFRONTAL COLD POOL/OUTFLOW FROM OLD REMNANT MCS THAT HI-
RES/CONVECTION-ALLOWING MODELS HAVE STRUGGLED ALL DAY TO CAPTURE.
THIS ACTIVITY WILL MAKE A RUN FOR OUR WESTERN COUNTIES THIS
EVENING BUT SHOULD CONTINUE TO SLOWLY FIZZLE OUT AS IT SHIFTS
EAST. CONVECTIVE LINE IS ALREADY LOOKING OUTFLOW DOMINANT AND VERY
RAGGED PER LATEST KLOT RADAR IMAGERY AND CONTINUES TO MOVE WELL
OUT AHEAD OF MAIN SYNOPTIC SUPPORT. 12Z KILX AND KDTX UPPER AIR
SOUNDINGS ALSO SHOWED A VERY DRY AND CAPPED ENVIRONMENT THAT HAS
BEEN SLOW TO DISLODGE DUE TO WESTWARD DISPLACEMENT OF BETTER LLJ
AND MOISTURE FLUX CONVERGENCE. SPC/RAP MESOANALYSIS CONFIRM THIS
WITH MUCH DRIER AND MORE STABLE CONDITIONS OVER LOWER MICHIGAN AND
NORTHERN INDIANA. A FEW DECAYING SHOWERS/STORMS MAY SNEAK INTO OUR
WESTERN ZONES THIS EVENING BUT STILL EXPECT MUCH BETTER CHANCES
FOR RAIN TO HOLD OFF UNTIL AROUND MIDNIGHT TONIGHT.

ONLY REAL CHANGE TO GOING FORECAST WAS TO BUMP UP TIMING A BIT BASED
ON LATEST GUIDANCE AND UPSTREAM OBS. STILL THINK JUST LIKELY POPS
APPROPRIATE FOR OUR CWA...GIVEN FRONTAL PASSAGE DURING DIURNAL
INSTABILITY MINIMUM. SEVERAL HI-RES MODELS HAVE LITTLE MORE THAN SCT
SHOWERS AND WITH A LACK OF SUBSTANTIAL FORCING ALOFT...NOT
COMFORTABLE GOING CATEGORICAL. SEVERE WEATHER RISK IS VERY LOW BOTH
TONIGHT AND TOMORROW. POOR DIURNAL TIMING AND PALTRY MIDLEVEL LAPSE
RATES LIMIT AVAILABLE INSTABILITY AND DEEP LAYER SHEAR IS 15 KTS OR
LESS AHEAD OF THE FRONT. SLIGHT CHANCE FOR AN ISOLATED STRONG STORM
SOUTH OF US-24 TOMORROW GIVEN SLIGHTLY LATER FRONTAL PASSAGE BUT
EVEN THEN...BETTER SBCAPE VALUES REMAIN CONFINED SOUTHEAST OF OUR
CWA BORDER. BRIEF HEAVY RAIN POSSIBLE GIVEN PW VALUES AOA 2 INCHES
IMMEDIATELY ALONG FRONT BUT LACK OF GOOD INSTABILITY AND STRONG
FORCING SUGGEST ANY HEAVIER RAINFALL RATES/AMOUNTS WILL BE
ISOLATED. NOT EXPECTING MANY FLOODING ISSUES THANKS TO RECENT
STRETCH OF DRY WEATHER.

&&

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 344 PM EDT MON JUL 6 2015

COLD FRONT SHOULD EITHER BE THROUGH THE FORECAST AREA OR CONFINED TO
FAR S/SE SECTIONS AT THE START OF THE PERIOD. MAY BE A FEW LINGERING
SHOWERS OR STORMS IN ITS WAKE BUT MAJORITY OF TUESDAY NIGHT INTO
FIRST PART OF WEDNESDAY SHOULD BE DRY.

WHILE 12Z GFS/ECMWF ARE SIMILAR IN DEPICTION OF SERIES OF UPPER
LEVEL DISTURBANCES...SURFACE FEATURES VARY SOMEWHAT WITH ECMWF/09Z
SREF/12Z NAM12 ALL SHOWING FURTHER NORTH TRACK WITH VARYING AMOUNTS
OF QPF WEDS NGT INTO THURS AND ECMWF AGAIN THURS NGT INTO FRIDAY.
WITH GROUND STILL VERY WET TO SATURATED HYDRO CONCERNS COULD QUICKLY
MATERALIZE.

SINCE ANY OF THE SOLUTIONS ARE PLAUSIBLE AND CONFIDENCE IN ANY ONE
LOW (CONSIDERING HOW MODELS ARE HANDLING TODAY`S CONVECTION) NOT
COMFORTABLE MAKING ANY MAJOR CHANGES. MESOSCALE INFLUENCES ARE
LIKELY TO WRECK HAVOC ON THE FRONTAL POSITION AND POTENTIAL TRACKS
OF ANY COMPLEXES...RESULTING IN LOW TO MODERATE CONFIDENCE OF
ADDITIONAL RAINFALL BUT LOW CONFIDENCE ON WHERE IT OCCURS. HAVE
BLENDED HALF PREVIOUS FORECAST AND HALF SUPERBLEND OF MODELS WHICH
COMES UP WITH A COMPROMISE. TEMPERATURES SHOULD HOLD BELOW NORMAL
INTO FRIDAY BUT LOW LEVEL FLOW WILL INCREASE AND ALLOW HIGHS TO
CLIMB BACK NEAR OR SLIGHTLY ABOVE NORMAL LEVELS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1235 AM EDT TUE JUL 7 2015

CDFNT OVER NWRN IL WILL MOVE EAST ACROSS NRN INDIANA TODAY.
ALTHOUGH CONVECTION IN THE FRONTAL ZONE TO OUR WEST HAS BEEN
WKNG EARLY THIS MORNING... EXPECT INCREASE IN COVERAGE OF SHRA/TS
DURING THE DAY TUE WITH GREATEST IMPACT AT FWA WHERE FROPA LIKELY
WILL HOLD OFF UNTIL AFTN. CONTD WITH JUST VCTS MENTION IN THE FWA
TAF AS CLOUD COVER SHOULD LIMIT DESTABILIZATION ACROSS NRN
INDIANA. IFR/MVFR CONDITIONS IN THE FRONTAL ZONE UPSTREAM ATTM
AND EXPECTED TO MOVE THROUGH NRN INDIANA DURING THE DAY.
CONDITIONS SHOULD IMPROVE LATE TUE AFTN/EVE AS HIGH PRESSURE
BUILDS INTO THE UPR GRTLKS. IMPROVEMENT WILL BE SLOWER AT FWA HWVR
AS FRONT TAKES ON A MORE E-W ORIENTATION TONIGHT.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...BEACH HAZARDS STATEMENT FROM 7 AM CDT TUESDAY THROUGH TUESDAY
     EVENING FOR INZ003.

MI...BEACH HAZARDS STATEMENT FROM 8 AM EDT THIS MORNING THROUGH THIS
     EVENING FOR MIZ077.

OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO MIDNIGHT EDT
     TONIGHT FOR LMZ043-046.

&&

$$

SYNOPSIS...LASHLEY
SHORT TERM...AGD
LONG TERM...FISHER
AVIATION...JT


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