Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 281726
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
126 PM EDT TUE JUL 28 2015

.SYNOPSIS...
ISSUED AT 344 AM EDT TUE JUL 28 2015

A RIDGE OF HIGH PRESSURE ACROSS THE GREAT LAKES WILL CONTINUE TO
PROVIDE WARM AND HUMID CONDITIONS TO THE REGION TODAY. THIS HIGH
WILL BEGIN TO SHIFT OFF TO THE EAST TONIGHT WHICH WILL ALLOW
INCREASED MOISTURE TO MOVE INTO THE AREA...ALONG WITH A CHANCE OF
SHOWERS AND THUNDERSTORMS ACROSS PORTIONS OF NORTHERN INDIANA AND
SOUTHWEST LOWER MICHIGAN LATE TONIGHT. AN UPPER LEVEL DISTURBANCE
TRACKING OUT ACROSS THE NORTHERN TIER OF THE UNITED STATES WILL
PUSH A COLD FRONT INTO THE REGION ON WEDNESDAY PROVIDING THE NEXT
CHANCE OF THUNDERSTORMS. HIGH TEMPERATURES THIS AFTERNOON WILL
REACH INTO THE UPPER 80S TO AROUND 90. LOW TEMPERATURES TONIGHT
WILL RANGE FROM THE MID 60S TO AROUND 70.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 344 AM EDT TUE JUL 28 2015

ANOTHER QUIET DAY WEATHER WISE IS IN STORE WITH MAIN STORY IN THE
SHORT TERM ON THE HEAT/HUMIDITY FOLLOWED BY SHOWER/THUNDERSTORM
CHANCES LATE TONIGHT.

OVERALL SYNOPTIC PATTERN HAS CHANGED LITTLE IN COMPARISON TO PAST
FEW DAYS WITH GREAT LAKES ANTICYCLONE CONTINUING TO PROVIDE LOW
LEVEL EASTERLY FLOW. THIS PATTERN HAS LED TO A SHARP SOUTHWEST-
NORTHEAST MOISTURE GRADIENT WHICH SHOULD BE THE CASE ONCE AGAIN
TODAY. RATHER STAGNANT MID LEVEL PATTERN WILL ALLOW FOR CONTINUED
MID LEVEL RIDGING/SYNOPTIC SCALE SUBSIDENCE IN PLACE FOR TODAY.
CONTINUED MODERATION OF LOW LEVEL AIR MASS WITH HISTORY OF
SUBSIDENCE AND GOOD DEAL OF INSOLATION SHOULD ALLOW FOR SLIGHTLY
WARMER MAX TEMPS TODAY IN COMPARISON TO YESTERDAY. PREVIOUS FORECAST
APPEARS TO BE IN GOOD SHAPE WITH HIGHS GENERALLY IN THE UPPER
80S...ALTHOUGH WOULD EXPECT SOME SPOTS TO HIT THE 90 DEGREE MARK.
WITH EASTERLY FLOW REMAINING WEAK TODAY...HAVE TRENDED MORE TOWARD
RAP WIND FIELDS CLOSER TO LAKE MICHIGAN WHICH ARE MORE SUPPORTIVE OF
A WEAK SYNOPTICALLY MODIFIED N-NE LAKE BREEZE DEVELOPING AGAIN THIS
AFTERNOON. EVEN CLOSER TO THE LAKESHORE...WOULD EXPECT HIGHS TO TOP
OUT IN THE UPPER 80S BEFORE SOME COOLING LATE AFTERNOON WITH THE
MODIFIED LAKE BREEZE. WITH THE AFOREMENTIONED SOUTHWEST TO NORTHEAST
MOISTURE GRADIENT...HIGHEST AFTERNOON HEAT INDICES IN THE MID 90S
ARE STILL EXPECTED ACROSS SOUTHWEST HALF OR SOUTHWEST THIRD...AND
GENERALLY IN THE LOWER TO MID 90S ELSEWHERE. EXTREME SOUTHWEST
LOCATIONS COULD MAKE A RUN AT THE UPPER 90S FOR HEAT INDICES THIS
AFTERNOON BUT WILL CONTINUE TO HOLD OFF ON ANY HEAT HEADLINES AT
THIS TIME.

IN TERMS OF PRECIP POTENTIAL...ONGOING MCS EARLY THIS MORNING ACROSS
THE EASTERN DAKOTAS IS EXPECTED TO DROP SOUTHEAST THIS AFTERNOON
WITH HIGHER RES MODELS SUGGESTING THIS CONVECTION DECAYING ACROSS
THE MID MS RIVER VALLEY INTO NORTHEAST ILLINOIS LATE AFTERNOON/EARLY
EVENING.  GIVEN STOUT MID/UPPER RIDGING IN PLACE ACROSS GREAT
LAKES/OHIO VALLEY...HAVE GENERALLY BOUGHT IN ON THIS SCENARIO. A
STRONG UPPER LEVEL TROUGH LIFTING NORTHEAST OUT OF THE NORTHERN
PLAINS LATE TONIGHT WILL ALLOW FOR EASTWARD PROGRESSION OF COLD
FRONT TO MID/UPPER MS RIVER VALLEY BY DAYBREAK WEDNESDAY. A NARROW
BUT SIGNIFICANT LOW LEVEL MOISTURE AXIS WILL ADVECT INTO WESTERN
PORTIONS OF THE AREA LATE TONIGHT AHEAD OF THIS FRONT AS LOW LEVEL
WINDS BEGIN TO VEER.  IN ADDITION TO LOW LEVEL THETAE
ADVECTION...SOME RESIDUAL VORT MAX ENHANCED BY NORTHERN PLAINS
CONVECTION THIS MORNING MAY BE SLOWLY PROGRESSING THROUGH MEAN FLOW
TO THE WESTERN GREAT LAKES BY LATER TONIGHT...SO HAVE CONTINUED LOW
CHANCE TSRA MENTION ACROSS WESTERN THIRD OF THE AREA AFTER 09Z
TONIGHT.

&&

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 344 AM EDT TUE JUL 28 2015

PERIOD WILL START FOCUSED ON WEAKENING COLD FRONT PASSING THROUGH
THE REGION. ISOLATED TO SCATTERED CONVECTION MAY ALREADY EXIST ALONG
THE FRONT...SUPPORTED BY WEAK CONVERGENCE AND ABUNDANT MOISTURE.
SOME OF THE HI RES MODELS WOULD SUGGEST A DECENT EML POTENTIAL...BUT
GOOD DEGREE OF WARM AIR LIKELY CAPPING MUCH OF THIS OFF...LIMITING
SEVERE POTENTIAL. AT THIS POINT MID TO HIGH END CHC (SCT) POPS STILL
WARRANTED WITH CONTINUED PASSING MENTION OF STRONG TO ISOLATED
SEVERE STORM. TEMPERATURES PRIOR TO FROPA MAY BE TRICKY DEPENDING ON
AMOUNT OF CLOUD COVER AS WELL AS TIMING OF FRONT. WARMEST READINGS
SE STILL LOOK MOST REASONABLE.

SEMI ACTIVE NW FLOW WILL CONTINUE THE REMAINDER OF THE PERIOD WITH
SEVERAL WEAK RIPPLES AND SURFACE REFLECTIONS MAKING THEIR WAY INTO
THE REGION. CHANCES FOR SHOWERS AND STORMS EXIST DURING THE PERIOD
IN MORE SUMMER LIKE...ISOL TO SCT CONVECTIVE PATTERN AT BEST WITH
BEST DYNAMICS REMAINING REMOVED FROM THE REGION. TIMING OF EACH
SYSTEM LIKELY TO VARY IN THE COMING DAYS SO ONLY MADE MINOR CHANGES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 119 PM EDT TUE JUL 28 2015

RIDGE OVER THE GREAT LAKES WILL PERSIST...GRADUALLY WEAKENING AND
SHIFTING EAST OVERNIGHT. WINDS REMAIN LIGHT WITH VFR CONDITIONS
THROUGH 12UTC. APPROACHING COLD FRONT AND DECAYING CONVECTION FROM
THE PLAINS WILL ENTER THE WESTERN THIRD OF THE AREA BETWEEN
12-15UTC. WINDS BECOME MORE SOUTHERLY AND BEGIN TO INCREASE AS
WELL. SHRA SPREAD WEST TO EAST AND EXPECT ISOLD -TSRA AFTER 15UTC.

WHILE NOT INCLUDED IN EITHER TAF...LATER IN THE FORECAST PERIOD
WILL HAVE TO MONITOR FOR POSSIBLE LLWS AS THE BOUNDARY LAYER MIXES
OUT AND LOW- LEVEL WINDS BEGIN TO INCREASE AHEAD OF THE MID LEVEL
TROF.

&&

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

$$

SYNOPSIS...MARSILI
SHORT TERM...MARSILI
LONG TERM...FISHER
AVIATION...LEWIS


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