Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 182316
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
716 PM EDT FRI JUL 18 2014

.SYNOPSIS...
ISSUED AT 715 PM EDT FRI JUL 18 2014

LOW PRESSURE WILL TRACK INTO THE OHIO VALLEY TONIGHT INTO
SATURDAY. THIS WILL BRING INCREASING CLOUDS AND A CHANCE FOR
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS TO PORTIONS OF EASTERN
INDIANA AND NORTHWESTERN OHIO. LOWS TONIGHT WILL FALL INTO THE
UPPER 50S. HIGHS ON SATURDAY WILL CLIMB INTO THE LOWER 80S EXCEPT
EASTERN AREAS WHICH MAY REMAIN IN THE UPPER 70S.

&&

.UPDATE...
ISSUED AT 715 PM EDT FRI JUL 18 2014

WATER VAPOR IMAGERY AS OF 23Z SHOWS AN UPPER SHORTWAVE OVER
CENTRAL INDIANA. THIS FEATURE IS MODELED TO STRENGTHEN
NORTHEASTWARD INTO NORTHWEST OHIO BY LATER TONIGHT/SATURDAY
MORNING. ASSOCIATED INCREASE IN MID LEVEL DYNAMIC
FORCING/DEFORMATION INTO OUR EAST MAY BE ENOUGH TO PROVIDE ENOUGH
MOISTENING/ISENTROPIC ASCENT FOR RAIN TO MEASURE LATE THIS EVENING
INTO THE OVERNIGHT. LATEST HRRR IS STARTING TO PICK UP ON TRENDS
WITH LIGHT RAIN ALREADY BEING REPORTED AT KVES ALONG LEADING EDGE
OF MID LEVEL MOISTURE (700 MB THETA-E GRADIENT). GIVEN THESE
TRENDS BUMPED UP POPS A BIT EAST OF INTERSTATE 69...WITH DRY
ANTECEDENT CONDITIONS LIKELY SLOWING NWD PROGRESSION...HENCE THE
LOWER POPS/UNCERTAINTY. OTHERWISE...ALSO INCREASED SKY COVER TO
READ MOSTLY CLOUDY/CLOUDY ACROSS EASTERN TWO THIRDS OF THE IWX CWA
THIS EVENING INTO THE EARLY OVERNIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 354 PM EDT FRI JUL 18 2014

SFC RIDGE WILL CONTINUE TO SHIFT EAST INTO SATURDAY. UPPER LEVEL
TROUGH CURRENTLY TO THE WEST OF THE AREA INTO THE ARKLATEX AREA WILL
SLOWLY EJECT TOWARDS THE LOWER OHIO VALLY...SPREADING MOISTURE
TOWARDS MAINLY SE PARTS OF THE FORECAST AREA LATER TONIGHT INTO
SATURDAY. NOT AN OVERLY STRONG SYSTEM BY ANY MEASURE WITH MAIN
IMPACTS BEING INCREASE IN CLOUDS AND MARGINAL CHANCE FOR RAIN LATER
TONIGHT AND SOMEWHAT BETTER CHANCES ON SATURDAY. IF POPS WEREN`T IN
ALREADY WOULD PROBABLY HOLD OFF DESPITE MODELS SHOWING LIGHT QPF IN
FAR EAST/SE AREAS. HOWEVER...ENOUGH CONSENSUS FROM MODELS TO KEEP
FROM FLIP FLOPPING SO HAVE LEFT POPS INTACT. DID TRY TO ADD A BIT
MORE DETAIL/TIMING.

AWAY FROM THE CLOUDS AND PRECIP WITH THIS SYSTEM A NICE DAY SHOULD
BE IN STORE WITH HIGHS INTO THE LOWER 80S. LOWERED HIGHS A FEW
DEGREES IN SE AREAS WITH INCREASED CLOUD COVER LIKELY LIMITING
OVERALL HEATING.

&&

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 354 PM EDT FRI JUL 18 2014

AN UPPER LEVEL SHORT WAVE TROUGH WILL SLOWLY TRACK INTO THE EASTERN
GREAT LAKES SATURDAY NIGHT. SOME LINGERING LOW CLOUDINESS IS
POSSIBLE ACROSS MAINLY EASTERN PORTIONS OF THE AREA SATURDAY NIGHT.
IN THE WAKE OF THIS SHORT WAVE SATURDAY NIGHT/SUNDAY...LOCAL AREA
SHOULD BE CAUGHT BETWEEN TWO AXES OF DEEPER MOISTURE...ONE DEPARTING
INTO THE EASTERN GREAT LAKES...AND ANOTHER CONFINED WELL TO THE
NORTHEAST ACROSS THE UPPER MS VALLEY. WITH GENERALLY WEAK MID/UPPER
FORCING INTO MOST OF TUESDAY...WILL CONTINUE TO KEEP THIS PERIOD
DRY. GRADUAL MODIFICATION OF AIR MASS ALONG WITH UPSWING IN LOW
LEVEL WAA AND GOOD DEAL OF INSOLATION SHOULD RESULT IN MORE
PRONOUNCED WARMING TREND FOR MONDAY AND TUESDAY AS UPPER LEVEL
RIDGING AMPLIFIES TO THE WEST. A SERIES OF RIDGE-RIDING SHORT WAVES
WILL GENERALLY REMAIN WELL NORTH OF THE AREA AND DAMPEN AS THEY
PROGRESS EASTWARD EARLY NEXT WEEK...WITH BETTER PROSPECTS OF MORE
SIGNIFICANT FRONTAL PUSH HOLDING OFF UNTIL MID WEEK WHEN A STRONGER
EASTERN PACIFIC WAVE PROGRESSES THROUGH THE UPPER RIDGE. SOME LOW
CONFIDENCE STILL PERSISTS IN REGARDS TO TIMING THIS FORCING AND
ASSOCIATED FRONTAL ZONE DUE TO INFLUENCES FROM UPSTREAM
CONVECTION...AND MODELS LIKELY STRUGGLING WITH CONVECTIVE FEEDBACK
ISSUES. GFS/GEM REMAIN SOMEWHAT FASTER OUTLIERS IN TERMS OF FRONTAL
PROGRESSION INTO WEDNESDAY...BUT HAVE OPTED TO SIDE TOWARD A
SLIGHTLY SLOWER ECMWF/GEFS MEAN IDEA AT THIS TIME WITH SOME
SUSPICION THAT GFS MAY BE LOWERING MID LEVEL HEIGHTS A BIT FAST DUE
TO FEEDBACK ISSUES. THIS SOLUTION ALSO MAINTAINS FORECAST
CONTINUITY...WITH INCREASING CHANCE POPS FROM NORTHWEST TO SOUTHEAST
DURING THE DAY WEDNESDAY. APPROACH OF THIS WAVE WILL ALSO BE
ACCOMPANIED BY MORE SIGNIFICANT LOW LEVEL MOISTURE POOLING IN
ADVANCE OF THE FRONT LATE TUE-WED...WHICH ARGUES FOR MID TO HIGH
CHANCE POPS WITH THIS SYSTEM. CHANCES OF SHOWERS AND STORMS TO
LINGER INTO WEDNESDAY NIGHT AND PARTS OF THURSDAY AS UPPER WAVE
BECOMES SOMEWHAT DIVORCED FROM PRIMARY BELT OF WESTERLIES.

HAVE CONTINUED FORECAST TREND OF SLIGHTLY WARMER HIGHS FOR
TUESDAY...WITH INDICATIONS THAT ACTIVE SOUTHERN CANADIAN PATTERN
SHOULD SUPPORT SOME DAMPENING OF UPPER RIDGING AND EASTWARD
TRANSLATION OF STRONGER LOW LEVEL THERMAL RIDING ACROSS THE PLAINS.
SOME 90 DEGREE READINGS MAY BE WITHIN REACH...PARTICULARLY ON
TUESDAY. FORECAST CONFIDENCE FOR TEMPS IS SOMEWHAT LOWER FOR
WEDNESDAY WITH UNCERTAINTIES INTO TIMING INCREASE OF HIGH
CLOUDINESS. AFTER A FEW DAYS OF TEMPS AT OR ABOVE NORMAL...A COOLER
AIR MASS SHOULD SETTLE BACK INTO THE GREAT LAKES/OHIO VALLEY TOWARD
THE END OF THE PERIOD...WITH HIGHS IN UPPER 70S TO LOWER 80S FOR
THU-FRI.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 715 PM EDT FRI JUL 18 2014

VFR WITH LIGHT ESE WINDS THROUGH THE PERIOD AS BATCH OF LIGHT RAIN
ASSOCIATED WITH A STRENGTHENING SHORTWAVE TRACKS JUST EAST OF THE
TERMINALS THROUGH SATURDAY MORNING.

&&

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

$$

UPDATE...STEINWEDEL
SYNOPSIS...LOTHAMER
SHORT TERM...FISHER
LONG TERM...MARSILI
AVIATION...STEINWEDEL


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