Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 050559
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
159 AM EDT TUE MAY 5 2015

.SYNOPSIS...
ISSUED AT 152 AM EDT TUE MAY 5 2015

A FRONT WILL MEANDER ACROSS THE AREA THROUGH TODAY...AND BE
ACCOMPANIED BY OCCASIONAL SHOWERS AND ISOLATED TO SCATTERED
THUNDERSTORMS. CLOUD COVER AND RAINFALL WILL KEEP TEMPERATURES IN
THE 60S ACROSS FAR SOUTHERN LOWER MICHIGAN TO THE MID 70S INTO
WEST CENTRAL INDIANA. LOWS TONIGHT WILL FALL BACK INTO THE 50S.

&&

.UPDATE...
ISSUED AT 646 PM EDT MON MAY 4 2015

LOWERED POPS AND DROPPED THUNDER MENTION (EXCEPT FOR FAR SOUTHERN
ZONES) THROUGH THE EARLY MORNING HOURS WITH WEAKENING MULTICELL
CLUSTERS TO REMAIN FOCUSED JUST SSW OF THE LOCAL AREA ALONG
LEFTOVER COMPOSITE OUTFLOW/INSTABILITY GRADIENT. ONLY MINOR
CHANGES OTHERWISE WITH BETTER RAIN/THUNDER CHANCES STILL ON TRACK
FOR LATER TONIGHT/TUE AM WITH MCS/MCV REMNANTS.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 239 PM EDT MON MAY 4 2015

KIWX RADAR AND LATEST SURFACE ANALYSIS INDICATING REMNANTS OF
SHOWERS HAS EXITED THE AREA AS FRONTAL BOUNDARY NOW SINKING DOWN
INTO NORTHERN CWA. 17Z MESOANALYSIS INDICATING SBCAPES HAVE
REBOUNDED TO 1500J/KG ACROSS CENTRAL ILLINOIS SUGGESTING WE STILL
MAY SEE SOME AIRMASS RECOVERY IN THE SOUTH BY LATE
AFTERNOON/EARLY EVENING SO WILL KEEP CHANCE POPS GOING THERE.
MAIN FOCUS WILL BE FOR CONVECTIVE REDEVELOPMENT OUT WEST IN THE
PRESENCE OF BETTER DYNAMICS. WATER VAPOR IMAGERY SHOWING SHORT
WAVE ENERGY MOVING UP ALONG THE BACKSIDE OF UPPER RIDGE AND WILL
COINCIDE WITH AXIS OF THETAE RIDGE AND EFFECTIVE SHEAR VALUES
AROUND 50KT. HIRES GUIDANCE INDICATING THIS WILL EVOLVE INTO
NOCTURNAL MCS AND PROPAGATE EASTWARD ALONG STALLED FRONTAL
BOUNDARY TONIGHT. BASED ON THIS SCENARIO WILL KEEP WINDOW OF
LIKELY POPS GOING AFTER 06Z IN ANTICIPATION OF MCS ARRIVAL.
FRONTAL BOUNDARY THEN LIFTS BACK NORTHWARD ON TUESDAY AND WILL
FOCUS BEST CHANCES FOR PRECIP IN THE NORTHERN HALF OF THE
CWA...BUT ALL HINGES ON HOW OVERNIGHT CONVECTION EVOLVES SO WILL
KEEP EVERYTHING IN CHANCE RANGE FOR NOW. EXPECT TEMPS IN 55-60
RANGE FOR LOWS TONIGHT WHILE FRONTAL BOUNDARY IS EXPECTED TO
PRODUCE STRONG GRADIENT ACROSS THE FORECAST AREA ON TUESDAY WITH
UPPER 70S IN THE FAR SOUTH TO MID 60S IN THE NORTH.

&&

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 239 PM EDT MON MAY 4 2015

STOUT MID LVL RIDGE DVLPMNT XPCD DOWNSTREAM OF WRN US TROUGHING
THIS PD W/MUCH ABV NORMAL TEMPS AND GENERALLY DRY UNTIL LT PD.

MUCH SLWR 12Z MODEL CONSENSUS OF NEWD EJECTION OF FOUR CORNERS
IMPULSE LT NXT WEEKEND LOOKS IDEAL ESP IN LIGHT OF FLW SEPARATION
ACRS THE WRN US AND COMMON MODEL BIASES. THUS DOWNPLAYED POPS FRI
AFTN THROUGH SUN IN REFLECTION OF GENERAL POOR SYNOPTIC SPRT HERE
AND LACKLUSTER MOISTENING EWD OF THE MS RVR. AT SOME POINT NO
DOUBT UPSTREAM CONV EVOLUTION AND/OR PIECEMEAL EJECTION OF WRN
ENERGY WILL AUGMENT MUCH HIGHER MESOSCALE FORCING AT TIMES HWVR
BASED ON GROSS SPECTRAL SOLUTION SCOPE...THAT DOES NOT SEEM
PLAUSIBLE UNTIL FRI NIGHT AT THE EARLIEST AND MOST LIKELY LT SAT
AND AGAIN ON SUN.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 144 AM EDT TUE MAY 5 2015

FAVORABLE DOWNSTREAM CONVECTIVE MAINTAINENCE PARAMETERS SUGGEST
ERN IA/NWRN MO/NWRN IL CONVECTIVE COMPLEX TO MAINTAIN
SUFFICIENTLY FOR INCLUSION OF TEMPO TSRA LATER THIS AM ACRS NRN
IN. THEREAFTER...ABUNDANCE OF TRAILING STRATIFORM RAFL TO LIKELY
PERSIST AND SATURATE LOW LEVELS AMID COOL/BACKED FLOW LOW LEVEL
REGIME FOR CIGS TO LWR. KEPT KFWA AOA FUELING/ALTERNATE LEVEL
CRITERIA FOR NOW AS SHALLOW SRLY AFTN FLOW TO PROVIDE SOME
SUBCLOUD DRYING..THOUGH DEPENDENT UPON WHERE MEANDERING SFC
BOUNDARY LIES OUT IN WAKE OF AM CONVECTION.

&&

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

$$

UPDATE...STEINWEDEL
SYNOPSIS...MURPHY
SHORT TERM...LOGSDON
LONG TERM...T
AVIATION...MURPHY


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