Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 271416
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1016 AM EDT SUN JUL 27 2014

.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 412 AM EDT SUN JUL 27 2014

A COLD FRONT WILL DROP SOUTHEAST ACROSS CENTRAL INDIANA TODAY AS AN
UPPER WAVE PIVOTS SOUTHEAST FROM THE UPPER MIDWEST TO THE GREAT
LAKES. THESE FEATURES WILL INTERACT WITH A MOIST AND UNSTABLE
AIRMASS AND RESULT IN SCATTERED THUNDERSTORMS...SOME OF WHICH COULD
BE STRONG TO SEVERE...ESPECIALLY ACROSS SOUTHEASTERN PARTS OF
CENTRAL INDIANA. DRIER AND MUCH COOLER AIR WILL FILTER IN BEHIND THE
FRONT WITH AFTERNOON HIGHS ONLY IN THE 70S EARLY TO MID WEEK. SMALL
THUNDERSTORM CHANCES WILL RETURN BY WEDNESDAY AS CYCLONIC FLOW
CONTINUES.

&&

.NEAR TERM /TODAY/...
ISSUED AT 412 AM EDT SUN JUL 27 2014

STRONG TO SEVERE THUNDERSTORMS WILL BE THE MAIN FOCUS TODAY AS AN
UPPER WAVE PIVOTS SOUTHEAST FROM NEBRASKA TO WISCONSIN AND
EVENTUALLY MICHIGAN. THIS WAVE WILL FORCE A COLD FRONT SOUTHEAST
ACROSS CENTRAL INDIANA THIS AFTERNOON. THIS FRONT WILL INTERACT WITH
AN UNSTABLE AIRMASS /AFTERNOON MIXED LAYER CAPES 1500 TO 2500 J/KG/
AND 50 TO 60 KNOT DEEP SHEAR TO TRIGGER SCATTERED THUNDERSTORMS
TODAY. THE BEST CHANCE OF SEVERE STORMS LOOKS TO BE ACROSS OUR
SOUTHEASTERN HALF IN LEFT EXIT REGION OF 65 KNOT MID LEVEL JET
STREAK AND NEAR 850 MILLIBAR 30 KNOT MAX. STILL...THE WHOLE FORECAST
AREA IS IN THE DAY1 SPC SLIGHT RISK WHICH LOOKS REASONABLE. WITH
DEEP MOSTLY UNI-DIRECTIONAL SHEAR...DAMAGING WINDS LOOKS TO BE A
BIGGER THREAT THAN TORNADOES...HOWEVER WOULD NOT RULE OUT AN
ISOLATED ONE OR TWO ESPECIALLY ACROSS OUR SOUTHEASTERN COUNTIES.

CURRENTLY...STRONG STORMS WERE MARCHING SOUTHEAST ACROSS EAST
CENTRAL ILLINOIS IN THE NORTHWEST FLOW ALOFT. AFTERNOON SEVERE
POTENTIAL WILL HINGE ON HOW WIDESPREAD THE MORNING CONVECTION IS.
WIDESPREAD MORNING STORMS WOULD LIKELY KEEP MODEL INSTABILITY
NUMBERS FROM BEING REALIZED AND LIMIT THE SEVERE POTENTIAL DESPITE
THE STRONG SYNOPTIC FORCING.

WITH DRIER AIR WORKING IN ALOFT AND STORM MOTION OF 30 KNOTS OR
MORE...FLASH FLOODING DOES NOT LOOK LIKE A HUGE CONCERN.

00Z MOS VERY CLOSE ON TEMPERATURES TODAY...LOOKS REASONABLE AND
MATCHES WITH REGIONAL BLEND.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
ISSUED AT 412 AM EDT SUN JUL 27 2014

THE MAIN FOCUS FOR THE SHORT TERM WILL BE TEMPERATURES AS DRY AND
MUCH COOLER AIR INVADES THE AREA IN THE WAKE OF A COLD FRONT.

MODELS IN GOOD AGREEMENT THAT AN UPPER TROUGH WILL PIVOT EAST ACROSS
THE EASTERN GREAT LAKES TONIGHT SWEEPING A STRONG COLD FRONT WELL
EAST OF THE AREA. WOULD NOT RULE OUT AN EVENING
THUNDERSTORM...ESPECIALLY SOUTHEAST CLOSER TO THE BETTER INSTABILITY
AND DEPARTING COLD FRONT...HOWEVER...BETTER BET IS ANY ACTIVITY WILL
BE EAST OF THE AREA BY 00Z TONIGHT WITH JUST SOME LEFT OVER STRATUS
POSSIBLE WITH MODEL SOUNDINGS SHOWING LINGERING LOW LEVEL MOISTURE.
THE REMAINDER OF THE SHORT TERM...CYCLONIC FLOW AROUND THE BASE OF
STRONG HUDSON BAY VORTEX EXPECTED TO GENERATE A DECENT AMOUNT OF
DIURNAL CU. WOULD NOT COMPLETELY RULE OUT AN INSTABILITY SHOWER OR
TWO...BUT CHANCES TOO LOW TO MENTION.

MODEL 850 MILLIBAR TEMPERATURES FROM 9 TO 11 DEGREES CELSIUS
SUGGESTS LEANING TOWARDS THE COOLER 00Z NAM MOS WITH WELL BELOW
NORMAL HIGHS IN THE LOWER TO MID 70S. NORMAL HIGHS FOR THIS TIME OF
YEAR ARE IN THE MID 80S. MEANWHILE...SIMILAR MOS LOWS IN THE LOWER
60S LOOK GOOD TONIGHT WITH LOWS IN THE 50S THEREAFTER. WOULD NOT
EVEN RULE OUT UPPER 40S IN SOME LOCALIZED AREAS MONDAY NIGHT.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY NIGHT/...

ISSUED AT 340 AM EDT SUN JUL 27 2014

A VERY BROAD UPPER LOW CENTERED OVER THE HUDSON BAY WILL EXTEND INTO
THE EASTERN U.S.  THIS SYSTEM WILL BE RESPONSIBLE FOR PERIODS OF
SHOWERS AND THUNDERSTORMS THROUGHOUT THE PERIOD AS SEVERAL SHORT
WAVES RIDE ALONG THAT UPPER LOW. LATEST INITIALIZATION IS
HIGHLIGHTING BEST PRECIP CHANCES DURING THE AFTERNOON HOURS
THROUGHOUT THE EXTENDED PERIOD IN ASSOCIATION WITH PEAK HEATING OF
THE DAY.  MODELS CLOSE OFF AN UPPER LOW OVER THE OHIO VALLEY ON
SATURDAY AND INCREASE PRECIP CHANCES AS A RESULT.  TEMPS THROUGH THE
PERIOD WILL BE BELOW NORMAL WITH HIGHS IN THE UPPER 70S/LOW 80S AND
LOWS IN THE UPPER 50S/LOW 60S.

&&

.AVIATION /DISCUSSION FOR THE 271500Z TAF UPDATE/...
ISSUED AT 1016 AM EDT SUN JUL 27 2014

WEAK SURFACE WAVE ACROSS WESTERN INDIANA WITH AN ASSOCIATED
BOUNDARY. AIRMASS REMAINS MOIST WITH SCATTERED CONVECTION AHEAD OF
IT...ALONG WITH IFR CONDITIONS. FOCUS OF THE UPDATE IS TO BETTER
TIME THE WINDSHIFT AS THE BOUNDARY PASSES BY EARLY AFTERNOON...AS
WELL AS ADJUST CEILINGS BASED ON CURRENT OBS. SOME CLEARING JUST
WEST OF KIND WHICH MAY ALLOW FOR A BRIEF PERIOD OF SUN LATE THIS
MORNING BEFORE STRATOCU RETURNS WITH CEILINGS AT 1500-2500FT. STILL
ANTICIPATE VFR CEILINGS ONCE THE BOUNDARY PASSES BY 17-18Z WITH
SCATTERED CONVECTIVE REDEVELOPMENT LATER THIS AFTERNOON AS STRONG
UPPER WAVE APPROACHES FROM THE NORTHWEST.

12Z DISCUSSION FOLLOWS.

SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THROUGH MID-
MORNING. AFTER THAT...EXPECT A WINDOW OF DRY CONDITIONS THROUGH
EARLY AFTERNOON...AND THEN ANOTHER ROUND OF CONVECTIVE DEVELOPMENT
AS UPPER LOW MOVES THROUGH THE AREA. WILL CARRY VCTS AT ALL TAF
SITES FOR NOW UNTIL A BETTER TIME FRAME CAN BE PINPOINTED WITH
LATER TAF ISSUANCE. CLOUD DECKS SHOULD REMAIN RIGHT AROUND THE
MVFR/VFR MARK /MAINLY VFR/ THROUGHOUT THE DAY. TONIGHT...MVFR FOG
WILL BE A POSSIBILITY WITH LINGERING LOW LEVEL MOISTURE. WINDS
WILL BECOME NORTHWESTERLY THROUGH THE COURSE OF THE MORNING...
INCREASING THIS AFTERNOON TO 14 TO 18 KTS SUSTAINED/GUSTING TO 28
KTS. WINDS WILL TAPER OFF THIS EVENING BUT REMAIN NORTHWESTERLY.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SYNOPSIS...MK
NEAR TERM...MK
SHORT TERM...MK
LONG TERM....TDUD
AVIATION...TDUD/RYAN

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