Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 301650
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1250 PM EDT WED JUL 30 2014

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

&&

.SYNOPSIS...
ISSUED AT 251 AM EDT WED JUL 30 2014

CENTRAL INDIANA WILL CONTINUE TO BE UNDER THE INFLUENCE OF LOW
PRESSURE CENTERED OVER EASTERN ONTARIO WHILE A LARGE RIDGE OF HIGH
PRESSURE RESIDES OVER THE WESTERN U.S. THIS PATTERN WILL RESULT IN
SLIGHTLY BELOW NORMAL TEMPERATURES THROUGH THE PERIOD AND DAILY
CHANCES FOR SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THE FIRST
HALF OF THE WEEKEND. HOWEVER...CONDITIONS WILL BE DRY FOR MOST OF
THE EXTENDED AS AFOREMENTIONED RIDGE MOVES CLOSER TO CENTRAL INDIANA.

&&

.NEAR TERM /REST OF TODAY/...

ISSUED AT 1013 AM EDT WED JUL 30 2014

14Z UPDATE...REALLY DID NOT STRAY TOO FAR FROM CURRENT FORECAST.
THOUGHT ABOUT INCREASING POPS ACROSS THE NE COUNTIES BASED ON
LATEST NAM TRENDS BUT WOULD LIKE TO SEE MORE SUPPORT FOR THIS
AMONGST THE SHORT TERM GUIDANCE. OTHERWISE MADE SOME MINOR CHANGES
TO TEMPS/DW PTS/SKY BASED ON LATEST TRENDS. PREVIOUS DISCUSSION
FOLLOWS.

TODAY WILL BE THE LAST DAY OF THE ESPECIALLY COOLER THAN NORMAL
TEMPS AS CENTRAL INDIANA REMAINS IN NORTHWEST FLOW. TEMPS WILL TOP
OFF IN THE MID TO UPPER 70S WHICH WAS CAPTURED WELL WITH A MODEL
BLEND.

TODAY/S WEATHER WILL BE SIMILAR TO YESTERDAY/S...AFTERNOON AND
EVENING SHOWER/THUNDERSTORM ACTIVITY FUELED BY THE BROAD LOW
PRESSURE SYSTEM OVER EASTERN ONTARIO. ANTICIPATE ACTIVITY TO BE
MORE WIDESPREAD THIS AFTERNOON THOUGH /ACROSS THE NORTHERN
COUNTIES/ AS A TROUGH AT THE SURFACE INCREASES LIFT AFTER WED
18Z...SUPPORTED BY WEAK ENHANCEMENT IN VORTICITY AT 500 MB.
SO...WILL CARRY CHANCE POPS OVER THE NORTHERN HALF OF CENTRAL
INDIANA...SLIGHT CHANCE OVER MOST OF THE SOUTH...AND DRY OVER THE
EXTREME SOUTHERN COUNTIES.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...

ISSUED AT 251 AM EDT WED JUL 30 2014

THE MAIN FOCUS CONTINUES TO BE DIURNAL SHOWER/THUNDERSTORM
DEVELOPMENT THROUGH THE PERIOD.

THE LOW PRESSURE SYSTEM OVER EASTERN ONTARIO/JAMES BAY WILL REMAIN
SOMEWHAT STATIONARY THROUGH FRIDAY...FINALLY PUSHING OFF TO THE
EAST ON FRIDAY EVENING. PERTURBATIONS IN THE UPPER FLOW WILL BE
JUST ENOUGH TO TRIGGER DAILY SHOWER/THUNDERSTORM ACTIVITY WITH
PEAK HEATING. HOWEVER...WILL ONLY CARRY SLIGHT CHANCE POPS ON
THURSDAY SINCE THOSE PERTURBATIONS WILL BE LIMITED. ON FRIDAY
THOUGH...A MORE DEFINED SHORT WAVE IS PROVIDING A DECENT VORT MAX
IN THE MID LEVELS...WHICH JUSTIFIES CARRYING CHANCE POPS ACROSS
ALL OF CENTRAL INDIANA.

CENTRAL INDIANA WILL BREAK OUT OF THE NORTHWEST FLOW ON THURSDAY
AND FALL UNDER MORE OF A WEST/SOUTHWESTERLY FLOW...WHICH WILL LEAD
TO A WEAK WARMING TREND. HIGHS WILL CLIMB BACK INTO THE LOW 80S
WITH LOWS IN THE LOW 60S. MODELS ARE IN AGREEMENT WITH THE
CHANGING PATTERN...SO CONTINUED TO USE A BLEND.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...

ISSUED AT 251 AM EDT WED JUL 30 2014

LONG TERM FOCUS WILL BE ON A POTENTIAL CHANGE IN THE PERSISTENT
CYCLONIC FLOW PATTERN THAT HAS KEPT IT COOL ACROSS THE AREA.

EXTENDED MODELS IN DECENT AGREEMENT THAT THE JAMES BAY VORTEX WILL
OPEN UP AND BECOME ABSORBED BY THE ICELANDIC LOW BY SATURDAY.
MEANWHILE...REMNANT BROAD UPPER TROUGH WILL MOVE EAST OF CENTRAL
INDIANA ON SUNDAY WITH MODELS IN GOOD AGREEMENT ON DECENT SUBSIDENCE
ACROSS CENTRAL INDIANA. THIS SHOULD ALLOW FOR THE DIURNAL
THUNDERSTORM CHANCES TO END ON SUNDAY WITH DRY CONDITIONS UNTIL
MONDAY AS SURFACE HIGH PRESSURE SETTLES IN. FINALLY...MODELS HINT
THAT A COLD FRONT WILL BE DROPPING DOWN ACROSS THE REGION IN TUESDAY
IN NORTHWEST FLOW ALOFT. THIS MAY BRING A FEW MORE THUNDERSTORMS TO
THE AREA PER THE REGIONAL BLEND.

REGIONAL BLEND HAS THE RIGHT IDEA REGARDING RISING TEMPERATURES
AS THE PERSISTENT UPPER TROUGH MOVES TO THE EASTERN STATES AND
DAMPENS THIS WEEKEND AND EARLY NEXT WEEK. AFTERNOON HIGHS SHOULD BE
BACK IN THE 80S ACROSS ALL OF CENTRAL INDIANA BY MONDAY OR EARLIER.

&&

.AVIATION /DISCUSSION FOR 301800Z TAFS/...

ISSUED AT 1233 PM EDT WED JUL 30 2014

FORECAST PERIOD WILL BE MAINLY VFR WITH WIND UNDER 10 KTS.
EXCEPTION PERIODS INCLUDE ISOLATED THUNDERSTORMS THROUGH SUNDOWN
POSSIBLY CAUSING BRIEF MVFR VISIBILITY THEN DAYBREAK LOCALIZED
MVFR FOG...ESPECIALLY IF A TAF SITE SEES RAIN.

SATELLITE SHOWS A VERY WEAK TROUGH AXIS ROTATING SOUTHEAST ACROSS
CENTRAL INDIANA RIGHT AT TAF ISSUANCE TIME AND A SECOND WEAK
TROUGH OVER SOUTHERN MICHIGAN AND MOVING SOUTHEAST. INDIANAPOLIS
APPEARS TO BE THE SITE MOST LIKELY FOR ANY THUNDERSTORMS TODAY
THOUGH THE TAIL END OF EACH WAVE COULD CLIP KLAF OR KBMG. HAVE
ONLY INCLUDED KBMG IN THAT SCENARIO.

WINDS DROPPING TO NEAR CALM UNDER MOSTLY CLEAR SKY TO YIELD
DEWPOINT DEPRESSIONS OF ONE TO FOUR DEGREES SUGGESTIVE OF MVFR
FOG...ESPECIALLY AT THE MORE RURAL SITES OF KLAF KHUF AND KBMG.

&&

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

$$

SYNOPSIS...TDUD
NEAR TERM...SMF/TDUD
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...TUCEK

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