Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 211736
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
136 PM EDT THU AUG 21 2014

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

&&

.SYNOPSIS...
ISSUED AT 335 AM EDT THU AUG 21 2014

A RIDGE OF HIGH PRESSURE WILL STRENGTHEN OVER THE EASTERN THIRD OF
THE NATION INTO EARLY NEXT WEEK...BRINGING THE WARMEST WEATHER OF
THE SUMMER. HOWEVER WEAK WAVES WILL ROTATE AROUND THAT
RIDGE...KEEPING CHANCES FOR SHOWERS AND THUNDERSTORMS OVER CENTRAL
INDIANA THROUGH SATURDAY. A DRY SPELL WILL COMMENCE ACROSS THE
REGION EARLY NEXT WEEK BEFORE ANOTHER DISTURBANCE IS SET TO IMPACT
THE AREA BY NEXT TUESDAY.

&&

.NEAR TERM /REST OF TODAY/...
ISSUED AT 955 AM EDT THU AUG 21 2014

THUNDERSTORMS CONTINUE ACROSS MAINLY THE NORTHEASTERN PORTIONS OF
THE FORECAST AREA THIS MORNING...SO UPPED POPS THERE AS NEEDED.
FORCING FOR THESE STORMS WILL WEAKEN INTO EARLY AFTERNOON AS LOW
LEVEL WINDS DIMINISH.

WITH THE WEAKER FORCING COVERAGE OF CONVECTION WILL DECREASE. HI RES
RAPID UPDATE MODELS SUPPORT THIS THOUGHT WITH LITTLE IF ANY
CONVECTION THIS AFTERNOON. THUS KEPT POPS IN THE CHANCE CATEGORY
THIS AFTERNOON.

STORM PREDICTION CENTER HAS KEPT MOST OF THE AREA IN A SLIGHT RISK.
EXPECT INSTABILITY TO BUILD AGAIN THIS AFTERNOON AS CLOUDS THIN SO
THIS LOOKS REASONABLE.

FOR NOW KEPT TEMPERATURE FORECAST PRETTY MUCH AS IS...BUT WILL WATCH
FOR LATER ADJUSTMENTS DEPENDING ON HOW CLOUD COVER CHANGES.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
ISSUED AT 335 AM EDT THU AUG 21 2014

HIGH PRESSURE WILL CONTINUE TO STRENGTHEN OVER THE AREA FOR THE
REMAINDER OF SHORT TERM PERIOD...BUT WEAK WAVES IN THE FLOW WILL
DRIFT ALONG THE RIDGE...KEEPING PESKY CHANCES FOR ON/OFF SHOWERS AND
THUNDERSTORMS IN THE FORECAST THROUGH SATURDAY. BY SATURDAY NIGHT IT
APPEARS CONDITIONS WILL FINALLY DRY OUT ACROSS THE AREA.

AS FOR TEMPERATURES...SOME OF THE HIGHEST TEMPS OF THE SEASON WILL
OCCUR DURING THIS PERIOD /AND INTO THE NEXT/ WITH HIGHS REACHING
INTO THE LOW TO MID 90S ON FRIDAY AND SATURDAY SOUTH OF INTERSTATE
70. THESE TEMPS COMBINED WITH LOW TO MID 70S DEW POINTS WILL ALLOW
HEAT INDICES TO REACH AND EXCEED THE 100 MARK IN SOME LOCATIONS
ACROSS THE AFOREMENTIONED AREA. WILL NEED TO KEEP AN EYE ON THIS
WARM UP AND SEE IF A HEAT ADVISORY IS WARRANTED FOR A FEW DAYS
THIS PERIOD AND POSSIBLY INTO EARLY NEXT WEEK. AND ACTUALLY
TRENDED ON THE LOWER SIDE OF GUIDANCE DUE TO PERSISTENCE.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
ISSUED AT 335 AM EDT THU AUG 21 2014

MODELS CONTINUE TO DEPICT PERHAPS THE LONGEST WARM STRETCH OF THE
SEASON THUS FAR CONTINUING THROUGH THE WEEKEND AS AN UPPER LEVEL
RIDGE DOMINATES OVER THE LOWER MISSISSIPPI AND OHIO VALLEYS. IF WE
HAVE STILL NOT MADE 90 BY THEN...THERE WILL STILL BE AT LEAST A
COUPLE OF OPPORTUNITIES EARLY IN THE LONG TERM PERIOD TO DO SO. THAT
SAID...SEVERAL FACTORS WILL HAVE A HAND IN DETERMINING WHETHER OR
NOT WE GET THERE. WHILE SUMMER BEGAN ON QUITE A WET NOTE WITH ONE OF
THE TOP 15 WETTEST JUNES...WHICH HAS LIKELY CONTRIBUTED AT LEAST IN
SOME SMALL PART TO THE LACK OF HEAT THUS FAR...THE ATMOSPHERE HAS
REVERSED ITSELF SOMEWHAT SINCE THE START OF JULY...AND INDIANAPOLIS
IS ROUGHLY TWO TO TWO AND A HALF INCHES BELOW NORMAL ON PRECIP SINCE
THEN...OR AROUND THE SAME AMOUNT THAT JUNE WAS ABOVE NORMAL.
HOWEVER...THE GUIDANCE DEPICTS A MOIST AIRMASS WITH DEWPOINTS
PUSHING THE LOW TO MID 70S AT TIMES. ADDITIONALLY...WHILE THE
FORECAST WILL ONLY CARRY POPS LATE IN THE PERIOD AS THE RIDGE BREAKS
DOWN AND TEMPERATURES MODERATE/...THE PERIPHERY OF THE RIDGE...WHERE
CONVECTION MAY OCCUR IN A RING OF FIRE STYLE...AND THE CORRIDOR
WHERE ANY ORGANIZED CONVECTIVE COMPLEXES MAY TRACK...WILL NOT BE
THAT FAR NORTH OF THE AREA...AND THIS COULD COMPLICATE MATTERS AS
WELL. IF SOME ISOLATED DIURNAL CONVECTION MANAGES TO OCCUR DESPITE
THE QUITE WARM MIDLEVEL TEMPERATURES PUSHING 10 TO 12C...THAT WOULD
ALSO POTENTIALLY WORK AGAINST THE HEAT. WILL BE INTERESTING TO SEE
HOW CLOSE WE GET TO 90 OR IF WE MANAGE TO FINALLY BREACH THE MARK.
IF IT OCCURS IN THE NEXT SEVERAL DAYS...IT WILL BE THE LATEST FIRST
90 DEGREE DAY SINCE 1960...WHEN 90 WAS NOT REACHED UNTIL SEPTEMBER
FIRST. THIS IS OF COURSE EXCLUDING 2004...THE ONLY YEAR ON RECORD
THUS FAR WITHOUT A 90 DEGREE READING.

IT IS WORTH NOTING THAT THE ECMWF ENSEMBLE MOS REMAINS QUITE
WARM...A FEW DEGREES ABOVE WHAT WILL BE THE OFFICIAL FORECAST
NUMBERS. GFS ENSEMBLE MOS MEANS ARE MUCH COOLER AND WITH MUCH LOWER
STANDARD DEVIATION. WILL BE CURIOUS TO SEE HOW EACH PERFORMS...BUT
THE SIGNIFICANT SPREAD IN THE ECMWF MOS CONTINUES TO NOT INSPIRE
CONFIDENCE AT THIS TIME.

&&

.AVIATION /DISCUSSION FOR THE 21/18Z TAF ISSUANCE/...

ISSUED AT 129 PM EDT THU AUG 21 2014

THE MAIN CHALLENGE OF TAF PERIOD IS TIMING OF ANY POSSIBLE
CONVECTION. AT THIS TIME...SHOWERS AND THUNDERSTORMS HAVE MOVED
EAST OF ALL TAF SITES...BUT A WARM FRONT AND UNSTABLE ENVIRONMENT
WILL BE CONDUCIVE TO MORE DEVELOPMENT LATER IN THE TAF PERIOD.
BEST CHANCES WILL BE AT KLAF AND KIND AFTER FRI 06Z WHEN A WEAK
VORT MAX DRIFTS OVER THE AREA. THIS EXTRA FORCING COMBINED WITH
LIFT FROM THE FRONT WILL MAKE DEVELOPMENT MOST FAVORABLE OVER
THOSE NORTHERN TAF SITES IN THE FRI 06-12Z TIME FRAME. OUTSIDE OF
ANY SHOWERS AND THUNDERSTORMS...CONDITIONS WILL BE VFR. WINDS WILL
BE WEST/SOUTHWESTERLY AT 3 TO 8 KTS.


&&

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

&&

$$

SYNOPSIS...SMF
NEAR TERM...50
SHORT TERM...SMF
LONG TERM...NIELD
AVIATION...TDUD

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