Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 020720
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
320 AM EDT THU APR 2 2015

.UPDATE...

THE LONG TERM SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 240 AM EST THU APR 2 2015

UNSETTLED WEATHER EXPECTED THROUGH FRIDAY NIGHT AS A FRONTAL SYSTEM
DROPS SOUTHEAST ACROSS THE OHIO VALLEY. THUNDERSTORMS WILL RETURN
EARLY NEXT WEEK AS WELL WITH ANOTHER SYSTEM. THERE COULD BE A FEW
SEVERE STORMS TODAY AND THIS EVENING AS WELL AS NEXT WEEK. HEAVY
RAIN IS ALSO POSSIBLE AT TIMES THROUGH FRIDAY. MEANWHILE...HIGH
PRESSURE WILL RESULT IN DRY BUT COOLER WEATHER SATURDAY AND
SUNDAY.

&&

.NEAR TERM /TODAY THROUGH FRIDAY NIGHT/...
ISSUED AT 240 AM EDT THU APR 2 2015

MAIN FOCUS FOR THE NEAR TERM WILL BE THUNDERSTORMS TODAY THROUGH
FRIDAY ALONG WITH POTENTIAL FOR SEVERE WEATHER THIS AFTERNOON AND
EVENING AND HEAVY RAIN THIS AFTERNOON THROUGH FRIDAY.

DETERMINISTIC MODELS STILL HAVE TIMING DIFFERENCES REGARDING UPPER
AND SURFACE WAVES AND CONSEQUENTLY TIMING OF THE COLD FRONT...THAT
WAS OVER THE UPPER MIDWEST AND SOUTHERN PLAINS THIS OVERNIGHT.
HOWEVER...THE DIFFERENCES IN THE 00Z RUN THIS EVENING...SAVE THE
NAM...ARE NOT AS GREAT AS THEY ONCE WERE. THE 00Z GFS IS TRENDING
FURTHER NORTH WITH ITS TRACK OF SURFACE WAVES AND THEREFORE FRONTAL
POSITION ON FRIDAY PER THE STEADIER 12Z ECMWF. A FEW GEFS MEMBERS
WERE CLOSE TO THE OPERATIONAL 12Z ECMWF AS WAS ECMWF ENSEMBLE MEAN.
MEANWHILE...THE 00Z CANADIAN IS A BIT QUICKER WITH THE
FRONT...ALBEIT SLOWER WITH THE UPSTREAM TROUGH. OVERALL...FEEL A
BLEND OF THE 00Z GFS...12Z ECMWF AND 12Z ECENS LOOKS BEST.

THE COLD FRONT SHOULD DROP SOUTHEAST TO NEAR MERRIVILLE AROUND 18Z
THIS AFTERNOON...TO FAR NORTHERN PARTS OF CENTRAL INDIANA 00Z THIS
EVENING...AND TO NEAR THE OHIO RIVER ON FRIDAY...BEFORE IT
TEMPORARILY STALLS WITH THE WAVES MOVING ALONG IT. FINALLY...THE
FRONT SHOULD MOVE INTO EASTERN KENTUCKY BY 00Z SATURDAY...WHICH
SHOULD PUT AN END TO THE SHOWERS ACROSS WESTERN PARTS OF THE
FORECAST AREA. THIS REST OF THE AREA SHOULD SEE THE SHOWERS EXIT
BY 06Z SATURDAY WITH COOLER AIR MOVING IN BEHIND THE FRONT.

SPC SREF ENSEMBLES WERE SHOWING INCREASING MIXED LAYER CAPE TODAY
WITH NEAR 500 J/KG NEAR MUNCIE AND AROUND 1000 J/K NEAR VINCENNES
AT 21Z THIS AFTERNOON. THIS INSTABILITY SHOULD GRADUALLY WANE
TONIGHT WITH NIGHTFALL AND FRIDAY WITH THE FRONT MOVING SOUTHEAST.
DEEP MOISTURE AND STRONG FORCING WARRANT CATEGORICAL POPS TODAY
THROUGH FRIDAY. AREA OF THUNDERSTORMS...CURRENTLY OVER SOUTHEASTERN
MISSOURI AND NORTHEASTERN ARKANSAS AND ASSOCIATED WITH AN UPPER
WAVE...SHOULD MOVE TO VINCENNES AND TERRE HAUTE AFTER 5 AM AND
EAST OF THE AREA LATE MORNING PER THE 05Z HRRR RAPID REFRESH
REFLECTIVITY PROGS. THUNDERSTORMS SHOULD MOVE BACK INTO THE AREA AND
OTHERS POP UP THIS AFTERNOON AHEAD OF ANOTHER UPPER WAVE AND AGAIN
TONIGHT WITH ANOTHER ONE. THUNDERSTORMS SHOULD BE CONFINED TO THE
FAR SOUTHERN TIER OR TWO BY FRIDAY AS THE FRONT SETTLES SOUTHEAST
AND STABILITY INCREASES NORTH OF THE FRONT. FINALLY...WILL ONLY
CARRY EVENING SHOWER CHANCES ACROSS EAST CENTRAL INDIANA BY FRIDAY
NIGHT.

REGARDING SEVERE WEATHER POTENTIAL...THE 500-1000 J/KG CAPES
COMBINED WITH AROUND 200 METERS SQUARED PER SECONDS SQUARED
HELICITY...PER 21Z SPC SREF ENSEMBLES...SHOULD BE SUFFICIENT FOR AT
LEAST ISOLATED SEVERE WEATHER THIS AFTERNOON...ESPECIALLY SOUTHWEST
OF INDIANAPOLIS...WHERE INSTABILITY SHOULD BE GREATER. SEVERE THREAT
SHOULD END THIS EVENING...ESPECIALLY NORTH OF BLOOMINGTON...WITH
LOSS OF SOLAR HEATING AND BETTER SHEAR SOUTH OF THERE. OVERALL...SPC
DAY1 ENHANCED RISK ACROSS SOUTHERN PARTS OF KNOX...DAVIESS AND
MARTIN COUNTIES AND SLIGHT RISK ELSEWHERE OVER CENTRAL INDIANA LOOKS
GOOD WITH MAIN SEVERE THREATS BEING DAMAGING WINDS AND LARGE HAIL.
HOWEVER...CAN NOT RULE OUT A TORNADO OR TWO AS LIFTED CONDENSATION
LEVELS ARE FORECASTED TO LESS THAN 3000 FEET. IF EVEN BRIEF BREAKS
OCCUR IN THE CLOUD COVER OCCUR...THIS COULD ALSO AID IN ROTATING
STORMS.

RAINFALL WILL BE ANOTHER ISSUE THROUGH FRIDAY AS JET STREAKS MOVE
THROUGH THE 100 PLUS KNOT UPPER JET THAT WILL BE OVER THE AREA
TONIGHT AND FRIDAY...PROVIDING STRONG UPPER DIVERGENCE. JET
INTERACTIONS ALONG WITH DEEP MOISTURE...DISPLAYED BY PRECIPITABLE
WATER VALUES TO NEAR 1.5 INCHES...OR TWICE OR MORE ABOVE NORMAL FOR
EARLY APRIL...SUGGEST HEAVY RAIN MENTION TONIGHT WITH HEAVY RAIN
ALSO POSSIBLE MAINLY SOUTH OF INTERSTATE 70 ON FRIDAY.

FINALLY...SHOULD SEE BREEZY CONDITIONS TODAY WITH BUFKIT SUGGESTING
GUSTS TO 30 MPH OR MORE ARE POSSIBLE THIS AFTERNOON...AFTER THE
INVERSION DIES.

WENT WITH DAYTIME TEMPERATURES AT OR BELOW 00Z MOS DO TO THICK CLOUD
COVER. ALSO...WENT CLOSER TO THE MORE MILD 00Z NAM TEMPERATURES FOR
OVERNIGHT LOWS...ESPECIALLY SOUTH OF THE FRONT.

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
ISSUED AT 240 AM EST FRI APR 02 2015

FOCUS FOR THE SHORT TERM WILL BE ON TEMPERATURES AS MODELS IN GOOD
AGREEMENT THAT SURFACE HIGH PRESSURE WILL SETTLE OVER THE AREA.
MODEL RH TIME SECTIONS AND CU DEVELOPMENT PROGS SUGGEST THERE WILL
BE LITTLE CLOUD COVER AROUND ON SATURDAY WITH PERHAPS SOME CIRRUS
SPILLING OVER TOP OF A MISSISSIPPI RIDGE AND ACROSS CENTRAL INDIANA
SATURDAY NIGHT.

850 MILLIBAR TEMPERATURE PROGS BRING IN SUB-ZERO TEMPERATURES
SATURDAY MORNING BUT WARM IT UP TO 2 TO 4 DEGREES ABOVE ZERO
SATURDAY NIGHT. HOWEVER...WITH SUNNY SKIES...SIMILAR 00Z MOS...
SLIGHTLY BELOW NORMAL TEMPERATURES...LOOK OK WITH HIGHS IN THE
50S AND LOWS IN THE 30S.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
ISSUED AT 320 AM EDT THU APR 2 2015

NUMEROUS OPPORTUNITIES FOR SHOWERS AND THUNDERSTORMS ARE EXPECTED IN
THE LONG TERM PERIOD AS BROAD LOW PRESSURE DEVELOPS TO THE WEST AND
SLOWLY MOVES THROUGH THE REGION. THIS COULD POTENTIALLY EXACERBATE
AN EXISTING HYDROLOGIC ISSUE DEPENDING ON HOW MUCH RAIN OCCURS IN
THE NEXT 24 TO 48 HOURS. INSTABILITY INDICES SUGGEST THUNDER IS A
POSSIBILITY IN NEARLY ALL PERIODS AND FORECAST WILL REFLECT THAT.

&&

.AVIATION.../DISCUSSION FOR THE 02/06Z TAFS/
ISSUED AT 147 AM EDT THU APR 2 2015

VFR CONDITIONS WILL CONTINUE FOR A FEW HOURS AFTER ISSUANCE TIME
BEFORE MVFR CEILINGS MOVE INTO THE AREA TOWARDS MORNING. BRIEF IFR
CONDITIONS ARE NOT OUT OF THE QUESTION IN ANY HEAVY RAINFALL OR
THUNDERSTORMS THROUGHOUT THE DAY ON THURSDAY.

SOUTHEASTERLY WINDS AT 5-10 KTS WILL TURN MORE SOUTHERLY OVERNIGHT
ADVECTING MOISTER AIR INTO THE AREA. HOWEVER...WITH DEW POINTS STILL
IN THE LOW TO MID 30S AT ISSUANCE TIME...IT MAY TAKE LONGER THAN
PREVIOUSLY FORECAST FOR MVFR CEILINGS AND ASSOCIATED PRECIPITATION
TO REACH THE TERMINALS WHICH WILL NEED TO BE WATCHED.

VAD WIND PROFILE INDICATES WINDS AROUND 2KFT AT 50KT...SUGGESTING
FORECAST SOUNDINGS ARE UNDERDOING DEGREE OF LOW LEVEL WIND SHEAR
OVERNIGHT. WILL CARRY SHEAR THROUGH THE MORNING WHEN GUSTS BEGIN.

EVEN WITH PLENTIFUL CLOUD COVER THROUGHOUT THE DAY...THERE WILL BE
ENOUGH INSTABILITY TO INCLUDE THUNDER AT ALL SITES DURING THE
AFTERNOON. WINDS AROUND 15 KTS WILL TURN MORE WESTERLY THROUGHOUT
THE DAY ON THURSDAY WITH GUSTS APPROACHING 30 KTS POSSIBLE.

&&

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

&&

$$

SYNOPSIS...MK
NEAR TERM...MK
SHORT TERM...MK
LONG TERM...NIELD
AVIATION...LEE/NIELD

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