Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 010736
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
336 AM EDT MON SEP 1 2014

.UPDATE...THE SYNOPSIS...NEAR TERM...SHORT TERM AND LONG TERM
SECTIONS HAVE BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 336 AM EDT MON SEP 1 2014

A COLD FRONT WILL MOVE INTO CENTRAL INDIANA TONIGHT AND TUESDAY
BRINGING SHOWERS AND THUNDERSTORMS. AFTER A BRIEF BREAK
WEDNESDAY...ANOTHER FRONTAL SYSTEM WILL BRING ADDITIONAL CHANCES FOR
RAIN THURSDAY INTO SATURDAY. NEAR TO ABOVE AVERAGE TEMPERATURES WILL
GIVE WAY TO COOLER THAN AVERAGE NUMBERS BY THE WEEKEND.

&&

.NEAR TERM.../TODAY/
ISSUED AT 336 AM EDT MON SEP 1 2014

ISOLATED SHOWERS HAVE DEVELOPED ACROSS CENTRAL INDIANA EARLY THIS
MORNING DUE TO SOME ISENTROPIC LIFT. LINE OF THUNDERSTORMS ACROSS
IOWA INTO KANSAS LOOKS TO BE SPLITTING WITH NORTHERN END MOVING
NORTHEAST AND SOUTHERN END MOVING MORE SOUTH THAN EAST. OUTFLOW
BOUNDARY FROM THESE STORMS HAS MOVED EAST INTO EASTERN MISSOURI AND
WESTERN ILLINOIS.

SOME UNCERTAINTY ON HOW CONVECTION WILL DEVELOP TODAY...WITH
REMNANTS OF EARLY MORNING CONVECTION MOVING INTO THE AREA THIS
MORNING. EXPECT BULK OF RAIN TO HAVE DRIED UP BY THE TIME IT REACHES
HERE...BUT THE OLD OUTFLOW WILL MOVE IN THIS MORNING. WORKING
AGAINST NEW CONVECTION EARLY TODAY WILL BE THE INCREASED CLOUD COVER
FROM THE DYING STORMS.

FOR NOW HAVE KEPT SLIGHT CHANCE POPS ALL AREAS THIS MORNING TO
ACCOUNT FOR LINGERING SHOWERS FROM ISENTROPIC LIFT AND FOR ANY
CONVECTION THAT CAN DEVELOP ALONG THE OLD OUTFLOW BOUNDARY.

WILL GRADUALLY INCREASE POPS THIS AFTERNOON FROM NORTHWEST TO
SOUTHEAST AS AN UPPER TROUGH AND COLD FRONT BEGIN THEIR APPROACH.
WILL KEEP POPS IN CHANCE CATEGORY THOUGH AS BEST FORCING DOES NOT
ARRIVE UNTIL AFTER 00Z.

WILL GO CLOSER TO THE COOLER MAV MOS FOR HIGHS TODAY AS CLOUD COVER
SHOULD SLOW THE TEMPERATURE CLIMB TODAY. THIS HEATING WILL BUILD
ENOUGH INSTABILITY FOR PERHAPS SOME STRONG TO SEVERE STORMS LATE IN
THE PERIOD.

&&

.SHORT TERM.../TONIGHT THROUGH WEDNESDAY NIGHT/
ISSUED AT 336 AM EDT MON SEP 1 2014

FOCUS IS ON RAIN CHANCES THROUGH THE PERIOD ALONG WITH HEAVY RAIN
POTENTIAL. OPERATIONAL MODELS ARE CLOSE ENOUGH THAT A BLEND WAS USED.

TONIGHT RAIN CHANCES WILL INCREASE AS THE COLD FRONT AND UPPER
TROUGH MOVE INTO THE AREA. 850MB WINDS INCREASE INTO THE 30-40KT
RANGE BY 06Z...AND CENTRAL INDIANA GETS PLACED INTO THE RIGHT REAR
QUADRANT OF AN 100KT UPPER JET. THE PLENTIFUL MOISTURE IN THE AREA
WILL COMBINE WITH THE FORCING PROVIDED BY THESE FEATURES TO PRODUCE
SHOWERS AND STORMS.

WENT LIKELY TO CATEGORICAL POPS ALL AREAS TONIGHT WITH THE HIGHEST
POPS AROUND 06Z AS FORCING LOOKS TO PEAK IN THAT TIME FRAME. THERE
WILL BE ENOUGH SHEAR AND INSTABILITY FOR A FEW SEVERE STORMS MAINLY
DURING THE EVENING. PRECIPITABLE WATER VALUES OVER 2 INCHES WILL
ALSO LEAD TO THE THREAT OF HEAVY RAIN AND LOCALIZED FLOODING.

INTERESTINGLY...THE 00Z NCEP WRF-NMM AND 00Z NSSL WRF ARE MUCH LESS
BULLISH WITH RAINFALL TONIGHT...WITH FORECAST REFLECTIVITY IMAGES
SHOWING LITTLE IF ANY CONVECTION AT 06Z TONIGHT. GIVEN THE EXPECTED
FORCING AND ENSEMBLES OF THE OPERATIONAL MODELS ALSO SHOWING
WIDESPREAD RAIN...WILL IGNORE THESE OUTLIERS FOR NOW.

FORCING WILL STILL BE ENOUGH FOR LIKELY POPS TUESDAY MORNING ACROSS
THE SOUTHERN HALF OF THE AREA /CHANCE NORTH/. POPS WILL DECREASE
THROUGH THE DAY FROM NORTH TO SOUTH AS THE FRONT EXITS.

WENT DRY TUESDAY NIGHT THROUGH WEDNESDAY NIGHT AS WEAK HIGH PRESSURE
MOVES THROUGH. THE OLD FRONT WILL BEGIN TO RETURN NORTH AS A WARM
FRONT WEDNESDAY NIGHT BUT AT THE MOMENT BELIEVE FORCING WILL BE WEAK
ENOUGH TO LEAVE OUT MENTION OF RAIN.

FOR TEMPERATURES...STUCK WITH A MODEL BLEND FOR LOWS. FOR HIGHS
TUESDAY WENT CLOSER TO THE COOLER MET WITH CLOUDS AND RAIN AROUND
DURING THE MORNING. ON WEDNESDAY WENT WITH A BLEND OF RAW MODEL
NUMBERS.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...

ISSUED AT 336 AM EDT MON SEP 1 2014

THE EXTENDED FORECAST WILL FEATURE A WARM AND HUMID START WITH EARLY
WEEKEND THUNDERSTORM CHANCES AND FINALLY A DRY AND COOL LATE
WEEKEND. IN ADDITION...THERE COULD BE A FEW STORMS AROUND ON
THURSDAY AS A WARM FRONT LIFTS NORTHEAST ACROSS THE AREA.
HOWEVER...THE BEST CHANCES FOR THUNDERSTORMS LOOK TO BE FRIDAY AND
FRIDAY NIGHT AS A STRONG COLD FRONT SLIDES SOUTHEAST ACROSS CENTRAL
INDIANA. COULD SEE SOME LINGERING ACTIVITY INTO SATURDAY...BUT BY
SATURDAY NIGHT THE FRONT SHOULD BE FAR ENOUGH SOUTH OF THE OHIO
RIVER TO LEAVE POPS OUT.

PRETTY DECENT COLD ADVECTION FOR THIS TIME OF YEAR WILL ARRIVE
BEHIND THE COLD FRONT WITH MODEL 850 MILLIBAR TEMPERATURES DROPPING
FROM AROUND 20 DEGREES CELSIUS ON THURSDAY TO 10 DEGREES OR LESS BY
SUNDAY. AS SUCH...REGIONAL BLEND LOOKS IN THE BALLPARK WITH ABOVE
NORMAL HIGHS IN THE MID 80S TO LOWER 90S THURSDAY AND FRIDAY AND
WELL BELOW NORMAL READINGS IN THE 70S ON SUNDAY.

&&

.AVIATION /DISCUSSION FOR 010600Z TAF ISSUANCE/...

ISSUED AT 1238 AM EDT MON SEP 1 2014

UPDATED CURRENT CONDITIONS ONLY. PREVIOUS DISCUSSION FOLLOWS...

SITES WILL START OUT VFR BUT WITH DEW POINTS AROUND 70 AND WINDS
AROUND 3-5 KTS EXPECT TO SEE SOME FOG DEVELOP. FORECAST SOUNDINGS
SHOW A STEEP INVERSION DEVELOPING AT KLAF AND KHUF AND DIPPING PAST
CROSSOVER TEMPERATURES AS WELL. KIND AND KBMG SOUNDINGS SHOW
INVERSIONS THAT ARE NOT AS STEEP. WILL GO WITH A PERIOD OF IFR FOG
AT ALL THE OUTLYING SITES WITH THE WORST CONDITIONS AT KLAF AND KHUF.
INCREASING CHANCES FOR THUNDERSTORMS WILL ARRIVE LATE IN THE TAF
PERIOD AND WILL INCLUDE VCTS TO INDICATE THIS POTENTIAL. AS EVENT
GETS CLOSER HOPE TO PIN DOWN PLACEMENT AND TIMING BETTER TO USE
EXPLICIT THUNDER MENTION.

&&

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

$$

SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM....MK
AVIATION...CP

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