Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 261430
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1030 AM EDT TUE AUG 26 2014

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

&&

.SYNOPSIS...
ISSUED AT 225 AM EDT TUE AUG 26 2014

A VERY WARM AND HUMID AIR MASS WILL REMAIN IN PLACE OVER CENTRAL
INDIANA THE NEXT FEW DAYS. THIS IN COMBINATION WITH A SLOWLY MOVING
COLD FRONT FRONT THE NORTH MAY RESULT IN SHOWERS AND THUNDERSTORMS
EACH DAY.

LATE THIS WEEK A FRONTAL BOUNDARY IS EXPECTED TO BE LINGERING
ACROSS CENTRAL INDIANA THROUGH THE LABOR DAY WEEKEND. ALTHOUGH THE
FRONTAL BOUNDARY WILL COOL TEMPERATURE BACK TOWARD SEASONAL
NORMALS...IT WILL KEEP CHANCES FOR SHOWERS AND THUNDERSTORMS IN
THE FORECAST EACH DAY THROUGH THE HOLIDAY WEEKEND.

&&

.NEAR TERM /REST OF TODAY/...

ISSUED AT 959 AM EDT TUE AUG 26 2014

SATELLITE AND OBSERVATIONS SHOW ALTOCUMULUS CASTELLANUS ACROSS THE
AREA SHOWING SOME MID LEVEL INSTABILITY. RADAR SHOWS SHOWERS POPPING
UP IN THIS AREA IN MADISON COUNTY. MEANWHILE SCATTERED THUNDERSTORMS
CONTINUE TO DEVELOP ACROSS NORTHERN INDIANA.

HAVE EXPANDED SLIGHT CHANCE POPS SOUTH THIS MORNING TO ACCOUNT FOR
THE SHOWERS POPPING UP. OTHERWISE MADE NO SIGNIFICANT CHANGES TO
POPS AT THIS TIME AS NORTHERN FORECAST AREA STILL LOOKS TO HAVE BEST
CHANCES FOR STORMS TODAY.

STORM PREDICTION CENTER HAS PLACED OUR AREA IN A SEE TEXT SO WILL
CONTINUE TO WATCH DEVELOPMENT CLOSELY.  FOR NOW HAVE MADE NO
SIGNIFICANT CHANGES TO TEMPERATURES BUT WILL WATCH TO SEE IF THEY
NEED ADJUSTED DUE TO ANY PRECIPITATION.

PREVIOUS DISCUSSION FOLLOWS...
SURFACE ANALYSIS EARLY THIS MORNING SHOWS HIGH PRESSURE IN PLACE
OVER THE APPALACHIANS. A WEAK COLD FRONT WAS FOUND ACROSS CENTRAL
WISCONSIN...STRETCHING SW ACROSS SE IOWA TO CENTRAL KANSAS. LIGHT
EASTERLY FLOW WAS IN PLACE ACROSS CENTRAL
INDIANA...HOWEVER...EARLIER CONVECTION HAS LEFT SEVERAL BOUNDARIES
LINGERING ACROSS THE FORECAST AREA LATE TONIGHT. DEW POINTS ACROSS
THE AREA REMAINED VERY MOIST...HOLDING IN THE MIDDLE AND UPPER 60S.

MAIN FORECAST CHALLENGE TODAY WILL BE POPS.

GFS DEPICTS THE RIDGE WITHIN THE UPPER FLOW SAGGING SOUTHWARD
TOWARD AND ALLOWING THE FLOW ALOFT TO BECOME A BIT MORE ZONAL TO
NWERLY DURING THE COURSE OF THE DAY. BEST AREA FOR CONVECTIVE
DEVELOPMENT WILL BE TO THE NORTHWEST...ALONG THE FRONTAL
BOUNDARY...HOWEVER AS WE SAW ON MONDAY PROPAGATION SUGGESTS THAT
ANY CONVECTION THAT DEVELOPS MAY HAVE THE ABILITY TO PROPAGATE SE
INTO OUR MOISTURE RICH AIR AND CONDITIONALLY UNSTABLE AIR.
FORECAST SOUNDINGS ALSO SHOW CONVECTIVE TEMPERATURES NEAR
90...WHICH WE FINALLY REACHED...AND PLENTY OF CAPE WITH VALUES
OVER 2500 J/KG. THUS WILL INCLUDE LOW CHCS FOR POPS THIS
AFTERNOON...WITH BEST POPS FOUND ACROSS THE NORTHERN PARTS OF THE
FORECAST AREA...CLOSEST TO THE LIKELY PROPAGATION AREA FROM
CONVECTION UPSTREAM.

WITH A SIMILAR AIR MASS IN PLACE ACROSS THE FORECAST AREA TODAY
WILL TREND TOWARD PERSISTENCE FOR HIGHS.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...

ISSUED AT 225 AM EDT TUE AUG 26 2014

GFS AND NAM DEPICT THE UPPER FLOW BECOMING MORE NORTHWESTERLY
DURING THIS PERIOD...ALLOWING SEVERAL SHORT WAVE TO PUSH OUT OF
THE UPPER MIDWEST TOWARD CENTRAL INDIANA. MEANWHILE AT THE
SURFACE...THE FRONTAL BOUNDARY PREVIOUSLY MENTIONED WILL ALSO SAG
SOUTHWARD TO NORTHERN INDIANA BY WEDNESDAY...AND THEN STALL ACROSS
CENTRAL INDIANA ON THURSDAY. FORECAST SOUNDINGS THROUGH THURSDAY
SHOW LITTLE IN THE WAY OF CHANGE AS THEY REMAIN MOIST THROUGH
THURSDAY WITH REACHABLE CONVECTIVE TEMPERATURES AND CAPE
AVAILABLE. CONFIDENCE REMAINS LOW IN ANY SPECIFIC SHORT WAVE
THROUGH THURSDAY...HOWEVER PLENTY OF INGREDIENTS REMAIN CONSTANT
THROUGH THE PERIOD. THOSE INGREDIENTS BEING...THE VERY MOIST AIR
MASS...DAYTIME HEATING LEADING TO INSTABILITY AND THE BREAKDOWN
OF THE RIDGE AND SAGGING COLD FRONT TOWARD CENTRAL INDIANA. THUS
WILL NEED TO CONTINUE DAILY POPS THROUGH THURSDAY NIGHT...FOCUSING
HIGHEST POPS DURING THE MAX HEATING HOURS OF THE AFTERNOON AND
EVENING.

OVERALL...TEMPERATURES WILL COOL SLIGHTLY THROUGH THE PERIOD AS
THE FRONTAL BOUNDARY TO THE NORTH SLOWLY SAGS SOUTHWARD ACROSS THE
FORECAST AREA. WILL TREND LOWS AT OR ABOVE GUIDANCE GIVEN THE
MOIST DEW POINTS AND MINIMAL ADVECTION. AS FOR HIGHS WILL TREND
WARMER THAN GUIDANCE ALSO.

&&

.LONG TERM /FRIDAY THROUGH NEXT MONDAY/...
ISSUED AT 225 AM EDT TUE AUG 26 2014

ENSEMBLES INDICATE AN UPPER TROUGH WILL BE PASSING THROUGH THE
GREAT LAKES OVER THE UPCOMING WEEKEND. IT APPEARS THAT THE SOUTHERN
END OF THIS TROUGH MAY HANG BACK ACROSS THE LOCAL AREA INTO NEXT
MONDAY.

ENSEMBLES SUGGEST SOME PRECIPITATION POTENTIAL ON FRIDAY ALONG A
STALLED OUT FRONTAL SYSTEM...BUT IT APPEARS THE BEST CHANCES WILL BE
OVER NEXT WEEKEND WITH THE APPROACH OF THE UPPER TROUGH. WILL
CONTINUE TO CARRY POPS THROUGHOUT THE EXTENDED...WITH THE HIGHEST
CHANCES ON SATURDAY AND SUNDAY.

&&

.AVIATION /DISCUSSION FOR THE 261500Z IND TAF UPDATE/...
ISSUED AT 1030 AM EDT TUE AUG 26 2014

ONLY MINOR TWEAK TO THE TAF.

PREVIOUS DISCUSSION FOLLOWS...

IFR VISIBILITY RESTRICTIONS HAVE FAILED TO MATERIALIZE SO FAR AS IT
APPEARS CONVECTION/OUTFLOWS FROM LAST NIGHT HAS MIXED UP THE AIR
MASS TO SOME DEGREE. WILL SEE HOW TRENDS GO UNTIL ISSUANCE
TIME...BUT AT THIS POINT IT APPEARS ANY IFR RESTRICTIONS WILL BE
BRIEF...AROUND SUNRISE.

OTHERWISE...WIDELY SCATTERED CONVECTION DEVELOPING FROM NORTHWEST
ILLINOIS INTO SOUTHERN MICHIGAN AHEAD OF A COLD FRONT. MODEL DATA
SUGGEST THIS FEATURE WILL SAG SOUTH DURING THE DAY. AIR MASS IS
EXPECTED TO BECOME QUITE UNSTABLE LATER TODAY...SO THINK AT LEAST
SOME CONVECTION WILL BE POSSIBLE...STARTING AS EARLY AS THE MIDDAY
HOURS AND LINGERING INTO THE EVENING. NOT CLEAR AT THIS POINT THE
EXTENT AND COVERAGE OF CONVECTION...SO WILL LEAVE OUT AN EXPLICIT
MENTION AT THIS TIME. BRIEF IFR VISIBILITY RESTRICTIONS AND GUSTY
SHIFTING WINDS POSSIBLE IN AND NEAR ANY CONVECTION. CB CLOUD BASES
AROUND 030.

OUTSIDE OF CONVECTION...SURFACE WINDS GENERALLY 7 KTS OR LESS
TODAY.

&&

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

$$

SYNOPSIS...PUMA
NEAR TERM...PUMA/50
SHORT TERM...PUMA
LONG TERM....JAS
AVIATION...JAS/MK

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