Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 191824
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
224 PM EDT TUE AUG 19 2014

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

&&

.SYNOPSIS...
ISSUED AT 220 PM EDT TUE AUG 19 2014

A FRONTAL SYSTEM IS EXPECTED TO MOVE INTO THE AREA TONIGHT AND
STALL OUT IN THE VICINITY FOR MOST OF THE WEEK. THIS WILL SERVE
TO KEEP THE WEATHER UNSETTLED OVERALL INTO THE WEEKEND. THIS FRONT
MAY DISSIPATE BY EARLY NEXT WEEK.

&&

.NEAR TERM /REST OF THIS AFTERNOON AND TONIGHT/...
ISSUED AT 220 PM EDT TUE AUG 19 2014

CONVECTIVELY INDUCED VORTICITY CENTER CURRENTLY MOVING THROUGH
ILLINOIS...WITH SHORT TERM MODELS SUGGESTING THIS FEATURE WILL BE
ENTERING THE WESTERN ZONES OVER THE NEXT 2-3 HOURS. MOST OF THE
EARLIER CONVECTION HAS DISSIPATED...HOWEVER AIR MASS IS QUITE
UNSTABLE OVER THE AREA...AND STARTING TO SEE SCATTERED CONVECTION
REDEVELOP WITH THIS FEATURE. SHORT TERM MODELS SUGGEST THIS
FEATURE WILL PASS OFF TO THE EAST AROUND 200300Z. APPEARS THE BEST
THREAT FOR PRECIPITATION WILL BE WITH THIS UPPER WAVE FROM LATER
AFTERNOON INTO THE LATE EVENING HOURS. WILL MAKE A LAST MINUTE
DECISION ON WHETHER TO GO LIKELY OR SCATTERED POPS BASED ON
CONVECTIVE TRENDS.

LATEST MODEL GUIDANCE SUGGESTS LAPSE RATES SUFFICIENT FOR STORM
ORGANIZATION/SEVERE THREAT...BUT DEEP SHEAR CONTINUES TO BE A LITTLE
WEAK AT THIS TIME. SHEAR MAY INCREASE LATER THIS AFTERNOON/EVENING
AS AN UPPER TROUGH APPROACHES FROM THE NORTHWEST.

DON/T HAVE ANY MAJOR ARGUMENTS WITH THE GFS MOS LOWS TONIGHT
CONSIDERING LOW LEVEL THICKNESSES.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
ISSUED AT 220 PM EDT TUE AUG 19 2014

NORTHWEST UPPER FLOW EXPECTED ACROSS THE AREA DURING THIS
PERIOD...AS AN UPPER TROUGH GRADUALLY SHIFTS INTO NEW ENGLAND AND A
HEAT RIDGE BUILDS INTO THE LOWER MISSISSIPPI VALLEY AND GULF COAST
STATES.

FRONTAL ZONE THAT MOVES INTO THE AREA TONIGHT LOOKS TO LINGER IN THE
VICINITY THROUGH THE REST OF THE PERIOD. WARM ADVECTION BEGINS
WEDNESDAY AFTERNOON...AND THIS COMBINED WITH A POTENTIALLY VERY
UNSTABLE AIR MASS MAY SPARK OFF SOME CONVECTION BY LATE IN THE DAY
WEDNESDAY. WILL GO WITH CHANCE POPS DURING THE AFTERNOON HOURS.

WARM ADVECTION PATTERN GETS STRONGER BY WEDNESDAY NIGHT INTO
THURSDAY...SO BETTER CHANCES OF CONVECTION ARE PROBABLE DURING THOSE
TIMES. WILL KEEP POPS IN THE HIGH CHANCE CATEGORY FOR NOW DUE TO
QUESTIONS REVOLVING AROUND THE LOCATION/TIMING OF CONVECTION...BUT
LAPSE RATES/DEEP SHEAR CONTINUE TO LOOK FAVORABLE FOR STORM
ORGANIZATION/POTENTIAL SEVERE THREAT INTO THURSDAY.

BEYOND THURSDAY...DEEP SHEAR DIMINISHES WITH TIME...HOWEVER THE LOCAL
AREA CONTINUES TO BE ON THE EDGE OF A MID LEVEL CAP. AS A
RESULT...ADDITIONAL CONVECTIVE CLUSTERS MAY BE POSSIBLE INTO FRIDAY
WITH ANY POSSIBLE DISTURBANCES THAT MAY RIPPLE THROUGH THE FLOW.
WILL KEEP CHANCE POPS GOING INTO FRIDAY. PRECIPITABLE WATERS
1.50-2.00 INCHES SUGGEST HEAVY RAINFALL POSSIBLE THROUGH THE PERIOD.

LOW LEVEL THICKNESS PROGS SUGGEST THE GFS MOS TEMPERATURE GUIDANCE
THROUGH THE SHORT TERM LOOK REASONABLE FOR THE MOST PART.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 207 PM EDT TUE AUG 19 2014

ONLY CERTAINTY WITH THIS FORECAST DURING THIS PERIOD IS THE
CONTINUATION OF SOME VERY WARM SUMMER WEATHER DURING THE WEEKEND.
GFS AND ECMWF CONTINUE TO KEEP THE STRONG RIDGE IN PLACE ALOFT
DURING THIS PERIOD AND NOW HAVE BACKED OFF ON THE FLATTENING OF
THE RIDGE UNTIL TUESDAY AS A COLD FRONT GOES THROUGH THE AREA AND
RETURNS TEMPERATURES CLOSER TO SEASONAL NORMALS. PRIOR TO
TUESDAY...MODELS AND ALLBLEND CONTINUE TO INDICATE POPS ON
SATURDAY NIGHT THROUGH SUNDAY NIGHT AS SEVERAL BOUNDARIES LOOK TO
REMAIN IN PLACE NEAR CENTRAL INDIANA. THUS WILL CONTINUE WITH LOW
CHC POPS FOR NOW DURING THAT TIME AS A VERY WARM AND HUMID AIR
MASS WILL REMAIN IN PLACE.

&&

.AVIATION /DISCUSSION FOR THE 191800Z TAFS/...
ISSUED AT 1225 PM EDT TUE AUG 19 2014

VFR CONDITIONS EXPECTED FOR MUCH OF THIS AFTERNOON. CONVECTIVE
COMPLEX OVER CENTRAL ILLINOIS IS EXPECTED TO PROGRESS EAST ACROSS
CENTRAL INDIANA LATE THIS AFTERNOON. RAPID REFRESH DEPICTS A
DECAYING CONVECTIVE COMPLEX WORKING ACROSS THE TAF SITES LATE THIS
AFTERNOON. WITH CONDITIONAL INSTABILITY IN PLACE AND MARGINAL
SHEAR...THE INTENSITY OF THE APPROACHING STORMS REMAINS IN
QUESTION. THUS FOR NOW WILL USE SOME TEMPO GROUPS FOCUSING THE
PRIME WINDOW OF SHRA/TSRA PASSAGE. ANY TSRA MAY PRODUCE BREIF IFR
OR WORSE CONDITIONS.

IFR CONDITIONS ARE EXPECTED AGAIN OVERNIGHT AT LAF...BMG AND HUF
AS HIGH DEW POINTS...EARLIER LIGHT RAIN AND LIGHT WINDS SHOULD
RESULT IN ANOTHER MORNING OF FOG FORMATION. HEAT ISLAND EFFECTS AT
IND SHOULD KEEP MVFR CONDITIONS AT INDIANAPOLIS.

AFTER SUN UP ON WEDNESDAY...FOG WILL ONCE AGAIN BURN OFF...QUICKLY
LEADING TO SCT DIURNAL CU.

&&

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

$$

SYNOPSIS...JAS
NEAR TERM...JAS
SHORT TERM...JAS
LONG TERM....PUMA
AVIATION...JP

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