Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 020144
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
944 PM EDT FRI AUG 1 2014

.UPDATE...

THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 234 PM EDT FRI AUG 1 2014

AN UPPER LEVEL DISTURBANCE ACROSS NORTHERN ILLINOIS WILL MOVE EAST
SOUTHEAST ACROSS OUR REGION TONIGHT AND SATURDAY RESULTING WITH
SCATTERED SHOWERS AND THUNDERSTORMS.  THIS UPPER DISTURBANCE WILL
MOVE ON TO THE EAST SATURDAY NIGHT AND WEAK HIGH PRESSURE WILL BUILD
ACROSS OUR REGION SUNDAY AND MONDAY.

IN THE LONG TERM...CHANCES FOR SHOWERS AND THUNDERSTORMS WILL
INCREASE ONCE AGAIN AS A FRONTAL SYSTEM MOVES SOUTH INTO OUR REGION
TUESDAY AND WEDNESDAY AND THEN STALLING NEAR THE OHIO RIVER THURSDAY
AND THEN MOVING BACK TO THE NORTH ON FRIDAY.

&&

.NEAR TERM /TONIGHT AND SATURDAY/...
ISSUED AT 944 PM EDT FRI AUG 1 2014

AS EXPECTED...COVERAGE AND INTENSITY OF CONVECTION HAS WANED
CONSIDERABLY AS THE SUN HAS SET. GENERALLY EXPECTING ONLY ISOLATED
TSTORM COVERAGE AT BEST REMAINDER OF THE NIGHT. THE SOLE POTENTIAL
EXCEPTION TO THIS IS SMALL STORM COMPLEX OVER NORTHERN
ILLINOIS/SOUTHERN WISCONSIN WHICH HAS THE ASSISTANCE OF A COMPACT
SHORTWAVE DROPPING THROUGH WISCONSIN AND NUMEROUS BOUNDARIES FROM
PRIOR CONVECTION...AS WELL AS POTENTIAL REMNANT LAKE BREEZE
BOUNDARY...AND HAS HELD ITS OWN FOR A WHILE NOW. THAT
SAID...ENVIRONMENT REMAINS EXTREMELY WEAKLY SHEARED IF AT
ALL...INSTABILITY IS 1000 J/KG OR LESS AND WANING...AND CONVECTIVE
INHIBITION IS INCREASING. THUS...EXPECT THIS COMPLEX TO WEAKEN OR
DIE BEFORE MAKING THE AREA...AND HRRR BEARS THIS OUT.

DID ADD A PATCHY FOG MENTION TO THE NORTHWESTERN FORECAST AREA
WHERE SIGNIFICANT RAINFALL AND ACCUMULATING HAIL OCCURRED DURING
THE LATE AFTERNOON HOURS. SOME LIGHT FOG MAY OCCUR ELSEWHERE BUT
BE LIMITED BY CLOUD COVER AND LIKELY NOT WORTH A GRID MENTION.
REMAINDER OF FORECAST IN EXCELLENT SHAPE AND DID NOT MAKE MAJOR
CHANGES.

PREVIOUS DISCUSSIONS FOLLOW.

ISSUED AT 634 PM EDT FRI AUG 1 2014

FOR THE UPDATE...HAVE INCREASED POPS WHERE NECESSARY OWING TO
RECENT CONVECTIVE COVERAGE. SHOULD STILL SEE ACTIVITY ON A
DOWNSWING AROUND SUNSET AS HEATING IS LOST...BUT WITH UPPER TROUGH
SWINGING THROUGH THE AREA...WILL AS WITH PRIOR FORECAST CONTINUE
AT LEAST SOME LOW POPS THROUGHOUT THE NIGHT. STRONGEST STORMS WILL
REMAIN CAPABLE OF PRODUCING SMALL HAIL...PERHAPS PRODIGIOUSLY AS
OCCURRED WITHIN THE LAST TWO HOURS IN THE LAFAYETTE AREA...VERY
HEAVY RAINFALL...LIGHTNING AND GUSTY WINDS...ALTHOUGH THEY ARE
UNLIKELY TO BECOME SEVERE AS SHEAR IS EXTREMELY WEAK. THE LARGE
AMOUNTS OF SMALL HAIL FROM THE STRONGEST CORE OF THE DAY IN
LAFAYETTE IS TYPICAL OF SUCH CORES IN WEAKLY SHEARED ENVIRONMENTS.
PREVIOUS DISCUSSION FOLLOWS.

ISSUED AT 234 PM EDT FRI AUG 1 2014

RADAR INDICATED SCATTERED THUNDERSTORMS HAVE DEVELOPED ACROSS
NORTHWEST INDIANA AS WELL AS CENTRAL AND NORTHEAST ILLINOIS.  THIS
IS IN RESPONSE TO AN UPPER LEVEL DISTURBANCE OVER NORTHERN
ILLINOIS.  MODELS INDICATE THIS UPPER LEVEL DISTURBANCE WILL MOVE
EAST SOUTHEAST ACROSS THE NORTHERN AND THE EAST CENTRAL PARTS OF OUR
REGION LATER TONIGHT.

ONE QUESTION IS HOW MUCH OF THIS CONVECTION WILL CONTINUE AFTER
SUNSET AS IT HAS BEEN QUITE DIURNAL LAST FEW DAYS.  BOTH THE NAM AND
GFS KEEP SOME CONVECTION ACROSS THE NORTHERN AND CENTRAL PARTS OF
OUR REGION TONIGHT AS THE UPPER TROUGH SHARPENS UP. IT MAY BE A BIT
OVERDONE...BUT NERVELESS WILL KEEP POPS IN CHANCE CATEGORY OVER
NORTHERN AND CENTRAL SECTIONS THIS EVENING AND EAST CENTRAL PARTS
INTO LATE TONIGHT PER MODELS. IN OTHER AREAS SHOWERS SHOULD DIMINISH
LATE TONIGHT.

ON SATURDAY EXPECT SCATTERED SHOWERS AND THUNDERSTORMS OVER EASTERN
AND CENTRAL SECTIONS AND WIDELY SCATTERED THUNDERSTORMS ELSEWHERE.
THERE MAY BE SOME INCREASE WITH DAYTIME HEATING...BUT AT THE SAME
TIME THE UPPER DISTURBANCE WILL BE MOVING ON EAST INTO OHIO.

IN REGARDS TO TEMPERATURES WENT WITH A MOS BLEND MOST AREAS
TONIGHT.  WILL KEEP NORTHEAST AREAS AT OR ABOVE 60 WITH MORE CLOUDS
THERE LATER TONIGHT.

ON SATURDAY PREFER THE COOLER MET TEMPERATURES OVER CENTRAL AND
WESTERN AREAS AND WENT WITH A MOS BLEND IN THE EAST.  THE MET HAS 74
FOR A HIGH AT MUNCIE...WHILE THE MAV IS 82.  MORE CLOUDS IN THE EAST
COULD HOLD TEMPERATURES DOWN THERE A LITTLE MORE...BUT 74 SEEMS A
BIT TOO COOL.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
ISSUED AT 234 PM EDT FRI AUG 1 2014

SHOWERS WILL QUICKLY END SATURDAY EVENING...FOR NOW WILL CONTINUE
SLIGHT CHANCE POPS IN THE EAST SATURDAY EVENING. OTHERWISE...DRY ALL
AREAS REST OF THE SHORT TERM AS WEAK HIGH PRESSURE BUILDS ACROSS OUR
REGION. A COLD FRONT WILL BE MOVING INTO THE SOUTHERN GREAT LAKES ON
MONDAY...BUT IT SHOULD BE STILL FAR ENOUGH TO THE NORTH FOR US TO
REMAIN DRY.

MODEL SOUNDINGS INDICATE MOSTLY CLEAR CONDITIONS WILL BE THE RULE AS
AIR MASS BECOMES A LITTLE DRIER AND HEIGHTS RISE A LITTLE.  850 MB
TEMPERATURES WARM UP ONLY ABOUT A DEGREE SUNDAY AND MONDAY AS MODELS
KEEP A WEAK THERMAL TROUGH ACROSS OUR REGION.  OVERALL A MOS BLEND
BLEND ON TEMPERATURES SEEM REASONABLE WITH HIGHS IN THE LOWER TO
MIDDLE 80S BOTH DAYS AND LOWS IN THE UPPER 50S TO LOWER 60S.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ISSUED AT 234 PM EDT FRI AUG 1 2014

AFTER A DRY SPELL ENSEMBLES HINTING AT CENTRAL INDIANA POSSIBLY
RETURNING TO A WETTER PATTERN AS HIGH PRESSURE MOVES OFF THE EAST
MONDAY/MONDAY NIGHT AND IS REPLACED BY AN UPPER TROUGH THAT WILL
SLOWLY SHIFT EASTWARD THROUGH THURSDAY WITH SEVERAL UPPER WAVES
MOVING THROUGH THIS FEATURE THAT COULD PRODUCE CHANCES FOR SHOWERS
AND THUNDERSTORMS. THERE IS NOT A LOT OF CONSISTENCY AND TIMING TO
THIS LATEST SOLUTION SO CONFIDENCE IS LOW...AND THEREFORE LEFT POPS
AT LOW END CHANCE MOST TIMES. MODELS HINTING AT A MORE SIGNIFICANT
COLD FRONTAL PASSAGE TOWARD THE END OF THE PERIOD BUT TIMING DIFFERS
AMONGST THE GUIDANCE. ALLBLEND IS CARRYING SLIGHTLY HIGHER POPS
TOWARD THE END OF THE WORK WEEK...WITH 20-30 PERCENT CHANCES LEADING
UP TO THURSDAY. TEMPERATURES WILL BE BACK AROUND THE NORMAL RANGE
FOR THIS TIME OF YEAR...LOW TO MID 80S HIGHS FOR HIGHS AND LOWS IN
THE MID TO UPPER 60S.

&&

.AVIATION /DISCUSSION FOR THE 020000Z TAFS/...
ISSUED AT 642 PM EDT FRI AUG 1 2014

WIDELY SCATTERED CONVECTION IS SLOWLY DIMINISHING WITH TIME AS
INCREASED MID LEVEL CLOUD AND OUTFLOWS ARE BEGINNING TO CUT DOWN
ON HEATING. MAY NOT NEED TO CARRY ANY EXPLICIT MENTION OF THUNDER IN
THE FORECAST ANYMORE...BUT WILL MONITOR TRENDS UP TO ISSUANCE TIME.
APPEARS THE HIGHEST THREAT FOR CONVECTION MAY BE AT
KIND/KBMG...WHERE OUTFLOWS/CLOUD COVER REALLY HAVEN/T HAD MUCH OF AN
IMPACT ON INSTABILITY YET.

REGARDLESS...ANY LINGERING CONVECTION EXPECTED TO DIMINISH WITH
SUNSET. HOWEVER WITH SHORT TERM MODELS SUGGESTING THE PASSAGE OF AN
UPPER DISTURBANCE...THERE WILL PROBABLY BE A LOW THREAT FOR
CONVECTION OVER THE TAF SITES MOST OF THE NIGHT.

LOW CONFIDENCE IN VISIBILITY FORECAST. FROM A SYNOPTIC
STANDPOINT...CONDITIONS QUITE FAVORABLE FOR FOG FORMATION WITH
LITTLE GRADIENT AND RELATIVELY NARROW TEMPERATURE/DEWPOINT SPREADS
FOR THIS TIME OF DAY. NEGATIVE FACTOR WILL BE RATHER EXTENSIVE
MID/HIGH LEVEL CLOUD COVER ASSOCIATED WITH THE PASSAGE OF THE UPPER
WAVE. BEST CHANCE OF IFR RESTRICTIONS APPEARS TO BE IN THE KLAF
AREA...WHERE THERE HAS BEEN QUITE A BIT OF RAINFALL. WILL GO WITH
IFR RESTRICTIONS THERE AFTER 020700Z...BUT KEEP THE OTHER TAF SITES
ABOVE IFR FOR NOW.

&&

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

&&

$$

SYNOPSIS...JH
NEAR TERM...JH/NIELD
SHORT TERM...JH
LONG TERM...SMF
AVIATION...JAS

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