Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 061917
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
317 PM EDT MON JUL 6 2015

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

&&

.SYNOPSIS...
ISSUED AT 311 PM EDT MON JUL 6 2015

CLOUDS AND PRECIPITATION CHANCES WILL INCREASE TONIGHT AS A COLD
FRONT APPROACHES FROM THE NORTHWEST. THIS COLD FRONT WILL MOVE
ACROSS CENTRAL INDIANA TUESDAY...STALL OUT NEAR THE OHIO VALLEY
TUESDAY NIGHT...THEN SHIFT BACK NORTH ON WEDNESDAY. AS A RESULT
THERE WILL BE SHOWER AND THUNDERSTORM CHANCES DUE TO THIS FEATURE
THROUGH MID WEEK. FURTHER OUT...SHOWERS AND THUNDERSTORMS WILL
REMAIN IN THE FORECAST INTO THE EXTENDED PERIOD...BUT HIGH PRESSURE
OVER THE DEEP SOUTH WILL INHIBIT MOISTURE A BIT. A SHORT WAVE WILL
PROVIDE SOME EXTRA REINFORCEMENT ON FRIDAY. THEN A SLIGHTLY DRIER
WEATHER PATTERN BUT WARM AND HUMID CONDITIONS ARE ON TAP FOR THIS
WEEKEND.

&&

.NEAR TERM /REST OF THIS AFTERNOON THROUGH TONIGHT/...

ISSUED AT 311 PM EDT MON JUL 6 2015

RIDGING ALOFT WILL HOLD FOR THE REST OF THIS AFTERNOON HOWEVER SKY
COVER WILL INCREASE IN COVERAGE THIS EVENING AS A COLD FRONT SLOWLY
APPROACHES THE REGION FROM THE NORTHWEST.

THE NEAR TERM MODEL GUIDANCE IS IN GENERAL AGREEMENT WITH TIMING AND
MOISTURE AMOUNTS WITH THIS FRONT AND GENERALLY HAS BEEN SINCE
LATE LAST WEEK...WITH A FEW EXCEPTIONS. THE GFS APPEARS TO BE THE
FASTEST/MOST PROGRESSIVE OF THE MODELS AND SLIGHTLY BIT OF AN
OUTLIER. STUCK CLOSER TO A SREF/NAM/EURO BLEND FOR THE NEXT 24-36
HOURS. THUS INTRODUCED ONLY 20 PERCENT POPS ACROSS THE FAR
NORTHWESTERN COUNTIES OF THE CWA AROUND 02-03Z...AND THEN STEADILY
INCREASING ACROSS MAINLY THE NORTHWEST COUNTIES FROM
04-08Z...AFTERWARDS SPREADING CHANCES SOUTH OF THE INTERSTATE 70
CORRIDOR WITH LIKELY TO CATEGORICAL POPS IN THE FORECAST ACROSS
THE NW AFTER 08/09Z...INCREASING TO 90 PERCENT BY 12Z TUESDAY
MORNING...WITH LOW SCATTERED CHANCES FINALLY REACHING THE
SOUTHEAST COUNTIES OF THE CWA BY THIS HOUR.

FELT CONFIDENT ENOUGH IN THE MODELS PER CONSISTENCY AND CONSENSUS TO
INCREASE POPS BY 20 TO 30 PERCENT IN SOME CASES...AND SHOW AN HOURLY
TREND OF THE MOVEMENT OF THIS PRECIPITATION BEGINNING MOVING THROUGH
OVERNIGHT. WENT SLIGHTLY HIGHER THAN MAVMOS FOR LOWS CONSIDERING THE
ABUNDANT CLOUD COVER AND PRECIP CHANCES...ESPECIALLY ACROSS THE
NORTHWEST. LOWS TONIGHT 70-72.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...

ISSUED AT 311 PM EDT MON JUL 6 2015

AS MENTIONED ABOVE GOOD MODEL CONSENSUS/CONSISTENCY ALLOWED POPS TO
BE RAISED TO 90 TO 100 PERCENT ALL LOCATIONS DURING PORTIONS OF THE
DAY TUESDAY AS THIS COLD FRONT SLOWLY WORKS IT/S WAY SOUTHEAST
ACROSS THE FORECAST AREA. THAT WAS THE MAIN CHANGE TO THE FORECAST
THIS PORTION OF THE FORECAST WAS TO RAISE POPS THIS HIGH.

INSTABILITY INDICES DO NOT LOOK TOO IMPRESSIVE AND SPC HAS DROPPED
THE MARGINAL RISK ACROSS THE NORTHWEST COUNTIES OF THE CWA...BECAUSE
AFTER 12Z THE FRONT SHOULD BE MOSTLY THROUGH THESE COUNTIES AND THUS
THE SOURCE OF MOISTURE AND LIST WILL BE GONE. ELSEWHERE ACROSS
CENTRAL INDIANA SHOWERS ALONG WITH THUNDERSTORMS ARE LIKELY...WITH
THE POTENTIAL FOR SOME OF THESE STORMS TO BECOME STRONG WITH SMALL
HAIL...STRONGER WINDS AND VERY HEAVY RAINFALL AS THE MAIN THREATS.
BEST FORCING STILL LOOKS TO BE BETWEEN THE HOURS OF TUE 18Z-WED 00Z.

THE FRONT BEGINS TO SLOW DOWN AND EVENTUALLY STALL OUT TUESDAY
NIGHT ACROSS THE OHIO VALLEY. THIS WILL KEEP LIKELY TO EVEN
CATEGORICAL POPS (CATEGORICAL EARLY IN THE EVENING) IN THE
FORECAST ACROSS THE SOUTHEAST HALF OF THE FORECAST AREA. THEN THIS
FEATURE APPEARS TO MEANDER BACK NORTHWARD THROUGH WEDNESDAY
KEEPING SCATTERED CHANCES FOR SHOWERS/TSTORMS IN THE FORECAST
THROUGH MID WEEK...HOWEVER CHANCES WED WILL BE 50 PERCENT OR
LESS...WITH HIGHEST POPS ACROSS THE SOUTH. A SECOND WAVE MOVING
THROUGH WEDNESDAY NIGHT MAY KICK THE BOUNDARY AWAY FROM THE REGION
FOR GOOD...WITH ONLY SOME LINGERING WEAK CHANCES LEFT IN THE
FORECAST FOR THURSDAY.

TEMPERATURES ARE LOOKING TO TAKE EVEN MORE OF A DIVE THAN PREDICTED
EARLIER AFTER THE COLD FRONT MOVES THROUGH ON TUESDAY. GENERALLY WENT
A FEW DEGREES LOWER ALL THROUGHOUT THE SHORT TERM THAN PREVIOUS
FORECAST BASED ON LATEST GUIDANCE...LINGERING CLOUD COVER AND
PRECIPITATION CHANCES.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...

ISSUED AT 240 PM EDT MON JUL 6 2015

STRONG UPPER RIDGE WILL RETROGRADE FROM THE SOUTHEAST U S BACK
INTO THE ROCKIES THROUGHOUT THE EXTENDED RESULTING IN A SHIFT FROM
ZONAL FLOW ALOFT TO A MUCH MORE BLOCKY REGIME. WITH A FRONTAL
BOUNDARY OSCILLATING OVER THE REGION...PERIODIC STORMS WITH A
VERY WARM...MUGGY AIRMASS CAN BE EXPECTED THROUGH EARLY NEXT WEEK.

ECMWF CONTINUES TO TREND TOWARDS MODEL CONSENSUS IN TIMING THE
WESTWARD SHIFT TO THE UPPER RIDGE OVER THE WEEKEND. THE FRONTAL
BOUNDARY WILL MOVE NORTH INTO THE LOWER GREAT LAKES IN RESPONSE TO
THE MOVEMENT OF THE RIDGE WITH HEIGHT RISES OVER THE OHIO VALLEY.
WILL KEEP LOWER POPS PRIMARILY OVER FAR NORTHERN PORTIONS OF THE
FORECAST AREA SATURDAY AND SUNDAY.

AS THE RIDGE AXIS REESTABLISHES OVER THE ROCKIES AND HIGH
PLAINS...STRONGER WAVE RIDING UP AND OVER THE RIDGE WILL DIVE
INTO THE REGION SUNDAY NIGHT AND MONDAY AS HEIGHTS ALOFT BUCKLE.
AT FIRST GLANCE...THIS MAY END UP BEING THE BEST CHANCE DURING THE
EXTENDED FOR MORE ROBUST CONVECTION IN THE FORM OF AN MCS TO
IMPACT CENTRAL INDIANA. WILL BUMP UP TO HIGH CHANCE POPS SUNDAY
NIGHT AND MONDAY.

WITH THE FRONT TO THE NORTH OVER THE WEEKEND EXPECT HIGHS
MAINLY IN THE UPPER 80S...WITH LOWER 90S LIKELY CONFINED TO JUST
THE FAR SOUTHERN COUNTIES. TEMPS WILL FALL BACK INTO THE LOWER/MID
80S MONDAY WITH THE ARRIVAL OF THE AFOREMENTIONED WAVE.

&&

.AVIATION /DISCUSSION FOR 061800Z TAF ISSUANCE/...
ISSUED AT 1236 PM EDT MON JUL 6 2015

VFR CONDITIONS EXPECTED THROUGH TONIGHT...MVFR AND LOWER CEILINGS
DEVELOPING ON TUESDAY.

CU HAS DEVELOPED EARLY THIS AFTERNOON AS CONVECTIVE TEMPS ARE
REACHED. BROAD CIRRUS SHIELD APPROACHING FROM THE NORTHWEST IN
ASSOCIATION WITH FRONTAL CONVECTION OVER WISCONSIN AND IOWA. THE
CU WILL REMAIN THROUGH THE AFTERNOON...LARGELY DIMINISHING NEAR OR
SHORTLY AFTER SUNSET AS HEATING IS LOST. MUCH OF THE CIRRUS
INITIALLY WILL THIN WITH DEEPER SUBSIDENCE ALOFT CURRENTLY
PRESENT. HOWEVER AS MOISTURE STEADILY INCREASES...EXPECT SKIES TO
BECOME MAINLY CLOUDY LATE TONIGHT WITH CEILINGS LOWERING TOWARDS
DAYBREAK TUESDAY AS FRONTAL CONVECTION MOVES INTO THE REGION FROM
THE WEST. S/SW WINDS AT 10-15KTS TODAY WILL DECREASE TO 5-10KTS
TONIGHT.

THE FRONTAL BOUNDARY WILL SAG INTO CENTRAL INDIANA ON TUESDAY WITH
CONVECTION INCREASING IN COVERAGE. EXPECT THUNDERSTORMS BUT
CONFIDENCE IS LOW AT THIS POINT AS TO HOW EXTENSIVE THUNDER WILL
BE WITH PRECIP THROUGH THE FIRST HALF OF THE DAY. WILL CARRY VCSH
AT ALL SITES BEGINNING TOWARDS DAYBREAK IN THE WEST AND BY MID
MORNING AT KIND. MODEL SOUNDINGS AND 925MB RH PROGS SUGGEST MVFR
STRATOCU WILL BECOME MORE NUMEROUS DURING THE COURSE OF THE
DAY...WITH EVEN SOME POTENTIAL FOR CEILINGS TO SLIP DOWN CLOSER TO
IFR LEVELS PERIODICALLY AT KHUF AND KLAF. WINDS WILL EVER TO
WESTERLY LATE IN THE PERIOD AT KLAF AS THE FRONT PASSES...WITH
CONTINUED SOUTHWEST FLOW AT THE OTHER THREE TERMINALS.


&&

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

$$

SYNOPSIS...SMF
NEAR TERM...SMF
SHORT TERM...SMF
LONG TERM....RYAN
AVIATION...RYAN

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