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 VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON FACEBOOK...TWITTER AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSINDIANAPOLIS WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS

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