Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000 FXUS63 KIND 281054 AFDIND AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 554 AM EST WED JAN 28 2015 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 300 AM EST WED JAN 28 2015 A COUPLE OF LOW PRESSURE SYSTEMS WILL BRING CHANCES OF PRECIPITATION TO CENTRAL INDIANA THURSDAY AND AGAIN FOR THE SECOND HALF OF THE WEEKEND INTO EARLY NEXT WEEK. TEMPERATURES WILL GO FROM NEAR TO ABOVE NORMAL EARLY IN THE PERIOD TO WELL BELOW AVERAGE BY EARLY NEXT WEEK. && .NEAR TERM.../TODAY/ ISSUED AT 300 AM EST WED JAN 28 2015 SATELLITE SHOWS SOME MID AND HIGH CLOUDS STARTING TO ARRIVE IN CENTRAL INDIANA. EXPECT A GRADUAL INCREASE IN MID AND HIGH CLOUD TODAY AS WARM ADVECTION AND ISENTROPIC LIFT INCREASE ALOFT. TEMPERATURES WILL START OUT COLD...ESPECIALLY ACROSS THE NORTHEAST WHERE SOME SNOW COVER LINGERS. HOWEVER THERE WILL BE ENOUGH SUNSHINE TODAY TO BOOST TEMPERATURES TO IN BETWEEN THE MET AND MAV MOS NUMBERS. && .SHORT TERM.../TONIGHT THROUGH FRIDAY NIGHT/ ISSUED AT 300 AM EST WED JAN 28 2015 FOCUS IS ON CHANCES FOR PRECIPITATION TONIGHT INTO THURSDAY NIGHT. MODELS ARE CLOSE ENOUGH THAT A BLEND WAS USED. ISENTROPIC LIFT WILL RAMP UP THIS EVENING WITH 850MB WINDS INCREASING TO AROUND 50KT. HOWEVER THIS LIFT WILL HAVE LITTLE MOISTURE TO WORK WITH. WILL KEEP THE EVENING DRY BUT INCREASE THE CLOUDS. OVERNIGHT...ADDITIONAL FORCING WILL MOVE IN AS AN UPPER TROUGH APPROACHES. HOWEVER...MOISTURE IS STILL PRETTY LIMITED IN THE LOWEST LEVELS. THUS ONLY WENT SLIGHT CHANCE TO LOW CHANCE CATEGORY POPS STARTING ABOUT 08Z. TEMPERATURES WILL BOTTOM OUT EARLY IN THE EVENING THEN RISE OVERNIGHT WITH GOOD WARM ADVECTION. BY THE TIME ANY PRECIPITATION WOULD START...THE ATMOSPHERE WILL BE WARM ENOUGH FOR JUST RAIN. A COUPLE OF UPPER WAVES WILL MOVE THROUGH THE AREA THURSDAY. BEST COMBINATION OF FORCING AND MOISTURE OCCURS BETWEEN 12Z AND 18Z THURSDAY. HOWEVER...EVEN DURING THAT PERIOD THE BEST MOISTURE ARRIVES AFTER FORCING HAS PEAKED. THUS JUST WENT CHANCE POPS MOST AREAS...WITH A THIN AREA OF LIKELY POPS IN THE FAR NORTHEAST. CHANCES FOR RAIN WILL DIMINISH THROUGH THURSDAY AFTERNOON AS FORCING WEAKENS. TEMPERATURES COOL QUICKLY ALOFT...BUT SURFACE TEMPERATURES STAY MILD FOR A WHILE. THUS ONLY INTRODUCED A MIX OF SNOW AND RAIN LATE IN THE AFTERNOON. KEPT SLIGHT CHANCE POPS ACROSS THE EASTERN HALF OF THE AREA THURSDAY EVENING AS SYSTEM EXITS. CONTINUED WITH SLIGHT CHANCE POPS NORTHEAST OVERNIGHT THURSDAY NIGHT TO ACCOUNT FOR ANY LAKE EFFECT SNOW THAT MAKES IT INTO THE AREA. HIGH PRESSURE WILL THEN MOVE IN AND PROVIDE DRY BUT COOL CONDITIONS FRIDAY AND FRIDAY NIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... ISSUED AT 249 AM EST WED JAN 28 2015 PRIMARY FOCUS FOR THE EXTENDED PERIOD REMAINS ON THE GROWING POTENTIAL FOR A HIGH IMPACT WINTER WEATHER SYSTEM ACROSS THE OHIO VALLEY FOR THE SECOND HALF OF THE WEEKEND. 00Z MODEL GUIDANCE HAS COME IN GENERALLY WITH A MORE PHASED LOOK TO THE UPPER JET STRUCTURES CONSEQUENTLY PRODUCING A STRONGER SURFACE WAVE TRACKING THROUGH THE REGION. AFTER A DRY DAY SATURDAY AS HIGH PRESSURE MOVES ACROSS THE AREA...FOCUS WILL TURN TO DEVELOPING LOW PRESSURE OVER TEXAS EARLY SUNDAY. THIS SYSTEM WILL LIFT NORTHEAST INTO THE OHIO AND TENNESSEE VALLEYS AS AN UPPER TROUGH AMPLIFIES OVER THE CENTRAL PLAINS. VARIATIONS ARE PRESENT BETWEEN THE DIFFERENT MODELS WHICH IS TO BE EXPECTED. THE GGEM AND OP GFS ARE PARTICULARLY AGGRESSIVE IN PHASING THE UPPER ENERGY OVER THE REGION BY LATE SUNDAY... CONSEQUENTLY PRODUCING A DEEPENING LOW GOING SUB-1000MB SUNDAY NIGHT AS IT PASSES THROUGH THE AREA. ECMWF IS FLATTER IN THE UPPER LEVELS INITIALLY LENDING TO A FASTER MOVING WAVE WITH THE PHASING ENERGY ALOFT NOT TAKING PLACE UNTIL AFTER THE SYSTEM PASSES. THE INDIVIDUAL GFS ENSEMBLE MEMBERS HAVE YET TO ORGANIZE INTO A CONSENSUS SURFACE LOW TRACK AT THIS POINT...SHOWCASING THE DIFFERENCES WITH RESPECT TO THE DEGREE AND TIMING OF THE POLAR AND SUBTROPICAL JETS PHASING. AT THIS POINT...THE FORECAST TRACK IS IN A FAIRLY IDEAL LOCATION FOR SNOW TO BE A PREDOMINANT PRECIP TYPE FOR MOST OF THE REGION. AS MENTIONED ON TUESDAY MORNING HOWEVER...THE OVERALL HANDLING OF LOW LEVEL WARM INTRUSIONS THIS WINTER BY MODELS HAVE BEEN PROBLEMATIC AND TRACK OF THE 850MB LOW ACROSS CENTRAL INDIANA ON THE BULK OF THE EXTENDED GUIDANCE DOES NOTHING TO QUELL THAT CONCERN AT THIS TIME. WITH THIS STORM STILL 4-5 DAYS OUT...IT REMAINS PREMATURE TO SPECULATE ON DETAILS UNTIL A GREATER MODEL CONSENSUS CAN BE ACHIEVED. THE MAIN TAKEAWAY AT THIS EARLY STAGE IS THAT CONFIDENCE IS GROWING IN A WINTER STORM TO IMPACT THE REGION LATE SATURDAY NIGHT THROUGH EARLY MONDAY. WILL CARRY MAINLY SNOW OVER THE NORTHERN HALF OF THE FORECAST AREA WITH A RAIN/SNOW MIX ON SUNDAY ACROSS SOUTHERN COUNTIES. SHOULD SNOW END UP AS THE PREDOMINANT PRECIP TYPE...POTENTIAL EXISTS FOR SEVERAL INCHES OF ACCUMULATION. STAY TUNED. MUCH COLDER AIR WILL BE DRAWN SOUTH INTO THE REGION FOR EARLY NEXT WEEK BEHIND THIS SYSTEM WITH POTENTIAL FOR COLDEST TEMPS IN ABOUT 3 WEEKS WITH HIGHS STRUGGLING TO GET OUT OF THE TEENS IN SOME LOCATIONS MONDAY AND TUESDAY. COULD SEE LOWS NEAR OR JUST BELOW ZERO IN SPOTS TUESDAY MORNING. && .AVIATION /DISCUSSION FOR 281200Z TAF ISSUANCE/... ISSUED AT 554 AM EST WED JAN 28 2015 VFR CONDITIONS EXPECTED THROUGHOUT THE FORECAST PERIOD. HIGH PRESSURE CENTERED OVER THE OHIO VALLEY THIS MORNING WILL DRIFT EAST THROUGH THE COURSE OF THE DAY. PLENTY OF SUNSHINE IS ANTICIPATED TODAY...WITH MID AND HIGH LEVEL CLOUDS SLOWLY INCREASING DURING THE AFTERNOON. SOUTHEAST WINDS WILL INCREASE TO 10-15KTS BY THE AFTERNOON. SKIES WILL BECOME CLOUDY TONIGHT AS LOW PRESSURE APPROACHES FROM THE WEST. LIGHT RAIN SHOWERS WILL DEVELOP ACROSS CENTRAL INDIANA AFTER 06Z AS THE LOW TRACKS INTO THE LOWER GREAT LAKES. WINDS WILL VEER TO SOUTHERLY BY LATE TONIGHT...INCREASING TO AROUND 15KTS WITH GUSTS 20-25KTS. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...50 NEAR TERM...50 SHORT TERM...50 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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