Area Forecast Discussion
Issued by NWS Northern Indiana

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000 FXUS63 KIWX 211053 AFDIWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 653 AM EDT TUE OCT 21 2014 .SYNOPSIS... ISSUED AT 351 AM EDT TUE OCT 21 2014 LOW PRESSURE WILL DRIFT SLOWLY EAST OUT OF THE GREAT LAKES INTO THE CAROLINAS BY WEDNESDAY. SKIES WILL CLEAR ACROSS WESTERN AREAS BY LATE AFTERNOON WITH MOSTLY CLOUDY SKIES HOLDING UNTIL TONIGHT IN THE EAST. HIGHS WILL CLIMB INTO THE 50S TODAY WITH LOWS TONIGHT INTO THE LOWER TO MIDDLE 30S. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 351 AM EDT TUE OCT 21 2014 UPPER LEVEL TROUGH WILL CONTINUE TO DEEPEN AS IT MOVES SLOWLY SOUTHEAST OUT OF THE GREAT LAKES AND TOWARDS THE CAROLINAS. LAKE EFFECT CLOUDS AND LIMITED SHOWER ACTIVITY SHOULD QUICKLY DIMINISH BY LATE AFTERNOON AS FLOW BECOMES MORE N AND NE. WHILE SKIES WILL CLEAR IN WESTERN AREAS LATER TODAY INTO TONIGHT...CLOUD COVER WILL LINGER LONGER AS CYCLONIC FLOW REMAINS ACROSS EASTERN AREAS WITH SOME CONTRIBUTION FROM LAKE HURON. THE RESULT WILL BE PARTLY IF NOT MOSTLY CLOUDY SKIES LINGERING INTO TONIGHT ALONG/EAST OF I-69. AS SKIES CLEAR...TEMPERATURES SHOULD BE ABLE TO REBOUND SOMEWHAT BUT WILL STILL REMAIN BELOW NORMAL WITH HIGHS IN THE LOW TO MID 50S. CLEARING IN THE WEST WILL SET THE STAGE FOR A COLD NIGHT WITH NE FLOW USHERING IN DEWPOINTS IN THE LOWER 30S AND LOWS IN A SIMILAR RANGE (LOW TO MID 30S). FROST WILL BE POSSIBLE...BUT WITH END OF CLIMATOLOGICAL GROWING SEASON NO HEADLINES WILL BE ISSUED. && .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 351 AM EDT TUE OCT 21 2014 SLIGHTLY BELOW NORMAL TEMPERATURES TO BEGIN THE PERIOD WILL MODERATE TO NEAR NORMAL OR SLIGHTLY ABOVE NORMAL FOR THIS WEEKEND INTO THE EARLY PARTS NEXT WEEK. ON TUESDAY...UPPER TROUGH DIGGING ACROSS THE EASTERN GREAT LAKES WILL EVENTUALLY DEVELOP INTO A CLOSED OFF UPPER LEVEL CIRCULATION ACROSS THE MID ATLANTIC STATES. THIS WILL PLACE LOCAL AREA INTO UPPER LEVEL INFLECTION ZONE WITH THE POSSIBILITY OF SOME STRATOCU PERSISTING ACROSS MAINLY EASTERN LOCATIONS. MID LEVEL HEIGHT RISES BUILDING IN MORE AGGRESSIVELY FOR TUESDAY NIGHT SHOULD RESULT IN MAINLY CLEAR SKIES. SLOW PROGRESSION OF CLOSING OFF SYSTEM ACROSS MID ATLANTIC WILL RESULT IN ONLY A VERY SLOW EASTWARD MIGRATION OF UPPER LEVEL RIDGING...WHICH WILL KEEP LOW LEVEL ANTICYCLONE ANCHORED ACROSS THE REGION THROUGH WEDNESDAY NIGHT. THIS SETUP SHOULD PROVIDE HIGHS IN THE MID TO UPPER 50S...AND A FEW GOOD NIGHTS OF RADIATIONAL COOLING CONDITIONS WITH LOWS IN THE MID 30S (POSSIBLY LOWER 30S IN COOL SPOTS). PER PUBLIC INFORMATION STATEMENT SENT YESTERDAY...FROST/FREZE HEADLINES HAVE BEEN DISCONTINUED FOR LOCAL AREA DUE TO EFFECTIVE ENDING OF THE GROWING SEASON. NEXT FEATURE OF INTEREST FOR THURSDAY WILL BE UPPER PV ANOMALY APPROACHING THE AREA FROM THE NORTHERN PLAINS. UPPER LEVEL DEFORMATION ASSOCIATED WITH SLOW MOVING UPPER LEVEL RIDGE SHOULD ATTENUATE THIS PV ANOMALY ACROSS THE GREAT LAKES REGION THURSDAY NIGHT INTO EARLY FRIDAY RESULTING IN WANING UPPER FORCING. NONETHELESS...ANOTHER NARROW LOW LEVEL MOISTURE AXIS WILL PRECEDE THIS UPPER PV ANOMALY WITH WEAK LOW LEVEL WAA/MOISTURE ADVECTION AND WEAK LOW LEVEL CONVERGENCE AXIS OVERSPREADING THE AREA. NO CHANGE NEEDED TO PREVIOUS SLIGHT CHANCE RAIN SHOWER POPS ACROSS THE WEST THURSDAY NIGHT...WITH LESSER CONFIDENCE ACROSS THE EAST DUE TO WEAKENING NATURE OF UPPER PV ANOMALY. UPPER RIDGE SHOULD EVENTUALLY GET PINCHED OFF FROM AFOREMENTIONED TWO SYSTEMS...WITH RENEWED MID/UPPER LEVEL HEIGHT RISES WORKING INTO THE REGION FOR THE WEEKEND. THIS WILL MARK A MORE DISTINCT WARMING TREND FOR SATURDAY/SUNDAY...ALTHOUGH MEDIUM RANGE GUIDANCE CONTINUES TO INDICATE SOUTHEAST CANADIAN UPPER SHORT WAVE PROVIDING MORE SUBSTANTIAL LOW LEVEL COLD ADVECTION PUSH ACROSS THE EASTERN GREAT LAKES. ONLY ADJUSTMENT TO PREVIOUS FORECAST WAS FOR SLIGHTLY WARMER CONDITIONS ON SUNDAY...WITH A BIT SHARPER SOUTHWEST TO NORTHEAST GRADIENT IN MAX TEMPS ALTHOUGH STILL A GOOD DEAL OF UNCERTAINTY IN HOW FAR SOUTH STRONGER LOW LEVEL COLD ADVECTION IS ABLE TO PUSH ACROSS THE EASTERN GREAT LAKES. A SLIGHTLY FLATTER AND MORE PROGRESSIVE PATTERN SHOULD SET UP EARLY NEXT WEEK WITH NEXT BROAD EASTERN PACIFIC WAVE BRINGING THE NEXT CHANCE OF RAIN SHOWERS TOWARD THE END OF THE PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 646 AM EDT TUE OCT 21 2014 SCATTERED LIGHT LAKE EFFECT RAIN SHOWERS WILL CONTINUE THIS MORNING WITH MARGINAL LAKE INDUCED INSTABILITY. A SHEARED UPPER LEVEL VORTICITY ASSOCIATED WITH UPPER JET STREAK WILL ALSO BE SHIFTING SOUTH ACROSS THE REGION OVER NEXT SEVERAL HOURS PROVIDING SOME SYNOPTIC ENHANCEMENT. MAY INCLUDE A TEMPO -SHRA MENTION FOR KSBN WITH THE 12Z TAFS ALONG WITH THE POSSIBILITY OF SHORT LIVED 2-3K FT CIGS. OTHERWISE...GENERALLY VFR STRATOCU TODAY...AND SHOULD DIMINISH IN COVERAGE LATER THIS AFTERNOON INTO THIS EVENING AS UPPER RIDGE AXIS BEGINS TO BUILD ACROSS THE AREA. NORTHWEST WINDS AROUND 10 KNOTS WILL VEER TO THE NORTH THIS AFTERNOON...AND BECOME LIGHT NORTHEAST TONIGHT AS LOW LEVEL RIDGE AXIS OVERSPREADS THE WESTERN GREAT LAKES. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 5 AM EDT WEDNESDAY FOR LMZ043-046. && $$ SYNOPSIS...FISHER SHORT TERM...FISHER LONG TERM...MARSILI AVIATION...MARSILI VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA

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