Area Forecast Discussion
Issued by NWS Northern Indiana

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000 FXUS63 KIWX 310636 AFDIWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 236 AM EDT FRI OCT 31 2014 .SYNOPSIS... ISSUED AT 822 PM EDT THU OCT 30 2014 A STRONG STORM SYSTEM ACROSS THE NORTHERN GREAT LAKES WILL DROP INTO THE REGION ON FRIDAY BRINGING RAIN SHOWERS ALONG WITH WINDY AND COLDER CONDITIONS. AS COLDER AIR FILTERS INTO THE AREA FOR FRIDAY...SOME SNOW IS ALSO POSSIBLE...BUT LITTLE OR NO SNOW ACCUMULATION IS EXPECTED. SNOW SHOWERS ARE EXPECTED TO DIMINISH FRIDAY NIGHT AS THE STORM SYSTEM PULLS OFF TO THE EAST...BUT UNSEASONABLY COOL CONDITIONS WILL PERSIST INTO THE WEEKEND. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 408 PM EDT THU OCT 30 2014 UPPER LEVEL SYSTEM DIGGING INTO THE GREAT LAKES TONIGHT WILL BRING STRONG NORTHWEST WINDS TO THE AREA...ALONG WITH A LIKELIHOOD OF RAIN AND SNOW SHOWERS LATE TONIGHT THROUGH FRIDAY. WATER VAPOR IMAGERY THIS AFTERNOON DEPICTS A SHORT WAVE ACROSS THE MID MS RIVER VALLEY THAT SHOULD TAKE A TRACK PRIMARILY JUST SOUTH OF THE LOCAL AREA THIS EVENING. A NARROW ZONE ZONE OF WEAK WARM ADVECTION/FRONTOGENESIS MAY ALLOW A FEW SPRINKLES TO OVERSPREAD MAINLY FAR SOUTHERN PORTIONS OF THE AREA LATE AFTERNOON/EARLY EVENING. ATTENTION FOR THE REMAINDER OF THE NIGHT WILL FOCUS ON MORE POTENT UPPER PV ANOMALY CURRENTLY DROPPING ACROSS THE NORTHERN GREAT LAKES. AN INITIAL WEAK SFC TROUGH IS EXPECTED TO TRACK ACROSS THE LOCAL AREA DURING THE OVERNIGHT HOURS IN ASSOCIATION WITH EASTWARD PROGRESSION OF AFOREMENTIONED MID MS VALLEY SHORT WAVE...WHICH WILL BE FOLLOWED BY THE MUCH STRONGER COLD FRONTAL PUSH AFTER DAYBREAK FRIDAY. ISALLOBARIC COUPLET IS NOT EXPECTED TO BE OVERLY STRONG WITH THIS SYSTEM...BUT STRONG COLD ADVECTION AND DEEPENING MIXED LAYER WILL SUPPORT POST FRONTAL WIND GUSTS OF AROUND 40 TO 45 MPH ACROSS ESPECIALLY NORTHWEST THIRD OF THE AREA FRIDAY MORNING...WITH A FEW GUSTS TO 50 TO 55 MPH NOT OUT OF THE QUESTION CLOSER TO THE LAKE MICHIGAN SHORELINE. GUSTS MAY BE SOMEWHAT MORE TEMPERED ACROSS SOUTHEAST HALF OF THE FORECAST AREA WHERE LOW LEVEL GRADIENT WILL BE A BIT WEAKER AND CHARACTERIZED BY MORE PRONOUNCED LOW LEVEL CYCLONIC FLOW. WILL ISSUE A WIND ADVISORY FOR FAR WEST/NORTHWEST LOCATIONS FOR FRIDAY MORNING THROUGH FRIDAY EVENING. CRITERIA LEVEL GUSTS ARE EXPECTED TO BE MAINTAINED THE LONGEST INTO FRIDAY EVENING CLOSER TO THE LAKE MICHIGAN SHORELINE. A LAKE SHORE FLOOD ADVISORY WILL REMAIN IN EFFECT FOR FRIDAY/FRIDAY NIGHT WITH SOME BEACH EROSION AND MINOR SHORELINE FLOODING POSSIBLE GIVEN STRONG WINDS/WAVES AND SLIGHTLY ABOVE AVERAGE LAKE MICHIGAN WATER LEVELS. IN TERMS OF PRECIPITATION...A BAND OF FAIRLY STRONG LOW LEVEL FRONTOGENESIS PRECEDING MAIN UPPER TROUGH SHOULD SPREAD RAIN SHOWERS ACROSS NORTHWEST PORTIONS OF THE AREA IN THE 09Z-12Z TIMEFRAME...OVERSPREADING THE REMAINDER OF THE AREA THROUGH FRIDAY MORNING. A BRIEF LULL IN PRECIP COVERAGE MAY OCCUR BETWEEN MORE FRONTALLY FORCED PRECIP AND STRONGER UPPER LEVEL DPVA ACCOMPANYING THE STRONGER UPPER VORT MAX. LOW LEVEL WET BULBS SHOULD SUPPORT PRIMARILY RAIN SHOWERS THROUGH EARLY AFTERNOON ACROSS MOST LOCATIONS...WITH SOME SNOW SHOWERS POSSIBLY MIXING IN FROM NORTHWEST TO SOUTHEAST FRIDAY AFTERNOON INTO EARLY EVENING. ALL INDICATIONS STILL POINT TOWARD LAKE EFFECT RAIN SHOWERS BECOMING MORE PROMINENT BY LATE MORNING...LIKELY EVOLVING INTO A DOMINANT SINGLE BAND...ALTHOUGH FORECAST SOUNDINGS DO SUGGEST ABOUT 30 DEGREES OF SHEAR IN CLOUD BEARING LAYER. LAKE INDUCED INSTABILITY PROFILES STILL LOOK QUITE IMPRESSIVE PER NAM BUFFER SOUNDINGS...WITH LAKE INDUCED EQUILIBRIUM LEVELS TO AROUND 20K FT BY MIDDAY. THUS...HAVE MAINTAINED CHANCE THUNDER MENTION THROUGH THE DAY ACROSS THE EXTREME NORTHWEST. WITH A LONG RESIDENCE TIME OF LOW LEVEL PARCELS GIVEN NORTHERLY FETCH...CONFIDENCE REMAINS LOW IN EXTENT OF SNOW SHOWERS LATER IN THE AFTERNOON WITH CONCERN THAT BOUNDARY LAYER MODIFICATION MAY BE A BIT TOO MUCH TO OVERCOME. HAVE LARGELY REMAINED WITH PREVIOUS FORECAST IDEA OF INCH OR LESS ACCUMULATIONS DOWNWIND OF THE LAKE...AND MAINLY A BIT INLAND WHERE INFLUX OF SLIGHTLY DRIER LOW LEVEL AIR MAY AID IN FROZEN PTYPE FOR A TIME. EXACTLY WHERE MORE DOMINANT BANDING SETS UP IS ALSO OF LOW CONFIDENCE DEPENDING ON EXACT TRACK/STRENGTH OF MID LEVEL SYSTEM AS IT DROPS INTO THE SOUTHERN GREAT LAKES...AND A CLUSTER OF HIGHER RES SOLUTIONS DEPICT MORE DOMINANT BANDING SHIFT WEST OF THE AREA. FOR TEMPS...HAVE UTILIZED NON-DIURNAL CURVE FOR FRIDAY WITH STEADY OR SLOWLY FALLING TEMPS THROUGH THE DAY UNDER STRONG COLD ADVECTION. && .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 408 PM EDT THU OCT 30 2014 INITIAL FOCUS WILL BE ON EXPECTED LAKE EFFECT BAND WHICH MAY BE RESIDING NEAR OR JUST OVER FAR WESTERN PARTS OF THE FORECAST AREA. BEST WINDOW FOR ANY PRECIP (LIKELY IN THE FORM OF SOME WET SNOW) WILL BE IN THE 00Z TO 03Z WINDOW BEFORE THE FLOW BECOMES MORE NNE AND MOVES INTO FAR NW INDIANA. MORE INTENSE SNOW SHOWERS COULD PRODUCE SOME LIGHT ACCUMULATIONS IN GRASSY AREAS BUT ROADS SHOULD HOPEFULLY REMAIN ONLY WET EXCEPT FOR ELEVATED SURFACES. IN THE EAST...SFC LOW WILL BE RAPIDLY REFORMING OVER THE CAROLINAS FRIDAY EVENING AND MOVE OFF THE EAST COAST ON SATURDAY. INVERTED TROUGH FROM THE LOW INTO THE OHIO VALLEY...WILL PERSIST THROUGH SATURDAY MORNING BEFORE SHIFTING EAST. HIGHEST POPS WILL PERSIST IN THE EVENING WITH TAPERING OVERNIGHT. PRECIP BY THIS POINT SHOULD ALSO BE IN THE FORM OF WET SNOW WITH A DUSTING OF SNOW POSSIBLE ON GRASSY AREAS. WINDY CONDITIONS WILL SLOWLY SUBSIDE THROUGH THE NIGHT WITH GREATEST HEADLINE WORTHY AREA BEING ALONG THE LAKE SHORE WITH TIGHTEST GRADIENT EARLY EVENING. COLD HIGH PRESSURE MOVES ACROSS THE AREA OVER THE WEEKEND WITH HIGHS IN THE 40S (THINK MANY AREAS MAY STRUGGLE TO REACH 40 EVEN WITH SUNSHINE ON SATURDAY). TEMPERATURES WILL MODERATE BACK CLOSER TO NORMAL FOR THE START OF THE WEEK AS LOW PRESSURE DEVELOPS ACROSS THE PLAINS AND TRACKS INTO CANADA FOR THE MIDDLE OF THE WEEK. A COLD FRONT WILL EXTEND FROM THE FRONT WITH AT LEAST SOME MOISTURE RETURN BY THE MONDAY NIGHT TO TUESDAY NIGHT PERIOD. LIKELY POPS WERE INTRODUCED IN LAST FORECAST AND WHILE NOT OVERLY WILD THIS FAR OUT WITH POPS THIS HIGH WILL STICK WITH SIGNALS AND KEEP GENERAL IDEA IN PLACE. YET ANOTHER WAVE WILL QUICKLY APPROACH WEDS NGT WARRANTING SLGT CHC POPS MAINLY NE WHERE BETTER MSTR AND LIFT WILL EXIST AS MAIN TROUGH IMPACT CENTRAL/NORTH GREAT LAKES. && .AVIATION...
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(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 158 AM EDT FRI OCT 31 2014 A SURFACE LOW WAS OVER NORTHERN LAKE HURON AT THE START OF THIS TAF PERIOD WITH A STRONG COLD FRONT EXTENDING SOUTHWEST INTO SOUTHERN WISCONSIN. RAIN WAS CHANGING TO SNOW FARTHER NORTHWEST BEHIND THE FRONT WHERE THERMAL PROFILES SUPPORTED ALL SNOW. A VERY TIGHT PRESSURE GRADIENT WILL BE OVER THE AREA THIS AFTERNOON...WITH WINDY CONDITIONS IN THE MIDST OF DETERIORATING AVIATION CONDITIONS. MAY NEED TO RAISE SUSTAINED WINDS AT SBN FOR THIS AFTERNOON. MADE SOME MINOR ADJUSTMENTS TO TIMING OF LOWER CIGS AND INCLUDED THE MENTION OF A RAIN/SNOW MIX AS LOW LEVEL 1000/850 THICKNESSES DROP BELOW 1300M. CONCERN FOR A FASTER CHANGEOVER TO RAIN/SNOW OR JUST SNOW WITH VERY COLD AIR IN THE MID LEVELS...-16C AT 700 MB BY LATE MORNING WITH NEARLY THE ENTIRE PROFILE BELOW FREEZING. THE DENTRITIC GROWTH ZONE VERY FAVORABLE FOR SNOW GROWTH IN THE CLOUD LAYER FROM 15Z TO 21Z IN SBN AREA. FOR NOW...WENT WITH A MIX AT SBN STARTING AT 20Z... BUT THIS TIME MAY NEED TO BE MOVED UP.
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&& .IWX WATCHES/WARNINGS/ADVISORIES...
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IN...WIND ADVISORY FROM 7 AM THIS MORNING TO 10 PM CDT THIS EVENING FOR INZ003. LAKESHORE FLOOD ADVISORY FROM 7 AM THIS MORNING TO 4 AM CDT SATURDAY FOR INZ003. WIND ADVISORY FROM 10 AM EDT /9 AM CDT/ THIS MORNING TO 8 PM EDT /7 PM CDT/ THIS EVENING FOR INZ004-005-012>015-020-022. MI...WIND ADVISORY FROM 8 AM THIS MORNING TO 11 PM EDT THIS EVENING FOR MIZ077. LAKESHORE FLOOD ADVISORY FROM 8 AM THIS MORNING TO 5 AM EDT SATURDAY FOR MIZ077. WIND ADVISORY FROM 10 AM THIS MORNING TO 8 PM EDT THIS EVENING FOR MIZ078-079. OH...NONE. LM...STORM WARNING FROM 8 AM THIS MORNING TO 8 PM EDT THIS EVENING FOR LMZ046. GALE WARNING FROM 8 PM THIS EVENING TO 5 AM EDT SATURDAY FOR LMZ046. GALE WARNING FROM 8 AM THIS MORNING TO 5 AM EDT SATURDAY FOR LMZ043.
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&& $$ SYNOPSIS...MARSILI SHORT TERM...MARSILI LONG TERM...FISHER AVIATION...SKIPPER 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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