140  
FXUS63 KAPX 242101  
AFDAPX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GAYLORD MI  
401 PM EST MON NOV 24 2014  
   
SYNOPSIS
 
 
ISSUED AT 401 PM EST MON NOV 24 2014  
 
RAIN AND MILD TEMPERATURES WILL GIVE WAY TO A PERIOD OF LAKE  
ENHANCED SNOW LATE THIS AFTERNOON INTO TUESDAY MORNING. COLDER  
TEMPERATURES ALONG WITH ADDITIONAL CHANCES FOR SNOW WILL CONTINUE  
ALL THE WAY THROUGH THE THANKSGIVING DAY HOLIDAY WEEKEND.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH TONIGHT)  
ISSUED AT 401 PM EST MON NOV 24 2014  
 
OVERVIEW: 975 MB SFC LOW NOW UP ALONG THE ONTARIO/QUEBEC BORDER THIS  
AFTERNOON...OCCLUDED FRONT RUNS DOWN THROUGH LOWER MICHIGAN. SFC  
COLD FRONT AND BIG SURGE OF COLD AIR HAS BEEN PLOWING ACROSS THE  
LOWER LAKES/OHIO VALLEY OVER THE LAST SEVERAL HOURS (SNOWING IN  
PARTS OF SRN LOWER MICHIGAN ALREADY). THIS IS ALSO WHERE THE CORE OF  
STRONGEST WINDS RESIDES AND GUSTS IN EXCESS OF 50 KNOTS HAVE BEEN REPORTED  
ACROSS SRN LOWER MICHIGAN INTO OHIO. MEANWHILE...WELL DEFINED  
DEFORMATION AXIS AND NEXT BATCH OF WIDESPREAD PRECIP WRAPS AROUND  
THE DEPARTING LOW ALONG THE TIGHT THERMAL GRADIENT...FROM WESTERN  
UPPER MICHIGAN DOWN THROUGH WISCONSIN INTO LOWER MICHIGAN...AND IS  
LIFTING QUICKLY NORTHWARD THROUGH THE CWA. WEDGE OF WARM AIR ALOFT  
WRAPS BACK UP ACROSS NRN MICHIGAN INTO WISCONSIN AND HAS/IS  
KEEPING PRECIP ALL RAIN AT THIS POINT (KACB AWOS SITE REPORTING  
-SN IS BOGUS). BUT THAT WILL CHANGE SHORTLY.  
 
TONIGHT...FIRST OFF...P-TYPE. AS MENTIONED...RAIN VERY EARLY ON. BUT  
WEDGE OF "WARM" AIR ALOFT GETS PINCHED OFF W-E THIS EVENING WITH  
THERMAL PROFILES SUPPORTING ALL SNOW ACROSS THE CWA BY MID TO LATE  
EVENING. THIS MAY DELAY THE ONSET OF ACCUMULATING SNOW JUST A LITTLE  
BIT ESPECIALLY AS SFC TEMPS WILL TAKE A LITTLE WHILE TO DIP BACK BELOW 32F.  
BUT HEAVIER SNOWFALL LATER ON WILL PROBABLY MAKE UP FOR IT.  
 
FORECAST...STRONG DEFORMATION AXIS/FORCING SWINGS UP INTO NRN  
MICHIGAN AND BECOMES FOCUSED FROM EASTERN WISCONSIN E/NE ACROSS  
THE CWA THIS EVENING...BEFORE WEAKENING TOWARD TUESDAY MORNING.  
GUIDANCE SUGGESTS STRONGEST QG-UPWARD ASCENT AND HIGHEST QPF/SNOW  
AMOUNTS WILL RUN ACROSS THE NRN HALF OF THE CWA...COINCIDENT WITH  
LOW LEVEL TROUGH/CONVERGENCE AXIS THAT DRAGS ITS WAY UP THROUGH  
THE REGION TONIGHT. ALSO...PER FORECAST SOUNDINGS...AM ALSO  
PARTICULARLY IMPRESSED/WORRIED ABOUT THE DEEP SATURATED ISOTHERMAL  
LAYER THAT CUTS THROUGH THE DGZ BY EARLY MORNING THAT WILL ADD TO  
THE SNOW "FLUFF FACTOR."  
 
LAKE CONTRIBUTION...LAKE EFFECT/ENHANCED CONVECTION WILL INCREASE  
RATHER RAPIDLY BY MID TO LATE EVENING AS -9C TO -12C H8 AIR  
OVERSPREADS THE LAKES. COMBINED WITH THE STRONG SYNOPTIC  
ASCENT...THERE WILL BE SEVERAL HOURS OF DECENT LAKE ENHANCED SNOWS  
FOCUSED INTO THE HIGHER TERRAIN OF NW LOWER MICHIGAN AS LOW LEVEL  
MEAN WINDS GO FROM WEST TO WNW OVERNIGHT. THIS WILL ONLY ADD TO  
THE SNOW TOTALS.  
 
ALL TOLD...EXPECT HIGHEST SNOW TOTALS TO OCCUR ACROSS A GOOD CHUNK  
OF NW LOWER MICHIGAN...WHERE THE COMBINATION OF STRONG ASCENT AND  
LAKE CONTRIBUTION WILL BE MAXIMIZED. HAVE PUSHED TONIGHT SNOW  
TOTALS INTO THE 5 TO 8 INCH RANGE ACROSS THAT AREA. A GOOD 3 TO 5  
INCHES ACROSS THE NRN HALF OF THE CWA OUTSIDE THE SNOW BELTS...AND  
JUST AN INCH OR TWO OVER THE FAR E/SE COUNTIES. WINTER WEATHER  
ADVISORIES STILL LOOK GOOD EVEN WITH LOWER SNOW AMOUNTS IN THE SE  
COUNTIES GIVEN THE GUSTY WINDS AND QUICKLY FALLING TEMPS. BUT WILL  
ALSO ADD EASTERN UPPER MICHIGAN INTO THE ADVISORY MIX AS I/M  
WORRIED THAT THE HEAVIER QPF AXIS SHIFTS A LITTLER FURTHER NORTH  
THAN ADVERTISED. WARNING CRITERIA SNOWFALL (>8 INCHES/12 HOURS) IS  
NOT OUT OF THE QUESTION FOR SOME SPOTS IN THE NW LOWER SNOW BELTS.  
EVENING SHIFT WILL HAVE TO KEEP AN EYE ON HOW THINGS UNFOLD.  
 

 
   
LONG TERM
 
(TUESDAY THROUGH MONDAY)  
ISSUED AT 401 PM EST MON NOV 24 2014  
 
HIGH IMPACT WEATHER POTENTIAL: ACCUMULATING SNOW CONTINUES THROUGH  
MIDDAY TUESDAY...WITH ADDITIONAL MAINLY LIGHT SNOW CHANCES TOWARD  
WEDNESDAY NIGHT AND THURSDAY...POSSIBLY ENHANCED NEAR THE STRAITS.  
 
PATTERN SYNOPSIS/EVOLUTION: NORTHERN STREAM TROUGH DOMINATION  
RETURNS ACROSS THE GREAT LAKES/CENTRAL CONUS THROUGH MIDWEEK...  
COURTESY OF REX BLOCK REDEVELOPMENT THROUGH THE GULF OF ALASKA AND  
SUBSEQUENT RIDGE AMPLIFICATION ALONG THE WEST COAST OF NORTH  
AMERICA. EMBEDDED WITHIN THE OVERALL MEAN UPPER TROUGH WILL BE  
SEVERAL INDIVIDUAL SHORTWAVES...WITH THE FIRST LIFTING TOWARD  
SOUTHERN LAKE MICHIGAN AT THE MOMENT - OUR FUN FOR TONIGHT/TUESDAY.  
ADDITIONAL SHORTWAVE ENERGY IS EXPECTED TO DIVE FROM ALBERTA DOWN  
THROUGH THE TENNESSEE VALLEY WITH A SEPARATE PIECE OF ENERGY ROLLING  
THROUGH OUR NECK OF THE WOODS TOWARD WEDNESDAY NIGHT/THURSDAY. AS  
WOULD BE EXPECTED...EACH SYSTEM WILL PROVIDE ITS OWN SET OF FORECAST  
CHALLENGES...MAINLY OF THE "HOW MUCH SNOW" VARIETY.  
 
TUESDAY: BY FAR THE PERIOD WITH THE MOST WIDESPREAD ACTIVE WEATHER.  
SECONDARY UPPER TROUGH SLATED TO BRING A QUICK ROUND OF SNOW TO THE  
AREA TONIGHT WILL LIFT TO OUR NORTHEAST...WITH ANOTHER WEAK WIGGLE  
IN THE FLOW WORKING ACROSS THE REGION INTO EARLY AFTERNOON.  
PREVALENT DEEP LAYER MOISTURE COMBINED WITH LINGERING MID LEVEL  
DEFORMATION FORCING SHOULD YIELD A PERSISTENT THOUGH LESS INTENSE  
AXIS OF SNOW WORKING ACROSS MUCH OF THE CWA. STARK LOW LEVEL  
CYCLONIC CURVATURE THROUGH THE MORNING WORKING IN TANDEM WITH MODEST  
LAKE INSTABILITY (DELTA T'S AROUND 18C) SHOULD ADD A BOOST TO THE  
OVERALL LIGHT SNOW SHIELD FOR FAVORED NW TO W/NW FLOW AREAS. RATHER  
DEEP AXIS OF DENDRITIC GROWTH POTENTIAL LOOKS TO BE UNDERCUT BY THE  
BEST LAKE-INDUCED OMEGA...SUGGESTING RATIOS MAY NOT BE OVERLY  
HIGH...THOUGH LIKELY STILL ON THE ORDER OF 15+ TO 1 SIMPLY GIVEN THE  
DEEPER NATURE OF THE DGZ. ALL TOLD...EXPECT A GENERAL 1-1.5" OF  
ADDITIONAL SYNOPTIC SNOW ACCUMULATION THROUGH THE DAY...PRIMARILY  
DURING THE MORNING...WITH LOCALIZED HIGHER AMOUNTS PUSHING 2-4" FOR  
THE FAVORED AREAS.  
 
TUESDAY NIGHT-WEDNESDAY: DEEP MOISTURE WILL THIN QUICKLY BY TUESDAY  
EVENING...WITH WEAKENING FLOW EXPECTED AS LOW LEVEL RIDGING ATTEMPTS  
TO BRIDGE THE GREAT LAKES. THESE TYPES OF SETUPS ARE ALWAYS A  
CHALLENGE FROM A LAKE SNOW STANDPOINT AS WEAK FLOW IN A STILL  
UNSTABLE ENVIRONMENT TENDS TO PROMOTE PLENTY OF MESOSCALE  
PROCESSES... AND INDEED WE MAY WELL SEE THIS TYPE OF SETUP PLAY OUT.  
BACKED FLOW REGIME MORE W/SW SHOULD FAVOR PERSISTENT LIGHTER SNOW  
SHOWERS UP TOWARD THE TIP OF THE MITT COUNTIES...WITH AT LEAST SOME  
POTENTIAL FOR A MESOSCALE VORTEX OR TWO TO SPIN UP AS HINTED AT BY  
SEVERAL PIECES OF GUIDANCE THE PAST FEW DAYS. OVERALL...DON'T  
ANTICIPATE ANY SIGNIFICANT SNOW AMOUNTS...WITH PERHAPS EVEN SOME  
SUNSHINE FOR INLAND AREAS ON WEDNESDAY.  
 
WEDNESDAY NIGHT-THURSDAY: NEXT NORTHERN STREAM WAVE DROPS INTO THE  
NORTHERN LAKES...FURTHER HELPING ENHANCE EXISTING LAKE-INDUCED  
TROUGHING. INCREASE IN SYNOPTIC MOISTURE SHOULD WORK WITH WEAKER  
SOUTHWEST FLOW TO DELIVER AN ENHANCED SNOW BAND SOMEWHERE UP TOWARD  
THE TIP OF THE MITT COUNTIES (PLACEMENT VERY UNCERTAIN)...WITH A  
NICE FLAREUP OF SNOW SHOWERS EXPECTED ALONG A COLD FRONT DROPPING  
THROUGH THE CWA BY THURSDAY MORNING. HAVE SEEN THESE TYPES OF SETUPS  
QUITE A FEW TIMES OVER THE YEARS...AND TYPICALLY THERE IS A QUICK  
BURST OF 1-2" OF SNOW THAT ACCOMPANIES THE BOUNDARY...PARTICULARLY  
JUST DOWNWIND OF LAKES SUPERIOR AND MICHIGAN. SEE NO REASON THAT  
COULDN'T HAPPEN HERE...WITH A QUICK TRANSITION OVER TO NW OR N/NW  
FLOW LAKE SNOW SHOWERS ANTICIPATED FOR THE DAY ON THURSDAY AS A  
CHUNK OF QUITE CHILLY AIR (H8 TEMPS AROUND -18C) PLUNGES INTO  
NORTHERN MICHIGAN.  
 
EXTENDED PERIODS (THURSDAY NIGHT THROUGH SUNDAY)...  
 
WEAK SHORT WAVE CONTINUES TO PUSH EAST OF THE AREA THURSDAY NIGHT  
WITH THE MAJORITY OF ANY LINGERING LAKE EFFECT ENDING BY 12Z FRIDAY  
AS 1000-850 MB WINDS SHIFT FROM NORTH-NORTHWEST TO SOUTH-SOUTHWEST.  
SLIGHT DIFFERENCES BETWEEN TIMING OF NEXT DISTURBANCE APPROACHING  
FRIDAY AFTERNOON...BUT EITHER WAY LOOKS LIKE A DECENT SHOT OF WARM  
ADVECTION/OVERRUNNING SNOW FRIDAY AFTERNOON INTO FRIDAY NIGHT.  
 
STRONG WARM AIR ADVECTION CONTINUES SATURDAY AS SURFACE LOW PASSES  
NORTH THROUGH ONTARIO WHICH MAY LEAD TO TEMPERATURES ONCE AGAIN  
RISING ABOVE FREEZING...BUT WON'T LAST LONG AS THE LOW CONTINUES  
INTO QUEBEC AND SWINGS A COLD FRONT THROUGH NORTHERN MICHIGAN DURING  
THE LATE SATURDAY NIGHT/SUNDAY TIMEFRAME. COLD TEMPERATURES ALONG  
WITH HIGH PRESSURE IS EXPECTED TO BUILD IN TO START THE NEXT WORK  
WEEK...BRINGING WHAT LOOKS TO BE AT LEAST A SHORT STRETCH OF QUIET  
WEATHER.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)  
ISSUED AT 1234 PM EST MON NOV 24 2014  
 
IFR/MVFR CIGS AND VSBY CURRENTLY ACRS NRN MI TAF SITES WILL REMAIN  
THE GENERAL TREND DURING MUCH OF THE UPCOMING TAF PERIOD. THE MAIN  
FORECAST CONCERN TONIGHT WILL BE CENTERED AROUND THE TRANSITION  
FROM RAIN TO SNOW ACRS THE GREAT LAKES...MOSTLY EXPECTED TO TAKE  
PLACE AROUND OOZ. PERIODS OF HVY SNOW AND POOR VISIBILITIES CAN  
BE EXPECT AFTER 00Z AS AN UPPER TROUGH AND SFC SYSTEM PUSH ACRS THE  
GREAT LAKES.  
 

 
   
MARINE
 
 
ISSUED AT 401 PM EST MON NOV 24 2014  
 
GUSTY SW WINDS WILL DEVELOP ACROSS PARTS OF LAKE HURON THIS  
EVENING WITH GALE FORCE WIND GUSTS ANTICIPATED...MAINLY SOUTH OF  
PRESQUE ISLE. SMALL CRAFT ADVISORIES FOR THE REST OF THE  
NEARSHORE WATERS THROUGH TUESDAY. WINDS AND WAVES WILL DIMINISH  
SUBSTANTIALLY LATER TUESDAY INTO WEDNESDAY.  
 

 
   
APX WATCHES/WARNINGS/ADVISORIES
 
 
MI...WINTER WEATHER ADVISORY UNTIL 5 PM EST TUESDAY FOR MIZ008-  
015>036-041-042.  
 
LH...SMALL CRAFT ADVISORY UNTIL 4 PM EST TUESDAY FOR LHZ345-347.  
 
GALE WARNING UNTIL 7 AM EST TUESDAY FOR LHZ348-349.  
 
SMALL CRAFT ADVISORY UNTIL 4 PM EST TUESDAY FOR LHZ346.  
 
LM...SMALL CRAFT ADVISORY UNTIL 4 PM EST TUESDAY FOR LMZ323-341-342-  
344>346.  
 
LS...SMALL CRAFT ADVISORY UNTIL 4 PM EST TUESDAY FOR LSZ321-322.  
 

 
 

 
 
SYNOPSIS...MJG  
SHORT TERM...ADAM  
LONG TERM...LAWRENCE/MJG  
AVIATION...SWR  
MARINE...ADAM  
 
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