105  
FXUS63 KAPX 111509  
AFDAPX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GAYLORD MI  
1009 AM EST MON DEC 11 2017  
   
UPDATE
 
 
ISSUED AT 1009 AM EST MON DEC 11 2017  
 
LOW PRESSURE CONTINUES TO SWING SE OUT OF CENTRAL CANADA AND INTO  
THE UPPER MISSISSIPPI VALLEY LATE THIS MORNING. SOUTHERLY LOW  
LEVEL FLOW IS STRENGTHENING ACROSS THE WESTERN GREAT LAKES REGION  
AHEAD OF THIS SYSTEM...PUMPING MOISTURE INTO MICHIGAN AS LIFT  
INCREASES. AREA OF MAINLY LIGHT SYNOPTIC SNOW CONTINUES TO SPREAD  
EASTWARD INTO OUR CWA AS A RESULT. THIS AREA OF LIGHT SNOW WILL  
IMPACT MOST OF OUR CWA THRU THE BALANCE OF THE DAY AND INTO THIS  
EVENING AS THE SURFACE LOW CENTER CONTINUES TO DIVE SE INTO  
INDIANA BY 00Z TUESDAY. EXPECTED QPF IS RATHER LIGHT AND ONLY  
EXPECT NEW SNOW AMOUNTS OF AN INCH OR TWO WITH THIS SYSTEM. THE  
EXCEPTION WILL BE MACKINAC COUNTY WHERE S/SW LOW LEVEL FLOW LAKE  
ENHANCEMENT WILL BOOST NEW SNOW AMOUNTS TO 2 TO 4 INCHES TODAY.  
WILL CERTAINLY MAINTAIN THE ADVISORY CURRENTLY IN EFFECT FOR  
MACKINAC COUNTY THRU 23Z THIS EVENING. HIGH TEMPS WILL BE MAINLY  
IN THE 20S THIS AFTERNOON.  
 

 
   
NEAR TERM
 
(TODAY THROUGH TONIGHT)  
ISSUED AT 347 AM EST MON DEC 11 2017  
   
..ANOTHER ROUND OF SNOW/LAKE EFFECT SNOW
 
 
HIGH IMPACT WEATHER POTENTIAL...PROLONGED PERIOD OF LAKE EFFECT  
SNOW FOR SOME AREAS THROUGH TUESDAY NIGHT.  
 
PATTERN SYNOPSIS/FORECAST...HIGHLY AMPLIFIED PATTERN REMAINS  
INTACT OF COURSE WITH A SHARP BLOCKING RIDGE UP THROUGH THE  
WESTERN CONUS AND DOWNSTREAM TROUGHING ENCOMPASSING MUCH OF  
CENTRAL AND EASTERN NOAM. WE DO HAVE JUST A HINT OF LOW AMPLITUDE  
SHORT WAVE RIDGING SLIDING THROUGH THE WESTERN LAKES REGION  
CURRENTLY...AND ATTENDING SURFACE HIGH PRESSURE SLIDING THROUGH  
THE REGION. THUS...WE HAVE CAUGHT AT LEAST A LITTLE BIT OF A  
BREAK...ALTHOUGH THERE REMAINS SOME LIGHTER NW FLOW LAKE SNOW  
SHOWERS IMPACTING SOME AREAS.  
 
UPSTREAM...A RATHER WELL DEFINED SHORT WAVE AND ATTENDING SURFACE  
LOW IS DROPPING QUICKLY SOUTHEASTWARD INTO THE UPPER MIDWEST...WITH  
A SECONDARY PIECE OF ENERGY IS NOTED OVER WESTERN HUDSON BAY.  
WARM ADVECTION "SYNOPTIC" SNOWFALL AHEAD OF THE LEAD WAVE IS  
ALREADY SLIDING INTO WISCONSIN AND WILL BE REACHING US THIS  
MORNING. THIS SYSTEM WILL SLIP QUICKLY SOUTHEAST THROUGH THE  
WESTERN GREAT LAKES REGION INTO THE OHIO VALLEY THROUGH THIS  
EVENING BEFORE PIVOTING AND SUBSTANTIALLY DEEPENING HEADING INTO  
THE NEW ENGLAND REGION ON TUESDAY. THIS WILL BRING ALL AREAS SOME  
LIGHT ACCUMULATING SNOW TODAY. BUT...LAKE EFFECT SNOW IS ANOTHER  
MATTER.  
 
PRIMARY FORECAST CONCERNS...SW FLOW LAKE ENHANCED SNOWFALL ON THE  
FRONT END OF THIS SYSTEM...PROLONGED NNW FLOW LAKE EFFECT SNOW AND  
GUSTY WINDS ON THE BACK.  
 
AS MENTIONED...SHORT WAVE TROUGH AND ATTENDING SURFACE LOW WILL  
DROP QUICKLY SOUTHEASTWARD THROUGH THE WESTERN GREAT LAKES THROUGH  
THE COURSE OF THE DAY. UPSTREAM SWATH OF WARM ADVECTION FORCED  
SNOWFALL WILL OVERSPREAD THE REGION THROUGH THE MORNING BEFORE  
PEELING OFF TO THE EAST THROUGH THE AFTERNOON. SHOULDN'T BE A BIG  
DEAL OVERALL WITH MUCH OF THE CWA PICKING UP AND INCH OR TWO OF  
SNOW. HOWEVER...S/SW FLOW AHEAD OF WAVE COUPLED WITH INCREASING  
FORCING/SYNOPTIC MOISTURE WILL BRING SEVERAL HOURS OF ENHANCED  
LAKE EFFECT BANDING INTO THE WESTERN PORTIONS OF MACKINAC COUNTY  
AND POTENTIAL FOR 3, 4, 5 INCHES OF SNOW. WITH THAT IN MIND...PLAN  
ON HOISTING A WINTER WEATHER ADVISORY FOR MACKINAC COUNTY FOR  
TODAY...FOCUSING ON THE WESTERN/CENTRAL PART OF THE COUNTY.  
 
GETS MUCH MORE INTERESTING TONIGHT (AND BEYOND). CLIPPER WILL BE  
PIVOTED THROUGH THE OHIO VALLEY THIS EVENING BEFORE HEADING  
NORTHEASTWARD TOWARD NEW ENGLAND...WHILE SECONDARY NORTHERNMOST  
SHORT WAVE DIVES DOWN THROUGH THE WESTERN GREAT LAKES AND BRINGS  
ALONG A BIG PLUNGE OF ARCTIC AIR. FAIRLY SHARP LOW LEVEL TROUGH  
AXIS/COLD FRONT WILL BE PASSING THROUGH THE CWA THIS EVENING  
AHEAD OF THE ARCTIC PLUNGE...LIKELY ACCOMPANIED BY A PERIOD OF  
ENHANCED SNOWFALL. BEHIND THE TROUGH...WINDS STILL LOOKING TO  
TURN SHARPLY NNW AND SET THE STAGE FOR A PROLONGED PERIOD OF  
HEALTHY LAKE EFFECT SNOWS LATER TONIGHT THROUGH TUESDAY NIGHT.  
EXTREME INSTABILITY (BUFKIT FORECAST SOUNDS AT MBL/TVC GIVE OVER  
1000 J/KG LAKE INDUCED CAPE) PERSISTENT NNW FLOW ALL SUGGEST SOME  
RATHER HEALTHY SNOW TOTALS ALONG THE LAKE MICHIGAN COASTLINE FROM  
LEELANAU COUNTY SOUTHWARD...ASSUMING THE FLOW DOES LOCK IN AS  
FORECAST. COUPLED WITH GUSTY WINDS/BLOWING SNOW POTENTIAL...PLAN  
ON ISSUING A WINTER STORM WARNING FOR LEELANAU THROUGH MANISTEE  
COUNTIES AS WELL AS GRAND TRAVERSE COUNTY...BORDERED BY AN  
ADVISORY.  
 

 
   
SHORT TERM
 
(TUESDAY THROUGH WEDNESDAY)  
ISSUED AT 347 AM EST MON DEC 11 2017  
   
..FRIGID ARCTIC AIR AND SIGNIFICANT LAKE EFFECT SNOW
 
 
HIGH IMPACT WEATHER POTENTIAL...SIGNIFICANT LAKE EFFECT SNOW ON  
TUESDAY AROUND AND SOUTH OF GRAND TRAVERSE BAY. BLUSTERY WINDS  
WILL RESULT IN BLOWING SNOW AND VERY FRIGID WIND CHILLS AT TIMES.  
 
PATTERN SYNOPSIS/FORECAST...DEEP TROUGHING OVERHEAD (2 TO 3  
STANDARD DEVIATIONS BELOW THE MEAN) WILL BE REINFORCED BY ANOTHER  
LOBE OF ENERGY DROPPING SOUTH FROM WESTERN ONTARIO TUESDAY MORNING.  
ARCTIC AIR WILL SURGE SOUTHWARD WITH THIS TROUGH ON THE BACKSIDE OF  
AN INTENSE DEPARTING SURFACE LOW, WITH 850MB TEMPERATURES DROPPING  
TO AROUND -20C OVER NORTHERN MICHIGAN. SURFACE RIDGE WILL DRIFT  
ACROSS THE REGION TUESDAY NIGHT INTO WEDNESDAY, BUT LAKE AGGREGATE  
TROUGHING WILL HOLD FAST. ANOTHER INCOMING SHORTWAVE WILL  
BECOME SHEARED OUT AS IT PASSES THROUGH THE REGION ON WEDNESDAY.  
 
PRIMARY FORECAST CONCERNS...COLD TEMPERATURES, SIGNIFICANT LAKE  
EFFECT SNOW, AND WEDNESDAY'S CLIPPER SYSTEM.  
 
THE COLDEST SURGE OF ARCTIC AIR THUS FAR THIS SEASON WILL ARRIVE ON  
TUESDAY, THOUGH THE AIRMASS WILL MODERATE SLIGHTLY AS IT PLUNGES  
SOUTH INTO THE UPPER GREAT LAKES. NOT LOOKING AT ANY STRONG  
TEMPERATURE ANOMALIES (ONLY AROUND 1 TO 2 STANDARD DEVIATIONS BELOW  
THE MEAN AT 925 AND 850MB), BUT THIS AIRMASS WILL BE SIGNIFICANT  
JUST BECAUSE OF IT BEING THE COLDEST THUS FAR. HIGHS WILL BE IN THE  
TEENS BOTH TUESDAY AND WEDNESDAY FOR MOST. LOWS TUESDAY NIGHT (THE  
COLDEST PERIOD) WILL BE IN THE SINGLE DIGITS ON EITHER SIDE OF ZERO  
EVERYWHERE EXCEPT WEST OF M-37. FACTOR IN THE BLUSTERY WINDS TUESDAY  
MORNING AND SOMEWHAT BRISK WINDS WEDNESDAY MORNING, AND WIND CHILLS  
WILL PLUNGE WELL BELOW ZERO ACROSS MUCH OF NORTHERN MI BOTH MORNINGS.  
IF SKIES MANAGE TO CLEAR OUT MORE THAN CURRENTLY EXPECTED TUESDAY  
NIGHT, TEMPERATURES COULD DROP EVEN LOWER THAN THE CURRENT FORECAST  
EAST OF I-75, BUT DON'T EXPECT THE BOUNDARY LAYER WILL COMPLETELY  
DECOUPLE TO ALLOW FOR AN IDEAL RADIATIONAL COOLING SETUP.  
 
AS FOR SNOW, FORECAST SOUNDINGS SHOW A VERY IDEAL LAKE EFFECT SETUP  
FOR AREAS SOUTH OF GRAND TRAVERSE BAY ON TUESDAY. STEEP LOW LEVEL  
LAPSE RATES AND STRONG LAKE-INDUCED INSTABILITY. INVERSION HEIGHTS  
AT MBL APPROACH 8 KFT, AND STRONG UNIDIRECTIONAL NNW WINDS FROM THE  
SURFACE THROUGH THE UPPER LEVELS WILL PROVIDE STRONG LOW LEVEL  
CONVERGENCE ALONG THE COAST. VERY IMPRESSIVE LOW LEVEL OMEGA  
COINCIDENT WITH THE DENDRITIC GROWTH ZONE AND PRETTY HIGH RH FROM  
THE SURFACE UP THROUGH ~750MB. THUS, EXPECTING SOME VERY IMPRESSIVE  
SNOW BANDS TO DEVELOP BY DAYBREAK TUESDAY, AND THE HI-RES ARW/NMM  
SHOW JUST THAT WITH BANDING FOCUSED FROM LEELANAU COUNTY SOUTH TO  
MANISTEE THROUGHOUT THE DAY. RELIED HEAVILY ON ARW/NMM QPF. THIS  
WOULD YIELD DAYTIME SNOW ACCUMULATIONS OF AROUND 4-8 INCHES ACROSS  
OUR SOUTHWESTERN COUNTIES, LIKELY HIGHEST OVER BENZIE AND MANISTEE  
COUNTIES. AND, OF COURSE, THIS SNOWFALL WOULD BE ON TOP OF WHAT  
FALLS IN THAT AREA TONIGHT. HENCE THE HEADLINE DECISIONS  
MENTIONED ABOVE. DO EXPECT SOME NW FLOW LAKE EFFECT OFF LAKES HURON  
AND SUPERIOR AS WELL, BUT NOT OF THE SAME MAGNITUDE. UPSTREAM  
SURFACE RIDGE SLIDING IN TUESDAY NIGHT WILL CAUSE LAKE EFFECT TO  
DIMINISH IN COVERAGE AND INTENSITY WITH ONLY LIGHT ADDITIONAL  
ACCUMULATION EXPECTED THROUGH WEDNESDAY MORNING. NEXT CLIPPER SYSTEM  
WILL DIVE IN FROM THE NW LATE MORNING INTO THE AFTERNOON, BUT MODELS  
STILL DON'T HAVE ITS PRECISE TRACK PINNED DOWN. ONLY LOOKING LIKE  
LIGHT SNOW ACCUMULATION POTENTIAL FROM THIS SYSTEM, HOWEVER.  
   
LONG TERM
 
(WEDNESDAY NIGHT THROUGH SUNDAY)  
ISSUED AT 347 AM EST MON DEC 11 2017  
 
HIGH IMPACT WEATHER POTENTIAL...ONGOING LAKE EFFECT SNOW WITH  
ADDITIONAL ENHANCEMENT FROM A CLIPPER SYSTEM OR TWO.  
 
A SLOW MODERATION IN TEMPERATURES EXPECTED THE REMAINDER OF THE  
WEEK...EVEN SIGNALS OF TEMPERATURES CLIMBING /ABOVE/ FREEZING THIS  
WEEKEND! BUT STILL AN ACTIVE WINTRY PATTERN TO DEAL WITH IN THE  
MEANTIME WITH LAKE EFFECT SNOW AND AN OCCASIONAL CLIPPER SYSTEM.  
 
DEEP LONGWAVE TROUGHING OVER THE EASTERN CONUS IS PROGGED TO  
GRADUALLY LIFT NE HEADING INTO THURSDAY WITH UPPER FLOW TURNING  
ZONAL FOR A BRIEF TIME AS THE STRONG RIDGE OUT WEST BEGINS TO  
FLATTEN. ADDITIONAL ENERGY DROPS SOUTH FROM CANADA ON FRIDAY,  
YIELDING A SHARP BUT QUICK MOVING TROUGH OVER THE REGION. FLOW  
THEN TURNS LARGELY ZONAL AGAIN TOWARDS NEXT WEEKEND.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)  
ISSUED AT 643 AM EST MON DEC 11 2017  
   
..OVERALL MVFR CONDITIONS CONTINUE
 
 
LOW PRESSURE SYSTEM WILL MOVE THROUGH THE REGION TODAY AND BRING A  
PERIOD OF MAINLY LIGHT SNOWFALL TO THE REGION...AND CONTINUED MVFR  
CONDITIONS AT THE TERMINAL SITES. SYSTEM EXITS EAST THIS EVENING  
WITH WINDS TURNING SHARPLY NW...PULLING ARCTIC AIR INTO THE REGION  
AND SETTING THE STAGE FOR HEAVY LAKE EFFECT SNOWS IMPACTING  
PORTIONS OF NW LOWER MI. TVC/MBL WILL SEE THE BIGGEST  
IMPACT...WITH MVFR AND PERIODIC IFR CONDITIONS TONIGHT INTO  
TUESDAY.  
 
IN ADDITION TO THE SNOW...GUSTY NW WINDS DEVELOP TONIGHT AND  
PERSIST THROUGH TUESDAY.  
 

 
   
MARINE
 
 
ISSUED AT 643 AM EST MON DEC 11 2017  
 
CLIPPER SYSTEM WILL PASS THROUGH THE REGION TODAY AND EXIT EAST OF  
THE STATE TONIGHT. BEHIND THIS SYSTEM...WINDS TURN SHARPLY NW AND  
GUSTY...WITH GALE FORCE GUSTS ANTICIPATED FOR MUCH OF THE WESTERN  
GREAT LAKES REGION TONIGHT THROUGH TUESDAY.  
 

 
   
APX WATCHES/WARNINGS/ADVISORIES
 
 
MI...WINTER STORM WARNING FROM 10 PM THIS EVENING TO MIDNIGHT EST  
TUESDAY NIGHT FOR MIZ020-025-026-031.  
WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO MIDNIGHT EST  
TUESDAY NIGHT FOR MIZ021-027-032-033.  
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR MIZ015.  
LH...GALE WARNING FROM MIDNIGHT TONIGHT TO 6 PM EST TUESDAY FOR  
LHZ347>349.  
SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EST  
WEDNESDAY FOR LHZ345-346.  
LM...GALE WARNING FROM MIDNIGHT TONIGHT TO 6 PM EST TUESDAY FOR  
LMZ323-342-344>346.  
SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EST  
WEDNESDAY FOR LMZ341.  
LS...GALE WARNING FROM MIDNIGHT TONIGHT TO 6 PM EST TUESDAY FOR  
LSZ321-322.  

 
 

 
 
UPDATE...MR  
NEAR TERM...BA  
SHORT TERM...MK  
LONG TERM...MK  
AVIATION...BA  
MARINE...BA  
 
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