482  
FXUS63 KAPX 101748  
AFDAPX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GAYLORD MI  
1248 PM EST SUN DEC 10 2023  
   
UPDATE  
 
ISSUED AT 1230 PM EST SUN DEC 10 2023  
 
NORTHWEST FLOW LAKE EFFECT SNOW HAS GOTTEN GOING IN THE WAKE OF  
THE COLD FRONT THAT CAME THROUGH THE AREA EARLIER TODAY. THE  
MOST PERSISTENT BANDS IMPACTING THE FORECAST AREA ARE PRIMARILY  
IMPACTING ANTRIM AND KALKASKA COUNTIES (WITH A LAKE SUPERIOR  
CONNECTION EVIDENT, AND ANOTHER IN EXTREME EASTERN LAKE SUPERIOR  
CUTTING ACROSS CENTRAL CHIPPEWA COUNTY SOUTH OF THE SAULT. THE  
SETUP IS STILL NOT IDEAL WITH INVERSION HEIGHTS NOT MUCH HIGHER  
THAN 4K FEET AND INVERSION TOP TEMPERATURES NOT MUCH COOLER THAN  
-10C TO -11C. STILL, LAKE-INVERSION TO DELTA TS ARE ABOUT 15C OR  
A LITTLE GREATER. ALSO, A LITTLE SYNOPTIC FORCING  
BOOST/MOISTURE ENHANCEMENT IS EXPECT OVER THE NEXT SEVERAL  
HOURS AS AN IMPULSE WITHIN THE MEAN UPPER-LEVEL TROF OVERHEAD  
SLIDES ACROSS THE AREA. THE ONGOING FORECAST STILL LOOKS  
REASONABLE AND HAVE ONLY MADE MINOR TWEAKS TO THE NEAR TERM AT  
THIS TIME.  
 
 
   
NEAR TERM /UNTIL 6 AM MONDAY MORNING/  
 
HIGH IMPACT WEATHER POTENTIAL: ACCUMULATING LAKE EFFECT SNOW TODAY-  
TONIGHT.  
 
PATTERN SYNOPSIS:  
 
A SHORTWAVE TROUGH/VORTICITY MAX EVIDENT ON SATELLITE IMAGERY WILL  
CONTINUE TO PIVOT OVER THE GREAT LAKES THIS MORNING AS A SECONDARY  
COLD FRONT SWINGS ACROSS NORTHERN MICHIGAN. A SECOND WAVE LOOKS TO  
PROGRESS OVER THE GREAT LAKES LATER THIS AFTERNOON AND EVENING AS  
MUCH BROADER LONGWAVE TROUGHING ENCOMPASSES MOST OF THE CONUS EAST  
OF THE ROCKY MOUNTAINS.  
 
FORECAST DETAILS:  
 
THE PRIMARY CONCERN TODAY AND TONIGHT WILL BE ACCUMULATING LAKE  
EFFECT SNOW ACROSS PORTIONS OF NORTHWEST LOWER AND EASTERN UPPER  
MICHIGAN. WHILE LIGHT RAIN/SNOW SHOWERS ARE ONGOING ACROSS PARTS OF  
THE CWA, BETTER SHOWER CHANCES WILL ARRIVE LATER THIS MORNING AFTER  
THE PREVIOUSLY MENTIONED FRONT WORKS ACROSS THE AREA. NORTHWEST LOW-  
LEVEL FLOW BEHIND THE FRONT WILL BRING LAKE EFFECT CHANCES TO THE  
TYPICAL SNOWBELT AREAS OF NORTHWEST LOWER AND EASTERN UPPER.  
FORECAST SOUNDINGS DISPLAY SATURATED PROFILES THROUGH THE LOWEST 2KM  
WITH DELTA-TS AROUND 15C TODAY. SOMEWHAT MEAGER LAPSE RATES LOOK TO  
STEEPEN INTO THIS EVENING/TONIGHT WITH CONTINUED COOLING OF THE  
PROFILE ABOVE THE SURFACE. A MORE CELLULAR MODE OF LAKE EFFECT  
PRECIP IS ANTICIPATED DURING DAYLIGHT HOURS AS THE AFOREMENTIONED  
WAVE WORKS OVER THE GREAT LAKES WITH MORE DOMINANT BANDING EXPECTED  
TO SET UP HEADING INTO TONIGHT. THIS SHOULD LEAD TO MORE LOCALIZED  
HIGHER SNOWFALL AMOUNTS ACROSS PARTS OF THE AREA OVERNIGHT INTO  
MONDAY MORNING -- WITH THE MOST LIKELY AREA BEING ANTRIM AND  
KALKASKA COUNTIES. MANY PARTS OF NORTHWEST LOWER AND EASTERN UPPER  
ARE EXPECTED TO SEE TOTALS AROUND 1" OR LESS BY MONDAY MORNING WITH  
HIGHER TOTALS AROUND 2-3" ACROSS AREAS WHERE MORE CONCENTRATED BANDS  
SET UP. LOCALIZED TOTALS IN ANTRIM AND KALKASKA COUNTIES OF 4-8"  
WILL BE POSSIBLE BY THE END OF THE PERIOD. OTHERWISE, MUCH COOLER  
TEMPERATURES ARE IN STORE FOR TODAY. CURRENT TEMPERATURES IN THE MID  
TO UPPER 30S WILL GRADUALLY DROP DURING THE DAY BEHIND THE  
AFOREMENTIONED COLD FRONT. OVERNIGHT LOWS IN THE 20S ARE IN STORE  
FOR THE AREA.  
 
 
   
SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/  
 
HIGH IMPACT WEATHER POTENTIAL: MODERATE...WATCHING POTENTIAL FOR  
ACCUMULATING LAKE EFFECT SNOW AND GUSTY WINDS MONDAY NIGHT-TUESDAY  
 
PATTERN SYNOPSIS/FORECAST:  
 
LONGWAVE TROUGH AXIS TIGHTENING UP OVER THE CENTER OF THE  
COUNTRY...AS RIDGING SLIPS INTO THE WESTERN US, ALONG WITH 1038MB  
SURFACE HIGH CENTERED OVER THE ROCKIES. STRONG 120+KT UPPER LEVEL  
JET SNAKES FROM THE PAC NW DOWN INTO THE BASE OF THE TROUGH IN THE  
SOUTHERN PLAINS, AND THEN UP INTO THE GREAT LAKES...DRIVING A COUPLE  
OF TIGHT VORT MAXES IN THE NORTHEAST PORTION OF THE TROUGH. INITIAL  
VORT MAX THAT INTENSIFIED A SURFACE LOW OVER N. MI AND DRAGGED THOSE  
STRONG WINDS THROUGH THE REGION SATURDAY AFTERNOON LOCATED OVER S.  
ONTARIO AS OF 3Z; SECONDARY VORT MAX SPINNING INTO THE REGION IN ITS  
WAKE ALONG WHAT LOOKS LIKE A TROWAL AXIS, ACCOMPANIED BY SOME LIGHT  
PRECIP. COLD FRONT STRETCHES FROM THE INITIAL SURFACE LOW OVER  
ONTARIO DOWN INTO SOUTHERN TX, WITH SOME SEVERE CONVECTION AHEAD OF  
IT AMID BETTER MOISTURE AND WARMER TEMPS. SECONDARY COLD FRONT IS  
BEHIND THIS, STRETCHING FROM HUDSON BAY DOWN INTO THE DAKOTAS.  
 
SECONDARY TROUGH EXPECTED TO SLIP THROUGH TODAY, AIDED BY SOME  
ADDITIONAL ENERGY IN THE BACK OF THE TROUGH OVER WI. THE OVERALL  
TROUGH AXIS SHOULD BE DEPARTING THE REGION BY MONDAY...LIFTING  
NORTHEASTWARD AND DEVELOPING A POTENT EAST COAST STORM OVER NEW  
ENGLAND. MEANWHILE...WE SHOULD SEE SOME IMPROVEMENTS HERE IN  
NORTHERN MICHIGAN...AS SHORTWAVE RIDGING BRIEFLY TOUCHES THE REGION  
AHEAD OF ANOTHER POTENT NORTHERN STREAM SHORTWAVE TROUGH DIVING OUT  
OF CENTRAL CANADA. THIS FEATURE WILL STRENGTHEN THE PRESSURE  
GRADIENT OVER US MONDAY NIGHT INTO TUESDAY AS IT SLAMS A LARGELY  
ZONAL COLD FRONT INTO THE REGION...LEADING TO ANOTHER ROUND OF  
STRONG WINDS...AS WELL AS POTENTIAL FOR ADDITIONAL LAKE EFFECT,  
ESPECIALLY ACROSS THE EUP. CURRENTLY EXPECTING THIS BOUNDARY TO HANG  
UP OVER THE REGION FOR A TIME...AS RIDGING BEGINS TO BUILD TO OUR  
WEST AGAIN IN RESPONSE TO TROUGHING OVER THE WESTERN US AND CANADA.  
 
PRIMARY FORECAST CONCERNS: WINDS MONDAY NIGHT/TUESDAY...  
ACCUMULATING LAKE EFFECT SNOW FOR THE EUP TUESDAY...  
 
TO BE HONEST, SETUP FOR MONDAY NIGHT AND TUESDAY, AT LEAST AS FAR AS  
WINDS ARE CONCERNED, IS NOT ALL THAT DISSIMILAR TO TODAY...WITH A  
STRONG PV MAXIMA PUNCHING INTO THE REGION WITH A DRY SLOT BENEATH A  
DECENT JET ALOFT (APPEARING SOMEWHAT WEAKER THAN TODAY'S GIVEN  
PROXIMITY TO THE BASE OF ITS ATTENDANT TROUGH AND GREATER  
AGEOSTROPHIC FLOW). TIGHTENING PRESSURE GRADIENT LEADING TO  
STRENGTHENING SWLY BACKGROUND SURFACE FLOW THROUGH THE NIGHT...WITH  
SUSTAINED WINDS OF 15-25KTS A REASONABLE IDEA, PARTICULARLY WHERE  
MESOSCALE INFLUENCES SUCH AS CHANNELING COULD ENHANCE WINDS (SUCH AS  
BETWEEN NW LOWER AND BEAVER ISLAND, AND/OR PERHAPS THE STRAITS, FOR  
A WSW/SW WIND). FOR NOW...THINK THE 6Z-15Z TIMEFRAME WILL BE THE  
WINDIEST PORTION OF THE PERIOD...WITH THE DRY SLOT/COLD FRONT MOVING  
IN ALONG WITH THE STRONGEST FLOW ALOFT. 30-40KT GUSTS ARE FAIRLY  
ACHIEVABLE, NOTING EVEN 925MB FLOW SHOULD RUN AROUND THAT MAGNITUDE.  
CAN'T HELP BUT NOTICE THAT 40+KT POTENTIAL IS NOT OUT OF THE  
QUESTION, EITHER...WITH SOME SIGNALS OF THIS SHOWING UP AT 850MB,  
AND EVEN STRONGER WINDS AT 700MB (GREATER THAN 50KTS). TAPPING INTO  
THAT 700MB JET ATTM DOESN'T SEEM AS VIABLE AN IDEA...BUT WILL HAVE  
TO KEEP AN EYE OUT IN CASE SIGNALS STRENGTHEN WINDS BELOW THAT IN  
THE COMING RUNS. GUSTINESS INTO THE 30-40KT RANGE HAS POTENTIAL TO  
LAST LONGER INTO THE AFTERNOON ACROSS THE EUP TUESDAY...WHERE HIGHER  
INVERSION HEIGHTS (PERHAPS AROUND 6KFT OR SO) WILL ALREADY BE  
SUPPORTIVE OF DEEPER LAKE-INDUCED CONVECTION...FURTHER COMPLICATING  
POTENTIAL IMPACTS ACROSS THE EUP.  
 
DO HAVE TO WONDER IF THERE WILL BE A DECENT BURST OF SNOW ALONG THE  
FRONT TUESDAY MORNING...NOTING SIGNALS FOR FGEN TO ENHANCE LIFT  
ALONG THE FRONT...THOUGH MOISTURE MAY NOT BE QUITE DEEP ENOUGH, SAVE  
FOR PERHAPS ACROSS THE EUP, WHERE MOISTURE DOES APPEAR A LITTLE  
DEEPER. SIGNALS FOR SW FLOW LAKE ENHANCEMENT WITH THE FRONT ARE  
WEAK, PARTICULARLY IF WE END UP A LITTLE DRIER IN THE BOUNDARY  
LAYER. THE EUP WILL ALSO BE THE PRIMARY FOCUS FOR LES AS FLOW  
BECOMES MORE W/WNW BEHIND THE FRONT IN THE COLDER AIR, AND CLOSER TO  
THE VORT MAXIMA WITH THIS LITTLE SYSTEM. WILL HAVE TO SEE WHERE THE  
BOUNDARY ENDS UP STALLING OUT TUESDAY...AS THIS COULD HAVE SOME  
IMPACT ON WIND DIRECTION AND SUBSEQUENT POSITION OF LES BANDS. WNW  
FLOW DOES HAVE BETTER FETCH FOR WHITEFISH POINT. THEREFORE, WOULD  
NOT BE SURPRISED IF LOCALIZED AREAS GOT INTO ADVISORY-LEVEL SNOWFALL  
TOTALS, AS THE FLOW IS A LITTLE BETTER FOR A SINGLE-BAND TYPE SETUP  
FOR THEM. JUST HOW MUCH OF A NW CANT THE FLOW ENDS UP HAVING WILL  
INFLUENCE HOW FAR SOUTH ACROSS THE EUP THE BANDING WILL GET...AND  
WILL BE WATCHING THIS GOING FORWARD...PARTICULARLY IF THE BAND ENDS  
UP NOT MOVING AS MUCH AND THE LES FIREHOSE STAYS IN THE SAME SPOT.  
COMBINED WITH THE POTENTIAL FOR GUSTY WINDS...THINK WE WILL HAVE TO  
KEEP AN EYE ON AT LEAST CHIPPEWA COUNTY TUESDAY.  
 
 
   
LONG TERM /WEDNESDAY THROUGH SUNDAY/  
 
HIGH IMPACT WEATHER POTENTIAL: LOW FOR NOW...WATCHING BREEZY  
CONDITIONS WEDNESDAY INTO THURSDAY...  
 
PATTERN SYNOPSIS/FORECAST:  
 
TROUGHING GETS CUT OFF OVER THE WESTERN US FOR MIDWEEK, AND BECOMES  
A MAJOR FACTOR IN THE REMAINDER OF THE EXTENDED. FOR ONE, IT SHOULD  
BEGIN TO BUILD RIDGING AND ATTENDANT SURFACE HIGH OVER THE OH  
VALLEY, AS WARM ADVECTION SPREADS ACROSS CENTRAL CANADA. SOME  
POTENTIAL FOR THE UPPER GREAT LAKES TO REMAIN UNDER THE INFLUENCE OF  
HIGH PRESSURE AND MILDER WEATHER...THOUGH AS WE SHOULD BE ON THE  
NORTHERN EDGE OF THIS...HAVE SOME CONCERNS WE MAY REMAIN A LITTLE  
BREEZY INTO THE LATTER HALF OF THE WEEK, AS ANOTHER NORTHERN STREAM  
SYSTEM BEGINS TO TREK ACROSS CENTRAL CANADA. WILL HAVE TO SEE HOW  
FAR SOUTH THIS SYSTEM'S INFLUENCE ENDS UP, AS IT COULD LINGER A BCZ  
OVER THE REGION, AND PLAY A ROLE IN INTERACTION WITH THAT UPSTREAM  
CUT OFF LOW AS IT EJECTS INTO THE PLAINS. BOTTOM LINE...CURRENTLY  
LOOKING AT A BREEZY BUT PERHAPS MILDER MID/LATE WEEK...WITH  
INCREASING POTENTIAL (DESPITE LINGERING UNCERTAINTY) FOR MORE  
UNSETTLED WEATHER LATE IN THE WEEK INTO NEXT WEEKEND.  
 
 
   
AVIATION /18Z TAFS THROUGH 18Z MONDAY/  
 
LOW CLOUDS, ENHANCED BY OVER-LAKE INSTABILITY, WILL PROVIDE  
MAINLY MVFR CIGS ACROSS THE AREA THROUGH THE 18Z TAF VALID TIME.  
MOST OF THE LAKE EFFECT SNOW IN THIS SETUP IS EXPECTED TO MISS  
THE TERMINALS, WITH KCIU BEING THE MOST NOTABLE EXCEPTION. GUSTY  
NORTHWEST WINDS WILL GRADUALLY TAPER OFF TONIGHT, WITH A SHIFT  
TO WESTERLY LATE IN THE PERIOD.  
 
 
   
MARINE  
 
SMALL CRAFT WINDS AND WAVES WILL CONTINUE ACROSS NORTHERN GREAT  
LAKES NEARSHORE WATERS TODAY BEFORE DIMINISHING THIS EVENING.  
ADVISORY CONDITIONS ARE EXPECTED TO LINGER ACROSS SOME LAKE HURON  
NEARSHORE ZONES INTO TONIGHT. LOOKING AHEAD, SMALL CRAFT WINDS AND  
WAVES ARE EXPECTED AGAIN MONDAY NIGHT INTO TUESDAY -- ALONG WITH THE  
POTENTIAL FOR GALES OVER SOME NEARSHORE WATERS DURING THAT  
TIME FRAME.  
 
 
   
APX WATCHES/WARNINGS/ADVISORIES  
 
MI...WINTER WEATHER ADVISORY UNTIL 6 AM EST MONDAY FOR MIZ021-027.  
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LHZ345-  
346.  
SMALL CRAFT ADVISORY UNTIL 1 AM EST MONDAY FOR LHZ347>349.  
SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LMZ323-  
341-342-344>346.  
SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LSZ321-  
322.  
 
 
 
 
 
UPDATE...PBB  
NEAR TERM...  
SHORT TERM...  
LONG TERM...  
AVIATION...PBB  
MARINE...  
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