517  
FXUS63 KAPX 230755  
AFDAPX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GAYLORD MI  
355 AM EDT THU OCT 23 2014  
   
SYNOPSIS
 
 
ISSUED AT 347 AM EDT THU OCT 23 2014  
 
HIGH PRESSURE WILL START TO EXIT EAST TODAY. THIS WILL ALLOW A  
WEAK DISTURBANCE WITH A PERIOD OF LIGHT RAIN AND DRIZZLE TO CROSS  
THE REGION TONIGHT INTO TOMORROW MORNING. A COLD FRONT WILL THEN  
CROSS NORTHERN MICHIGAN SATURDAY...BRINGING SOME GUSTY WINDS AND  
COOLER TEMPERATURES.  
 
THE NEXT LOW PRESSURE SYSTEM WILL ARRIVE IN THE EARLY TO MIDDLE  
PARTS OF NEXT WORK WEEK...RESULTING IN ADDITIONAL CHANCES FOR  
RAIN.  
 

 
   
SHORT TERM
 
(TODAY THROUGH TONIGHT)  
ISSUED AT 347 AM EDT THU OCT 23 2014  
   
..A CHILLY START FOR SURE
 
 
IMPACTS: REDUCED VISIBILITY EARLY THIS MORNING. LOCALIZED DENSE FOG.  
 
CURRENT WEATHER AND SYNOPTIC PATTERN:  
 
UPPER LEVEL RIDGE CURRENTLY OVERHEAD IS SHALLOWING OUT AS AN  
UPSTREAM FAIRLY SHARP TROUGH IS MAKING WAY TOWARD THE FAR WESTERN  
GREAT LAKES. AN ASSOCIATED COLD/OCCLUDED FRONT WAS SEEN ACROSS  
MN/IA/KS/NE WITH A CORRIDOR OF MOISTURE AND WEAK-MODEST -DIVQ WHICH  
WAS PRODUCING SOME LIGHT RAIN AND SPRINKLES. NOT MUCH LIQUID IN  
THESE SHOWERS...AS THE DEEPER MOISTURE IS WORKING INTO WHAT WAS A  
VERY DRY AIR MASS. LATEST SATELLITE AND SHORT TERM DATA SUGGEST/SHOW  
POTENTIALLY TWO SEPARATE VORTICITY MAXIMA WITHIN THIS TROUGH...EACH  
SHOWING A CONGEALED AREA OF SHOWERS. THESE TWO WAVES ARE LIKELY  
WORKING IN OPPOSITE DIRECTIONS...ONE EAST AND ANOTHER TO THE  
NORTH...PER SFC DEWPOINT ANALYSIS SHOWING THE MOISTURE SHEARING OUT  
WITH TIME.  
 
OVER NRN MICHIGAN...THE DEEPEST OF DRY AIR IS OVERHEAD...ALONG WITH  
THE UPPER AND SFC RIDGES. STRONG RADIATIONAL COOLING HAS LED TO SOME  
SHALLOW FOG AND STRATUS DEVELOPMENT. THIS WAS MAINLY ONGOING ACROSS  
NE LOWER...WHERE YESTERDAYS VISIBLE SATELLITE SHOWED A LINGERING  
STRATUS DECK...SURPRISINGLY WELL INTO THE DAY YESTERDAY. THIS KEPT  
SFC/LOW LEVEL MOISTURE FROM MIXING OUT...AND HENCE THE STRATUS/FOG.  
SOME VISIBILITIES WERE DOWN TO A QUARTER OF A MILE IN SPOTS. TEMPS  
WERE AS COLD AS THE LOWER 20S IN THE LOWEST LYING AREAS.  
 
SYNOPTIC PATTERN/WEATHER EVOLUTION:  
 
NOTHING TO CRAZY IN OUR WEATHER OVER THE NEXT 24 HRS...BUT WE WILL  
HAVE THE AFOREMENTIONED UPPER TROUGH HEADING INTO THE REGION. THE  
TWO SUGGESTED SEPARATE VORTICITY MAXIMA WILL CONTINUE TO TAKE ON  
DIFFERENT TRACKS. ONE...LIFTING ENE INTO ONTARIO...AND THE OTHER  
INTO SRN LAKE MICHIGAN. THIS WILL CONTINUE TO SHEAR OUT THE MOISTURE  
AND FORCING...WHILE PUSHING INTO OUR VERY DRY AIR MASS. THEREFORE  
NOT EXPECTING ANY SORT OF COVERAGE AS WE SEE CURRENTLY UPSTREAM.  
FORCING AND FCST BFR SOUNDINGS HOWEVER DO SUGGEST THAT SOME LIGHT  
RAIN OR SPRINKLES COULD MOVE IN TOWARD EVENING IN NW LOWER AND  
EASTERN UPPER...AND THEN POSSIBLY INTO THE I75 CORRIDOR THROUGH  
MIDNIGHT OR SO. BEHIND THAT...AND VERIFIED BY UPSTREAM SFC OBS...A  
PERIOD OF DEEP LOW LEVEL MOISTURE WILL ARRIVE. THIS WILL LEAVE SKIES  
CLOUDY IN THE LOW LEVELS...WITH A PERIOD OF DRIZZLE LIKELY...WHICH  
WILL LAST FOR A BIT INTO FRIDAY MORNING.  
 
SKIES WILL INCREASE IN CLOUDINESS THIS AFTERNOON...AND ESPECIALLY  
THROUGH THE NIGHT TO ALL CLOUDY. PRIOR TO THE CLOUDS ACROSS NE LOWER  
THIS EVENING...TEMPERATURES WILL DROP VERY QUICKLY WITH PATCHY FOG  
DEVELOPMENT LIKELY. THESE TEMPS HERE WILL CLIMB AFTER THAT.  
 
HIGH TEMPS TODAY WILL BE IN THE LOWER TO MIDDLE 50S...WITH LOWS  
TONIGHT RANGING FROM THE UPPER 20S LOWER LOWER 30S IN NE LOWER...TO  
THE UPPER 30S AND AROUND 40F WEST OF I-75 (WHERE CLOUDS WILL ALREADY  
BE BY THIS EVENING).  
 

 
   
LONG TERM
 
(FRIDAY THROUGH WEDNESDAY)  
ISSUED AT 347 AM EDT THU OCT 23 2014  
   
..WET WEATHER FOR MONDAY THROUGH WEDNESDAY
 
 
HIGH IMPACT WEATHER POTENTIAL: NONE.  
 
PRIMARY FORECAST CHALLENGES: HOW DOES THIS SYSTEM NEXT WEEK EVOLVE?  
 
OVERVIEW...THE PROCESS OF FLATTENING THE CURRENTLY AMPLIFIED PATTERN  
CONTINUES WITH THE 500 MB LOW OVER THE EAST COAST, NOW CUTTING OFF  
FROM THE 500 MB FLOW. THIS IS WHAT LEADS TO THE SPLIT FLOW OVER THE  
UPPER GREAT LAKES BY FRIDAY MORNING.  
 
(10/24)FRIDAY...THE MODELS ARE IN GOOD AGREEMENT WITH THE 500 MB  
FLOW SPLIT, WITH THE 850 MB AND LOWER MOISTURE STALLING AS IT MOVES  
ACROSS THE FORECAST AREA. THE MODEL SOUNDINGS SHOW MOISTURE  
INCREASING WITH HEIGHT UNDER THE INVERSION SO THAT THERE IS STRONG  
CHANCE THAT WE'LL HAVE PATCH DRIZZLE AT 12Z. IT LOOKS LIKE BY  
SOUNDINGS THAT THE MOISTURE SHOULD MIX OUT. SO KEPT THE DRIZZLE IN  
THROUGH 15Z, AND THEN WITH THE THINNING MOISTURE, STOP THE DRIZZLE  
AS THE CLOUDS BEGIN TO LIFT UP WITH THE MIXING IN THE LOWER  
ATMOSPHERE.  
 
FRIDAY NIGHT...AS A 500 MB SHORTWAVE TROUGH MOVE THROUGH THE UPPER  
GREAT LAKES THE MOISTURE IN THE 700-500 MB LAYER STAYS NORTH OF THE  
STRAITS, THIS LEAVES MOISTURE ALONG THE SFC FRONT AT 850 MB AND  
BELOW A LITTLE THIN. IT LOOKS AS THOUGH OVERNIGHT THERE MAY BE SOME  
ADDED MOISTURE AS THE SYSTEM MOVES TO THE SOUTHEAST OVER NE LOWER.  
HOWEVER, IT LOOKS LIKE THE CHANCE FOR RAIN IS PRETTY SMALL.  
CONTEMPLATED TAKING THE RAIN OUT OF THE FORECAST THERE, BUT WILL  
LEAVE IN THE SMALL CHANCE WE HAVE FOR NOW.  
 
(10/25)SATURDAY...500 MB HEIGHTS BEGIN BUILD INTO THE UPPER GREAT  
LAKES. 850 MB TEMPERATURES BEGIN TO FALL OFF AS THE COLD FRONT MOVES  
THROUGH. WILL HAVE TO WATCH FOR LE RAIN BY THE EARLY EVENING AS THE  
850 MB TEMPERATURES GET TO AROUND 0C TO -2C IF THE GFS IS RIGHT.  
THEN TEMPERATURES WARM BETWEEN 06Z AND 12Z AS THE SFC HIGH BEGINS TO  
BUILD INTO THE UPPER GREAT LAKES. FOR NOW WILL LEAVE THE DRY  
WEATHER, BUT THIS COULD CHANGE INTO A CHILLY DAMP NIGHT IN NW LOWER  
IF THE MODELS TREND MORE THIS WAY.  
 
EXTENDED (SUNDAY THROUGH WEDNESDAY)...(10/26)SUNDAY...MODELS ARE IN  
BETTER AGREEMENT AND KEEP THE PERIOD DRY AS THE SFC HIGH FORCES THE  
MOISTURE EAST AGAIN AND ALLOWING THE 850 MB AND SFC TEMPERATURES TO  
RISE. (10/27)MONDAY...THERE ARE SOME MINOR TIMING ISSUES WITH THE  
ONSET OF TH RAIN WITH THE GFS A LITTLE FASTER, AND A FLATTER RIDGE  
AT 500 MB. THE ECWMF IS A LITTLE MORE AMPLIFIED, SO THINK THAT IT  
MAY BE ONTO THE RIGHT TRACK WITH THE SLOWER ONSET OF RAIN.  
(10/28)TUESDAY...THE RAIN CONTINUES THROUGH THE DAY NOW, BUT THE GFS  
STILL WRAPS THE SFC LOW PRETTY TIGHT. AM BEGINNING TO WONDER IF THE  
THERE IS SOME CONVECTIVE FEEDBACK ISSUES WITH THE GFS WITH ALL OF  
THE PRECIPITATION IT FORMS, AND THE MUCH DEEPER LOW. THIS WOULD  
ACCOUNT FOR THE DIFFERENCES BETWEEN THE TWO MODELS.  
(10/29)WEDNESDAY...AGAIN BOTH MODELS HAVE RAIN FOR DIFFERENT  
REASONS. WILL CONTINUE THE CHANCES OF RAIN AND NOT SIDE WITH HOW WE  
GET TO THIS POINT UNTIL THERE ARE FEW MORE RUNS IN.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)  
ISSUED AT 125 AM EDT THU OCT 23 2014  
 
VFR CONDITIONS AND MAINLY CLEAR SKIES ARE EXPECTED AT ALL NRN LWR  
MICHIGAN TAF SITES THRU WEDNESDAY EVENING AS STRONG HIGH PRESSURE  
AND DRY AIR REMAIN OVERHEAD. THERE IS ONLY A SMALL CHANCE THAT  
STRATUS WILL REDEVELOP ACROSS PORTIONS OF NRN LOWER...AND THOSE  
AREAS STILL ARE EXPECTED TO REMAIN OUTSIDE OF THE AIRPORTS. CALM  
WINDS TONIGHT WILL BECOME S/SE BLO 10 KTS ON THURSDAY AND BACK TO  
CALM WEDNESDAY NIGHT.  
 

 
   
MARINE
 
 
ISSUED AT 347 AM EDT THU OCT 23 2014  
   
..POSSIBLE ADVISORY LEVEL WINDS BY THE WEEKEND
 
 
SFC HIGH PRESSURE AND VERY DRY AIR OVERHEAD WILL SLOWLY PUSH EAST  
THROUGH TONIGHT...WHILE A DECAYING SFC TROUGH ARRIVES TONIGHT. LIGHT  
WINDS WILL TURN SOUTHERLY OVER THIS TIME...BUT REMAIN WELL BELOW  
ADVISORY LEVELS. A MORE SUBSTANTIAL FRONT ARRIVES FRIDAY NIGHT BRING  
POSSIBLE ADVISORY LEVEL SW WINDS TO LAKE MICHIGAN. COLD AIR POURING  
IN SATURDAY VIA A WIND SHIFT OUT OF THE WNW WILL RESULT IN  
INCREASING OVERLAKE INSTABILITY AND A BETTER CHANCE FOR ADVISORY  
LEVEL WINDS.  
 

 
   
APX WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
LH...NONE.  
LM...NONE.  
LS...NONE.  
 

 
 

 
 
SYNOPSIS...SMD  
SHORT TERM...SMD  
LONG TERM...JL  
AVIATION...SMD  
MARINE...SMD  
 
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