134  
FXUS63 KAPX 301446  
AFDAPX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GAYLORD MI  
1046 AM EDT SAT JUL 30 2016  
   
UPDATE
 
 
ISSUED AT 1039 AM EDT SAT JUL 30 2016  
 
UNEVENTFUL START TO THE DAY AS EAST FLOW AROUND ONTARIO CENTERED  
HIGH PRESSURE CONTINUES TO BRING IN PLENTY OF DRY AIR. SAME CANNOT  
BE SAID JUST TO OUR SOUTH, WITH SLOW MOVING SHOWERS AND  
THUNDERSTORMS WITHIN BROAD DEFORMATION AXIS BRINGING SOME RATHER  
HEAVY RAIN TOTALS TO PARTS OF SOUTHERN LOWER MICHIGAN. THIS  
SOUTHERN LAKES MOISTURE WILL SLOWLY BEGIN TO PIVOT NORTH, PERHAPS  
BRINGING A SHOWER OR TWO TO AREAS ALONG AND SOUTH OF M-55.  
DEFINITELY NOT ANTICIPATING THE RAIN AMOUNTS BEING REALIZED TO  
OUR SOUTH, BUT A FEW SHOWERS ARE INDEED POSSIBLE. OTHERWISE, A  
MOSTLY TO PARTLY SUNNY DAY IS EXPECTED, WITH HIGHS RANGING  
THROUGH THE 70S, WITH A FEW LOWER 80S ANTICIPATED IN THOSE FAVORED  
EAST FLOW DOWNSLOPE REGIONS OF NORTHWEST LOWER MICHIGAN.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 344 AM EDT SAT JUL 30 2016  
 
OVERVIEW...THERE IS AN AREA OF LOW PRESSURE IN THE OHIO VALLEY AND  
HIGH PRESSURE OVER THE UPPER GREAT LAKES, JAMES BAY, AND THE  
NORTHERN PLAINS. AT 500 MB, THERE IS A SERIES OF TROUGHS AND RIDGES  
IN THE VICINITY OF THE UPPER LAKES, WHICH HAVE ALLOWED THE MOISTURE  
TO REMAIN IN S LOWER AND PORTIONS OF S LAKE MICHIGAN, LEADING TO  
SHOWERS AND THUNDERSTORMS. IT IS THE WEAK FLOW/SFC LOW THAT WILL BE  
THE MAIN CONCERN THROUGH THE NEXT SEVERAL PERIODS AS THIS SYSTEM  
LOOKS TO THROW MORE MOISTURE BACK NORTH TODAY AND TONIGHT.  
 
TODAY...MODELS HAVE A PRETTY DISTINCT DRY SLOT AT THE SFC AND UP  
THROUGH 700 MB, THAT IS MOVING MAINLY WEST ALONG AND SOUTH OF THE M-  
55 CORRIDOR. WHILE THE ANALYSIS FROM THE RAP13 HAS THIS, THE RADAR  
AS OF 07Z IS STILL SHOWING THAT THE RAIN IS MOVING NORTH. HOWEVER,  
THE RAIN IS STAYING OUT OF THE SE COUNTIES AT THE MOMENT, SO MAYBE  
THE RAIN WILL STOP SHORT OF THE US-10 CORRIDOR. IF THAT IS THE CASE,  
AND I HAVE THAT IN MY GRIDS THIS MORNING, AREAS WEST OF I-75 AND  
ALONG M-55 WILL HAVE MINIMAL CHANCES FOR RAIN SHOWERS THROUGH 18Z,  
AND PROBABLY 00Z. BOUNDARY LAYER CAPES ARE ONLY A COUPLE HUNDRED  
J/KG AT MOST THROUGH THE DAY, AND MOST OF THE OTHER TRADITIONAL  
CONVECTIVE INDICES KEEP THE NUMBERS LOW ENOUGH FOR RAIN SHOWERS,  
WITH MAYBE A THUNDERSTORM.  
 
TONIGHT...AFTER 00Z, THE EXPECTATION IS FOR THE DEFORMATION RAIN  
SHOWERS TO REDEVELOP ON THE EAST SIDE OF THE STATE WITH THE HI-RES  
MODELS SUGGESTING AS FAR NORTH AS THE M-32 CORRIDOR THROUGH 06Z. THE  
NMM SUGGESTS ALMOST TO THE STRAITS BY 12Z. HOWEVER, WITH THE GFS AND  
ECMWF IN THE ARW CAMP AND WILL BE KEEPING THE RAIN SOUTH OF M-32 AND  
MAINLY EAST OF I-75.  
   
LONG TERM
 
(SUNDAY THROUGH FRIDAY)  
ISSUED AT 344 AM EDT SAT JUL 30 2016  
   
..SOME SHOWERS NORTHERN LOWER SUNDAY/WARMER NEXT WEEK
 
 
 
HIGH IMPACT WEATHER POTENTIAL: MINIMAL THROUGH THE WEEKEND.  
 
PATTERN SYNOPSIS/FORECAST: LONG WAVE TROUGH AXIS LIES ACROSS THE  
GREAT LAKES/OHIO VALLEY WITH A BIT OF A SPLIT FLOW PATTERN ACROSS  
THE MIDWEST/GREAT LAKES WITH MICHIGAN WITHIN WEAK UPPER LEVEL FLOW  
BETWEEN THE TWO STREAMS. SHORT WAVE TROUGH IN THE SOUTHERN BRANCH  
OF THIS SPLIT OVER THE MISSISSIPPI VALLEY WILL PASS SOUTH OF THE  
FORECAST AREA AND INTO THE LOWER GREAT LAKES THIS WEEKEND (ACTUALLY  
A PAIR OF SHORT WAVE TROUGHS). A NEW ROUND OF HEIGHT FALLS MOVES  
INTO WESTERN CANADA THIS WEEKEND...AND EVENTUALLY PUSHES SHORT WAVE  
RIDGING INTO THE MIDWEST AND GREAT LAKES DURING THE FIRST PART  
OF NEXT WEEK.  
 
BROAD/WEAK HIGH PRESSURE CENTERED OVER NORTHERN ONTARIO/UPPER GREAT  
LAKES/UPPER MIDWEST EARLY THIS MORNING...WAVY FRONTAL BOUNDARY  
STRETCHES FROM THE MID ATLANTIC WEST INTO THE CENTRAL/NORTHERN HIGH  
PLAINS. FRONTAL WAVE EXPECTED TO PASS SOUTH OF MICHIGAN SATURDAY  
ALONG WITH THE SHORT WAVE TROUGHING...WITH A GENERAL WEAK PRESSURE  
GRADIENT ACROSS THE FORECAST AREA EXPECTED THROUGH THE WEEKEND  
AND THE FIRST PART OF NEXT WEEK.  
 
PRIMARY FORECAST CONCERNS: A FARTHER NORTH TREND WITH SHORT WAVE  
ENERGY MOVING THROUGH SOUTHERN MICHIGAN IS THREATENING TO BRING SOME  
SHOWERS TO AT LEAST NORTHEAST LOWER...ALONG WITH SOME POTENTIAL  
ALONG LAKE MICHIGAN BREEZE ACROSS NORTHWEST LOWER.  
 
SUNDAY...SOME MIXED SIGNALS WITH REGARD TO PRECIP CHANCES FOR  
SUNDAY. NAM-WRF IS MOST AGGRESSIVE IN PULLING A WEAK MID LEVEL  
CIRCULATION INTO CENTRAL LOWER AND SUBSEQUENTLY A DECENT SWATH OF  
RAINFALL FOR A GOOD CHUNK OF NORTHEAST/NORTH CENTRAL LOWER. SOME  
HINTS IN OTHER GUIDANCE THAT ENOUGH DEEP MOISTURE WILL SPREAD INTO  
NORTHEAST LOWER AT LEAST DURING THE FIRST HALF OF THE DAY TO JUSTIFY  
SOME POPS. DURING THE AFTERNOON...WEAK GRADIENT WILL ALLOW FOR LAKE  
BREEZE DEVELOPMENT WITH SOME SIGNALS FOR SCATTERED SHOWER  
DEVELOPMENT WEST OF THE I-75 CORRIDOR. PROBABLY NOT UNREASONABLE  
THOUGH GFS REALLY LIKES THIS IDEA ALONG WITH ITS UPPER 60S DEW  
POINTS ALONG AND WEST OF THE US-131 CORRIDOR WHICH APPEARS TO BE A  
BIT EXCESSIVE. SHOWER CHANCES EXPECTED TO WANE WITH LOSS OF HEATING  
SUNDAY EVENING. MEANWHILE...A NICE DAY EXPECTED ACROSS EASTERN UPPER  
WITH TEMPERATURES WARMING TO AROUND 80 DEGREES ACROSS THE INTERIOR.  
 
MONDAY...SHORT WAVE RIDGING BUILDS INTO THE UPPER MIDWEST MONDAY  
WITH SOME HEIGHT RISES PUSHING INTO MICHIGAN. SURFACE PRESSURE  
GRADIENT REMAINS PRETTY FLAT WHICH SHOULD ALLOW FOR ANOTHER ROUND OF  
LAKE BREEZE DEVELOPMENT. BUT ANTICIPATING A DRIER BOUNDARY LAYER  
MONDAY AFTERNOON...WITH A COMMENSURATE DECREASE IN SHOWER CHANCES  
ALONG SAID LAKE BOUNDARIES. MORE SUNSHINE ACROSS NORTHERN LOWER  
(AND CONTINUED SUN ACROSS THE UPPER PENINSULA) WILL PUSH  
TEMPERATURES INTO THE LOWER-MID 80S MONDAY AFTERNOON.  
 
EXTENDED FORECAST (TUESDAY THROUGH FRIDAY)...EXPECTING A WARMING  
TREND HEADING INTO MIDWEEK...AND LOOKS TO BE MAINLY DRY THROUGH  
MIDWEEK THOUGH WITH WARM AIR RETURNING ALWAYS WARY OF SOME UPSTREAM  
CONVECTIVE REMNANTS WREAKING HAVOC WITH A SUNNY/WARM FORECAST  
(TUESDAY?). TEMPERATURES BOTH TUESDAY AND WEDNESDAY LIKELY TO FLIRT  
WITH 90 DEGREES OVER NORTHERN LOWER...AND SHOULD START TO GET A BIT  
MORE SULTRY ESPECIALLY BY WEDNESDAY/THURSDAY. APPROACHING HEIGHT  
FALLS AND AN ASSOCIATED COLD FRONT WILL ARRIVE THURSDAY NIGHT/FRIDAY  
MORNING WHICH WILL LIKELY BE THE BEST CHANCE FOR RAIN NEXT WEEK.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)  
ISSUED AT 709 AM EDT SAT JUL 30 2016  
 
MAIN CONCERN THIS MORNING IS THIS WANDERING BOUNDARY TO THE SOUTH  
THAT KEEPS GENERATING SHOWERS AND THUNDERSTORMS TO THE SOUTH OF  
THE FORECAST AREA, AND OCCASIONALLY, SHOWERS AT OR NEAR ONE OF THE  
AERODROMES. MODELS ARE SHOWING A WEDGE OF DRY AIR FROM THE SFC TO  
ABOUT 15,000 FEET OVER N LOWER THIS MORNING, THAT IS KEEPING THE  
RAIN TO THE SOUTH. THIS IS DUE TO THE SFC HIGH FORCING THE DRY AIR  
SOUTH INTO THE FORECAST AREA. IT IS BEGINNING TO LOOK LIKE THAT  
WHILE THE RAIN WILL STAY SOUTH OF THE TAF SITES FOR MOST OF THE  
DAY, THE HIGH WILL WEAKEN A BIT AS A WEAK MID LEVEL TROUGH OF LOW  
PRESSURE MOVES INTO THE UPPER GREAT LAKES, AND PUSHES THE  
MOISTURE UP THE EAST SIDE OF THE STATE TO AROUND APN. THERE IS A  
SMALL CHANCE FOR SHOWERS AFTER 06Z TONIGHT AS THE TROUGH AND  
MOISTURE MOVE THROUGH THE FORECAST AREA. HAVE DECIDED TO KEEP IT  
OUT OF THE FORECAST, FOR NOW, AS IT IS LOOKING LIKE A LOW CHANCE  
EVENT. IT IS MORE LIKELY RAIN SHOWERS WILL FORM SOUTH OF APN AND  
THE REST OF THE TAF SITES THROUGH 12Z SUNDAY MORNING.  
 

 
   
MARINE
 
 
ISSUED AT 344 AM EDT SAT JUL 30 2016  
 
TODAY THROUGH SUNDAY NIGHT...WINDS BRIEFLY THIS AFTERNOON MAY JUST  
GET TO SMALL CRAFT IN LAKE MICHIGAN AS THE PRESSURE GRADIENT BRIEFLY  
TIGHTENS UP, AND WITH SOME COASTAL CONVERGENCE IT IS POSSIBLE, BUT  
FOR THE TIME THAT IT WOULD BE THERE LOOKS RATHER SHORT(ABOUT AN HOUR  
OR TWO) AND WOULD EXPECT A RAPID DROP OFF AS THE GRADIENT RELAXES BY  
00Z. WINDS FOR TONIGHT THROUGH SUNDAY NIGHT, CONTINUE AS WE HAVE  
SEEN THE LAST FEW DAYS, WINDS GENERALLY OUT OF THE EAST AT 5 TO 10  
KNOTS WITH OCCASIONAL GUSTS TO 15 KNOTS THROUGH THE DAY, AND  
VARIABLE WINDS AT 10 KNOTS OR LESS OVERNIGHT.  
 

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

 
 

 
 
UPDATE...MSB  
SHORT TERM...JSL  
LONG TERM...JPB  
AVIATION...JSL  
MARINE...JSL  
 
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