163  
FXUS63 KAPX 290337  
AFDAPX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GAYLORD MI  
1137 PM EDT FRI APR 28 2017  
   
UPDATE
 
 
ISSUED AT 1013 PM EDT FRI APR 28 2017  
 
EVENING SURFACE ANALYSIS REVEALS AN ILL-DEFINED FRONT/SURFACE  
TROUGH STRETCHING FROM THE SAGINAW BAY AREA DOWN THROUGH  
CHICAGO...SLOWLY SAGGING SOUTHWARD WITH TIME. UPPER JET AXIS  
STRETCHES FROM THE MIDWEST ACROSS LOWER MICHIGAN INTO CANADA...AND  
SUBTLE SHORT WAVE MOVING EASTWARD THROUGH CENTRAL WISCONSIN. SHORT  
WAVE FORCING...INTERACTING WITH SOME HINTS OF SUBTLE DEFORMATION/  
FRONTOGENESIS OCCURRING NORTH OF THE SURFACE FRONT...HAS LEAD TO  
NARROW AXIS OF PRECIPITATION SLIDING OUT OF CENTRAL WISCONSIN AND  
INTO PARTS OF NORTHERN AND CENTRAL LOWER MICHIGAN THIS EVENING.  
MAINLY LIGHT RAIN/SPRINKLES...WITH CIGS GENERALLY ABOVE 5K  
FEET...BUT MBL/CAD/GOV HAVE ALL BEEN REPORTING -RA FOR THE LAST  
FEW HOURS AND THERE ARE SOME SMALL POCKETS OF BETTER RADAR  
RETURNS. MBL HAS MEASURED 0.01" LAST HOUR.  
 
REST OF TONIGHT: NARROW AXIS OF LIGHT RAIN WILL SLIDE THROUGH THE  
SOUTHERN HALF OF THE CWA...EXITING BEFORE SUNRISE...AND ENOUGH TO  
WET THE GROUND IN SOME AREAS. HAVE TWEAKED POPS JUST A BIT TO PUSH  
LIGHT RAIN CHANCES JUST A LITTLE FURTHER NORTHWARD AND INCREASED  
POPS TO HIGH CHANCE. DIDN'T PUSH POPS INTO THE LIKELY CATEGORY  
HOWEVER SINCE MANY AREAS PROBABLY WILL NOT SEE MEASURABLE PRECIP  
WITH THIS.  
 

 
   
NEAR TERM
 
(TONIGHT THROUGH SATURDAY)  
ISSUED AT 401 PM EDT FRI APR 28 2017  
   
..STAYING COOL WITH SMALL CHANCES FOR MORE SHOWERS
 
 
HIGH IMPACT WEATHER POTENTIAL: NONE.  
 
PATTERN SYNOPSIS/FORECAST: CHILLY-WEATHER PRODUCING LOW PRESSURE  
CONTINUES TO PULL NORTHEAST AWAY FROM THE AREA THIS AFTERNOON. PER  
THE USUAL FOR NORTHERN MICHIGAN, SYSTEM BACKSIDE LOW LEVEL MOISTURE  
LINGERED QUITE A BIT LONGER THAN INITIALLY ANTICIPATED, AS PLENTY OF  
CLOUD COVER LINGERED ACROSS THE NORTH HALF OF THE AREA INTO EARLY  
THIS AFTERNOON (STILL MOSTLY CLOUDY ACROSS THE TIP OF THE MITT AND  
EASTERN UPPER MICHIGAN). DIFFERENT STORY DOWN NEAR SAGINAW BAY, WITH  
PLENTY OF SUNSHINE MOST OF THE DAY AND MUCH MILDER CONDITIONS.  
 
CURRENT SYSTEM IS PART OF BROAD TROUGHING NOW WELL ESTABILISHED  
ACROSS MUCH OF THE NORTHERN HALF OF THE COUNTRY. NEXT WAVE ALREADY  
ROTATING NORTHEAST WITHIN THIS TROUGHING BACK ACROSS THE CENTRAL  
PLAINS. LARGE WARM AIR ADVECTION DRIVEN WING OF RAIN RUNNING OUT  
AHEAD OF THIS SYSTEM THROUGH THE CORN BELT. THIS WAVE WILL LARGELY  
SHEAR OUT OVERNIGHT, WITH THE NORTHERN EXTENT OF THE WAA WING DOING  
THE SAME. A SURGE OF SOMEWHAT DRIER AIR FOLLOWS THIS SYSTEM TO START  
THE WEEKEND.  
 
PRIMARY FORECAST CONCERNS: CLOUD AND TEMPERATURE TRENDS THROUGH  
SATURDAY. ADDRESSING THAT LIGHT SHOWER POTENTIAL TONIGHT.  
 
DETAILS: DESPITE THE OMINOUS APPEARANCE OF UPSTREAM RADAR SHOWING  
WIDESPREAD RAIN, NOT OVERLY CONVINCED WE WILL SEE MUCH OF THIS  
ACTIVITY SURVIVE AS IT HEADS FURTHER NORTHEAST INTO OUR AREA THIS  
EVENING AS PARENT WAVE SHEARS OUT. THINK SOME VERY LIGHT  
RAIN/SPRINKLES ARE A DEFINITE POSSIBILITY FOR AT LEAST THE SOUTH  
HALF OF NORTHERN LOWER THIS EVENING, BUT WITH VERY MINIMAL RAINFALL  
AMOUNTS. CONDITIONS LOOK TO REMAIN DRY NORTH OF THE BIG BRIDGE.  
DRIER NORTHERLY FLOW BECOMES INCREASINGLY ESTABLISHED HEADING  
THROUGH THE OVERNIGHT, ENDING WHAT RAIN THREAT THERE IS IN THE  
PROCESS. DESPITE THE COOL START, THE RETURN OF MORE CLOUDS  
(ESPECIALLY NORTHERN LOWER) AND MAINTENANCE OF LIGHT WINDS WILL  
PREVENT TEMPERATURES FROM FALLING TOO MUCH, WITH READINGS LARGELY  
REMAINING IN THE 30S.  
 
THAT DRY NORTHERLY FLOW FURTHER INCREASES SATURDAY MORNING AS HIGH  
PRESSURE ROTATES THROUGH ONTARIO. ACTIVE BAROCLINIC ZONE TO OUR  
SOUTH BECOMES EVEN MORE SO DURING THE DAY ALONG AND NORTH OF A  
DEVELOPING OHIO VALLEY WARM FRONT. SOME OF THIS ACTIVITY MAY MAKE A  
RUN INTO SOUTHERN SECTIONS OF THE AREA (MOSTLY ALONG AND SOUTH OF M-  
55) BY VERY LATE IN THE AFTERNOON. THIS RAIN WILL BE THE BEGINNINGS  
OF A RATHER LONG DURATION AND POTENTIALLY HEAVY RAIN EVENT THAT  
LOOKS TO UNFOLD SATURDAY NIGHT THROUGH MONDAY. MORE DETAILS ON THAT  
EVENT CAN BE FOUND IN THE SHORT TERM SECTION TO FOLLOW. OTHERWISE,  
ACTUALLY EXPECTING TO SEE QUITE A BIT OF AT LEAST FILTERED SUNSHINE  
ON SATURDAY.  
 

 
   
SHORT TERM
 
(SATURDAY NIGHT THROUGH MONDAY)  
ISSUED AT 401 PM EDT FRI APR 28 2017  
   
..SOAKER SATURDAY NIGHT INTO SUNDAY NIGHT
 
 
HIGH IMPACT WEATHER POTENTIAL...RAIN COULD BE HEAVY AT TIMES WITH  
THE WARM ADVECTION ON SATURDAY NIGHT INTO SUNDAY NIGHT  
 
PATTERN SYNOPSIS/FORECAST...SATURDAY NIGHT THE WARM FRONT IS SET UP  
OVER LOWER MICHIGAN WITH THE GFS AND ECMWF IN LINE WITH THE GENERAL  
POSITION AND STRENGTH OF THE BAROCLINIC ZONE. AS THE SFC LOW MOVES  
INTO MISSOURI, THE SOUTHERLY FLOW IS EXPECTED TO INCREASE ACROSS THE  
BAROCLINIC ZONE WHICH IS EXPECTED TO BE ROUGHLY FROM THE  
MICHIGAN/INDIANA BORDER TO THE M-32. 500 MB PATTERN SHOWS DIFLUENCE  
ALOFT WITH JET STREAKS BEING EJECTED FROM THE 500 MB LOW AND INTO  
THE UPPER GREAT LAKES ALONG THE WARM FRONT. SUNDAY, THE MODELS MOVES  
THE AXIS OF THE HEAVIEST FROM DOWNSTATE INTO THE CENTRAL PART OF N  
LOWER BY 00Z. THE ISSUE TO WATCH WILL BE THE CONVECTION THAT WILL  
BREAK OUT NEAR THE SFC LOW. IF IT MOVES TOO FAR EAST, IT COULD  
DISRUPT THE SOUTHERLY FLOW INTO THE RAIN, AND WE COULD END UP WITH  
WHAT HAS HAPPENED THE LAST COUPLE OF POSSIBLE HEAVY RAIN SYSTEMS. AT  
THIS POINT, THE PWAT WITH THE SOUNDINGS FROM SUNDAY MORNING TO  
MONDAY MORNING HOLD ONTO VALUES AROUND OR JUST ABOVE AN 1.00" WITH  
THE MODEL SOUNDINGS OVER THE 90% THRESHOLD OF THE MEDIAN PWAT  
SOUNDING CLIMATOLOGY. THE SFC AND 500 MB LOW BEGIN TO STACK UP AND  
THE MODELS EXPECT HEAVY RAIN INTO SUNDAY NIGHT/MONDAY MORNING BEFORE  
THE COLD FRONT MOVES INTO THE UPPER GREAT LAKES. THE COLD FRONT  
MOVES THROUGH THE FORECAST AREA BY 18Z, AND THE 700-500 MB DRY SLOT  
AS WELL. THIS WOULD END THE HEAVIEST RAIN FOR THE REGION. THERE  
COULD BE PERIOD OF NOTHING, AND THEN DRIZZLE FOR THE AFTERNOON.  
 
PRIMARY FORECAST CONCERNS...AS HAS BEEN POINTED OUT BY SOME IN THE  
PUBLIC, WE HAVE HAD SYSTEMS LOOK GOOD THE LAST COUPLE OF WEEKS,  
ESPECIALLY THIS LAST ONE, AND THEN WE GET LITTLE RAIN. THE THINGS  
GOING FOR IT IS THAT MODELS, AND THE ENSEMBLES ARE IN BASIC  
AGREEMENT WITH THE MEANS AROUND THE 1.5 TO 2.0" AMOUNTS AND THE  
SPREADS BEING BETWEEN 0.10 TO 3.00". THE ENSEMBLES ARE CLUMPING  
AROUND THE MEANS SO THINK THAT THE MOST LIKELY 48 HOUR AMOUNTS WILL  
BE 1.00 TO 2.50" ACROSS THE FORECAST AREA.  
   
LONG TERM
 
(MONDAY NIGHT THROUGH FRIDAY)  
ISSUED AT 401 PM EDT FRI APR 28 2017  
 
MODELS ARE IN PRETTY GOOD AGREEMENT (AT THE MOMENT) WITH THE  
TRACKING OF THIS DEEP CENTER OF LOW PRESSURE NEXT WEEK. FROM MONDAY  
NIGHT THROUGH TUESDAY...THIS LOW WILL LIFT FROM WISCONSIN, RIGHT  
OVER THE U.P. AND SKIRT JUST SOUTH OF HUDSON BAY. SO AT THE START OF  
OUR PERIOD...WE'LL BE TRANSITIONING FROM THE GOOD SLUG OF GULF  
MOISTURE THAT BROUGHT RAINFALL MONDAY AND FIRST HALF OF TUESDAY...TO  
WRAP AROUND MOISTURE FOR THE SECOND HALF OF TUESDAY AND TUESDAY  
NIGHT. DURING THIS TIME...TEMPERATURES WILL DROP LOW ENOUGH THAT WE  
COULD SEE SOME WET SNOWFLAKES MIXING IN...PARTICULARLY IN THE HIGHER  
TERRAIN OF INTERIOR LOCATIONS. MOISTURE THEN STRIPS OUT ON  
WEDNESDAY, WITH TEMPERATURES BEGINNING TO MODERATE ON THURSDAY...AND  
NEARLY CLIMO ON FRIDAY.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)  
ISSUED AT 1137 PM EDT FRI APR 28 2017  
   
..VFR CONDITIONS THROUGH SATURDAY
 
 
A PERIOD OF LOWER CLOUD COVER (REMAINING VFR) WILL SLIDE ACROSS  
NORTHERN LOWER MICHIGAN TONIGHT, AS A SMALL AREA OF LOW PRESSURE  
MOVES THROUGH. SOME LIGHT RAINFALL IS POSSIBLE, BUT NOTHING  
SUBSTANTIAL. PRECIP ENDS AND CLOUD COVER THINS OUT FOR SATURDAY.  
 

 
   
MARINE
 
 
ISSUED AT 401 PM EDT FRI APR 28 2017  
 
WINDS WILL CONTINUE TO DIMINISH THROUGH THIS EVENING AS THEY  
VEER MORE NORTHERLY WITH TIME. WINDS WILL REMAIN WITH A DECIDEDLY  
NORTHWARD COMPONENT THROUGH SATURDAY, INCREASING IN SPEED SOME LATER  
TONIGHT AND SATURDAY MORNING. MAY SEE THE RETURN OF SOME ISOLATED  
SCA PRODUCING WINDS GUSTS DURING THIS PERIOD, ESPECIALLY DOWN NEAR  
MANISTEE. LOOKING AHEAD, WET AND COOL WEATHER IS EXPECTED FOR THE  
FIRST HALF OF NEXT WEEK WITH SCA CONDITIONS LIKELY RETURNING.  
 

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

 
 

 
 
UPDATE...TBA  
NEAR TERM...MSB  
SHORT TERM...JSL  
LONG TERM...KAB  
AVIATION...TBA  
MARINE...MSB  
 
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