799  
FXUS63 KAPX 181927  
AFDAPX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GAYLORD MI  
327 PM EDT SAT APR 18 2015  
   
NEAR TERM
 
(THIS EVENING THROUGH TONIGHT)  
ISSUED AT 327 PM EDT SAT APR 18 2015  
   
..SOME HIGH CLOUDS TONIGHT
 
 
HIGH IMPACT WEATHER POTENTIAL: MINIMAL.  
 
PATTERN SYNOPSIS/FORECAST: EARLY AFTERNOON SURFACE ANALYSIS SHOWS  
HIGH PRESSURE CENTERED OVER NORTHWEST ONTARIO BUILDING SOUTHEAST  
ACROSS THE GREAT LAKES REGION (3-4MB/3H PRESSURE RISES ACROSS  
NORTHEAST ONTARIO/LAKE HURON). A COLD FRONT THAT MOVED THROUGH  
NORTHERN MICHIGAN DURING THE EARLY MORNING HOURS NOW JUST SOUTH OF  
THE STATE LINE. CONFLUENT FLOW ALOFT ACROSS MICHIGAN BETWEEN  
NORTHWESTERLY NORTHERN BRANCH FLOW TO THE NORTH AND ANTICYCLONIC  
FLOW EMANATING TO THE EAST OF A BROAD SOUTHERN BRANCH UPPER LOW  
SPINNING OVER THE CENTRAL HIGH PLAINS AND ROCKIES. NICE POCKET OF  
DRY AIR HAS SETTLED ACROSS UPPER/NORTHERN LOWER MICHIGAN THIS  
AFTERNOON...AND WITH MIXING DEW POINTS HAVE DROPPED OFF AS A RESULT.  
 
SURFACE HIGH FORECAST TO MOVE INTO QUEBEC OVERNIGHT...WITH A TIGHTER  
PRESSURE GRADIENT AND STRONGER EAST/SOUTHEAST BOUNDARY LAYER FLOW  
DEVELOPING. RIDGING ALOFT WILL CROSS THE STATE OVERNIGHT AS WELL.  
 
PRIMARY FORECAST CONCERNS: MINIMAL.  
 
TONIGHT...ANOTHER QUIET NIGHT EXPECTED WITH JUST SOME HIGH CLOUDS  
ADVANCING FROM THE SOUTHWEST AS UPPER LEVEL RIDGE AXIS CROSSES THE  
STATE. WINDS SHOULD DROP OFF INITIALLY THIS EVENING BUT AS PRESSURE  
GRADIENT TIGHTENS UP OVERNIGHT WINDS WILL SWING AROUND TO THE  
EAST/SOUTHEAST AND PICK UP ONCE AGAIN. GIVEN DRY AIR MASS IN PLACE  
AND INITIALLY LIGHT WINDS EXPECT TEMPERATURES TO SLIP INTO THE 30S  
TONIGHT MOST AREAS...SOME 20S ACROSS NORTHWEST CHIPPEWA COUNTY WHERE  
AFTERNOON TEMPERATURES ARE STUCK IN THE UPPER 30S/40S THANKS TO  
WINDS OFF THE LINGERING LAKE SUPERIOR GLACIER.  
 

 
   
SHORT TERM
 
(SUNDAY THROUGH TUESDAY)  
ISSUED AT 327 PM EDT SAT APR 18 2015  
 
HIGH IMPACT WEATHER: MINIMAL  
 
FORECAST CHALLENGE: TIMING OF THE RAIN SUNDAY INTO SUNDAY NIGHT.  
 
(04/19)SUNDAY...LOOKING AT THE GFS THE LAST FEW DAYS, HAS BEEN ONE  
OF A BACK AND FORTH ON WHETHER THE RAIN WILL GET INTO E UPPER. ONE  
OR TWO 6 HOUR RUNS SAYS YES, THEN ON THE 12Z RUN NO. SUCH IS THE  
CASE, AGAIN ALTHOUGH IT DIDN'T BACK OFF THE RAIN ENTIRELY. LOOKING  
AT THE 850 MB MOISTURE, WHILE THE GFS HAS BEEN FAIRLY WELL IN LINE  
WITH THE ECMWF, THE QPF ON THE GFS HAS OUT RUN THE ECMWF. SEEING  
THAT THE LOW LEVEL MOISTURE HAS BEEN LACKING DUE TO THE SFC HIGH  
(TODAY A HUDSON BAY HIGH) MOVING IN AND AROUND THE REGION THIS WEEK.  
SO HEDGED CLOSER TO THE SREF MEAN IDEA, WHICH SEEMS A DECENT  
COMPROMISE BETWEEN THE TWO, AND FOR WHAT IT'S WORTH, THE NAM IS  
ABOUT AS SLOW AS THE ECMWF. SO THE RAIN WILL ARRIVE IN N LOWER  
PROBABLY AFTER 21Z AND IN E UPPER AFTER 00Z.  
 
AFTER 00Z, THE IDEA IS PRETTY SIMPLE, THE SFC LOW ROTATES UP OVER  
MICHIGAN THROUGH THE NIGHT WITH A COUPLE OF 500 MB SHORTWAVE TROUGHS  
MOVING THROUGH THE REGION AT THE SAME TIME. WITH THE PWAT OF 0.75"  
TO 1.0" AND THE FORCING WITH THE SYSTEM WILL EXPECT THAT THERE WILL  
BE PERIODS OF RAIN THROUGH THE NIGHT.  
 
(4/19)MONDAY...THE RAIN SHOULD CONTINUE INTO THE DAY AS THE 500 MB  
LOW MOVING OUT OF MANITOBA AND INTO THE UPPER GREAT LAKES, HOWEVER,  
IT WILL PROBABLY BECOME MORE SHOWERY AS DRY AIR ENTRAINED ALOFT GETS  
PULLED INTO THE REGION AHEAD OF THE LOW. SO HAVE CHANCE TO LIKELY  
POPS AS THE MOISTURE VARIES WITH TIME THROUGH THE DAY.  
 
AROUND 00Z AND THERE AFTER, IT LOOKS LIKE THE 850 MB TEMPERATURES  
FALL ENOUGH THAT THERE WILL BE A RAIN/SNOW MIX THAT WILL LAST  
THROUGH THE NIGHT. ALTHOUGH, IT COULD BE ALL SNOW BY DAY BREAK,  
ALBEIT MINOR TO LIGHT ACCUMULATIONS, AS THE 850 MB TEMPERATURES FALL  
TO AROUND -7C BY 12Z OVER N LAKE MICHIGAN.  
 
(4/20)TUESDAY...THE 500 MB LOW CONTINUES TO SPIN OVER THE UPPER GREAT  
LAKES. THIS CONTRIBUTES TO THE GFS BEING ABOUT 2C COOLER THAN THE  
ECMWF(00Z), SO WILL HAVE A MIX THROUGH THE DAY AS THE SFC  
TEMPERATURES RISE TO THE UPPER 30S TO LOWER 40S, EVEN IN E UPPER.  
 

 
   
LONG TERM
 
(TUESDAY NIGHT THROUGH SATURDAY)  
ISSUED AT 327 PM EDT SAT APR 18 2015  
 
A STUBBORN...SLOW MOVING...500MB CUTOFF LOW OVER THE GREAT LAKES AND  
ONTARIO WILL LEAD TO BELOW NORMAL TEMPS AND SOME PRECIPITATION INTO  
FRIDAY. THIS CUTOFF LOOKS TO STAY AROUND THROUGH MOST OF THE WEEKEND  
BEFORE FINALLY LIFTING INTO NEW ENGLAND. WITH SOME WEAKER SHORTWAVE  
ENERGY PASSING OVERHEAD AROUND THE MAIN LOW...CHANCES FOR SHOWERS  
WILL REMAIN THROUGH MOST OF THE PERIOD. AND...AS PREVIOUSLY  
MENTIONED...COOL OVERNIGHT TEMPS COULD SEE SOME SNOW MIXING IN.  
 
THINGS WILL BEGIN TO CLEAR UP THROUGH THE WEEKEND AS THE CUTOFF LOW  
LIFTS...BUT AN OMEGA BLOCK LOOKS TO BE SETTING UP BY SATURDAY NIGHT  
WITH ANOTHER CLOSED LOW IN THE GULF OF ALASKA/NORTHERN PACIFIC AND  
BROAD HIGH PRESSURE OVER THE CONUS. SITUATED SQUARELY IN THE  
DESCENDING/CAA SIDE OF THIS...WE COULD BE IN FOR A STRETCH OF DRY  
WEATHER AND BELOW NORMAL TEMPS UNTIL THE BLOCK BREAKS DOWN. ECMWF IS  
A BIT STRONGER WITH THIS...BUT OTHER GUIDANCE PICKING IT UP AS  
WELL.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)  
ISSUED AT 145 PM EDT SAT APR 18 2015  
 
VFR CONDITIONS EXPECTED THROUGH TONIGHT. LOW LEVEL WIND SHEAR WILL  
DEVELOP THIS EVENING THROUGH MID MORNING SUNDAY.  
 

 
   
MARINE
 
 
ISSUED AT 327 PM EDT SAT APR 18 2015  
 
TONIGHT: PRESSURE GRADIENT BUILDS TONIGHT AS HIGH PRESSURE BUILDS  
INTO QUEBEC AND PRESSURES FALL ACROSS THE PLAINS. EAST/SOUTHEAST  
WIND WILL INCREASE OVERNIGHT.  
 
OUTLOOK: SMALL CRAFT ADVISORIES LIKELY FOR SUNDAY/SUNDAY NIGHT MOST  
NEARSHORE ZONES.  
 

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

 
 

 
 
NEAR TERM...JPB  
SHORT TERM...JSL  
LONG TERM...ALM  
MARINE...JPB  
 
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