Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 011136
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
736 AM EDT SAT AUG 1 2015

.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 424 AM EDT SAT AUG 1 2015

...MORE SHOWERS/THUNDERSTORMS TODAY AND TONIGHT...

HIGH IMPACT WEATHER POTENTIAL: SOME THUNDERSTORMS TODAY/TONIGHT...
GUSTY WINDS POSSIBLE WITH ANY STORMS THAT DEVELOP.

PATTERN SYNOPSIS/FORECAST: MIDNIGHT SURFACE ANALYSIS SHOWS A TROUGH
AXIS OVER THE LOWER LAKES EXTENDING BACK ACROSS THE OHIO VALLEY TO A
WEAK LOW CENTER OVER SOUTHWEST ILLINOIS.  BROAD AREA OF HIGHER
PRESSURE ACROSS THE PLAINS/MID MISSISSIPPI VALLEY.  TRAIN OF SHORT
WAVE TROUGHS CONTINUES TO TRACK ACROSS THE GREAT LAKES...LAST IN THE
SERIES DROPPING SOUTHEAST OVER NORTHWEST ONTARIO TOWARD WESTERN LAKE
SUPERIOR...SOME CLOUDS AND SHOWERS OVER THE MINNESOTA ARROWHEAD WITH
THIS FEATURE...BUT SKIES WERE MAINLY CLEAR DOWNSTREAM ACROSS
NORTHERN MICHIGAN.  00Z APX SOUNDING EXHIBITED PRETTY STEEP LAPSE
RATES FROM THE SURFACE TO NEARLY 600MB.

ONTARIO SHORT WAVE TROUGH ON TRACK TO CROSS THE FORECAST AREA FROM
MID MORNING THROUGH EARLY AFTERNOON...WITH ANOTHER PIECE OF ENERGY
FORECAST TO PASS NORTH OF LAKE SUPERIOR EARLY SUNDAY MORNING.  THIS
LATTER SHORT WAVE TROUGH WILL PUSH A COLD FRONT TOWARD THE UPPER
LAKES BY SUNDAY MORNING.

PRIMARY FORECAST CONCERNS: SHOWER DEVELOPMENT TODAY (POSSIBLY EARLY
IN THE DAY)...IMPACTS OF WESTERLY WARM ADVECTION PATTERN DEVELOPING
TONIGHT.

TODAY...TIMING UPSTREAM VORTICITY CENTER BRINGS THIS FEATURE INTO
NORTHERN LOWER MICHIGAN IN THE 14Z-18Z TIME FRAME...WITH EARLY
HEATING/DESTABILIZATION LIKELY GIVE AFOREMENTIONED STEEP LAPSE RATES
ALREADY IN PLACE PER 00Z APX SOUNDING.  SO THINK WE MAY SEE SOME
EARLY SCATTERED CONVECTIVE DEVELOPMENT ACROSS MUCH OF THE AREA
PERHAPS SAVE FOR AREAS ALONG-WEST OF M-37 IN NORTHWEST LOWER.  ONCE
SHORT WAVE DISTURBANCE MOVES OUT INTO LAKE HURON BY MID AFTERNOON...
ADDITIONAL FOCUS POSSIBLE ALONG LAKE BREEZE BOUNDARIES ACROSS
EASTERN UPPER AND ALONG THE NORTHEAST LOWER SHORELINE COUNTIES...
WHILE EXPECT PRECIP THREAT TO DIMINISH ACROSS NORTHWEST LOWER LATER
IN THE DAY.  SOME WIND GUSTINESS WILL STILL BE AROUND DUE TO DEEP
MIXING BUT THE TREND SHOULD CONTINUE TO BE DOWNWARD AS COMPARED TO
THE LAST TWO AFTERNOONS.  STRONG WIND GUSTS ALSO POSSIBLE WITH SOME
OF THE PRECIPITATION THAT DEVELOPS TODAY AS WELL.  MOSTLY SEASONABLE
TEMPERATURES TODAY WITH 70S TO THE NORTH AND SOME LOWER 80S ACROSS
PARTS OF NORTHERN LOWER.

TONIGHT...ENERGY WITH NEXT SHORT WAVE TROUGH PASSING ACROSS NORTHERN
ONTARIO TONIGHT EXPECTED TO REMAIN WELL NORTH OF THE FORECAST AREA.
BUT THIS WILL INDUCE LOW LEVEL WARM ADVECTION MOVING INTO THE UPPER
LAKES.  DEEPER MOISTURE AXIS LOOKS TO BE SPREADING ACROSS LAKE
SUPERIOR/UPPER MICHIGAN IN ASSOCIATION WITH THIS ISENTROPIC ASCENT
PATTERN...WITH INCREASING ELEVATED INSTABILITY DEVELOPING AS WELL.
ASSUMING LAKE BREEZE CONVECTION IS DONE...SHOULD BE A QUIET START TO
THE NIGHT WITH AN INCREASING THREAT FOR SHOWERS/THUNDERSTORMS
OVERNIGHT.

&&

.SHORT TERM...(SUNDAY THROUGH MONDAY NIGHT)
ISSUED AT 424 AM EDT SAT AUG 1 2015

PRIMARY FORECAST CHALLENGE: THUNDERSTORMS FOR SUNDAY. LAKE EFFECT
RAIN FOR MONDAY?

(8/2)SUNDAY...AFTER THE BRIEF WARM UP OVERNIGHT SATURDAY NIGHT, THE
COLD FRONT LOOKS TO MOVE IN RAPIDLY ALONG WITH A 500 MB SHORTWAVE
TROUGH THAT SPINS UP A DECENT LITTLE SFC LOW ALONG IT. MODELS SEEM
TO THINK THAT THE WAVE MOVING UP OUT OF THE MID-MISSISSIPPI VALLEY
WILL JOIN WITH THE COLD FRONT DRIVING DOWN OUT OF CANADA. THIS WILL
PROBABLY CAUSE SOME THUNDER, BUT AM STILL NOT REALLY HYPED UP ON
THIS SYSTEM WILL GO WITH LIKELY RAIN, AND THE CHANCE OF THUNDER. IT
LOOKS LIKE THAT AS THE COLD FRONT DRIVES THROUGH AROUND 00Z, WE
COULD BE ON THE EDGE OF WHERE THE BIGGEST THUNDERSTORMS ARE EXPECTED
AS THE SFC LOW IS OVER N LOWER WITH THE WARM SECTOR ALONG M-55 OR M-
72. AS THE WAVE MOVES THROUGH THE FORECAST AREA, THIS WILL SWEEP THE
THUNDERSTORM ACTIVITY ALONG AND SOUTH OF M-72. HOWEVER, WITH THE
AREA NORTH OF M-55 ON THE COOL SIDE OF THE LOW, WILL EXPECT THAT OUR
SEVERE CHANCE WILL REMAIN MARGINAL.  THE FRONT MOVES EAST AND THINGS
INITIALLY LOOK LIKE THEY COULD DRY OUT, BUT...BY 09Z, IT LOOKS LIKE
THE COOLEST AIR BEGINS TO ARRIVE, AND THE LAKE CLOUDS WILL BE IN
FULL FORCE, AS WE MAY BE JUST STARTING TO SEE THAT MISTY LIGHT RAIN
IN NW LOWER THAT IS USUALLY FROM LAKE EFFECT RAIN.

(8/3)MONDAY...THE LE RAIN CONTINUES INTO THE DAY AS THE WINDS
THROUGH THE DAY LOOK TO REMAIN SOLIDLY OUT OF THE NW WITH THE 1000-
850 MB LAYER WINDS AROUND 15KNOTS. SO WOULD EXPECT THAT THE RAIN
WILL BE OF A CELLULAR NATURE, UNLESS WE CAN GET SOME BETTER SHEAR TO
ORGANIZE BANDS. DON`T THINK THAT THESE WILL DO MUCH ACCUMULATION
WISE, WHICH IS WHY THE POPS ARE 20-30%, BUT SOME LOCATIONS MAY GET
FAIRLY DAMP. THE 850 MB TEMPERATURES FALL TO AROUND +5C ON THE GFS,
+8C ON THE ECMWF. THE ISSUE AT HAND IS THAT THE WATER TEMPERATURES
OVER LAKE MICHIGAN ARE AROUND 20C + OR - A DEGREE OR TWO. THIS LEADS
TO SFC TO 850 MB DELTA TS OF ABOUT 10 TO 15C, WITH SOME AREAS
SOLIDLY AROUND 12 TO 13C. THIS LASTS INTO THE NIGHT, AND INTO
TUESDAY MORNING.

&&

.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 424 AM EDT SAT AUG 1 2015

EXTENDED (TUESDAY THROUGH FRIDAY)...WE MAY GET BACK TO NORMAL
TEMPERATURES FOR SUMMER FOR NEXT WEEKEND, BUT IN THE MEANTIME WE
HAVE TO DEAL WITH THE BELOW NORMAL TEMPERATURES FROM THE 500 MB LOW
OVER HUDSON BAY. DEPENDING ON THE MODEL (GFS IS MUCH COLDER THAN THE
ECMWF ON TUESDAY), WE COULD CONTINUE A VERY COOL, SHOWERY PATTERN
THAT LASTS INTO ABOUT WEDNESDAY MORNING WHEN THE TEMPERATURES DO
BEGIN TO WARM THROUGH THE WEEKEND.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 730 AM EDT SAT AUG 1 2015

PREVAILING VFR CONDITIONS EXPECTED THROUGH TONIGHT...SCATTERED
SHOWERS/THUNDERSTORMS AROUND APN FROM LATE MORNING THROUGH THE
AFTERNOON.

&&

.MARINE...
ISSUED AT 424 AM EDT SAT AUG 1 2015

TODAY/TONIGHT...GENERALLY WESTERLY WINDS TO START TODAY BUT
ANTICIPATE DIFFERENTIAL HEATING WILL ALLOW FOR LOCAL LAND BREEZE
CIRCULATIONS TO DEVELOP ON LAKE HURON/WHITEFISH BAY...WHILE WINDS
WILL BACK TO THE SOUTHWEST ON LAKE MICHIGAN DUE TO LOCAL PRESSURE
GRADIENT DEFORMATION DUE TO DIFFERENTIAL HEATING BETWEEN LAKE AND
LAND.  SOUTH/SOUTHWEST WINDS EXPECTED TO BECOME MORE UBIQUITOUS
TONIGHT.

OUTLOOK...SMALL CRAFT ADVISORIES MAY BE NEEDED OVER PARTS OF LAKE
MICHIGAN AND LAKE HURON SUNDAY.

&&

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

$$

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



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