Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 051106
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
706 AM EDT SAT SEP 5 2015

.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 444 AM EDT SAT SEP 5 2015

...FOGGY START IN SPOTS WITH A FEW SHOWERS THIS AFTERNOON...

HIGH IMPACT WEATHER POTENTIAL: DENSE FOG THIS MORNING OVER PARTS OF
NORTHERN LOWER MICHIGAN.

PATTERN SYNOPSIS/FORECAST: MIDNIGHT SURFACE ANALYSIS SHOWS HIGH
PRESSURE OVER QUEBEC BRINGING EASTERLY BOUNDARY LAYER FLOW TO
MICHIGAN TO THE NORTH OF A LINGERING FRONTAL BOUNDARY ALONG THE
SOUTHERN LOWER MICHIGAN BORDER AND EXTENDING WEST THEN NORTH INTO
THE UPPER MISSISSIPPI VALLEY.  A COLD FRONT LIES ACROSS FAR
NORTHWEST MINNESOTA/NORTH DAKOTA.  WEAK MID LEVEL LOW WAS CENTERED
OVER WEST CENTRAL LOWER MICHIGAN...WATER VAPOR IMAGERY SHOWS A
CONCENTRATED AREA OF VORTICITY OVER FAR SOUTHWEST LOWER MICHIGAN.
PLENTY OF MOISTURE LINGERING ACROSS THE MIDWEST AND GREAT LAKES
REGION (PRECIPITABLE WATER OFF THE 00Z APX SOUNDING WAS 1.77
INCHES/222 PERCENT OF NORMAL)...LARGE AREA OF GREATER THAN 20C
SURFACE DEW POINTS ACROSS THE MIDWEST.  DRIER AIR DOES EXIST TO THE
NORTH AND EAST OF LAKE SUPERIOR WHERE SKIES ARE MOSTLY CLEAR.  WEAK
ISENTROPIC ASCENT PRODUCING CLOUDS AND SPOTTY SHOWERS ACROSS A SMALL
PART OF NORTHERN LOWER...WHILE FOG WAS DEVELOPING ACROSS NORTHERN
LOWER AND GETTING THICK ALONG WESTERN PORTIONS OF THE M-55 CORRIDOR.

UPPER LEVEL DISTURBANCE WILL STILL HANG ACROSS LOWER MICHIGAN TODAY
BUT IS EXPECTED TO BEGIN SHIFTING EAST...AND WILL END UP OVER
SOUTHERN ONTARIO BY EARLY SUNDAY MORNING.  FORECAST AREA WILL REMAIN
IN BETWEEN HIGH PRESSURE OVER NEW ENGLAND...AND LOWER PRESSURES OVER
THE NORTHERN/CENTRAL PLAINS.

PRIMARY FORECAST CONCERNS: FOG TODAY AND TONIGHT...LINGERING SHOWER
CHANCES LATER TODAY.

TODAY...INITIAL CONCERN FOR TODAY LOOKS TO BE AREAS OF DENSE FOG
DEVELOPING OVER SOUTHERN PORTIONS OF THE FORECAST AREA...WILL
PROBABLY ISSUE A DENSE FOG ADVISORY THROUGH MID MORNING TO COVER
THIS.  INITIAL THINKING IS BENZIE/MANISTEE/WEXFORD/MISSAUKEE/
ROSCOMMON/GLADWIN COUNTIES BUT MAY ADJUST THIS BASED ON TRENDS PRIOR
TO PRESS TIME.  STILL A FEW SPOTTY SHOWERS AROUND OVER NORTHERN LAKE
HURON...SOME ADDITIONAL DEVELOPMENT OVER SOUTHERN LAKE MICHIGAN
ALONG AN INSTABILITY GRADIENT ACROSS THE UPPER MIDWEST AND WERE
MOVING EAST INTO SOUTHWEST LOWER.  EXPECT PRECIP CHANCES TODAY TO BE
MOSTLY TIED TO THE DIURNAL CYCLE...WITH SOME MODEST INSTABILITY
DEVELOPING THIS AFTERNOON (PERHAPS ON THE ORDER OF 500J/KG MLCAPE).
LINGERING FORCING WITH MID LEVEL TROUGH AXIS AND LOCALIZED
CONVERGENCE EXPECTED TO ALLOW FOR SCATTERED SHOWER PRIMARILY ACROSS
NORTHERN LOWER THIS AFTERNOON/EARLY EVENING.

TONIGHT...DIURNALLY DRIVEN PRECIPITATION EXPECTED TO WIND DOWN
DURING THE EVENING...POTENTIAL FOR SOME MORE FOG OVERNIGHT.  WILL
HAVE TO WATCH UPSTREAM WHERE CONVECTION LIKELY TO DEVELOP ALONG
SOUTHERLY LOW LEVEL JET...IF ANY OF THIS ACTIVITY SLIPS INTO
NORTHERN MICHIGAN COULD HAVE AN IMPACT ON A HOT/DRY FORECAST FOR
SUNDAY (NOT THAT THAT EVER HAPPENS AROUND HERE).

&&

.SHORT TERM...(SUNDAY THROUGH MONDAY NIGHT)
ISSUED AT 444 AM EDT SAT SEP 5 2015

HIGH IMPACT WEATHER: THUNDERSTORMS DURING THE LABOR DAY BRIDGE WALK

PRIMARY FORECAST CHALLENGE: TIMING OF THE THUNDERSTORMS THROUGH THE
STRAITS

(9/6)SUNDAY...500 MB RIDGE BEGINS TO BREAK DOWN AS THE 500 MB
TROUGH, COMING OUT OF THE CANADIAN ROCKIES, BEGINS TO MOVE INTO THE
NORTHERN PLAINS/CANADIAN PRAIRIES BY THE AFTERNOON. SO THE COLD
FRONT SHOULD BEGIN TO ADVANCE ON THE FORECAST AREA. THE QUESTION IS
IF THE GFS IDEA OF RAIN IN THE WARM SECTOR AHEAD OF THE FRONT WILL
HAPPEN OR THE DRIER ECMWF. THINK THAT THE DRIER ECMWF IS ON THE
RIGHT TRACK AS WAS SAID YESTERDAY, IT LOOKS LIKE THERE IS CAPPING,
INFACT THE LATEST MODELS ARE A LOT STRONGER WITH THE CAPPING SO WILL
HEDGE TO THE DRY SIDE OF THINGS.

IT LOOKS LIKE THE COLD FRONT MOVES INTO THE FORECAST AREA OVERNIGHT,
AND BEGINS TO BRING SHOWERS AND THUNDERSTORMS TO THE LAKE MICHIGAN
SHORE IN NW LOWER, THE STRAITS AND E UPPER BY 12Z.

(9/7)MONDAY...THE MODELS SHOW THE RAIN MOVES ACROSS THE FORECAST
AREA, SO THAT BY 18Z, NW LOWER AND THE STRAITS SHOULD BE ON THE BACK
SIDE OF THE RAIN. IT SEEMS THAT THE RAIN THREAT SHOULD DIMINISH
THROUGH THE AFTERNOON IN E UPPER AND N LOWER WITH THE AREAS OF SOUTH
OF M-32 IN NE LOWER STILL HAVING A LINGERING THREAT INTO THE
EVENING.

&&

.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 444 AM EDT SAT SEP 5 2015

EXTENDED (TUESDAY THROUGH FRIDAY)...BOTH MODELS SHOW A WAVE MOVING
UP THE FRONT OUT OF THE CENTRAL PLAINS THIS WILL PUSH THE FRONT
NORTH AS A WARM FRONT AND BRING THE RAIN BACK INTO THE AREA ON
TUESDAY. IT LOOKS LIKE THE JET STREAM TURNS ZONAL OVER THE NORTHERN
PLAINS AND INTO THE UPPER GREAT LAKES, SO THAT DRYING BEGINS ON
WEDNESDAY, AND LAST THROUGH THE NIGHT. THURSDAY, THE QUESTION IS
WHETHER THE RAIN ON THE GFS IS THAT FAST, OR IF THE FRONT STALLS
UPSTREAM AND DOESN`T CROSS INTO N MICHIGAN UNTIL THURSDAY NIGHT.
FRIDAY, A 500 MB WAVE DIVES INTO THE UPPER GREAT LAKES, AND BRINGS
THE CHANCE OF RAIN BACK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 704 AM EDT SAT SEP 5 2015

IFR/LIFR CONDITIONS TO START THIS MORNING IN LOW CLOUDS/FOG...
EXPECTED TO MIX TO MVFR CONDITIONS BY LATE MORNING...THEN VFR
DURING THE AFTERNOON. SOME SCATTERED SHOWERS POSSIBLE THIS
AFTERNOON. MAY SEE MORE FOG DEVELOP SATURDAY NIGHT.

&&

.MARINE...
ISSUED AT 444 AM EDT SAT SEP 5 2015

TODAY/TONIGHT...WEAK GRADIENT OVER THE NEXT 24 HOURS WILL KEEP
MARINE ISSUES TO A MINIMUM OUTSIDE OF REDUCED VISIBILITIES IN FOG AND
HAZE.

OUTLOOK...INCREASING SOUTH/SOUTHWEST WINDS EXPECTED SUNDAY MAY LEAD
TO SMALL CRAFT CONDITIONS ESPECIALLY WITHIN LAKE MICHIGAN NEARSHORE
ZONES.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR MIZ025-
     031>034-041.

LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

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


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