Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 230755
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
355 AM EDT THU OCT 23 2014

.SYNOPSIS...
ISSUED AT 347 AM EDT THU OCT 23 2014

HIGH PRESSURE WILL START TO EXIT EAST TODAY. THIS WILL ALLOW A
WEAK DISTURBANCE WITH A PERIOD OF LIGHT RAIN AND DRIZZLE TO CROSS
THE REGION TONIGHT INTO TOMORROW MORNING. A COLD FRONT WILL THEN
CROSS NORTHERN MICHIGAN SATURDAY...BRINGING SOME GUSTY WINDS AND
COOLER TEMPERATURES.

THE NEXT LOW PRESSURE SYSTEM WILL ARRIVE IN THE EARLY TO MIDDLE
PARTS OF NEXT WORK WEEK...RESULTING IN ADDITIONAL CHANCES FOR
RAIN.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 347 AM EDT THU OCT 23 2014

...A CHILLY START FOR SURE...

IMPACTS: REDUCED VISIBILITY EARLY THIS MORNING. LOCALIZED DENSE FOG.

CURRENT WEATHER AND SYNOPTIC PATTERN:

UPPER LEVEL RIDGE CURRENTLY OVERHEAD IS SHALLOWING OUT AS AN
UPSTREAM FAIRLY SHARP TROUGH IS MAKING WAY TOWARD THE FAR WESTERN
GREAT LAKES. AN ASSOCIATED COLD/OCCLUDED FRONT WAS SEEN ACROSS
MN/IA/KS/NE WITH A CORRIDOR OF MOISTURE AND WEAK-MODEST -DIVQ WHICH
WAS PRODUCING SOME LIGHT RAIN AND SPRINKLES. NOT MUCH LIQUID IN
THESE SHOWERS...AS THE DEEPER MOISTURE IS WORKING INTO WHAT WAS A
VERY DRY AIR MASS. LATEST SATELLITE AND SHORT TERM DATA SUGGEST/SHOW
POTENTIALLY TWO SEPARATE VORTICITY MAXIMA WITHIN THIS TROUGH...EACH
SHOWING A CONGEALED AREA OF SHOWERS. THESE TWO WAVES ARE LIKELY
WORKING IN OPPOSITE DIRECTIONS...ONE EAST AND ANOTHER TO THE
NORTH...PER SFC DEWPOINT ANALYSIS SHOWING THE MOISTURE SHEARING OUT
WITH TIME.

OVER NRN MICHIGAN...THE DEEPEST OF DRY AIR IS OVERHEAD...ALONG WITH
THE UPPER AND SFC RIDGES. STRONG RADIATIONAL COOLING HAS LED TO SOME
SHALLOW FOG AND STRATUS DEVELOPMENT. THIS WAS MAINLY ONGOING ACROSS
NE LOWER...WHERE YESTERDAYS VISIBLE SATELLITE SHOWED A LINGERING
STRATUS DECK...SURPRISINGLY WELL INTO THE DAY YESTERDAY. THIS KEPT
SFC/LOW LEVEL MOISTURE FROM MIXING OUT...AND HENCE THE STRATUS/FOG.
SOME VISIBILITIES WERE DOWN TO A QUARTER OF A MILE IN SPOTS. TEMPS
WERE AS COLD AS THE LOWER 20S IN THE LOWEST LYING AREAS.

SYNOPTIC PATTERN/WEATHER EVOLUTION:

NOTHING TO CRAZY IN OUR WEATHER OVER THE NEXT 24 HRS...BUT WE WILL
HAVE THE AFOREMENTIONED UPPER TROUGH HEADING INTO THE REGION. THE
TWO SUGGESTED SEPARATE VORTICITY MAXIMA WILL CONTINUE TO TAKE ON
DIFFERENT TRACKS. ONE...LIFTING ENE INTO ONTARIO...AND THE OTHER
INTO SRN LAKE MICHIGAN. THIS WILL CONTINUE TO SHEAR OUT THE MOISTURE
AND FORCING...WHILE PUSHING INTO OUR VERY DRY AIR MASS. THEREFORE
NOT EXPECTING ANY SORT OF COVERAGE AS WE SEE CURRENTLY UPSTREAM.
FORCING AND FCST BFR SOUNDINGS HOWEVER DO SUGGEST THAT SOME LIGHT
RAIN OR SPRINKLES COULD MOVE IN TOWARD EVENING IN NW LOWER AND
EASTERN UPPER...AND THEN POSSIBLY INTO THE I75 CORRIDOR THROUGH
MIDNIGHT OR SO. BEHIND THAT...AND VERIFIED BY UPSTREAM SFC OBS...A
PERIOD OF DEEP LOW LEVEL MOISTURE WILL ARRIVE. THIS WILL LEAVE SKIES
CLOUDY IN THE LOW LEVELS...WITH A PERIOD OF DRIZZLE LIKELY...WHICH
WILL LAST FOR A BIT INTO FRIDAY MORNING.

SKIES WILL INCREASE IN CLOUDINESS THIS AFTERNOON...AND ESPECIALLY
THROUGH THE NIGHT TO ALL CLOUDY. PRIOR TO THE CLOUDS ACROSS NE LOWER
THIS EVENING...TEMPERATURES WILL DROP VERY QUICKLY WITH PATCHY FOG
DEVELOPMENT LIKELY. THESE TEMPS HERE WILL CLIMB AFTER THAT.

HIGH TEMPS TODAY WILL BE IN THE LOWER TO MIDDLE 50S...WITH LOWS
TONIGHT RANGING FROM THE UPPER 20S LOWER LOWER 30S IN NE LOWER...TO
THE UPPER 30S AND AROUND 40F WEST OF I-75 (WHERE CLOUDS WILL ALREADY
BE BY THIS EVENING).

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 347 AM EDT THU OCT 23 2014

...WET WEATHER FOR MONDAY THROUGH WEDNESDAY...

HIGH IMPACT WEATHER POTENTIAL: NONE.

PRIMARY FORECAST CHALLENGES: HOW DOES THIS SYSTEM NEXT WEEK EVOLVE?

OVERVIEW...THE PROCESS OF FLATTENING THE CURRENTLY AMPLIFIED PATTERN
CONTINUES WITH THE 500 MB LOW OVER THE EAST COAST, NOW CUTTING OFF
FROM THE 500 MB FLOW. THIS IS WHAT LEADS TO THE SPLIT FLOW OVER THE
UPPER GREAT LAKES BY FRIDAY MORNING.

(10/24)FRIDAY...THE MODELS ARE IN GOOD AGREEMENT WITH THE 500 MB
FLOW SPLIT, WITH THE 850 MB AND LOWER MOISTURE STALLING AS IT MOVES
ACROSS THE FORECAST AREA. THE MODEL SOUNDINGS SHOW MOISTURE
INCREASING WITH HEIGHT UNDER THE INVERSION SO THAT THERE IS STRONG
CHANCE THAT WE`LL HAVE PATCH DRIZZLE AT 12Z. IT LOOKS LIKE BY
SOUNDINGS THAT THE MOISTURE SHOULD MIX OUT. SO KEPT THE DRIZZLE IN
THROUGH 15Z, AND THEN WITH THE THINNING MOISTURE, STOP THE DRIZZLE
AS THE CLOUDS BEGIN TO LIFT UP WITH THE MIXING IN THE LOWER
ATMOSPHERE.

FRIDAY NIGHT...AS A 500 MB SHORTWAVE TROUGH MOVE THROUGH THE UPPER
GREAT LAKES THE MOISTURE IN THE 700-500 MB LAYER STAYS NORTH OF THE
STRAITS, THIS LEAVES MOISTURE ALONG THE SFC FRONT AT 850 MB AND
BELOW A LITTLE THIN. IT LOOKS AS THOUGH OVERNIGHT THERE MAY BE SOME
ADDED MOISTURE AS THE SYSTEM MOVES TO THE SOUTHEAST OVER NE LOWER.
HOWEVER, IT LOOKS LIKE THE CHANCE FOR RAIN IS PRETTY SMALL.
CONTEMPLATED TAKING THE RAIN OUT OF THE FORECAST THERE, BUT WILL
LEAVE IN THE SMALL CHANCE WE HAVE FOR NOW.

(10/25)SATURDAY...500 MB HEIGHTS BEGIN BUILD INTO THE UPPER GREAT
LAKES. 850 MB TEMPERATURES BEGIN TO FALL OFF AS THE COLD FRONT MOVES
THROUGH. WILL HAVE TO WATCH FOR LE RAIN BY THE EARLY EVENING AS THE
850 MB TEMPERATURES GET TO AROUND 0C TO -2C IF THE GFS IS RIGHT.
THEN TEMPERATURES WARM BETWEEN 06Z AND 12Z AS THE SFC HIGH BEGINS TO
BUILD INTO THE UPPER GREAT LAKES. FOR NOW WILL LEAVE THE DRY
WEATHER, BUT THIS COULD CHANGE INTO A CHILLY DAMP NIGHT IN NW LOWER
IF THE MODELS TREND MORE THIS WAY.

EXTENDED (SUNDAY THROUGH WEDNESDAY)...(10/26)SUNDAY...MODELS ARE IN
BETTER AGREEMENT AND KEEP THE PERIOD DRY AS THE SFC HIGH FORCES THE
MOISTURE EAST AGAIN AND ALLOWING THE 850 MB AND SFC TEMPERATURES TO
RISE. (10/27)MONDAY...THERE ARE SOME MINOR TIMING ISSUES WITH THE
ONSET OF TH RAIN WITH THE GFS A LITTLE FASTER, AND A FLATTER RIDGE
AT 500 MB. THE ECWMF IS A LITTLE MORE AMPLIFIED, SO THINK THAT IT
MAY BE ONTO THE RIGHT TRACK WITH THE SLOWER ONSET OF RAIN.
(10/28)TUESDAY...THE RAIN CONTINUES THROUGH THE DAY NOW, BUT THE GFS
STILL WRAPS THE SFC LOW PRETTY TIGHT. AM BEGINNING TO WONDER IF THE
THERE IS SOME CONVECTIVE FEEDBACK ISSUES WITH THE GFS WITH ALL OF
THE PRECIPITATION IT FORMS, AND THE MUCH DEEPER LOW. THIS WOULD
ACCOUNT FOR THE DIFFERENCES BETWEEN THE TWO MODELS.
(10/29)WEDNESDAY...AGAIN BOTH MODELS HAVE RAIN FOR DIFFERENT
REASONS. WILL CONTINUE THE CHANCES OF RAIN AND NOT SIDE WITH HOW WE
GET TO THIS POINT UNTIL THERE ARE FEW MORE RUNS IN.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 125 AM EDT THU OCT 23 2014

VFR CONDITIONS AND MAINLY CLEAR SKIES ARE EXPECTED AT ALL NRN LWR
MICHIGAN TAF SITES THRU WEDNESDAY EVENING AS STRONG HIGH PRESSURE
AND DRY AIR REMAIN OVERHEAD. THERE IS ONLY A SMALL CHANCE THAT
STRATUS WILL REDEVELOP ACROSS PORTIONS OF NRN LOWER...AND THOSE
AREAS STILL ARE EXPECTED TO REMAIN OUTSIDE OF THE AIRPORTS. CALM
WINDS TONIGHT WILL BECOME S/SE BLO 10 KTS ON THURSDAY AND BACK TO
CALM WEDNESDAY NIGHT.


&&

.MARINE...
ISSUED AT 347 AM EDT THU OCT 23 2014

...POSSIBLE ADVISORY LEVEL WINDS BY THE WEEKEND...

SFC HIGH PRESSURE AND VERY DRY AIR OVERHEAD WILL SLOWLY PUSH EAST
THROUGH TONIGHT...WHILE A DECAYING SFC TROUGH ARRIVES TONIGHT. LIGHT
WINDS WILL TURN SOUTHERLY OVER THIS TIME...BUT REMAIN WELL BELOW
ADVISORY LEVELS. A MORE SUBSTANTIAL FRONT ARRIVES FRIDAY NIGHT BRING
POSSIBLE ADVISORY LEVEL SW WINDS TO LAKE MICHIGAN. COLD AIR POURING
IN SATURDAY VIA A WIND SHIFT OUT OF THE WNW WILL RESULT IN
INCREASING OVERLAKE INSTABILITY AND A BETTER CHANCE FOR ADVISORY
LEVEL WINDS.

&&

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

&&

$$

SYNOPSIS...SMD
SHORT TERM...SMD
LONG TERM...JL
AVIATION...SMD
MARINE...SMD






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