FXUS63 KAPX 271533
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1033 AM EST FRI NOV 27 2009
.SYNOPSIS.../ISSUED AT 517 AM/
AFTER SOME LINGERING LIGHT LAKE EFFECT SNOW SHOWERS TODAY... HIGH
PRESSURE BUILDING INTO THE REGION SHOULD PROVIDE DRY CONDITIONS
THROUGH AT LEAST SATURDAY EVENING. THE NEXT LOW PRESSURE SYSTEM WILL
MOVE THROUGH SUNDAY...WITH JUST A TOUCH OF LIGHT RAIN OR SNOW. COLD
AIR FLOWS IN BEHIND THIS SYSTEM FOR NEXT WEEK...WITH SEVERAL PERIODS
OF LAKE EFFECT SNOW POSSIBLE.
MSB
&&
.SHORT TERM.../ISSUED AT 1033 AM/...THIS AFTERNOON
SFC LOW PRESSURE OVER NRN HURON CONTINUES TO WEAKEN/FILL AS COASTAL
LOW BECOMES DOMINATE PLAYER OFF NEW ENGLAND. LAST BIT OF SHORT WAVE
ENERGY ROTATING DOWN ACROSS LAKE HURON...AWAY FROM THE REGION...WITH
LAST VESTIGES OF SYNOPTIC PRECIP NOTED ON RADAR THINNING AND ROTATING
THROUGH NE LOWER MICHIGAN (EVEN SOME ELEVATED CONVECTIVE LOOKING
PRECIP JUST OFFSHORE IN NRN LAKE HURON). A FEW ONGOING BANDS OF
LAKE EFFECT SHOWERS STREAMING OFF LAKE MICHIGAN INTO PORTIONS OF
NW LOWER MICHIGAN. MAINLY SNOW...ALTHOUGH STILL SOME MIXY PRECIP
OCCURRING IN THE LOWER ELEVATIONS NEAR THE COASTS (TVC/PZQ) WHERE
SFC TEMPS ARE 36F OR WARMER.
THIS AFTERNOON THROUGH TONIGHT...DRIER AIR/BUILDING HIGH PRESSURE/
SUBSIDENCE WILL COMBINE TO BRING AN END TO ONGOING PRECIP...BY MID
AFTERNOON OR SO. DRY CONDITIONS THEN ANTICIPATED TONIGHT.
INHERITED FORECAST ALREADY HAD THIS IDEA AND HAVE MADE ONLY MINOR
TWEAKS BASED ON LATEST TRENDS. DID NUDGE HIGH TEMPS DOWN A DEGREE
OR TWO GIVEN THE SLOW WARMING THUS FAR AND ENTRENCHED CLOUD COVER.
ADAM
&&
.LONG TERM.../ISSUED AT 458 AM/...TONIGHT AND BEYOND
TONIGHT AND SATURDAY...PRETTY QUIET WEATHER. MID LEVEL HEIGHT
RISES AND APPROACHING SFC RIDGE. STRATO CU MAY BE STUBBORN TO
LEAVE...AND COULD LINGER IN MANY AREAS THROUGH THIS EVENING.
HOWEVER...THIS IS NOT TOO MUCH OF A CONCERN FOR THE SKY
FORECAST...AS MID AND UPPER LEVEL MOISTURE IN WAA REGIME OUT TO
THE WEST WILL ALREADY BE PUSHING INTO THE REGION THIS EVENING.
HAVE GONE MOSTLY CLOUDY ALL AREAS THROUGH SATURDAY MORNING. MAYBE
SATURDAY AFTERNOON THIS CLOUD CAN THIN OUT ENOUGH FOR A PARTLY
CLOUDY FORECAST. LOWS IN THE MIDDLE TO UPPER 20S WITH HIGHS
SATURDAY MAINLY IN THE LOWER HALF OF THE 40S.
SATURDAY NIGHT...WEAK SFC TROUGH ARRIVES FROM THE WEST...WHILE A
RELATIVELY LIGHT SOUTHERLY FLOW ADVECTS LOW LEVEL MOISTURE INTO
OUR RETREATING COLD AIR MASS. MODELS STILL SHOWING POTENTIAL
DRIZZLE CONCERNS...JUST WONDER IF THE MODELS ARE OVER EMPHASIZING
THE MOISTURE. LOTS OF LOW TO MID 20S TD'S ACROSS THE ENTIRE
CENTRAL CONUS. KEPT FORECAST CONTINUITY WITH THE DRIZZLE
IDEA...BUT WITH LOWS DROPPING AROUND THE FREEZING MARK...MADE IT A
CHANCE OF DRIZZLE OR FREEZING DRIZZLE.
SUNDAY AND LATER PERIODS...POSITIVELY TILTED NRN STREAM SHORTWAVE
TROUGH WITH WEAK TO MODEST QG FORCING...WITH BEST MOISTURE
ADVECTING INTO THE OHIO VALLEY AND MISSING US. AS THIS SYSTEM
ARRIVES...COLDER AND COLDER AIR POURS INTO THE REGION. INCREASED
CHANCES OF SEEING PRECIPITATION...BUT AMOUNTS WILL BE LIGHT. MANY
SRN AREAS WILL START WITH A CHANCE OF RAIN...WITH RAIN AND SNOW
NORTH. PRECIP TYPE GRADUALLY CHANGES OVER TO SNOW WITH TIME AND
SHOWED THAT IN GRAPHICS. BEHIND THIS SYSTEM...AT LEAST THROUGH
MONDAY...THERE ARE A COUPLE OF WEAKER SHORTWAVES ARRIVING WITH H8
TEMPS DROPPING TO -8C TO -9C. MORE CONFIDENT IN THE DEVELOPMENT OF
LES...BUT DOESN'T LOOK LIKE ANYTHING TOO SIGNIFICANT ATTM AS
SYNOPTIC SUPPORT WILL LIKELY BE WEAK/MINIMAL.
MODEL GO IN DIFFERENT DIRECTIONS AFTER MONDAY...MADE ONLY COSMETIC
CHANGES TO THE FORECAST TO BETTER MESH WITH SURROUNDING
NEIGHBORING OFFICES. SMD
&&
.MARINE.../ISSUED AT 1033 AM/
PRESSURE GRADIENT IN THE PROCESS OF WEAKENING ACROSS THE REGION
WITH GALE GUSTS NO LONGER BEING REPORTED ON COASTAL OB PLATFORMS.
MIGHT YET BE SOME ISOLATED GALE GUSTS ACROSS LAKE HURON (OR AT 100+
FEET ABOARD SHIP)...BUT NO LONGER JUSTIFIES A GALE WARNING. WILL
MAINTAIN SMALL CRAFT HEADLINES THROUGH THE AFTERNOON WHILE
WINDS/WAVES CONTINUE TO DIMINISH THROUGH TONIGHT. THEREAFTER...NO
WIND/WAVE ISSUES ANTICIPATED THROUGH THE REST OF THE NEARSHORE
FORECAST.
ADAM
&&
.AVIATION.../ISSUED AT 640 AM/...VALID FOR 12Z TAFS
UPPER LOW EXITING EAST OF LAKE HURON THIS MORNING...WHILE COLD AIR
TRAVERSES THE GREAT LAKES...RESULTING IN LAKE EFFECT SNOW SHOWERS.
THESE SNOW SHOWERS WILL PRIMARILY AFFECT TVC WITH TEMPORARY IFR
VSBYS THRU 16Z. MVFR CIGS WILL BE COMMON ALL TAF SITES WITH LOW
LEVEL MOISTURE TRAPPED BENEATH AN INVERSION. GUSTY CONDITIONS WILL
WANE THRU THE DAY...AS HIGH PRESSURE APPROACHES FROM THE WEST.
MVFR CIGS LIKELY TO HOLD ON THRU AT LEAST THIS EVENING/03Z.
ADDITIONAL MID TO UPPER LEVEL CLOUD WILL ALREADY BE BUILDING
IN...BUT VFR CONDITIONS EXPECTED AFTER 03Z. SMD
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LMZ323-
341-342-344>346.
LH...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
LHZ345>349.
LS...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LSZ321.
&&
$$
