Expires:No;;307074
FXUS63 KAPX 272331
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
631 PM EST FRI NOV 27 2009
.SYNOPSIS.../ISSUED AT 408 PM/
COOLER WEATHER HAS ARRIVED AND IS EXPECTED TO REMAIN OVER THE GREAT 
LAKES THRU NEXT WEEK. LAKE EFFECT SNOW SHOWERS END TONIGHT AS HIGH 
PRESSURE BUILDS IN SAT. A WEAK LOW PRESSURE SYSTEM WILL MOVE THROUGH 
SUNDAY...WITH JUST A TOUCH OF LIGHT RAIN OR SNOW. COLD AIR FOLLOWS 
MON WITH LAKE EFFECT SNOW. ANOTHER LOW MOVES THRU TUE...WITH COLD 
REINFORCEMENT BEHIND AND POTENTIAL FOR ADDITIONAL LAKE SNOW MID-LATE 
NEXT WEEK.
JH
&&
.SHORT TERM.../ISSUED AT 408 PM/...TONIGHT
CYCLONIC FLOW SLOWLY LOSING IT/S GRIP ON NRN MICHIGAN AS SFC HIGH  
PRESSURE/DRIER AIR TRYING TO NOSE INTO THE REGION. NONETHELESS... 
STILL QUITE A BIT OF CLOUD COVER DRAPED ACROSS THE STATE...THE 
CULMINATION OF LAKE AND DIURNAL PROCESSES. LAKE EFFECT PRECIP HAD 
BEEN ON A STEADY DIMINISHING TREND EARLIER IN THE DAY. BUT TRUE TO 
FORM...LAKE EFFECT/INDUCED SHOWER ACTIVITY HAS ACTUALLY SHOWN AN 
UPTICK IN COVERAGE THIS AFTERNOON...POSSIBLY DUE TO DIURNAL 
PROCESSES. REGARDLESS...SHOWER ACTIVITY HAS BEEN SLOWER TO END THAN 
ORIGINALLY ANTICIPATED. SNOW IN THE HIGHER ELEVATIONS...BUT A MIX IN 
THE LOWER ELEVATIONS NEAR THE COASTS.
TONIGHT...FIRST OFF...GIVEN THE AFOREMENTIONED LAKE EFFECT/DIURNALLY 
ENHANCED SHOWER ACTIVITY...HAD TO STRETCH POPS THROUGH THE REMAINDER 
OF THE AFTERNOON AND INTO THE EARLY EVENING HOURS AS WELL AS INTO 
THE SAGINAW VALLEY. DRIER AIR/BUILDING HIGH PRESSURE/LOSS OF HEATING 
SHOULD BRING A DEMISE TO THE LAKE EFFECT BY MID EVENING OR SO...BUT 
WILL SEE HOW IT GOES. CLOUD COVER WILL BE ANOTHER TRICKY ISSUE. 
DRIER AIR NOSING INTO THE REGION MAY LEAD TO SOME THINNING OF THE 
CLOUD COVER TONIGHT...PARTICULARLY WELL DOWNWIND OF THE LAKES. BUT 
ENOUGH SHALLOW INSTABILITY LINGERS TO KEEP A MOSTLY CLOUDY FORECAST 
GOING IMMEDIATELY DOWNWIND OF THE LAKES. EVENING SHIFT CAN MAKE 
ADJUSTMENTS AS NEEDED. 
ADAM
&&
.LONG TERM.../ISSUED AT 408 PM/...SATURDAY AND BEYOND
SATURDAY...SFC RIDGE MOVES THROUGH THE FORECAST AREA WITH THE 500 MB 
HEIGHTS BEGINNING TO BUILD THROUGH THE DAY. THERE IS AN 850 MB 
TROUGH THAT IS MOVING THROUGH THE REGION AS WELL, BUT IT LOOKS LIKE 
ON THE PROFILES THAT THE MID LEVELS ARE DRY ENOUGH FOR THINGS TO BE 
PRECIPITATION FREE AND PROBABLY EVEN PARTLY CLOUDY. 
SATURDAY NIGHT...A WEAK SFC TROUGH MOVES THROUGH THE REGION LATE AN 
LOOKING AT THE PROFILES, THERE IS MOISTURE, INCREASING WITH HEIGHT 
AND WITH THE WIND PROFILE THERE WOULD BE DIRECTIONAL SHEAR TO CAUSE 
DRIZZLE. THE MID SHIFT PUT IN DRIZZLE OR FREEZING DRIZZLE WHICH IF 
THE GFS IS RIGHT THEN THE FZDZ IS POSSIBLE BY 12Z. 
SUNDAY/SUNDAY NIGHT...THE NEXT SYSTEM MOVES IN WITH THE CHANCE OF 
RAIN IN N LOWER AS THE TEMPERATURES ARE AROUND 40 BY THE AFTERNOON. 
THE 500 MB TROUGH IS MOVING INTO UPPER MICHIGAN WITH THE SFC LOW 
OVER US, ACCORDING THE GFS. THE NAM HAS LESS QPF, DUE TO THE SFC 
TROUGH BEING EAST OF THE FORECAST AREA. TEMPERATURES DO START TO 
COOL LATE IN THE AFTERNOON AND EARLY IN THE EVENING AS THE LOW GOES 
TO THE EAST. SO THE RAIN/SNOW MIX IN E UPPER LOOKS TO BE CHANGING 
INTO THE ALL SNOW AND THEN IN N LOWER BY THE LATE EVENING.
MONDAY...LES LOOKS TO BE LIKELY FOR THE DAY AS THE 850 MB 
TEMPERATURES DROP TO AROUND -10C WITH A PROFILE THAT IS MOSTLY BELOW 
FREEZING. INSTABILITY WOULD BE PRETTY AVAILABLE WITH THE DELTA TS 
AROUND 13 TO 15C. MOISTURE LOOKS TO BE AROUND 70-80% IN THE 850-700 
MB LAYER SO SCATTERED SNOW BANDS LOOK LIKE THEY WILL BE IN THE 
REGION. WITH NW FLOW DOMINANT IN THE MORNING AND WNW IN THE 
AFTERNOON. OVERNIGHT, THE WINDS WILL CONTINUE TO BACK AND 850 MB 
TEMPERATURES WILL RISE. SO THE CHANCES OF SNOW WILL BEGIN TO FALL 
OVERNIGHT. 
EXTENDED (TUESDAY THROUGH FRIDAY)...TUESDAY, THE HIGH PRESSURE 
BUILDS INTO THE OHIO VALLEY WITH A SFC RIDGE INTO THE UPPER 
MISSISSIPPI VALLEY. THERE IS A SFC TROUGH THAT IS MOVING THROUGH THE 
UPPER LAKES AROUND 12Z SO WOULD EXPECT CHANCE OF SNOW FOR THE DAY. 
WEDNESDAY, AN ALBERTA CLIPPER SYSTEM MOVES INTO W LAKE SUPERIOR. IF 
THE WARM FRONT MOVES THROUGH N LOWER THEN THERE WILL BE A CHANCE OF 
PRECIPITATION. PUT IT AS RAIN OR SNOW SINCE WE ARE ON THE CUSP ONE 
WAY OR THE OTHER. THURSDAY, THERE IS A DIFFERENCE IN THE MODELS ON 
HOW FAST IT WILL COOL OFF WITH THE FRONTAL PASSAGE. WILL GO WITH THE 
HPC/ECMWF IDEA FOR NOW SO WILL GO WITH A MIX DURING THE DAY AND ALL 
SNOW OVERNIGHT. FRIDAY, MORE SNOW AS WE GET INTO THE A SECOND LOW 
AND THEN LAKE EFFECT. 
JSL
&&
.MARINE.../ISSUED AT 408 PM/
GUSTY NW WINDS WILL LINGER INTO THE EVENING HOURS...AND KEEP SMALL 
CRAFT CONDITIONS INTACT OVER PORTIONS OF LAKE HURON. WINDS/WAVES 
SUBSIDE OVERNIGHT AS HIGH PRESSURE BUILDS INTO THE REGION. 
THEREAFTER...NO WIND/WAVE ISSUES ANTICIPATED THROUGH THE REST OF THE 
NEARSHORE FORECAST. 
ADAM
&&
.AVIATION.../ISSUED AT 631 PM/...VALID FOR 00Z TAFS
LAKE EFFECT SHOWERS NEAR PLN/APN WILL GRADUALLY FIZZLE OUT THIS 
EVENING...AS HIGH PRESSURE AND SOMEWHAT WARMER AIR WORKS IN FROM THE 
WEST. MVFR CIGS WILL BE SLOWER TO ERODE...BUT WILL BREAK UP AS THE 
NIGHT PROGRESSES. FAIRLY QUIET ON SATURDAY...THOUGH MVFR CIGS COULD 
RETURN LATE IN THE DAY...ESPECIALLY AT TVC/PLN.
JZ
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
LH...SMALL CRAFT ADVISORY UNTIL 11 PM EST THIS EVENING FOR LHZ347>349.
LS...NONE.
&&
$$