NATIONAL WEATHER SERVICE MARQUETTE MI 739 AM EDT THU SEP 1 2011
UPDATED AVIATION DISCUSSION FOR 12Z TAFS
.DISCUSSION...
UPPER AIR PATTERN CONSISTS OF A 500
MB TROUGH OVER THE LOWER GREAT LAKES...A 500
MB TROUGH IN THE NORTHERN ROCKIES AND A
RIDGE ACROSS THE SOUTH POKING UP INTO THE NORTHERN MISSISSIPPI RIVER VALLEY. THE UPPER AIR PATTERN WILL
HEAD EAST WITH THE
TROUGH IN THE NORTHERN ROCKIES HELPING TO FLATTEN THE
RIDGE TONIGHT AND WILL AFFECT THE AREA ON FRIDAY. AS THIS
TROUGH PASSES QUICKLY THROUGH...ANOTHER
TROUGH DIGS SOUTHEAST FROM SW CANADA AND AFFECTS THE AREA FOR
SAT AND
SAT NIGHT.
A WARM
FRONT PASSES ACROSS THE AREA TODAY WHICH WILL BE FOLLOWED BY A COLD
FRONT THAT WILL MOVE ACROSS THE AREA FRI. ANOTHER COLD
FRONT THEN PASSES THROUGH
SAT NIGHT.
NAM SHOWS 850-500
MB Q-VECTOR
CONVERGENCE AND
MOISTURE LATE TONIGHT AND FRI MORNING AND THIS MOVES OUT BY FRI EVENING. THESE BOTH RETURN FOR
SAT AFTERNOON.
GFS AND
ECMWF SHOW ABOUT THE SAME THING.
COMPLICATED FORECAST FOR TODAY. WARM
FRONT OVER CENTRAL MN IS KICKING OFF SOME
CONVECTION THIS MORNING THAT IS ON THE NOSE OF SOME 700
MB MOISTURE AND 850
MB WAA.
RUC ALSO SHOWING SOME
MLCAPE OF 1000-1500J/KG.
GFS TRIES TO BRING THIS OVER THE WESTERN LAKE THIS MORNING...AND THIS WILL HAVE TO BE WATCHED TO SEE IF IT STAYS TOGETHER OR NOT. LOW CLOUDS ARE BREAKING UP AND THIS SHOULD CONTINUE THIS MORNING. LOCALLY DENSE
FOG IS OCCURRING OVER THE SOUTHERN
CWA AND ISSUED AN SPS TO ACCOUNT FOR THIS. KIMT...KISQ AND KESC HAD VISIBILITIES DOWN TO 1/4 MILE OR LESS OVERNIGHT. THIS
FOG SHOULD BURN OFF QUICKLY AFTER SUNRISE. WITH PLENTY OF SUNSHINE...TEMPERATURES SHOULD WARM QUICKLY. 850
MB TEMPERATURES WARM TO 20C TO 24C OVER THE
CWA BY 00Z AND MIXING THIS DOWN WOULD GIVE ME HIGHS IN THE MID 90S. WITH WINDS BEING SOUTH AND LOWER SUN ANGLE...DOWNSLOPE WINDS COULD GET A FEW PLACES IN THE LOWER 90S FOR TODAY IN THE WEST.
MADE A FEW CHANGES TO THE GOING FORECAST. NOT REAL CONFIDENT THAT OUR AREA WILL SEE A WIDESPREAD
RAINFALL WITH THE PASSAGE OF THE COLD
FRONT. ALMOST SEEMS LIKE AN
MCS WILL MOVE NORTH OF THE AREA AND THEN A SECOND
SHORTWAVE COMES IN AND KICKS SOMETHING OFF OVER THE EASTERN
CWA FRI AFTERNOON WITH
SCATTERED CONVECTION MOSTLY. HARD TO SAY WHAT WILL HAPPEN...BUT WITH
DROUGHT IN THE AREA...HARD TO GET
RAINFALL AND WILL CUT
POPS BACK TO
SCATTERED OVER THE AREA FOR LATE TONIGHT AND ALSO FOR FRI. PUSHED TIMING OF
PCPN BACK UNTIL AFTER MIDNIGHT TONIGHT OVER THE
CWA AS
FRONT GETS CLOSER. WENT DRY FOR FRI NIGHT AND
SAT MORNING. BROUGHT SOME
PCPN IN FOR
SAT AFTERNOON WITH A
SHORTWAVE IN THE AREA AND
LAKE BREEZE CONVECTION COULD GET GOING AS WELL. LAKE EFFECT
PCPN THEN STARTS LATE
SAT NIGHT INTO MONDAY MORNING.
GFS AND
ECMWF SHOW 850
MB TEMPERATURES DROPPING TO 2C AND WITH LAKE SUPERIOR AT 15C TO 17C...THIS IS ENOUGH FOR LAKE EFFECT. SINCE IT IS STILL EARLY IN THE SEASON...WENT
SCATTERED LAKE EFFECT
POPS WITH A NORTH WIND. WITH COLDER 850
MB TEMPERATURES IN THE AREA FOR SUNDAY THROUGH TUE...LOWERED HIGH TEMPERATURES A COUPLE DEGREES. IN FACT...SUNDAY AND MONDAY A FEW PLACES MIGHT NOT GET OUT OF THE 50S FOR HIGHS. THESE ARE THE MAJOR CHANGES THAT WERE MADE. &&
.AVIATION /FOR THE 12Z
TAF ISSUANCE/...
VFR/
MVFR CLOUDS ARE EXPECTED TO LINGER THROUGH THE FIRST COUPLE OF HOURS OF THE
TAF PERIOD AT BOTH SITES. A FEW SHOWERS HAVE DEVELOPED ALONG AN ELEVATED WARM
FRONT IN NW WI AND COULD BRUSH KCMX TOWARDS MID DAY...BUT WITH CIGS ABOVE 10KFT AND NO
VSBY ISSUES EXPECTED DID NOT MENTION. OTHERWISE...WITH THE WARM
FRONT MOVING THROUGH...EXPECT
VFR CONDITIONS TO PREVAIL FOR MOST OF THE PERIOD. A COLD
FRONT SWEEPING THROUGH UPPER MICHIGAN LATE TONIGHT AND FRIDAY WILL PRODUCE
SCATTERED SHOWERS/THUNDERSTORMS. EXPECT KCMX TO HAVE THE BEST CHANCE LATE IN THE
TAF PERIOD...WITH KSAW POSSIBLY EXPERIENCING THEM FRIDAY MORNING INTO EARLY AFTERNOON. FINALLY...ADDED
LLWS FOR KSAW TONIGHT DUE TO A
LOW LEVEL JET AHEAD OF THE
FRONT.
