313
FXUS63 KMPX 202337
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
537 PM CST FRI NOV 20 2009
DISCUSSION
FORECAST ISSUE IN THE SHORT TERM IS THE POTENTIAL OF FOG...THIS
TIME IN EASTERN SECTIONS OF CWA. METARS STILL SHOWING SOME HZ IN
THE AIR FROM THE TWIN CITIES METRO AREA ON EAST WITH MID CLOUDS ON
THEIR WAY OUT. OVERNIGHT LOWS TONIGHT WILL GENERALLY BE A BIT
COOLER THAN LAST NIGHT WITH LITTLE OR NO CLOUD COVER.
MAX TEMPS TODAY REACHED INTO THE UPPER 40S TO MID 50S ACROSS AREA
THIS AFTERNOON. WITH AIRMASS WARMING TOMORROW IN ESTABLISHED
SOUTHERLY FLOW AND MOSTLY SUNNY SKIES...WILL BE ADD A FEW MORE
DEGREES. A BIT BREEZY WESTERN MINNESOTA WITH 850 MB WINDS UP INTO
THE 40 KNOT RANGE.
VIGOROUS TROUGH COMING ONSHORE ONTO WEST COAST WITH 12Z 500 MB
HEIGHT FALLS IN 100 METER RANGE. THIS FEATURE GETS DAMPENED OUT A
BIT AS IT APPROACHES OUR AREA SUNDAY WITH STRONGER TROUGH COMING IN
BEHIND IT. THE CONCERN FOR SATURDAY NIGHT/SUNDAY IS FOR STRATUS TO
IMPACT AREA IN CONTINUED SOUTH FLOW. EXPANDED AREA OF DRIZZLE
NORTHWARD SOMEWHAT FOR LATE SATURDAY NIGHT. ALSO BUMPED UP MIN TEMPS
JUST A BIT SATURDAY NIGHT WITH SOUTH WINDS AND CLOUDS.
WEAK ISENTROPIC LIFT FOR SUNDAY MAINLY ACROSS EASTERN AREA STILL
GOOD ENOUGH FOR CHANCE POPS AS AIRMASS MOISTENS UP.
SOME DIFFERENCES BETWEEN GFS/ECMWF ON SYSTEM FOR MID WEEK WITH ECMWF
BIT SLOWER WITH SOMEWHAT MORE SOUTHERLY TRACK ON DEEP UPPER LOW.
MAINTAINED HIGH CHANCE POPS...ESPECIALLY SOUTHERN CWA. MAY BE ENOUGH
COLD AIR VICINITY UPPER LOW FOR AT LEAST A MIX...BASED ON GFS
TIMING. ENUF COLD AIR IN PLACE BY LATER TUESDAY NIGHT/WED FOR ANY
PCPN TO BE -SN. INCREASED CLOUD COVER INTO THURSDAY WITH
COOL..CYCLONIC FLOW ACROSS AREA WITH TEMPERATURES CLOSER TO SEASONAL
NORMALS.
AVIATION
/00Z TAF ISSUANCE/
A SURFACE HIGH PRESSURE RIDGE IS OVER THE AREA TONIGHT. DRY AIR
ADVECTED AND MIXED INTO WRN MN TODAY...BUT STILL AMPLE LOW LEVEL
MOISTURE IS PRESENT ACROSS ERN MN AND WRN WI...ESPECIALLY FOR
THIS TIME OF YEAR WITH LONG NIGHTS. THIS REGIME IN PLACE IS
SIMILAR TO THIS MORNING OVER CTRL MN...WHERE DENSE FOG OCCURRED.
THE CROSSOVER TECHNIQUE ALSO FAVORS DENSE FOG. SO HAVE ADDED IN
MORE FOG ACROSS ERN MN AND WRN WI TAF SITES. COULD VERY WELL BE
VLIFR VISBYS FOR SEVERAL HOURS AT KEAU AND POSSIBLY AT KRNH...AND
LASTING THROUGH 14Z OR 15Z SAT MORNING. CLIMATOLOGICALLY KMSP IS
MOST FAVORED TO ONLY SEE MVFR VISBYS...BUT SATELLITE AIRPORTS
SHOULD FLIRT WITH IFR VISBYS FOR A WHILE TONIGHT. SRLY WINDS TO
BEGIN FROM WEST TO EAST ACROSS THE TAF SITES LATE TONIGHT INTO SAT
MORNING. THE SETUP IS FAVORABLE FOR GUSTY WINDS...PARTICULARLY IN
WRN MN. GUSTS IN EXCESS OF 20KTS LIKELY AT TIMES AT KAXN AND KRWF
DURING THE AFTN.
MPX WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
BAP/MTF
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