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000
FXUS63 KMPX 100536
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1136 PM CST TUE FEB 9 2010

.DISCUSSION...

SLOW MOVING STORM SYSTEM IS FINALLY CLEARING THE AREA...WITH
TEMPERATURES AND PRECIP CHANCES THURSDAY NIGHT THROUGH SATURDAY
BECOMING THE PRIMARY CONCERNS FOR THE FORECAST.

CURRENT H5 ANALYSIS AND WV IMAGERY SHOW MERGING OF SYSTEMS IS NOW
COMPLETE...WITH DEEP H5 LOW NOW CENTERED OVER ST. LOUIS. BEHIND
THIS...A RATHER DIFFUSE UPPER PATTERN IS IN PLACE...WITH THE NEAREST
WAVE OF INTEREST COMING ONSHORE IN CENTRAL CALIFORNIA. AT THE
SFC...BROAD AREA OF LOW PRESSURE SITS ACROSS THE OHIO VALLEY INTO
THE ERN GULF...WITH THE PESKY INVERTED TROUGH THAT BROUGHT THE AREA
SNOWS OVER THE LAST COUPLE OF DAYS LAYING ACROSS NRN IL INTO ERN IA.
1035 MB HIGH CENTERED OVER MANITOBA IS SENDING A RIDGE DOWN THE
PLAINS.

FOR TONIGHT...TEMPS WILL BE THE BIG ISSUE. FRESH SNOWFALL CERTAINLY
PRIMES THE AREA FOR SOME RATHER IMPRESSIVE RADIATIONAL COOLING GIVEN
CLEAR SKIES/CALM WINDS. THE RIDGE TO THE WEST WILL BE CENTERED OVER
WRN MN TONIGHT...THEN NEAR THE ST. CROIX VALLEY THURSDAY MORNING.
FOR TONIGHT DO EXPECT CLEAR SKIES ACROSS THE W...WITH CLOUDS
CLEARING EAST. CLOUDS WILL MAKE A TOUGH FORECAST IN THE EAST...WITH
ANY SITE SPENDING MORE THAN A COUPLE OF HOURS UNDER CLEAR SKIES
LIKELY TO GO BELOW ZERO. FOR FORECAST...BLENDED CURRENT FORECAST
WITH GFSBC... WHICH WAS THE COLDEST GUIDANCE OUT WEST...WHICH PAINTS
SOME DOUBLE DIGIT BELOW ZERO LOWS OUT BY SODAK. SFC RIDGE WILL BE
OVHD WEDNESDAY...WILL BE A SUNNY DAY...AND LONGER DAYS SHOULD ALLOW
TEMPS TO WARM INTO THE UPPER TEENS WEST/LOWER 20S EAST. THURSDAY
MORNING LOWS HOWEVER HAVE VERY LITTLE CONFIDENCE ATTACHED TO THEM.
FOR EXAMPLE... MAV HAS A LOW AT EAU OF -14F...BUT THE MET IS +1F.
WITH THE SFC RIDGE CENTERED OVER THE ERN CWA...DID FAVOR THE COOLER
MAV...BUT COMPLICATING FACTOR HERE WILL BE INCREASING CLOUD COVER
FROM THE WEST AS WAA/ISENTROPIC LIFT SETS IN ON BACK SIDE OF HIGH.
IF ERN SECTIONS OF CWA MANAGE TO STAY CLEAR MOST OF THE NIGHT...THEN
COULD SEE RATHER WIDESPREAD DOUBLE DIGIT BELOW ZERO LOWS FROM THE
TWIN CITIES EAST.

AFTER THAT...MESSY NW FLOW SETS IN FROM THURSDAY THROUGH SATURDAY
NIGHT. FOR THURSDAY...NOT MUCH SUPPORT FOR ANYTHING MORE THAN
INCREASING CLOUD COVER. BUT THURSDAY NIGHT...MODELS IN GOOD
AGREEMENT WITH BRINGING AN INITIAL SHORTWAVE ACROSS THE AREA...WITH
WEAK A LOW/INVERTED TROUGH FORMING OVER THE AREA. THEN...ANOTHER
STRONG/COMPACT H5 LOW IS PROGGED BY THE GEM/GFS/ECMWF TO QUICKLY
FOLLOW THIS FROM CANADA. THIS FEATURE NOT HANDLED WELL AT ALL...WITH
THE GFS A GOOD COMPROMISE BETWEEN THE FAST/EAST ECMWF AND THE
SLOW/WEST GEM. GIVEN THE AMOUNT OF DISCREPANCY OUT THERE...HAVE NOT
GONE TO HIGH WITH POPS AT THIS POINT...BUT WITH THE GFS/ECMWF
SHOWING YET ANOTHER INVERTED TROUGH SWINGING THROUGH THE AREA...HAVE
KEPT MENTIONABLE POPS GOING ACROSS THE AREA THURSDAY NIGHT THROUGH
SATURDAY NIGHT. OF INTEREST...GFS PUTS OUT ANOTHER 5 TO 8 INCHES
NEAR WHERE THE MOST RECENT HEAVY SNOW FELL /ECMWF MORE 1 TO 3/...SO
WILL HAVE TO KEEP AN EYE ON THIS IN THE COMING DAYS.

OTHER POSSIBILITY TO WATCH OUT FOR DURING THIS PERIOD IS THE
POTENTIAL FOR SOME FREEZING DRIZZLE YET AGAIN ACROSS MAINLY THE SRN
HALF OF THE CWA THURSDAY EVENING/NIGHT...AS LOW LEVEL MOISTURE ONCE
AGAIN OUTPACES DEEP MOISTURE AHEAD OF THE SERIES OF SHORTWAVES. NAM
BUFKIT SOUNDINGS AT FRM AND RWF DURING THIS PERIOD WOULD SUGGEST THE
POSSIBILITY OF SOME FREEZING DRIZZLE IN THOSE AREAS...BUT CONFIDENCE
IN THIS OCCURRING TOO LOW AT THIS POINT TO CARRY IN GRIDS.

WHERE THERE IS HIGH CONFIDENCE IS THAT BEHIND THIS SYSTEM...THE
WEEKEND LOOKS WINDY. GFS/GEM/ECMWF ALL SHOWING A PROLONGED PERIOD OF
TIGHT PRESSURE GRADIENT SATURDAY AFTERNOON THROUGH SUNDAY NIGHT AS
YET ANOTHER 1035MB HIGH BUILDS IN FROM THE NW...INCREASED WINDS
QUITE A BIT THIS WEEKEND...WITH 20 TO 25 MPH WINDS IN WIND FAVORED
REGIONS OF THE WEST AND SOUTH. DEPENDING ON HOW STRONG THE WINDS END
UP...MAY HAVE TO DEAL WITH BLOWING AND DRIFTING ISSUES...SO THIS
WILL BE YET ANOTHER ISSUE TO WATCH IN THE COMING DAYS.

&&

.AVIATION.../06Z TAF ISSUANCE/

MAIN AVIATION CONCERNS DEAL WITH MVFR CEILING ACROSS WEST CENTRAL
WISCONSIN WHICH WILL AFFECT KEAU/KRNH THROUGH 15Z. ALTHOUGH KRNH
WILL BE IN AND OUT OF THE VFR/MVFR CEILING...HAVE INTRODUCED A
TEMPORARY PERIOD OF 1800 FEET BETWEEN 8-12Z. OVERNIGHT FORECASTERS
WILL NEED TO UPDATE IF THIS CLOUD DECK MOVES FURTHER WESTWARD
THEN EXPECTED. KEAU...SHOULD CONTINUE AT LEAST FOR THE NEXT 6 TO 9
HRS IN MVFR CEILINGS WITH THE PREVAILING WINDS FROM THE N/NW.

KMSP...LIGHT NW WNDS WILL CONTINUE THROUGH MOST OF THE
TAF PERIOD...WITH A GENERAL SHIFT TO THE WEST/SW TONIGHT. STILL
SOME CONCERNS WITH BR THIS MORNING AND THE POSSIBILITY OF LOWER
CLDS DEVELOPING WEDNESDAY EVENING. HOWEVER...LOW CONFIDENCE
REMAINS FOR THIS SCENARIO. ..JLT..

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

MPG/JLT