Dense Fog Advisory 4, NWS Twin Cities, MN

AREA FORECAST DISCUSSION...UPDATED FOR 06Z TAFS
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
940 PM CDT TUE MAR 15 2011

.DISCUSSION...ISSUED 336 PM CST

PRIMARILY ZONAL FLOW WILL BRING PERIODIC FAST MOVING DISTURBANCES
THROUGH THE AREA THROUGH MOST OF THE FORECAST PERIOD... AS THE
FLOW BECOMES MORE AMPLIFIED ALONG THE WEST COAST WITH A GOOD UPPER
TROUGH DEVELOPING THERE BY THE END OF THE WEEK. THE MODELS ARE IN
REASONABLY GOOD AGREEMENT INTO THE WEEKEND... BUT SIGNIFICANT
DIFFERENCES BEGIN TO SHOW UP NEXT WEEK AS THEY DECIDE WHAT TO DO
WITH ENERGY THAT WILL EVENTUALLY EJECT EASTWARD FROM THE WESTERN
US TROUGH. THE OVERALL THEME OF A WARMING TREND THROUGH MOST OF
THE PERIOD STILL LOOKS ON TRACK... WITH A FEW CHANCES FOR PCPN
OVER THE COURSE OF THE SEVEN DAYS. HOWEVER... THERE APPEARS TO BE
AT LEAST SOME CHANCE FOR A DECENT COOL DOWN AT THE TAIL END OF THE
SEVEN DAY PERIOD AND PARTICULARLY LATER NEXT WEEK WITH AN UPPER
LOW POSSIBLY CLOSING OFF OVER THE NORTHEAST CONUS AND EASTERN
CANADA. UTILIZED A BLEND OF GUIDANCE THROUGH THE WEEKEND... THEN
TRENDED TOWARD A BLEND OF THE ECMWF AND HPC GUIDANCE BEYOND THAT
TIME. HAVE LOW CONFIDENCE IN THE FORECAST SPECIFICS FROM SUNDAY
ONWARD... WHICH IS UNFORTUNATE SINCE THE PCPN AND TEMPERATURE
TRENDS DURING THAT TIME WILL HAVE A SIGNIFICANT IMPACT ON SNOWMELT
AND POTENTIAL FLOODING ACROSS THE AREA NEXT WEEK. HOPEFULLY THINGS
WILL COME INTO BETTER AGREEMENT OVER THE NEXT FEW DAYS SO
SPECIFICS CAN BE TIED DOWN.

SHORTWAVE AND SURFACE TROUGH CURRENTLY MOVING THROUGH THE AREA MAY
BRING SOME LIGHT PCPN INTO THE EASTERN CWFA INTO EARLY EVENING...
BUT OTHERWISE LOOK FOR IMPROVING CONDITIONS TONIGHT LASTING
THROUGH WEDNESDAY AS WEAK RIDGING WORKS ACROSS THE AREA. THE NEXT
CHANCE FOR PCPN WILL WORK ACROSS THE AREA FROM LATER WEDNESDAY
NIGHT INTO THURSDAY EVENING AS ANOTHER QUICK MOVING PACIFIC
SHORTWAVE RIPPLES ALONG THE US/CANADIAN BORDER AND DRAGS A FRONTAL
BOUNDARY THROUGH THE AREA. THERE IS SOME CHANCE FOR SOUTHERLY FLOW
TO BRING MARGINALLY UNSTABLE AIR INTO THE FAR SOUTHERN CWFA DURING
THAT TIME FRAME... SO INCLUDED ISOLATED THUNDER CHANCES THERE
ALONG WITH CHANCES FOR RAIN ACROSS THE ENTIRE AREA. HIGH PRESSURE
WILL WORK INTO THE AREA ON FRIDAY AND SHOULD HANG ON INTO THE
WEEKEND BEFORE THE NEXT SYSTEM STARTS TO APPROACH SATURDAY NIGHT
INTO SUNDAY. GOOD UPPER RIDGING LOOKS TO DEVELOP FROM OUR AREA
EASTWARD AHEAD OF THIS SYSTEM... WITH SUBSTANTIAL SOUTHERLY FLOW
AHEAD OF THE SURFACE LOW WHICH WILL SLOWLY EMERGE FROM THE PLAINS.
IT IS AT THIS POINT IN THE FORECAST WHERE THE GUIDANCE STARTS TO
EXHIBIT QUITE A BIT OF SPREAD... WITH DIFFERING IDEAS AS TO HOW
THINGS WILL EVOLVE ACROSS OUR AREA. IT APPEARS WE SHOULD SEE AN
INITIAL PIECE OF ENERGY EJECT OUT AND HELP DRIVE A SURFACE LOW
ACROSS THE AREA DURING THE SUNDAY-MONDAY TIME FRAME... BUT THEN WE
LOOK TO HAVE A SECOND PIECE WITH A MORE SUBSTANTIAL PIECE OF THE
MAIN UPPER TROUGH WORK OUT BY SOME POINT TUESDAY. SO... INCLUDED
PCPN CHANCES FROM THE SECOND PART OF THE WEEKEND INTO MONDAY...
THEN BROUGHT SOME CHANCE POPS BACK TO PART OF THE AREA ON TUESDAY.
THERE IS SOME POTENTIAL FOR SIGNIFICANT PCPN ON SUNDAY DEPENDING
ON THE STRENGTH OF THE FEATURE WHICH EJECTS OUT INTO THE AREA AND
THE DEGREE OF MOISTURE AND DESTABILIZATION WHICH OCCUR... BUT IT
LOOKS LIKE THERE WILL BE CONVECTIVE POTENTIAL OVER A REASONABLE
PORTION OF THE AREA WHICH COULD CERTAINLY AUGMENT PCPN TOTALS AT
LEAST LOCALLY. THE BOTTOM LINE IS... STAY TUNED FOR LATER
FORECASTS... PARTICULARLY FOR DAYS 4-7 OF THE FORECAST.

&&

.AVIATION.../06Z TAF ISSUANCE/

SOME CONCERN IN THE OVERNITE WITH FOG DEVELOPMENT.  NARROW T/TD
SPREADS ACROSS AREA WITH SNOWMELT TODAY WIL MAKE AIRMASS SUSCEPTIBLE
TO FOG FORMATION.  SFC WNDS GOING QUITE FLAT ACROSS AREA...BUT
GRADIENT WILL PICK UP A BIT LT TNGHT IN W MN. AFT 08-09Z ALL TAFS
SHUD BE MVFR FOG. WENT IFR AT EAU/RNH WHERE PRESSURE GRADIENT WILL
REMAIN WEAK THRU THE NIGHT.  INCRSG SSE WINDS ON WED WITH GUSTS TO
ARND 25 KTS AT AXN/RWF AND 20 KTS ELSEWEHRE AFT 18Z.

MSP...EXPECT VSBYS 4-6SM BR TO DVLP ARND 08-09Z AND CONT UNTIL 12Z.
PRES GRADIENT INCRSG DRNG THE MRNG WITH G20 KTS BY AROUND 18Z.

&&

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

TRH/BAP

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1138 PM CDT TUE MAR 15 2011

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
170045-
DOUGLAS-TODD-MORRISON-MILLE LACS-KANABEC-STEVENS-POPE-STEARNS-
BENTON-SHERBURNE-ISANTI-CHISAGO-LAC QUI PARLE-SWIFT-CHIPPEWA-
KANDIYOHI-MEEKER-WRIGHT-HENNEPIN-ANOKA-RAMSEY-WASHINGTON-
YELLOW MEDICINE-RENVILLE-MCLEOD-SIBLEY-CARVER-SCOTT-DAKOTA-
REDWOOD-BROWN-NICOLLET-LE SUEUR-RICE-GOODHUE-WATONWAN-BLUE EARTH-
WASECA-STEELE-MARTIN-FARIBAULT-FREEBORN-POLK-BARRON-RUSK-
ST. CROIX-PIERCE-DUNN-PEPIN-EAU CLAIRE-
1138 PM CDT TUE MAR 15 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
MINNESOTA...EAST CENTRAL MINNESOTA...SOUTH CENTRAL MINNESOTA...
SOUTHEAST MINNESOTA...SOUTHWEST MINNESOTA...WEST CENTRAL
MINNESOTA...NORTHWEST WISCONSIN AND WEST CENTRAL WISCONSIN.

.DAY ONE...TONIGHT

LOCALLY DENSE FOG WILL BE ENCOUNTERED ACROSS WEST CENTRAL WISCONSIN.
MOTORISTS SHOULD EXPECT TO ENCOUNTER RAPIDLY VARYING VISIBILITIES.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THE SPRING SNOW MELT WILL BE ON THE INCREASE ACROSS THE OUTLOOK AREA
THROUGH THE WEEKEND. RIVERS AND STREAMS WILL BE ON A SLOW RISE LATE
IN THE WEEK AS RUNOFF DEVELOPS. ICE JAMS ON AREA RIVERS AND STREAMS
WILL ALSO BECOME AN INCREASING THREAT. PLEASE SEE THE LATEST
HYDROLOGICAL STATEMENT FOR MORE INFORMATION.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION WILL NOT BE NEEDED.

RAH