RSS FeedsIssued by NWS Sioux Falls, SD
000 FXUS63 KFSD 240308 AFDFSD AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 900 PM CST MON NOV 23 2009 .DISCUSSION... HAVE SEEN AREA OF RAIN EXPAND AND INTENSIFY OVER THE SOUTHEASTERN PORTIONS OF THE CWA THROUGH THE EVENING HOURS AS UPPER/MID LEVEL WAVE PUSHES ACROSS NEBRASKA. PRECIPITATION HAS BEEN ALIGNED PRETTY WELL WITH THE 700 TO 800 THERMAL GRADIENT...AND ANTICIPATE RAINFALL TO REMAIN MODERATE INTO THE LATE NIGHT HOURS AS BETTER UPPER LEVEL FORCING MOVES ACROSS THE AREA...THEN BEGIN TO SLOWLY DIMINISH AND PUSH OFF TO THE EAST AFTER 09Z. MADE A FEW MODIFICATIONS TO GRIDS...THOUGH OVERALL FORECAST ON TRACK. /JM && .AVIATION... RAIN BAND WITH MVFR TO IFR CIGS AND VSBYS WILL MOVE SLOWLY NWWD AS FAR NW AS LN EXTDG FM NR MML TO JUST NW OF FSD TO NW OF YKN BY 07Z OR SO...THEN PIVOT SLOWLY EWD THRU TUE MRNG. OTRW MVFR TO IFR CIGS IN AREAS OF STRATUS AND AREAS OF MVFR BR...BASICALLY EAST OF LN FM HON TO MHE TO YKN TNGT INTO TUE MRNG...FLWD BY VFR CX SPRDG FM WEST TO EAST ON TUES. /RYRHOLM && .PREV DISCUSSION... UPPER LEVEL WAVE PROGRESSING EAST ACROSS NEBRASKA SHOULD BEGIN TO INTERACT WITH THE INVERTED TROF/LOW TO MID LEVEL FRONT OVER THE NEXT SEVERAL HOURS. INITIAL SIGNS OF THIS ACTIVITY OCCURRING OVER NORTHWEST IOWA AT 2030Z...AND SHOULD SEE SOMETHING CLOSE TO THIS AREA EXPAND THROUGH THE EVENING. UPPER LEVEL PV ANOMALY SURGES INTO NW IA BETWEEN ABOUT 0Z TO 3Z AND SHOULD SET UP A NICE BAND OF RAIN. INSTABILITY NOT TOO BAD WITH THIS SYSTEM AND APPEARS THAT SOMETHING CLOSE TO THE 750MB FRONT SHOULD BE THE MOST ACTIVE. THIS WOULD PLACE THE BETTER CHANCE FOR RAIN FROM ABOUT VERMILLION TO WORTHINGTON EARLY THIS EVENING...THEN SHIFTING EAST OF THIS LINE BY LATE EVENING INTO THE OVERNIGHT HOURS. THE 650-700MB FRONT STILL LINGERING BACK FARTHER WEST...SO WILL KEEP LOWER POPS IN BY INTERSTATE 29 THROUGH 12Z. OTHERWISE...TEMPERATURES WILL BE FAIRLY MILD BEHIND THE INCOMING WIND SHIFT...SO RAISED LOWS A COUPLE OF DEGREES. UPPER LOW WL DRIFT SLOWLY EWD ACRS NRN MO ON TUES AND THIS WL CONT TO BRING A CHC OF PRECIP MAINLY ACRS SERN CWA ON TUES WITH BEST CHC ACRS NW IA. SO WL KEEP CAT POPS THERE AND GO DRY W OF I29 TUES. TEMPS ALOFT MARGINAL FOR ANY SNOW...BUT WL KEEP CHC OF A R/S MIXTURE ON WRN EDGE OF PRECIP TUES MORN. CLOUD COVER WILL PERSIST MOST OF DAY E OF I29 WITH MORE SUN ACRS THE WEST. SO WUD EXPECT WRN CWA TO BE WARMER WITH HIGHS FM 45 TO 50 WITH 40 TO 45 EAST. WL CLR OUT FOR A TIME TUES NITE ERN CWA AS LOW PULLS AWAY...BUT WL CLOUD BACK UP AGAIN FM THE NW AS S/W DROPS SEWD OUT OF ND. MOISTURE WL BE SOMEWHAT LACKING WITH THIS SYS...HWVR WITH VERY COLD AIR ALOFT ASSOCD WITH THIS FEATURE...WUD NOT BE SURPRISED TO GET CONVECTIVE SNOW SHOWERS OUT OF THIS WAVE ESPEC ACRS ERN CWA WITH FLURRIES TO THE WEST LATE TUES NITE INTO WED EVE. TEMPS WL BE ABOUT 10 DEG COLDER ON WED THAN TUES AND ALSO WINDY AS MIXING SHUD BRING GUSTIER WINDS ALOFT DOWN TO SFC. SHUD BE A DRY BUT COOL THANKSGIVING AS SFC HIGH PUSHES E ACRS THE DAKOTAS. WNDS MAY BE STILL A BIT GUSTY IN THE MORN AND TAPER OFF IN THE AFTN. WITH PLENTY OF SUN EXPECTED...TEMPS SHUD BE NEAR OR SLIGHTLY ABOVE NORM. PREFER THE EC SOLUTION IN THE EXTENED AND THE 12Z GFS HAS COME AROUND TO THIS SOLUTION. THIS WUD INDICATE THAT FRI SHUD WARM INTO THE 40S AND 50S AHEAD OF NEXT CDFNT THAT WL DROP SEWD ACRS CWA ON SAT. SO BUMPED UP TEMPS A FEW DEG FOR FRI AND ONLY SLIGHTLY COOLER ON SAT. MAIN SURGE OF COLDER AIR WL LIKELY LAG BEHIND FNT ON SAT AND MIXING WL ALLOW TEMPS TO RISE INTO 40S. UPPER LOW DROPPING SWD OUT OF ND ON SUN WL PBLY PRODUCE A FEW FLURRIES OR SCT SW- AND DID THROW A 20% INTO FCST ALONG WITH COLDER TEMPS. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. $$
