FXUS63 KFSD 062104
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
304 PM CST SUN DEC 6 2009
.DISCUSSION...
SNOW HAS WORKED INTO KYKN/KSUX AREAS AS OF 21Z AND WILL CONTINUE
ACROSS SOUTHERN HALF OF CWA THROUGH THE EVENING. HEAVIER SNOW
AMOUNTS SHOULD FOCUS NEAR 850-750MB FRONTAL BOUNDARY WHICH REMAINS
ALONG AND SOUTH OF KYKN-KSPW LINE THROUGH 06Z BEFORE WEAKENING AFTER
UPPER WAVE PASSES BY. CONTINUING WINTER WEATHER ADVISORY FOR 2 TO 4
INCHES OF SNOWFALL ACROSS WOODBURY/IDA COUNTIES...WITH GREATEST
POTENTIAL FOR 3+ INCHES IN SOUTHERN PORTIONS OF THOSE COUNTIES AND
GENERALLY SOUTH OF SIOUX CITY METRO AREA/HIGHWAY 20 CORRIDOR. COULD
SEE FLURRIES ACROSS NORTHERN HALF OF THE CWA WITH THE WIDESPREAD
STRATUS PERSISTING MUCH OF THE NIGHT...BUT GENERALLY EXPECT LITTLE
IF ANY ACCUMULATION NORTH OF INTERSTATE 90.
BY MONDAY MORNING...ANY PRECIPITATION SHOULD BE OUT OF OUR
AREA...WITH THE EXCEPTION OF A FEW LINGERING FLURRIES IN OUR EAST
WHERE LOW CLOUDS WILL RESIDE. WILL HAVE A SURFACE RIDGE PUSH ACROSS
THE REGION...SO WILL HAVE LIGHT NORTHERLY WINDS. HIGHS WILL BE CLOSE
TO TODAYS...MID TO UPPER TEENS...WITH SIMILIAR THERMAL
PROFILES...THOUGH SOME PLACES IN OUR SOUTH COULD BE A COUPLE OF
DEGREES COOLER WITH A COUPLE OF INCHES OF NEW SNOW.
MONDAY NIGHT WILL SEE CLOUDS INCREASING DURING THE NIGHT...WITH
LIGHT SNOW OVERSPREADING THE AREA WITH ISENTROPIC LIFT/MID LEVEL WAA
OUT AHEAD OF THE WAVE LIFTING OUT OF THE CENTRAL ROCKIES. NOT
EXPECTING A LOT OF SNOW MONDAY NIGHT...POSSIBLY JUST AROUND AN INCH
OVER THE MISSOURI RIVER CORRIDOR. LOWS WILL DROP BACK INTO THE
SINGLE DIGITS WITH A NONDIURNAL TREND DEPENDENT ON TIMING OF
INCREASING CLOUD COVER.
DID NOT MAKE A WHOLE LOT OF CHANGES TO THE FORECAST ON TUESDAY WITH
MODELS CONSISTENT IN BRINGING A FAIRLY SIGNIFICANT SNOWFALL TO OUR
SOUTHEASTERN AREAS AS A WOUND UP LOW TRACKS THROUGH THE CENTRAL
PLAINS ON TUESDAY AND TUESDAY NIGHT. APPEARS THAT THE HEAVIEST SNOW
WILL OCCUR BETWEEN 21Z TUESDAY AND 06Z WEDNESDAY WHEN BEST MID LEVEL
FRONT AND PV ADVECTION OCCUR. WITH THE MODEL RUN TO RUN CONSISTENCY
AND VERY SIMILAR QPF AMOUNTS...WHEN AHEAD AND ISSUED A WINTER STORM
WATCH FOR AREAS TO THE SOUTH AND EAST OF A LINE GENERALLY RUNNING
FROM CLAY COUNTY SOUTH DAKOTA TO DICKINSON COUNTY MINNESOTA. CURRENT
PROJECTED SNOWFALL AMOUNTS OVER THIS AREA WOULD RUN CLOSE TO 5
INCHES ALONG THE NORTHERN PERIPHERY OF THE WATCH AREA TO AROUND 9
INCHES IN OUR FAR SOUTHEASTERN COUNTIES. BOUNCED AROUND THE IDEA OF
A BLIZZARD WATCH AFTER 06Z ON WEDNESDAY WHEN WINDS REALLY BEGIN TO
CRANK UP...BUT LOOKS LIKE THIS WILL OCCUR AS PRECIP IS WINDING
DOWN...SO WOULD MAINLY BE A GROUND BLIZZARD TYPE SITUATION. WE MAY
STILL ELECT TO ISSUE THIS IN FUTURE SHIFTS...BUT WAS LITTLE HESITANT
TO DO SO THREE DAYS IN ADVANCE. INCREASINGLY COLD AIR WILL DRAIN IN
BEHIND THE SYSTEM...AND WITH THE SNOWFALL...TEMPERATURES WILL REALLY
PLUMMET ON TUESDAY NIGHT...WITH READINGS DOWN INTO THE NEGATIVE
SINGLE DIGITS OVER MUCH OF THE CWA.
MAY SEE A FEW LINGERING SNOW SHOWERS IN OUR FAR EAST ON WEDNESDAY
MORNING...AND WITH NORTHWEST WINDS OF 20 TO 25 KTS IN OUR EAST WILL
HAVE A GOOD BIT OF BLOWING SNOW. HIGHS LOOKING TO ONLY REACH A
COUPLE DEGREES EITHER SIDE OF 10 ABOVE.
MODELS IN AMAZINGLY GOOD AGREEMENT IN THE EXTENDED...THURSDAY
THROUGH SUNDAY...WITH OUR AREA IN A NORTHWESTERLY UPPER LEVEL FLOW
AND SURFACE RIDGING DOMINATING THROUGH EARLY ON SATURDAY. MAY THEN
SEE SOME WARMING FOR NEXT WEEKEND AS HIGH PRESSURE PUSHES TO THE
EAST AND A SOUTHERLY LOW LEVEL FLOW RETURNS TO THE REGION...ALBEIT
STILL BELOW NORMAL FOR THIS TIME OF YEAR. DOES NOT LOOK LIKE ANY
REAL CHANCE OF PRECIPITATION THROUGH THE PERIOD UNTIL POSSIBLY LATER
ON SUNDAY. /JM
&&
.AVIATION...
GRADUALLY LOWERING CIGS INTO MAINLY MVFR CATEGORY WILL CONTINUE TO
SPREAD ACROSS AREAS SOUTH OF INTERSTATE 90 INCLUDING KSUX TAF SITE
THIS EVENING AS SNOW SPREADS OVER THE AREA FROM THE SOUTHWEST.
IFR-LOCALLY LIFR VSBYS POSSIBLE WITH THE SNOW...ESPECIALLY SOUTH OF
KYKN-KSPW LINE...THROUGH 07/06Z. MVFR STRATUS OVER NORTHERN 2/3 OF
CWA INCLUDING KHON/KFSD TAF LOCATIONS WILL PERSIST THROUGH MUCH OF
THE TAF PERIOD...WITH OCCASIONAL MVFR VSBYS IN BR/-SN. /JM
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY
NIGHT FOR IAZ003-012>014-020>022-031-032.
WINTER WEATHER ADVISORY UNTIL 2 AM CST MONDAY FOR IAZ031-032.
MN...NONE.
NE...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY
NIGHT FOR NEZ013-014.
SD...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY
NIGHT FOR SDZ070-071.
&&
$$
