Freeze Warning 1, NWS Sioux Falls, SD

Clay County, IA, Dickinson County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Woodbury County, IA, Cottonwood County, MN, Jackson County, MN, Lincoln County, MN, Lyon County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN, Aurora County, SD, Beadle County, SD, Bon Homme County, SD, Brookings County, SD, Brule County, SD, Charles Mix County, SD, Clay County, SD, Davison County, SD, Douglas County, SD, Gregory County, SD, Hanson County, SD, Hutchinson County, SD, Jerauld County, SD, Kingsbury County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Sanborn County, SD, Turner County, SD, Union County, SD, Yankton County, SD

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
317 PM CDT MON OCT 13 2008

.DISCUSSION...

MAIN CONCERN TONIGHT IS FREEZING TEMPS. SFC RIDGE STAYS TO THE SW OF
THIS FA GIVING A BROAD SW FLOW. SW FLOW IS ALWAYS TRICKY...IN THAT
SOMETIMES IT REALLY DECOUPLES FM THE FLOW OFF THE SFC AND SOMETIMES
IT DOES NOT. AT ANY RATE...DECIDED TO ISSUE A FREEZE WARNING FOR THE
ENTIRE FA MINUS THE STORM LAKE IA AREA WHERE I SETTLED ON A FROST
ADVY. WITH THE CLEAR SKIES AND FAIRLY DRY DEWPTS ADVECTING IN...
WENT AOB THE COOLER GUIDANCE READINGS. HOWEVER THE FREEZING TEMPS
COULD BE SOMEWHAT ELEVATION DEPENDENT DUE TO THE SW WIND. FOR
EXAMPLE I DO HAVE A BULK OF SW MN NEAR 32 DEGS AS WELL AS S CENTRAL
SD. BUT OVERALL...AM CONCERNED THAT MOST LOCATIONS WL FREEZE.

AFTER THE VERY CHILLY START ON TUESDAY MORNING...WILL BEGIN TO SEE A
RECOVERY IN TEMPERATURES BY AFTERNOON. THIS IN RESPONSE TO AN
INCREASING SOUTHWESTERLY SURFACE FLOW AS HIGH PRESSURE OVER THE
REGION SAGS SOUTHWARD...AND SURFACE TROUGHING DEVELOPS OVER THE
WESTERN PLAINS. WILL START OUT WITH CLEAR SKIES EARLY IN THE
DAY...THEN WILL SEE AN INCREASE IN CLOUDS IN OUR SOUTH LATER AS
ENERGY OVER THE 4 CORNERS REGION MOVES NORTHWARD THROUGH THE DAY.

UNDER A SOUTHWESTERLY FLOW AND CLOUDS CONTINUING TO INCREASE ON
TUESDAY NIGHT...WILL IN TURN BE A WARMER NIGHT...SO FROST WILL NOT
BE AN ISSUE WITH LOWS A COUPLE OF DEGREES EITHER SIDE OF 40. MAY SEE
A FEW SHOWERS DEVELOP IN OUR FAR SOUTHEASTERN ZONES LATER IN THE
NIGHT AS AFOREMENTIONED 4 CORNERS SHORTWAVE PUSHES INTO OUR REGION.
MUCH OF THE ENERGY WITH THIS SYSTEM REMAINS TO OUR SOUTHEAST...THOUGH
MODELS CONTINUE TO DISAGREE ON HOW FAR BACK TO THE NORTH AND WEST
THIS SYSTEM WILL GET. THE ECMWF OFFERS THE FARTHEST NORTHERN
SOLUTION...WHILE NAM IS FARTHEST SOUTH. WENT IN BETWEEN AND KEPT
SMALL POPS IN OUR NE NEBRASKA AND NW IOWA ZONES INTO EARLY
WEDNESDAY MORNING.

WITH THIS SYSTEM EXITING THE REGION...A COLD FRONT WILL FOLLOW
BEHIND...PASSING THROUGH OUR CWA ON WEDNESDAY MORNING. NORTHWESTERLY
WINDS WILL PICK UP BEHIND THE FRONT...SO IT WILL BE A MIXY DAY...AND
AS A RESULT WILL NOT BE MUCH OF A COOL DOWN WITH TEMPERATURES CLOSE
TO OR JUST A LITTLE LOWER THAN TUESDAYS HIGHS. WITH HIGH PRESSURE
SETTLING IN BEHIND THE FRONT...WEDNESDAY LOOKS TO BE ANOTHER COLD
NIGHT WITH TEMPERATURES BACK INTO THE LOWER TO MID 30S OVER MUCH OF
THE AREA.

WITH A SHORTWAVE RIDING ALONG IN A MUCH LESS AMPLIFIED UPPER LEVEL
FLOW FOR MIDWEEK...KEPT WITH A CHANCE OF PRECIPITATION ON THURSDAY
AS THE SYSTEM PUSHES ACROSS OUR AREA. STILL SOME INCONSISTENCIES
AMONG THE MODELS WITH REGARD TO EXACT PATH OF THIS FEATURE...SO LEFT
SMALLER POPS IN THE FORECAST...THOUGH EXTENDED THEM SOUTHWARD JUST A
BIT. WITH THE CLOUDS AND SHOWERS...WILL BE A LITTLE COOLER ON THAT
DAY.

IN THE EXTENDED...FRIDAY THROUGH MONDAY...WITH UPPER LEVEL RIDGING
BUILDING INTO THE CENTRAL PORTION OF THE NATION INTO THE
WEEKEND...LOOKS LIKE A SLOW WARMING TREND WITH MAINLY DRY CONDITIONS
THROUGH THE PERIOD. BY SUNDAY...MODELS BEGIN TO INCREASINGLY DIVERGE
ON THE SYNOPTIC PATTERN...SO STUCK CLOSE TO HPC GUIDANCE FOR DAYS 6
AND 7.

&&

.AVIATION...

ASIDE FROM SOME POSSIBLE MVFR FOG AROUND SUNRISE...EVERYONE SHOULD
BE VFR TONIGHT AND TUESDAY MORNING.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...

IA...FREEZE WARNING FROM 4 AM TO 9 AM CDT TUESDAY FOR IAZ001>003-
     012>014-020-031.

     FROST ADVISORY FROM 4 AM TO 9 AM CDT TUESDAY FOR IAZ021-022-032.

MN...FREEZE WARNING FROM 4 AM TO 9 AM CDT TUESDAY FOR MNZ071-072-080-
     081-089-090-097-098.

NE...FREEZE WARNING FROM 4 AM TO 9 AM CDT TUESDAY FOR NEZ013-014.

SD...FREEZE WARNING FROM 4 AM TO 9 AM CDT TUESDAY FOR SDZ038>040-050-
     052>071.

&&

PUBLIC...JM
AVIATION...MJF

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1121 AM CDT MON OCT 13 2008

SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098-
IAZ001>003-012>014-020>022-031-032-NEZ013-014-141200-
AURORA-BEADLE-BON HOMME-BROOKINGS-BRULE-BUENA VISTA IA-
CHARLES MIX-CHEROKEE IA-CLAY-CLAY IA-COTTONWOOD MN-DAKOTA NE-
DAVISON-DICKINSON IA-DIXON NE-DOUGLAS-GREGORY-HANSON-HUTCHINSON-
IDA IA-JACKSON MN-JERAULD-KINGSBURY-LAKE-LINCOLN-LINCOLN MN-
LYON IA-LYON MN-MCCOOK-MINER-MINNEHAHA-MOODY-MURRAY MN-NOBLES MN-
OBRIEN IA-OSCEOLA IA-PIPESTONE MN-PLYMOUTH IA-ROCK MN-SANBORN-
SIOUX IA-TURNER-UNION-WOODBURY IA-YANKTON-
1121 AM CDT MON OCT 13 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA...
SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

FROST...
WIDESPREAD FROST CAN BE EXPECTED LATE TONIGHT INTO EARLY TUESDAY
MORNING...WEST OF A MARSHALL MINNESOTA TO YANKTON SOUTH DAKOTA
LINE. THIS IS BEING CLOSELY EVALUATED...AND THE ON GOING FROST
ADVISORY MAY HAVE TO BE EXTENDED EASTWARD FOR THE NEXT ISSUANCE
THIS AFTERNOON.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

&&

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT
WWW.WEATHER.GOV/SIOUXFALLS. THIS INCLUDES THE GRAPHICAL HAZARDOUS
WEATHER OUTLOOK.