Area Forecast Discussion
Issued by NWS Sioux Falls, SD

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KFSD 072037
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
337 PM CDT MON JUL 7 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 336 PM CDT MON JUL 7 2014

CONVECTIVE TRENDS THROUGH THE LATER AFTERNOON AND EVENING ARE THE
PRIMARY CONCERN OF THE SHORT TERM. CURRENTLY...THE CWA IS MAINLY
BETWEEN THE BETTER DYNAMIC FORCING TO THE NORTH ASSOCIATED WITH
STRONG MID LEVEL WAVE AND THE BETTER THERMODYNAMIC AIR MASS WHICH
HAS FOR THE MOST PART BEEN FORCED SOUTHWARD BY COOL AIR POOL FROM
EARLIER SOUTHERN SD/NORTHERN NE CONVECTION. STILL REMAINS A FAIR MID
LEVEL INSTABILITY CLOSER TO SOUTHERN CWA...AND SOMEWHAT STRONGER LOW
LEVEL INSTABILITY TO THE NORTH. COLD FRONT ARCING ACROSS EXTREME
NORTHWEST CORNER OF THE CWA WILL BE PUSHED STEADILY SOUTHEAST
THROUGH THE LATE AFTERNOON AND EVENING. CONVERGENCE ZONE IN HIGH
RESOLUTION SOLUTIONS WORKING ACROSS NORTH OF I 90 IS THE PRIMARY
FOCUS OF STRONGER UPDRAFTS MID TO LATE AFTERNOON. PREDOMINANT WEST
TO SOUTHWEST FLOW AT THE LOW LEVELS HAS REDUCED THE LOW LEVEL
SHEAR...AND TO SOME DEGREE THE DEEPER SHEAR. IF ANY SEVERE STORMS TO
OCCUR...AT THIS TIME WOULD LOOK TO FAVOR SOUTHWEST MINNESOTA TOWARD
THE IOWA GREAT LAKES AREA...AND THREAT WOULD BE LIKELY LIMITED TO
SOME MARGINAL SEVERE HAIL AND WIND...WITH A SLIGHTLY GREATER THREAT
JUST NORTH/EAST OF THE CWA.

THE SHOWER AND THUNDER THREAT ENDS FAIRLY QUICKLY DURING THE EVENING
AS WAVE CONTINUES TO SHEAR OFF TO THE NORTHEAST OF THE AREA AND THE
ADDED HELP FROM DIURNAL DESTABILIZATION AND CONVERGENCE WITH
BOUNDARY ALL START TO DWINDLE.

BOUNDARY LAYER MOISTURE LOOKS A BIT TOO HIGH IN THE COUPLE OF MODELS
THAT ACTUALLY PRODUCE SOME HEATING BASED SPRINKLES/LIGHT SHOWERS
ACROSS THE NORTHEAST HALF OF CWA TOMORROW AFTERNOON...AND PREFER TO
KEEP DRY WITH JUST A DIURNAL INCREASE IN CUMULUS. WELL MIXED
ENVIRONMENT AND HAVE PUT HIGHS MID TO HIGH RANGE SUGGESTED BY MODEST
MIXING.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 336 PM CDT MON JUL 7 2014

TUESDAY NIGHT INTO WEDNESDAY MORNING WILL BE QUIET A SEASONALLY COOL
AS A WEAK RIDGE OF HIGH PRESSURE MOVES INTO THE REGION. LOWERED LOWS
A TOUCH AND AIMING FOR MAINLY LOWER TO MID 50S.

WEDNESDAY INTO WEDNESDAY NIGHT WILL SEE GRADUALLY INCREASING
INSTABILITY BUT FOR NOW THE BETTER INSTABILITY AND BETTER CHANCES
FOR THUNDERSTORMS SHOULD REMAIN MAINLY WEST OF INTERSTATE 29. NO
MAJOR THREAT FOR SEVERE THUNDERSTORMS AT THIS TIME.

THURSDAY WILL ONLY SEE A SMALL CHANCE FOR THUNDERSTORMS DURING THE
DAY AS DEEP STRONG SOUTHERLY FLOW DEVELOPS. SHOULD BE QUITE A BIT OF
CLOUD COVER AND INCREASING LOW LEVEL MOISTURE SO WILL AIMING FOR
MAINLY AROUND 80 TO THE MID 80S FOR HIGHS.

IN THE OUTER PERIODS(FRIDAY THROUGH MONDAY)...THE MODELS ARE IN OK
AGREEMENT WITH THE LARGE SCALE BUT DIFFERING QUITE A BIT ON THE
STRENGTH OF THE TROUGH OVER SOUTHERN CANADA EXTENDING INTO THE GREAT
LAKES AREA. A FEW OF THE RUNS OF BROUGHT IN A MUCH DEEPER TROUGH
WHICH SWINGS TEMPERATURES WELL BELOW NORMAL BUT FOR NOW WILL NOT
BUY INTO 850MB TEMPERATURES COOLER THAN 10 DEGREES C. SO BASICALLY
AIMING FOR HIGHS IN THE 80S WITH MID 70S TO LOWER 80S ON MONDAY.
WHILE THERE IS A GOOD CHANCE SHOWER SHOWERS AND THUNDERSTORMS
THURSDAY NIGHT THE REMAINDER OF THE PERIOD SHOULD SEE MAINLY
ISOLATED TO SCATTERED THUNDERSTORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 116 PM CDT MON JUL 7 2014

LARGE COLD POOL SPREADING THROUGH THE LOWER MISSOURI VALLEY WILL
LIMIT SHORT TERM POTENTIAL FOR ADDITIONAL CONVECTIVE DEVELOPMENT.
MOST ACTIVITY IS EXPECTED TO DEVELOP ALONG AND EAST OF A KHON TO
KFSD TO KSLB LINE...WITH ADDITIONAL STORMS THROUGH THE MISSOURI
VALLEY. CEILINGS SHOULD BE LARGELY VFR OUTSIDE SOME SHORT
DURATION MVFR CONDITIONS WITHIN SCATTERED TO NUMEROUS THUNDERSTORMS
THIS AFTERNOON TO EARLY EVENING. SOME NORTHWESTERLY WIND GUSTS MAY
APPROACH 25 KNOTS BY LATER MORNING TUESDAY.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...CHAPMAN
LONG TERM...08
AVIATION...CHAPMAN






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.