Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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987
FXUS63 KFSD 052320
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
620 PM CDT THU MAY 5 2016

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 253 PM CDT THU MAY 5 2016

QUIET AND WARM WEATHER WILL CONTINUE THROUGH THE NEXT 24 HOURS. AN
INCREASING LOW LEVEL JET ATOP SHARP SURFACE-BASED INVERSION TONIGHT
SHOULD LEAD TO SOME ELEVATION INFLUENCE IN WINDS AND TEMPERATURES
AROUND/EAST OF THE BUFFALO RIDGE IN SOUTHWEST MINNESOTA...AS WELL AS
IN/NEAR HIGHER ELEVATIONS OF GREGORY COUNTY AND JUST WEST OF THE
JAMES RIVER VALLEY. SKY COVER WILL BE MINIMAL...THOUGH STARS/MOON
COULD APPEAR A BIT HAZY DUE TO A LOFTED SMOKE LAYER FROM CENTRAL
CANADIAN WILDFIRES.

FRIDAY LOOKS TO BE THE WARMEST DAY OF THE SEASON SO FAR...WITH
WIDESPREAD HIGHS IN THE MID TO UPPER 80S LIKELY IN WELL-MIXED
SOUTHWESTERLY FLOW AHEAD OF AN APPROACHING COOL FRONT. THE FRONT
SHOULD REACH NORTHWEST PORTIONS OF THE FORECAST AREA...ROUGHLY NEAR
CHAMBERLAIN TO BROOKINGS LINE BY LATE AFTERNOON. EXPECTED HEATING
RESULTS IN MODEST INSTABILITY NEAR THE BOUNDARY...BUT FORECAST
SOUNDINGS INDICATE DECENT CAP HOLDING FIRM FOR MOST AREAS UNTIL
AFTER 00Z WHEN COOLING BEGINS ALOFT. THE EXCEPTION COULD BE NEAR
BROOKINGS/MARSHALL WHERE THE CAP APPEARS TO WEAKEN A BIT MORE AFTER
21Z...SO HAVE INTRODUCED A VERY SMALL POP THERE LATE IN THE DAY.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 253 PM CDT THU MAY 5 2016

COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA FRIDAY NIGHT.  MODEL
SOUNDINGS CONTINUE TO SUGGEST SHALLOW SATURATION BETWEEN 800-700 MB.
IF ATMOSPHERE IS ABLE TO SATURATE...THERE IS THE POTENTIAL OF A
SHOWER OR THUNDERSTORM TO DEVELOP...AND THEREFORE CONTINUED THE
SLIGHT CHANCE MENTION.  ON SATURDAY MORNING...RAISED POPS IN THE
MISSOURI RIVER VALLEY AS MODEL SUGGEST SHORTWAVE MOVING THROUGH
POTENTIALLY INTERACTING WITH THE FRONT.

SATURDAY APPEARS TO BE BREEZY TO START OFF.  WEAK INVERSION WITH 30
KNOTS JUST OFF THE DECK COMBINED WITH PRESSURE RISES OF THREE TO
FIVE MB PER THREE HOURS AND MODEST COLD AIR ADVECTION IMMEDIATELY
BEHIND THE FRONT WILL AID IN BRINGING DOWN A PORTION OF THIS MOMENTUM
TO THE SURFACE.  SIDED WITH HIGHER GUIDANCE VALUES EARLIER IN THE
DAY...BUT SPEED LAYER MIXES OUT BY MID DAY.  SPEAKING OF
MIXING...WILL NEED TO KEEP AN EYE ON DEW POINTS FOR THE AFTERNOON
HOURS ON SATURDAY. WITH DRY LAYER ALOFT...WILL LIKELY SEE DEW POINTS
FALL INTO THE 20S/LOWER 30S...PROMOTING RHS OF 25 TO 30 PERCENT.

CLOUDS AND THE POTENTIAL FOR RAIN WILL INCREASE THROUGHOUT THE DAY
ON SUNDAY AS UPPER LOW APPROACHES FROM THE SOUTHWEST.  INITIAL
DYNAMICS WILL BE FIGHTING A FAIR AMOUNT OF DRY AIR...SO HAVE LIMITED
POPS TO THE MISSOURI RIVER VALLEY ON SUNDAY.  CHANCE OF RAIN
INCREASES FURTHER SUNDAY NIGHT INTO MONDAY AS UPPER LOW SEPARATES
INTO TWO MAIN PIECES OF ENERGY. THE EASTERN PIECE REMAINS OVER THE
AREA MONDAY AND MONDAY NIGHT...AND HAVE INCREASED INTO THE LIKELY
AND CATEGORICAL RANGE.  GFS SOUNDINGS SUGGEST A FAIR AMOUNT OF
SHEAR...BUT THE WINDS ARE CLOUDED WITH CONVECTION MUCH OF THE DAY.
FORECAST AREA WOULD BE ON THE VERY NORTHERN EDGE OF ANY POTENTIAL
SEVERE THREAT...AS IT LOOKS LIKE WE WILL REMAIN COVERED IN CLOUDS
THROUGHOUT THE DAY. GIVEN SEVERE THREAT IS VERY CONDITIONAL...WILL
NOT MENTION IN HWO AT THIS TIME.

ON TUESDAY...ONE SYSTEM BEGINS TO WORK TO THE EAST AS SECOND LARGE
UPPER LEVEL MOW MOVES IN FROM THE NORTHWEST.  TUESDAY NIGHT OFFERS
THE DRIEST CONDITIONS NEXT WEEK BETWEEN SYSTEMS...BUT OTHERWISE
APPEARS TO BE A FAIRLY WET WEEK WITH SEVERAL SLOW MOVING SYSTEMS
IMPACTION THE REGION.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 619 PM CDT THU MAY 5 2016

VFR THROUGH THE PERIOD. POTENTIAL FOR LLWS ACROSS SOUTHEAST SOUTH
DAKOTA INTO SOUTHWEST MINNESOTA LATE TONIGHT AND EARLY FRIDAY
MORNING.

&&

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

$$

SHORT TERM...JH
LONG TERM...BT
AVIATION...08



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