Area Forecast Discussion
Issued by NWS Sioux Falls, SD

Home | Current Version | Previous Version | Graphics & Text | 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 241148
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
648 AM CDT FRI APR 24 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 415 AM CDT FRI APR 24 2015

NOT EXACTLY A CLEAR CUT FORECAST WITH REGARD TO PRECIPITATION
CHANCES OVER THE NEXT 24 HOURS. SEEING JUST SPOTTY ELEVATED SHOWERS
IN OUR FAR SOUTHEAST THUS FAR THIS MORNING...WITH LOW LEVEL JET
FOCUSING MORE CONSOLIDATED PRECIPITATION WELL NORTH OF OUR AREA.
MORE CONCENTRATED LOW LEVEL MOISTURE INCREASE EXPECTED OVER THE
WESTERN CWA THROUGH THE EARLY MORNING...THOUGH THUS FAR THIS HAS
BEEN SLOWER TO DEVELOP THAN EXPECTED. NEVERTHELESS...BEGINNING TO
SEE SPOTTY ELEVATED ECHOES DEVELOP THROUGH EASTERN NEBRASKA AND HIGH
RES MODELS IN FAIR AGREEMENT DEVELOPING ISOLATED SHOWERS FROM NEAR
THE JAMES VALLEY TO WEST OF I-29 THIS MORNING. OVERALL THOUGH...
BETTER POTENTIAL FOR SHOWERS THROUGH THE DAY APPEARS TO BE IN OUR
FAR SOUTHEAST WHERE DEEP ISENTROPIC LIFT PERSISTS THROUGH MUCH OF
THE DAY. DEPTH OF MOISTURE A BIT OF A CONCERN AND HAVE TRIMMED BACK
RAINFALL AMOUNTS A BIT FROM PREVIOUS FORECAST FOR TODAY...WITH
AROUND A TENTH OF AN INCH OR A LITTLE MORE ALONG/SOUTHEAST OF
HIGHWAY 60 CORRIDOR...AND LESS THAN A TENTH ELSEWHERE IN THE CWA.

AS FOR TEMPERATURES...HOLDING A FEW DEGREES COOLER THAN THURSDAY IN
THE EAST DUE TO THICKER CLOUD COVER AND PRECIP CHANCES...BUT A SHADE
WARMER WEST WHERE 925MB TEMPERATURES ARE FORECAST TO CLIMB A DEGREE
OR TWO HIGHER THAN THURSDAY IN THERMAL RIDGE JUST AHEAD OF THE
SURFACE BOUNDARY. WITH THE WARMER TEMPERATURES AND BETTER LOW LEVEL
MOISTURE WEST...BEGIN TO SEE BETTER SURFACE BASED INSTABILITY AND
LEADING TO POSSIBLE ISOLATED TO SCATTERED THUNDERSTORM DEVELOPMENT
IN OUR FAR WEST BY LATE AFTERNOON. GFS/NAM SHOWING SBCAPE VALUES
REACHING 1000-1500 J/KG...BUT RAP CONSIDERABLY LOWER DUE TO WARMER
MID-UPPER LEVEL TEMPERATURES. IF GFS/NAM PROFILES PAN OUT...CANNOT
ARGUE WITH SPC MARGINAL THREAT FOR HAIL IN OUR SOUTHWEST CWA LATE
THIS AFTERNOON/EVENING.

FOR TONIGHT...UPPER TROUGH SWINGING OUT OF THE CENTRAL ROCKIES
SHOULD BRING INCREASING THREAT OF RAIN TO OUR SOUTHEAST AS IT
STRENGTHENS AND SLIDES EAST THROUGH THE CENTRAL PLAINS. QUESTION IS
HOW FAR NORTH THE PRECIP SHIELD WILL EXPAND BEFORE THE WAVE PULLS
EAST LATE TONIGHT. FOR NOW HAVE EXPANDED LIKELY POPS A BIT FARTHER
NORTH...TO NEAR A VERMILLION-WORTHINGTON LINE...WITH MORE WIDESPREAD
ACTIVITY SOUTH OF SIOUX CITY-SPENCER. PRECIP AMOUNTS AGAIN EXPECTED
TO REMAIN ON THE LIGHTER SIDE...AROUND A TENTH OR TWO OVER NORTHWEST
IOWA AND MUCH LESS FOR MOST OF SOUTHEAST SOUTH DAKOTA AND SOUTHWEST
MINNESOTA.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 415 AM CDT FRI APR 24 2015

ON SATURDAY MORNING...IT IS UNCLEAR HOW FAR TO EXTEND POPS FROM
NORTHWEST IOWA BACK TO THE WEST. MOST MODELS SUGGEST POPS ACROSS
NORTHWEST IOWA...BUT SOLUTIONS VARY TO THE WEST AS LIMITED DYNAMICS
AND RELATIVELY SHALLOW MOISTURE LIMIT PRECIPITATION POTENTIAL. WITH
EASTERLY FLOW CONTINUING THROUGH THE DAY...KEPT TEMPERATURES BELOW
NORMAL IN THE EAST WITH WARMER HIGHS ACROSS SOUTH CENTRAL SOUTH
DAKOTA.

MODELS SHOW SWATH OF DRIER AIR WORKING INTO THE REGION ON SUNDAY
FROM THE EAST.  WITH RELATIVELY DRY AIR...WENT AHEAD AND LOWERED DEW
POINTS AND SKY COVER AND RAISED TEMPERATURES.  THIS ONCE AGAIN WILL
CREATE ELEVATED FIRE WEATHER CONCERNS THOUGH WITH WINDS ALOFT ONLY
IN THE 15-20 KNOTS RANGE...AM NOT EXPECTING WINDS TO GET STRONG
ENOUGH FOR RED FLAG.

MONDAY LOOKS TO BE A RELATIVELY PLEASANT DAY ACROSS THE AREA WITH
WEAK WINDS AHEAD OF A FRONT MOVING THROUGH MONDAY EVENING. LEFT SOME
SLIGHT CHANCE POPS ACROSS THE NORTH WITH THE FRONTAL PASSAGE.
CONSIDERED REMOVING POPS ALL TOGETHER AS MOISTURE REMAINS QUITE
LIMITED.

LOOKS TO BE YET ANOTHER DRY WEEK ACROSS THE REGION. UPPER LEVEL JET
BUCKLES TO THE NORTH LEADING TO A WARMING TREND.  WINDS APPEAR TO
INCREASE LATE IN THE WEEK...POTENTIALLY CREATING ADDITIONAL FIRE
WEATHER CONCERNS LATE NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 648 AM CDT FRI APR 24 2015

AREAS OF MVFR CEILINGS NEAR/EAST OF I-29 CORRIDOR AT THE START OF
THE PERIOD EXPECTED TO BECOME MORE WIDESPREAD THROUGH THE DAY AS
INCREASING LOW LEVEL MOISTURE SPREADS INTO THE REGION. SHOWERS AND
ISOLATED THUNDERSTORMS WILL ALSO ACCOMPANY THE INCREASING MOISTURE
ACROSS THE AREA TODAY THROUGH TONIGHT. BOTH THE LOW CEILINGS AND
GREATER CHANCE OF PRECIPITATION WILL BE MORE PROMINENT EAST OF THE
JAMES RIVER VALLEY...WITH THE KHON TAF SITE LARGELY EXPECTED TO
REMAIN VFR UNTIL AFTER 03Z THIS EVENING WHEN A MORE EASTERLY LOW
LEVEL FLOW WILL PULL THE MVFR CEILINGS WESTWARD INTO THE JAMES
VALLEY.

GIVEN UNCERTAINTY REGARDING TIMING/LOCATION OF THUNDER CHANCES...
OPTED TO LEAVE OUT OF THE TAFS AT THIS TIME. HOWEVER...POTENTIAL
CANNOT BE RULED OUT GIVEN MID LEVEL INSTABILITY. KHON MAY ACTUALLY
SEE A GREATER THUNDER THREAT THAN KFSD/KSUX...AS INSTABILITY MAY
BECOME SURFACE BASED THERE IN THE LATE AFTERNOON/EVENING. HOWEVER
THIS THREAT CONDITIONAL ON WHETHER PRECIPITATION ACTUALLY DEVELOPS
IN THAT FAR NORTH...SO AGAIN WILL KEEP THE TAF DRY FOR NOW.

&&

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

$$

SHORT TERM...JH
LONG TERM...
AVIATION...JH


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