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 272021
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
321 PM CDT WED MAY 27 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 321 PM CDT WED MAY 27 2015

CONVECTIVE POTENTIAL OVER THE NEXT 24 HOURS IS MAIN CHALLENGE OF
THIS SHORT TERM FORECAST. EVENING SHOULD START OUT DRY...THOUGH A
FEW SPRINKLES FROM MID LEVEL CLOUD DECK MAY IMPACT FAR SOUTHWEST
AREAS IN THE LATE AFTERNOON/EARLY EVENING. BY LATE EVENING/AFTER
MIDNIGHT...INCREASING LOW LEVEL JET SHOULD RESULT IN STRONGER
MOISTURE TRANSPORT INTO WESTERN HALF OF THE FORECAST AREA FOR THE
LATTER HALF OF THE NIGHT. THIS WILL COMBINE WITH MODEST ELEVATED
INSTABILITY ABOVE 850MB TO PRODUCE ISOLATED/SCATTERED SHOWERS AND/OR
STORMS TO DEVELOP DURING THE EARLY MORNING HOURS...MAINLY IN AREAS
WEST OF I-29 THROUGH DAYBREAK. THE INCREASE IN CLOUDS ALONG WITH A
SOUTHERLY BREEZE OVERNIGHT SHOULD LIMIT LOWS TO AROUND 60 FOR MOST
AREAS.

THURSDAY DAYTIME FORECAST A BIT MORE TRICKY...AS MULTIPLE WEAK MID
LEVEL WAVES TRACK ACROSS THE CENTRAL/NORTHERN PLAINS. PARTS OF OUR
AREA COULD VERY WELL END UP BETWEEN THESE TWO WAVES...AND MODELS NOT
SHOWING GREAT AGREEMENT ON TIMING/LOCATION. HOWEVER...SOME CONSENSUS
HINTING AT CENTRAL PLAINS WAVE TRACKING A LITTLE CLOSER TO NORTHWEST
IOWA THAN PREVIOUS RUNS...BRINGING A BETTER CHANCE OF SHOWERS/STORMS
INTO SOUTHEAST PARTS OF THE AREA IN THE LATE MORNING/AFTERNOON. NOT
CONFIDENT ENOUGH JUST YET TO BUMP POPS INTO LIKELY RANGE FOR ANY ONE
LOCATION DURING THE DAY...BUT MORE FAVORED AREAS APPEAR TO BE IN OUR
SOUTHEAST AS MENTIONED ABOVE...THEN IN OUR FAR WESTERN AREAS LATE IN
THE DAY AS SURFACE BOUNDARY BEGINS TO APPROACH THAT AREA FROM THE
WEST. DEEP LAYER SHEAR IS QUITE WEAK THROUGH THE DAY THROUGHOUT THE
AREA...AND EASTERN AREAS ALSO SEE LIMITED INSTABILITY. WESTERN AREAS
SHOULD BECOME A LITTLE MORE UNSTABLE THROUGH THE AFTERNOON WITH MORE
FAVORABLE HEATING...BUT FAIRLY NARROW CAPE PROFILES DUE TO WEAK MID
LEVEL LAPSE RATES PER FORECAST SOUNDINGS...SO MARGINAL HAIL THREAT
IN OUR WESTERN AREAS AS CURRENTLY STATED IN HWO STILL REASONABLE.


.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 321 PM CDT WED MAY 27 2015

SHOWERS AND STORMS THURSDAY NIGHT SHOULD BE PLENTIFUL OVER THE NIGHT
AS A WHOLE...THOUGH DETAILS ON AMOUNT OF COVERAGE REMAIN TRICKY JUST
AS THEY APPEARED YESTERDAY. ON LAST NIGHTS MODEL RUNS SUPPORT SEEMED
AMPLE FOR ONLY SPOTTY COVERAGE SOUTHEAST...IN NORTHWEST IOWA...WITH
COVERAGE INCREASING FROM THE NORTHWEST AS THE COLD FRONT APPROACHED.
HOWEVER TODAYS RUNS ALL SHOW AT LEAST A SECONDARY CONCENTRATION IN
THE SOUTHEAST IN THE EARLY EVENING. WILL COVER WITH POPS MORE
GENERAL WITH JUST SLIGHTLY LOWER POPS IN THE MIDDLE OF THE AREA
THURSDAY EVENING...TRANSITIONING TO HIGHER COVERAGE SOUTHEAST
LATE AT NIGHT...WHEN THE COLD FRONT SHOULD BE MOVING OVER THE
NORTHWEST PART OF THE AREA. LOW TEMPERATURES WILL BE IN THE
UPPER 50S NORTHWEST TO THE LOWER 60S SOUTHEAST.

FRIDAY WILL BRING COVERAGE DECREASING FROM THE NORTHWEST BEHIND THE
FRONT. SHOWERS SHOULD END AND CLOUDS BEGIN TO DECREASE
NORTH/NORTHWEST IN THE AFTERNOON. COOLER TEMPERATURES WITH THE
CLOUDS AND COOLING WILL HOLD HGIHS TO THE 60S...EXCEPT SOME LOWER
70S SOUTHEAST.

A FEW SHOWERS MAY LINGER FAR SOUTHEAST FRIDAY EVENING. OTHERWISE
CLEARING IS EXPECTED OVER THE AREA. MODELS ARE IN GOOD AGREEMENT ON
THIS FASTER DRYING AND CLEARING THAN WE HAD BEFORE WITH HIGH
PRESSURE BEGINNING TO RIDGE INTO THE AREA FROM THE NORTH.

THE WEEKEND LOOKS DRY AND COOL THROUGH SATURDAY NIGHT THEN THE START
OF WARMING FROM THE WEST SUNDAY.

MONDAY THROUGH WEDNESDAY WILL BRING WARMER TEMPERATURES WITH THE
STRONG PLAINS UPPER RIDGING. THE STRONG RIDGING SHOULD PREVENT OR
LIMIT THUNDERSTORMS MONDAY AND TUESDAY DESPITE AN INCREASE IN
MOISTURE AND INSTABILITY. THE APPROACH OF AN UPPER TROUGH AND
SURFACE COLD FRONT WILL BRING ENOUGH LIFT TO INCREASE THUNDERSTORM
COVERAGE AT MIDWEEK. THE WARMER TEMPERATURES WILL BE NEAR TO A BIT
ABOVE NORMAL FOR THE START OF JUNE...BUT NOT SCORCHING.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1245 PM CDT WED MAY 27 2015

VFR CONDITIONS EXPECTED TO DOMINATE THROUGH THE PERIOD. WESTERLY
SURFACE FLOW 10-15KT EAST OF SURFACE RIDGE AXIS...LOCATED NEAR A
KHON-KSUX LINE AT THE START OF THE PERIOD...WILL BECOME SOUTHERLY
AS THE RIDGE AXIS SHIFTS EAST THROUGH THE AFTERNOON/EARLY EVENING.
SOUTHERLY WINDS SHOULD THEN GENERALLY STAY IN 5-10KT RANGE THROUGH
THE OVERNIGHT HOURS...AS LOW LEVEL JET INCREASES OVER AREAS WEST
OF I-29 CORRIDOR. LATEST MODELS A LITTLE WEAKER WITH THE STRONGEST
WINDS ALOFT SO HAVE REMOVED MENTION OF LLWS...BUT MAY STILL BE
MARGINAL FOR KHON AREA AFTER 06Z AND WILL HAVE TO WATCH.

MOISTURE RETURN STILL PRETTY MEAGER...BUT WITH ONGOING ELEVATED
ACTIVITY JUST WEST OF THE FORECAST AREA AT THE START OF THIS TAF
PERIOD...CLEARLY NOT IMPOSSIBLE FOR HIGH-BASED SHRA TO DEVELOP AS
THE LOW LEVEL JET INCREASES LATER TONIGHT/EARLY THURSDAY. HAVE
ADDED VCSH TO KHON...BUT THUNDER POTENTIAL TOO ISOLATED TO MENTION
AT THIS TIME. CONFIDENCE LOWER IN PROGRESSION OF SHRA/TSRA EAST
TOWARD THE I-29 CORRIDOR AFTER SUNRISE...SO KFSD/KSUX TAFS 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.