Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 300334
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1034 PM CDT WED APR 29 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 310 PM CDT WED APR 29 2015

PLEASANT SPRING WEATHER CONTINUES TONIGHT AND INTO THURSDAY ACROSS
THE REGION...UNDER THE INFLUENCE OF A STRENGTHENING UPPER RIDGE.
WINDS WILL BE LIGHT AND GRADUALLY TURN SOUTHEAST TONIGHT...THEN
INCREASE OUT OF THE SOUTH THURSDAY MORNING. WEST OF THE JAMES
RIVER...WINDS MAY BECOME MARGINALLY BREEZY AROUND 15 MPH WITH HIGHER
GUSTS LATE MORNING INTO THE AFTERNOON.

WITH MIXY CONDITIONS AND A WARM AIRMASS...TEMPERATURES WILL ONCE
AGAIN WARM INTO THE 70S AND COULD EVEN REACH THE LOWER 80S IN THE
FAR WEST ON THURSDAY. WHILE THERE IS SOME INDICATION THAT MOISTURE
RETURN WILL DEVELOP...THINK THAT DEWPOINTS WILL BE SLOWER TO IMPROVE
THAN GUIDANCE SUGGESTS. WENT LARGELY BELOW GUIDANCE...WHICH RESULTS
IN AFTERNOON HUMIDITY AROUND 20 TO 25 PERCENT. LIGHT WINDS WILL HELP
MITIGATE FIRE DANGER...ESPECIALLY IN THE EAST. HOWEVER...STRONGER
WINDS WEST OF THE JAMES WILL BOLSTER FIRE DANGER TO VERY HIGH IN THE
AFTERNOON. THINK THAT WINDS WILL REMAIN JUST BELOW RED FLAG
CONDITIONS...AND THE ARRIVAL OF INCREASED AFTERNOON MOISTURE IN THIS
AREA SHOULD BRING HUMIDITY VALUES UP LATER IN THE DAY.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 310 PM CDT WED APR 29 2015

THURSDAY NIGHT AND FRIDAY WILL BEGIN A MAJOR PATTERN TRANSITION TO A
ZONAL FLOW AS A STRONG PACIFIC WESTERLY FLOW DEVELOPS ALONG THE
CANADIAN BORDER AREA AND RIDGING DEVELOPS OVER THE SOUTHERN PLAINS.
THE FIRST SHOT IS A RIDGE FLATTENING WAVE AND WEAK OCCLUSION MOVING
OVER THE AREA THURSDAY NIGHT AND FRIDAY. MOISTURE AND INSTABILITY
WILL SHOW A MODEST INCREASE AS IT WILL STILL BE PRETTY DRY FURTHER
SOUTH OVER THE PLAINS. SHOWER AND THUNDERSTORM THREAT WITH VERY
MODEST RAINFALL POTENTIAL WILL PROGRESS WEST NORTHWEST TO EAST
SOUTHEAST WITH JUST A LITTLE SLOWDOWN FROM EARLIER PROJECTIONS. THIS
THREAT SHOULD MOVE OUT FOR FRIDAY NIGHT AND ANOTHER THREAT WILL
START SLOWLY OVER THE WEEKEND...BUT PICK UP STEAM AS MOISTURE AND
INSTABILITY CONTINUE TO INCREASE FROM THE SOUTH. AS A WEAK UPPER
WAVE CONES THROUGH AND A SURFACE FRONT PASSES...THE GREATEST THREAT
WILL BE SUNDAY NIGHT. BY THIS TIME RAINFALL POTENTIAL IN STORMS WILL
BE INCREASING QUITE A BIT.

THE STORM THREAT WILL THEN SUBSIDE BUT NOT GO AWAY FOR A COUPLE DAYS
WITH THE FRONT LYING NOT FAR TO THE SOUTH. MODELS CURRENTLY PROJECT
A PACIFIC TROUGH COMING ASHORE WAY DOWN ON THE BAJA COAST BEING
EJECTED NORTHEAST BY A DIGGING PACIFIC NORTHWEST TROUGH...SETTING UP
POTENTIAL FOR A MAJOR WET SYSTEM NEAR THE END OF THE PERIOD
WEDNESDAY/THURSDAY. WHILE THAT WILL DEPEND ON SEVERAL FACTORS FOR A
TIME PERIOD A WEEK AHEAD...THERE ARE PLENTY OF SIGNS FOR A
TRANSITION FROM OUR DRY EARLY SPRING INTO WHAT IS NORMALLY OUR
WETTEST MONTH.

TEMPERATURES WILL BE MILD TO WARM WITH LOTS OF 70S FOR HIGHS...SOME
80S ESPECIALLY SUNDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1033 PM CDT WED APR 29 2015

VFR CONDITIONS EXPECTED THROUGH THURSDAY. CIRRUS WILL CONTINUE TO
STREAM ACROSS THE AREA AS WINDS TURN SOUTHERLY BY THURSDAY
MORNING. A BRIEF PERIOD OF GUSTS TO 20-25 KNOTS MAY BE
POSSIBLE...ESPECIALLY WEST OF THE JAMES RIVER.

&&

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

$$

SHORT TERM...
LONG TERM...
AVIATION...DUX


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