Area Forecast Discussion
Issued by NWS Aberdeen, SD

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174
FXUS63 KABR 171126 AAA
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
626 AM CDT SUN MAY 17 2015

.UPDATE...
ISSUED AT 623 AM CDT SUN MAY 17 2015

SEE UPDATED AVIATION DISCUSSION BELOW.


&&

.SHORT TERM...(TODAY THROUGH TUESDAY AFTERNOON)
ISSUED AT 414 AM CDT SUN MAY 17 2015

RAINFALL IS BEGINNING TO SPREAD BACK INTO THE CWA AS THE MAIN UPPER
LOW ENERGY BEGINS MOVING INTO THE REGION. ARRIVAL IS ACTUALLY ABOUT
RIGHT ON TIME FROM WHAT HI RES MODELS HAD BEEN SHOWING LAST EVENING.
WILL CONTINUE TO SEE RAINFALL INCREASE IN AREAL COVERAGE AND
INTENSITY OVER THE NEXT SEVERAL HOURS. PRECIPITATION WILL THEN
REMAIN OVER THE REGION THROUGH MUCH OF THE DAY...ALTHOUGH THE FAR
WESTERN CWA MAY START TO DRY OUT LATER THIS AFTERNOON. THUNDERSTORM
POTENTIAL IS STILL THERE TOO...ALTHOUGH THREAT FOR SEVERE WEATHER
LOOKS TO BE ALONG THE EASTERN FRINGE OF THE CWA AND INTO MN. TRACK
OF THE SFC LOW TODAY IS ACROSS EASTERN SD/WESTERN MN AS IT DEPENDS
AND MOVES NORTHWARD. IF ANY STORMS GET GOING OVER THE VERY FAR
EASTERN CWA...AN ISOLATED TORNADO THREAT WILL EXIST GIVEN THE
SURFACE VORTICITY AND LOW LEVEL SHEAR PRESENT.

AS THE LOW MOVES NORTH OF THE REGION LATE THIS AFTERNOON AND
EVENING...FOCUS WILL THEN SHIFT TO THE STRONG NORTHWEST WINDS
DEVELOPING ON ITS BACK SIDE AND THE COLDER AIR MOVING IN. IN
FACT...STRONG COLD AIR ADVECTION THIS AFTERNOON WILL BRING FALLING
TEMPERATURES FOR MUCH OF THE CWA...ESPECIALLY ALONG AND WEST OF THE
JAMES VALLEY. BUFKIT SOUNDINGS SHOW PRETTY HEFTY WINDS LATE THIS
AFTERNOON INTO THE EVENING AS STEEPER LOW LEVEL LAPSE RATES DEVELOP.
850 MB WINDS ARE ON THE ORDER OF 40 TO 50 KNOTS. RIGHT NOW IT
APPEARS THE BEST POTENTIAL FOR WIND ADVISORY SPEEDS WILL BE ACROSS
THE NORTHERN CWA AND ESPECIALLY INTO THE HIGHER ELEVATION COTEAU
REGION OF NORTHEAST SD. HAVE ISSUED A WIND ADVISORY FROM LATE THIS
AFTERNOON/EVENING INTO THE OVERNIGHT HOURS. DAY SHIFT MAY HAVE TO
ADJUST TIMING A BIT AND WATCH IF POTENTIAL EXISTS FOR ADDITIONAL
COUNTIES. MUCH COLDER AIR ALSO MOVES IN TONIGHT AND THERMAL PROFILES
SUPPORT A RAIN/SNOW MIX OR EVEN ALL SNOW LATE TONIGHT FOR THE FAR
NORTHERN CWA. DO NOT EXPECT MUCH IN THE WAY OF ACCUMS BUT
NONETHELESS...SNOW THIS LATE IN MAY IS RATHER RARE.

ONCE THIS STORM SYSTEM IS HISTORY...WILL THEN BE WATCHING THE COOL
CANADIAN HIGH PRESSURE BUILDING SOUTH OVER THE DAKOTAS MONDAY INTO
MONDAY NIGHT. IT WILL BE BRINGING WITH IT SOME RATHER COLD
TEMPERATURES AND EXPECTING LOWS BY SUNRISE TUESDAY TO BE NEAR OR
BELOW FREEZING FOR MUCH OF THE CWA. HAVE INCLUDED FROST MENTION IN
THE FORECAST. WILL HAVE TO CLOSELY WATCH THE PRESSURE GRADIENT TO
SEE IF WIND SPEEDS STAY UP ENOUGH THROUGH 12Z TUESDAY TO PREVENT A
TOTAL FREE FALL IN TEMPS. AND ONCE AGAIN...THE WET GROUND MAY KEEP
TEMPS UP A TAD. THAT SAID THOUGH...THE COLD AIR MASS ALONE LOOKS TO
BRING THE POTENTIAL FOR UPPER 20S/LOW 30S BY EARLY TUESDAY MORNING.


.LONG TERM...(TUESDAY EVENING THROUGH SATURDAY)
ISSUED AT 414 AM CDT SUN MAY 17 2015

THE EXTENDED PERIOD WILL START OFF WITH HIGH PRESSURE TO THE NORTH
OF THE REGION AND PRECIPITATION ASSOCIATED WITH LOW PRESSURE OVER
THE WESTERN HIGH PLAINS OCCURRING ACROSS PORTIONS OF WESTERN AND
SOUTHERN SOUTH DAKOTA. THE HIGH WILL SLOWLY DRIFT SOUTHWARD AND
LOOKS TO SETTLE IN OVER THE REGION WEDNESDAY NIGHT THROUGH EARLY
FRIDAY BEFORE GETTING PUSHED EASTWARD AHEAD OF A STRENGTHENING LOW
PRESSURE SYSTEM OVER COLORADO. THIS LOW WILL TRACK EASTWARD OVER THE
CENTRAL PLAINS OVER THE WEEKEND...BRINGING INCREASED PRECIPITATION
CHANCES.

TEMPERATURES WILL BE A BIT COOL TO START THE PERIOD UNDER THE
INFLUENCE OF THE SURFACE HIGH...WITH HIGHS MAINLY IN THE 50S ON
WEDNESDAY. WILL THEN SEE A RETURN TO NEAR NORMAL VALUES WITH HIGHS
IN THE 60S THURSDAY THROUGH SATURDAY. A COUPLE OF COOL NIGHTS OF
LOWS IN THE 30S TUESDAY NIGHT AND WEDNESDAY NIGHT...THEN A RETURN TO
OVERNIGHT LOWS IN THE 40S FOR THE REMAINDER OF THE PERIOD.


&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 623 AM CDT SUN MAY 17 2015

SCATTERED SHOWERS AND THUNDERSTORMS WILL OCCUR ACROSS THE WESTERN
THIRD OF THE CWA TODAY...WITH MORE WIDESPREAD RAIN SHOWERS ACROSS
THE CENTRAL AND EAST. IFR/MVFR CIGS WILL BE COMMON ACROSS THE AREA
TODAY...WITH VSBYS LIKELY FALLING INTO THE MVFR CATEGORY WITH THE
PRECIPITATION. THE RAIN WILL PUSH OUT OF THE AREA AFTER 06Z...BUT
THE LOW CIGS WILL REMAIN IN PLACE.

&&


.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM 7 PM THIS EVENING TO 4 AM CDT MONDAY FOR SDZ007-
     008-011.

     WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 1 AM CDT MONDAY FOR
     SDZ005-006-010.

MN...NONE.
&&

$$

SHORT TERM...TMT
LONG TERM...PARKIN
AVIATION...PARKIN



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