Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 251750
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
1250 PM CDT SAT JUL 25 2015

.UPDATE...

SEE UPDATED AVIATION DISCUSSION FOR 18Z TAFS BELOW.

ISSUED AT 1030 AM CDT SAT JUL 25 2015

STILL A FEW LINGERING SHOWERS AND THUNDERSTORMS ACROSS
HAND...SPINK...MARSHALL COUNTIES AND EASTWARD. THEY ARE
DISSIPATING QUICKLY HOWEVER...AND SHOULD DIMINISH BY LATE MORNING
OR EARLY AFTERNOON. WE WILL THEN BE WATCHING HOW QUICKLY THE
CLEARING LINE PUSHES EAST. TRENDS SEEMS TO SHOW A PRETTY FAST
EASTWARD MOVEMENT...SO /AT THE VERY LEAST/ THE WESTERN HALF OF THE
CWA SHOULD HAVE AMBLE OPPORTUNITY TO DESTABILIZE THIS AFTERNOON.
DEWPOINTS ARE CURRENTLY IN THE LOW TO MID 60S ACROSS THE
WEST...BUT WILL MONITOR MOISTURE RETURN THROUGH THE DAY. MODELS
CONTINUE TO SHOW STEEP LAPSE RATES AND 40 TO 50 KTS OF BULK
SHEAR...SO THE SEVERE SET UP LOOKS PRETTY DECENT. HI RES MODELS
SEEM TO SUGGEST THE BEST SEVERE CHANCE IS SOUTH OF HIGHWAY
212...BUT EVEN MORE SPECIFICALLY THE PIERRE AREA AND SOUTHWARD
LOOKS TO REALLY BE IN THE PRIME LOCATION TODAY. THEREFORE...ADDED
SEVERE WORDING FOR THIS AREA. OTHER GRID CHANGES INCLUDE ADJUSTING
POPS/SKY AND LOWERING TEMPERATURES ACROSS THE EASTERN CWA JUST A
FEW DEGREES SINCE THEY WILL BE UNDER CLOUD COVER THE LONGEST
TODAY.

&&

.SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON)
ISSUED AT 332 AM CDT SAT JUL 25 2015

OVERALL VERY LOW CONFIDENCE IN FORECAST FOR TODAY. WEAK CONVECTION
CONTINUES IN WESTERN SOUTH DAKOTA ASSOCIATED WITH THE NEXT WAVE
WHICH ALSO FEATURES FAVORABLE PLACEMENT OF A 100KT JET ENTRANCE
REGION. AS THIS WAVE CONTINUES EAST...THE MAIN FOCUS SHIFTS TO
SEVERE WEATHER POTENTIAL FOR LATER THIS AFTERNOON. THE MAIN PROBLEM
COMES FROM POOR CONSISTENCY BETWEEN CAM SOLUTIONS AND DETERMINISTIC
GUIDANCE IN HANDLING THE OUTCOME OF THIS WAVE. LIKELY FACTORS ARE
CONVECTIVE DEBRIS AND A LACK OF ANY SURFACE FOCUS MECHANISM UNDER
LIGHT EASTERLY FLOW. BEST CAPE/MID LEVEL LAPSE RATES CONTINUES TO
CENTER AROUND KPIR TO K9V9 DESPITE HIGHER 700MB TEMPERATURES. EVEN
IF MLCAPE VALUES ONLY TOP OUT AROUND 1-2000 J/KG...0-6KT SHEAR IS
BETWEEN 30 AND 50KTS SUPPORTING STORM ORGANIZATION AND THE SEVERE
THREAT.  THERE IS NO LOW LEVEL JET SUPPORT TONIGHT...SO EXPECT
STORMS TO WEAKEN BUT CONTINUE EAST UNDER THE INFLUENCE OF THE
SHORTWAVE.

SUNDAY WILL SEE COOL MID LEVEL TEMPERATURES...BUT WITHOUT ANY
FEATURES ALOFT...CONVECTIVE POTENTIAL IS RATHER LIMITED IN SCALE AND
SCOPE. MID LEVEL TEMPERATURES BEGIN TO WARM LATE SUNDAY INTO
MONDAY...PEAKING AROUND +13C. STEEPENING MID LEVEL LAPSE RATES CAN
STILL RESULT IN SOME ACCAS SHOWERS/STORMS...BUT SURFACE BASED
CONVECTION APPEARS UNLIKELY.

.LONG TERM...(MONDAY EVENING THROUGH FRIDAY)
ISSUED AT 332 AM CDT SAT JUL 25 2015

A FAIRLY STRONG LOW PRESSURE SYSTEM WILL TRACK ACROSS THE NORTHERN
PLAINS MONDAY NIGHT AND TUESDAY...WITH THE MAIN FRONTAL BOUNDARY
TRACKING ACROSS THE CWA LATE MONDAY NIGHT AND TUESDAY MORNING. THERE
WILL BE SOME INSTABILITY AROUND...AND A DECENT LOW LEVEL JET SET UP
DURING THIS TIME...ALONG WITH 30-50 KTS OF SHEAR. HOWEVER...WILL
ALSO SEE A VERY STRONG MID LEVEL CAP...WITH 700 MB TEMPERATURES ON
THE ORDER OF +13C TO +17C...WHICH WILL LIKELY BE ENOUGH TO HINDER
CONVECTION. FOR NOW...WILL KEEP SOME SCHC TO LOW CHC POPS GOING IN
CASE THE MODELS ARE TOO HIGH WITH THESE TEMPERATURES. THE REMAINDER
OF THE PERIOD LOOKS DRY AS HIGH PRESSURE BECOMES THE DOMINANT
SURFACE FEATURE.

TEMPERATURES WILL GENERALLY BE NEAR TO SLIGHTLY ABOVE
NORMAL...MAINLY IN THE 80S FOR HIGHS AND IN THE UPPER 50S TO MID 60S
FOR OVERNIGHT LOWS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1240 PM CDT SAT JUL 25 2015

EARLY MORNING CONVECTION HAS WEAKENED AND PUSHED EAST OF THE AREA
AS OF 1730Z. IN ITS WAKE...SEEING CLEARING SKIES WITH VFR
CONDITIONS EXPECTED AREA-WIDE THRU MID/LATE AFTERNOON. STILL
EXPECTING THE POSSIBILITY FOR SCATTERED STRONG TO SEVERE
THUNDERSTORMS AFTER 22Z. STILL UNCERTAINTY WHERE THE MOST
WIDESPREAD STORM COVERAGE WILL BE AND WHETHER OR NOT IT WILL
IMPACT SPECIFIC TERMINALS. AT THIS TIME...FELT THE GREATEST
COVERAGE OF STORMS WOULD BE IN SRN SD...THUS INCLUDED A TEMPO
TSRA AT KPIR. AT KABR/KATY...INCLUDED ONLY A COUPLE HOURS OF VCTS
FOR NOW. ANY STORMS COULD PRODUCE STRONG GUSTY WINDS...HAIL...AND
A PERIOD OF MVFR/IFR VSBY AND CIGS. MOST OF THE ACTIVITY SHOULD BE
SOUTHEAST OF THE AREA AFTER 05Z.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

$$

UPDATE...SERR
SHORT TERM...CONNELLY
LONG TERM...PARKIN
AVIATION...FOWLE



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