Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 300523
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
1223 AM CDT TUE SEP 30 2014

.UPDATE...
UPDATE TO 06Z AVIATION DISCUSSION BELOW.

JUST A FEW MINOR CHANGES MADE TO POPS THIS EVENING BASED ON LATEST
RADAR AND HI-RES MODELS. SLOWED DOWN EASTWARD PROGRESSION BY A FEW
HOURS AND INCREASED CURRENT POPS ACROSS SOUTH CENTRAL SD.
OTHERWISE FORECAST LOOKS TO BE ON TRACK WITH THE APPROACHING LOW
PRESSURE SYSTEM. SEE UPDATED AVIATION DISCUSSION BELOW.

&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT

STRATUS CLOUDS HAVE BROKEN UP A BIT MORE THAN EXPECTED ACROSS THE
EASTERN CWA...WHICH IN TURN HAVE ALLOWED SFC TEMPS TO RISE A FEW
DEGREES ABOVE FORECAST HIGHS. RAINFALL REMAINS CONFINED TO WESTERN
SD WITH JUST A FEW VERY ISO LIGHT SHOWERS EAST OF THE MISSOURI.
MODELS STILL IN PRETTY GOOD AGREEMENT IN DEEPENING THE SFC LOW
OVER THE NEBRASKA PANHANDLE LATE TONIGHT AND MOVING IT NORTH INTO
SOUTHWEST SD BY TUESDAY MORNING. OVERNIGHT...MOST OF THE RAINFALL
WILL BE OVER WESTERN SD. THE INTERESTING DETAILS LIE IN THE
FORECAST FOR TOMORROW IN REGARDS TO INSTABILITY AND CLOUD COVER.
THIS IS WHERE THE HI RES MODELS SHOW SOME DIFFERENCES IN REGARDS
TO CONVECTION DURING THE AFTERNOON. GREATEST INSTABILITY WILL BE
OVER SOUTHEAST SD BASED ON WHAT MODELS ARE SHOWING. ALTHOUGH...IT
WILL GREATLY DEPEND ON CLOUD COVER. IF AREAS FURTHER NORTH SEE ANY
BREAKS IN CLOUDS THEN DESTABILIZATION WILL OCCUR. REGARDLESS...LOW
LEVEL SHEAR WILL BE IMPRESSIVE ON THE ORDER OF 35 TO 40 KNOTS AND
STORMS THAT MANAGE TO GET GOING OVER EASTERN SD COULD BE CAPABLE
OF A SMALL TORNADO THREAT. THIS WILL BE MORE LIKELY THOUGH WHERE
THE GREATEST INSTABILITY SETS UP...WHICH NOW LOOKS TO BE OVER
SOUTHEAST SD BUT WILL HAVE TO MONITOR CLOUD COVER TRENDS. WINDS
WILL BE RATHER STRONG WITH THIS SYSTEM AS WELL AND COULD BE
LOOKING AT A PERIOD OF WIND ADVISORY CRITERIA IN PLACES. FAVORED
AREA FOR THIS THOUGH LIKELY ACROSS SOUTH CENTRAL SD. WILL LEAVE
FOR OVERNIGHT SHIFT TO CONSIDER. SYSTEM EXITS THE AREA TUESDAY
NIGHT...LEAVING DRYING CONDITIONS FOR WEDNESDAY.


.LONG TERM...THURSDAY THROUGH MONDAY
THE MODELS SHOW A LARGE LOW PRESSURE TROUGH AXIS RIGHT OVER THE
CENTRAL US TO BEGIN THE LONG TERM. AT THE SURFACE...HIGH PRESSURE
RIDGING ACROSS OUR CWA WILL BRING A DRY AND MOSTLY SUNNY DAY WITH
WEST TO NORTHWEST WINDS. TEMPERATURES SHOULD BE RIGHT NEAR NORMAL
IN THE MID TO UPPER 60S. THE MODELS THEN SHOW A SHORT WAVE TROUGH
IN CANADA DROPPING SOUTHEAST ACROSS OUR REGION THROUGH FRIDAY
MORNING. A STRONG COLD FRONT WILL FOLLOW IN BEHIND FOR THURSDAY
NIGHT. THIS WILL USHER IN COOLER AIR FOR FRIDAY ALONG WITH
BREEZY/WINDY NORTHWEST WINDS. HIGHS ON FRIDAY WILL BE COOLER AND
MAINLY IN THE MID 50S TO AROUND 60 DEGREES. SURFACE HIGH PRESSURE
RIDGING WILL BUILD OVER THE REGION FRIDAY NIGHT/SATURDAY MORNING
WITH CLEARING SKIES. WITH LIGHT WINDS AND DEW POINTS IN THE UPPER
20S TO THE LOWER 30S...THERE COULD BE SOME FROST FORMATION.
OTHERWISE...THE MODELS SHOW THE UPPER LEVEL FLOW PATTERN
TRANSITIONING TO LARGE UPPER LEVEL RIDGING ACROSS THE WESTERN US
WITH LARGE TROUGHING ACROSS THE EASTERN US. THIS WILL PUT US IN A
DRY PATTERN WITH GENERALLY NEAR TO ABOVE NORMAL TEMPERATURES
THROUGH THE REST OF THE PERIOD.

&&

.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

AN AREA OF LOW PRESSURE WILL MOVE OVER WESTERN SD TUESDAY. BANDS
OF SHOWERS/TSTORMS WILL WRAP AROUND THE LOW AND MAY AFFECT THE TAF
SITES INTERMITTENTLY. HI-RES MODELS KEEP THE PRECIP VERY SPOTTY
AND HAVE SIGNIFICANTLY SLOWED DOWN ANY EASTWARD PROGRESSION.
THEREFORE HAVE REMOVED MENTION OF VCTS FOR NOW AS CONFIDENCE IS
TOO LOW IN TIMING AND AREAL COVERAGE. SOUTHEAST WINDS ARE STILL
EXPECTED TO INCREASE TO 20 TO 30 KTS ACROSS THE WEST TONIGHT AND
ACROSS THE EAST DURING THE MORNING. WINDS WILL SHIFT TO THE
SOUTHWEST AT KMBG/KPIR TUESDAY EVENING. PRIMARILY VFR CIGS ACROSS
THE REGION WILL DETERIORATE TO MVFR BETWEEN 7Z AND 10Z. CIGS WILL
FLUCTUATE ON TUESDAY BETWEEN MVFR AND VFR.

&&

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

$$
UPDATE...WISE
SHORT TERM...TMT
LONG TERM...MOHR
AVIATION...WISE/SCARLETT

WEATHER.GOV/ABERDEEN




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