Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 200917
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
417 AM CDT SUN JUL 20 2014

.SHORT TERM...TODAY THROUGH TUESDAY
MANY CHALLENGES THROUGH THE SHORT TERM PERIOD REVOLVING AROUND
EXCESSIVE HEAT AND THUNDERSTORMS CHANCES.

TODAY...A TROUGH CURRENTLY EXTENDING ACROSS THE WESTERN DAKOTAS
WILL SLOWLY SHIFT EAST THROUGH THE DAY. AS THIS HAPPENS WINDS WILL
GAIN A MORE WESTERLY COMPONENT...SO DESPITE THE RESIDUAL FOREST
FIRE HAZE/SMOKE LIKELY TO BE OVER THE REGION...SHOULD SEE A LITTLE
BETTER MIXING THAN THE LAST COUPLE OF DAYS. BECAUSE OF THAT...STILL
MAINTAINING TEMPERATURES IN THE 90S ACROSS THE REGION TODAY.
APPARENT T GRIDS LOOK TO STAY BELOW 100 DEGREES...SO NO
IMMEDIATE HEADLINES...ALTHOUGH IT COULD BE MARGINAL ACROSS OUR
SOUTHERN CWA. VERY LITTLE IN THE WAY OF ANY UPPER LEVEL
FORCING/HEIGHT FALLS THIS AFTERNOON...HOWEVER ALMOST ALL THE HIGH
RES MODELS ARE SHOWING DAYTIME HEATING CONVECTION DEVELOPING ALONG
THE SURFACE BOUNDARY LATER THIS AFTERNOON AND EVENING...SO THREW
IN AN ISOLATED CHANCE. VERY LITTLE IN THE WAY OF BULK SHEAR...SO
ANYTHING THAT DOES MANAGE TO GO UP WILL LIKELY FALL APART QUICKLY.

MONDAY...MID LEVEL WARM AIR CONTINUES TO SPREAD OVER THE
REGION...WITH 700 MB TEMPERATURES RANGING FROM 12C TO
14C...INITIALLY PUTTING A PRETTY STRONG CAP OVER THE CWA.
LIKEWISE MODEL 850 MB TEMPERATURES ARE ON THE RISE...WITH THE
NORTHERN CWA AROUND 20C BUT THE SOUTHERN CWA AS HIGH AS 30C. THIS
SHOULD ALLOW FOR AFTERNOON HIGH TEMPERATURES IN THE 90S NORTH TO
100 DEGREES SOUTH. MOISTURE WILL BE SURGING NORTHWARD AND WRAPPING
AROUND A DEEPENING SURFACE LOW AS WELL. THE COMBINED HEAT AND
HUMIDITY WILL RESULT IN APPARENT TEMPERATURES AT OR ABOVE 100
DEGREES FOR MUCH OF THE CWA. THEREFORE WENT AHEAD AND ISSUED A
HEAT ADVISORY FOR MONDAY. BEYOND THE HEAT...THE OTHER LARGE
CONCERN IS THE SEVERE THUNDERSTORM POTENTIAL ACROSS THE CWA. WHILE
A STRONG CAP WILL BE IN PLACE INITIALLY...THE COMBINATION OF
SHORTWAVE ENERGY/500 MB HEIGHTS FALLS AND STRONG INSTABILITY /CAPE
VALUES EXCEEDING 3000 J/KG/ SHOULD BE ENOUGH COMBINED FORCING TO
BREAK DOWN THE CAP AND RESULT IN RAPID STORM DEVELOP. AND WHEN
STORMS DO GET GOING THEY WILL BE SUSTAINED BY 30 TO 40 KTS OF 0-6
KM SHEAR. GIVEN WHAT SEEMS LIKE A BALANCED SHEAR/COLD POOL
SITUATION AND MEAN FLOW NEARLY PARALLEL TO THE SURFACE
BOUNDARY...WOULD EXPECT INITIAL ORDINARY CELLS TO DEVELOP INTO A
MULTI-CELL LINE OR CLUSTER. WENT AHEAD AND ADDED A SEVERE MENTION
INTO THE FORECAST FOR MONDAY AFTERNOON AND NIGHT.

RELATIVELY COOLER AIR FILTERS IN BEHIND THE COLD FRONT ON
TUESDAY...ALTHOUGH ADDITIONAL SHORTWAVE ENERGY WARRANTS AT LEAST A
LOW POP IN THE GRIDS THROUGH THE AFTERNOON.

.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
AS THE PERIOD OPENS...MEDIUM RANGE SOLUTIONS ALL HIGHLIGHT SURFACE
HIGH PRESSURE BUILDING IN...AND BRINGING WITH IT DRIER AND
RELATIVELY COOLER AIR. TUESDAY NIGHT AND WEDNESDAY ARE STILL DRY
WEATHER FORECAST PERIODS AS SUCH. HOWEVER...THE SURFACE HIGH IS
QUICKLY DEPARTING TO THE EAST BY WEDNESDAY NIGHT...WITH RETURN
FLOW SOUTHERLY WINDS /STRONG LOW LEVEL JET/ PUSHING HIGHER OCTANE
AIR BACK NORTH ACROSS THE CENTRAL AND NORTHERN HIGH PLAINS. THE
ECMWF AND GFS BOTH STILL HAVE A SMATTERING OF QPF ACROSS THE CWA
WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING WEST OF THE JAMES
RIVER VALLEY AND THIS SHOWS UP IN ALLBLEND POPS. AN UPPER LEVEL
RIDGE IS FORECAST TO RE-ESTABLISH ACROSS THE UPPER
MID-WEST/WESTERN GREAT LAKES REGION THURSDAY -> SATURDAY...WHILE
A SURFACE TROF SLOWLY TRUDGES EAST ACROSS THE CWA THURSDAY AND
FRIDAY. A SMALL RIBBON OF INSTABILITY /APPX 1500-2500 JOULES/ AND
SOMEWHERE BETWEEN 20 AND 30 KNOTS OF DEEP LAYER SHEAR ARE FORECAST
TO TRANSLATE EASTWARD WITH THE SURFACE TROF...AND THIS IS
PRESUMABLY WHAT FUELS THE ALLBLEND POPS/WX MENTION IN THE GRIDS
FOR THURSDAY/FRIDAY. EACH DAY WILL BE FILLED WITH ITS OWN
MID-LEVEL WARM TEMPS AND CONVECTION-CAPPING ISSUES/CHALLENGES.
BUT AT THIS POINT...CAN`T RULE OUT A STORM OR TWO GETTING GOING.
BY THE WEEKEND...THERE IS STILL SOME INDICATION OF ANOTHER STRONG
COLD FRONTAL BLAST SWEEPING THROUGH AND DRYING THINGS OUT/COOLING
TEMPS OFF OVER THE WEEKEND.

&&

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

PREVAILING VFR CONDITIONS ARE EXPECTED FOR ALL TERMINALS THROUGH
THE VALID TAF PERIOD. HAZY CONDITIONS ARE EXPECTED TO CONTINUE.
IT`S A LOW PROBABILITY OF OCCURRING BUT...BETWEEN NOW AND APPX
15Z SUNDAY...A FEW THUNDERSTORMS COULD DEVELOP ACROSS THE REGION.
LOW LEVEL JET SOUTHERLY WINDS ARE PUSHING WARMER...MORE MOIST AIR
INTO THE REGION...A TYPICALLY GOOD SET UP FOR ELEVATED
/ACCAS-TYPE/ CONVECTION. NOTHING SHOWING UP YET ON RADAR OR
SATELLITE THOUGH...SO TAFS CURRENTLY AREN`T CARRYING ANY THUNDER
MENTION.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...HEAT ADVISORY FROM 11 AM CDT /10 AM MDT/ TO 9 PM CDT /8 PM MDT/
     MONDAY FOR BROWN-BUFFALO-CLARK-CODINGTON-DAY-DEUEL-FAULK-
     GRANT-HAMLIN-HAND-HUGHES-HYDE-JONES-LYMAN-MARSHALL-ROBERTS-
     SPINK-STANLEY-SULLY.

MN...HEAT ADVISORY FROM 11 AM TO 9 PM CDT MONDAY FOR BIG STONE-
     TRAVERSE.

&&

$$
SHORT TERM...SERR
LONG TERM...DORN
AVIATION...DORN

WEATHER.GOV/ABERDEEN




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