Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 220908
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
408 AM CDT TUE APR 22 2014

.SHORT TERM...TODAY THROUGH THURSDAY
CURRENT SURFACE ANALYSIS SHOWS A HIGH PRESSURE RIDGE ACROSS
EASTERN SOUTH DAKOTA...WITH RETURN FLOW WINDS SETTING UP ACROSS
WESTERN SOUTH DAKOTA. MODEST MOISTURE RETURN IS EXPECTED
TODAY...BUT NOT ENOUGH TO ALLEVIATE FIRE WX CONCERNS. STRONG AND
GUSTY SOUTHEASTERLY WINDS /PROBABLY JUST BELOW ADVISORY CRITERIA/
WILL COMBINE WITH THE DRY CONDITIONS TO CREATE VERY HIGH FIRE
DANGER TODAY. IF MOISTURE DOES NOT RETURN AS EXPECTED...A FIRE
WEATHER HEADLINE MAY NEED TO BE ISSUED. A WEAK SURFACE TROUGH/WARM
FRONT WILL SHIFT NORTHWARD ACROSS CENTRAL SOUTH DAKOTA THIS
AFTERNOON. THE GFS IS THE MOST PRONOUNCED WITH THIS FEATURE...AND
SHOWS SURFACE CONVERGENCE AND WEAK MOISTURE POOLING ALONG THIS
LINE. ENOUGH TO FORCE THE MODEL TO PRODUCE QPF. OTHER MODELS ARE
NOT AS IMPRESSIVE...AND WITH THE DRY LOW LEVELS...SKEPTICAL OF
PRECIPITATION DEVELOPMENT. LEFT A SLIGHT CHANCE POP IN THIS
EVENING TO ACCOUNT FOR ANY DEVELOPMENT HOWEVER.

THE MAIN SURFACE LOW THEN WORKS OUT OF THE NORTH CENTRAL ROCKIES
TONIGHT AND WEDNESDAY. THE GULF SHOULD OPEN AND MOISTURE RETURN
SHOULD INCREASE. DEWPOINTS ARE ONLY FORECAST IN THE 40S
HOWEVER...PERHAPS RISING INTO THE 50S ACROSS THE SOUTHERN CWA.
LIKEWISE ML CAPE VALUES WEDNESDAY AFTERNOON WILL BE
LIMITED...WITH ONLY A COUPLE OF HUNDRED J/KG AVAILABLE ALONG THE
FRONTAL BOUNDARY. PLENTY OF UPPER LEVEL DYNAMICS HOWEVER AS
ENERGY WILL BE ROUNDING THE BASE OF THE TROUGH...MOVING THROUGH
SOUTHWEST FLOW ACROSS THE NORTHERN PLAINS. CROSS SECTIONS SHOW UP
TO 20 UNITS OF OMEGA ACROSS THE EASTERN CWA BY WEDNESDAY
AFTERNOON. SO WHILE SEVERE CONVECTION LOOKS TO BE
LIMITED...GENERAL SHOWERS AND THUNDERSTORMS ARE LIKELY. THE ONLY
OTHER REAL FORECAST CHALLENGE WILL BE IF AND WHERE A DRY SLOT SETS
UP AND HOW QUICKLY THIS DRY AIR CAN BE OVERCOME.

BY LATE WEDNESDAY AND THURSDAY THE SURFACE COLD FRONT WILL PRETTY
MUCH BE EAST OF THE REGION...AND IT LOOKS LIKE DRY AIR WILL BE
QUICK TO ADVECT IN BEHIND THE FRONT. BEYOND WEDNESDAY ALMOST ALL
POPS ARE LIMITED TO THE FAR EASTERN CWA. WOULDNT BE SURPRISED TO
SEE THE MODELS START TO SLOW DOWN THIS SYSTEM A LITTLE BIT IN
SUBSEQUENT RUNS HOWEVER.

.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
THE RECENT PROGRESSIVE MID LEVEL FLOW PATTERN ACROSS THE CONUS IS
NOW EXPECTED TO BECOME QUITE BLOCKY BY THE END OF THE PERIOD.
UPPER TROF/LOW OVER THE NORTHERN PLAINS AT THE BEGINNING OF THE
PERIOD WILL BE REPLACED BY S/W RIDGING AHEAD OF THE NEXT SYSTEM
COMING ASHORE THE WEST COAST THIS WEEKEND. THAT SYSTEM MOVES
EAST/NE INTO THE WESTERN HIGH PLAINS BEFORE GETTING CUT OFF AS
BLOCK FORMS OVER SOUTH CENTRAL CANADA. THE MODELS ARE IN FAIR
AGREEMENT WITH THIS SCENARIO. THE EVOLUTION OF THE MID LEVEL FLOW
SETS UP A NW/SE BAROCLINIC ZONE OVER THE REGION...ESPECIALLY THE
SOUTHERN AND WESTERN CWA WHERE FOR A TIME STRONGLY DIFFLUENT FLOW
ALOFT WILL CREATE DECENT UVM/OVERRUNNING OVER THE AREA. HOWEVER
THE NORTHEAST CWA WILL HAVE THE LOWEST POPS GIVEN SOME INFLUENCE
FROM LARGE SFC HIGH SITUATED OVER HUDSONS BAY. THAT SFC HIGH AND
PLENTY OF CLOUDS AND PCPN WILL CONTRIBUTE TO BELOW NORMAL
TEMPERATURES FOR THE WEEKEND AND EARLY NEXT WEEK.

&&

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

VFR CONDITIONS ARE EXPECTED AT ALL TAF LOCATIONS THROUGH TONIGHT
AND TUESDAY. AS SURFACE HIGH PRESSURE SLIDES EAST AND THE SURFACE
PRESSURE GRADIENT TIGHTENS UP AND THE MIXING LAYER DEEPENS ON
TUESDAY...SOUTHEAST WINDS WILL INCREASE ACROSS THE REGION. EXPECT
SOUTHEAST WINDS TO INCREASE INTO THE 15 TO 25 KNOT RANGE WITH
GUSTS TO 25 TO 35 KNOTS AT ALL LOCATIONS INTO TUESDAY AFTERNOON
AND EVENING. WITH STRONG WAA ALONG WITH SOME INSTABILITY...EXPECT
SOME SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP TUESDAY
EVENING POSSIBLY AFFECTING THE TAF LOCATIONS.

&&

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

$$
SHORT TERM...SERR
LONG TERM...TDK
AVIATION...TDK

WEATHER.GOV/ABERDEEN






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