126
FXUS63 KABR 241251 AAA
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
751 AM CDT THU JUL 24 2008
UPDATE
JUST A QUICK UPDATE TO ADJUST SKYCOVER MENTION TO MOSTLY CLOUDY
THIS MORNING AS LOW STRATUS HAS JUST ABOUT SOCKED IN THE ENTIRE
CWA THIS MORNING /AS OF 12Z/. ALSO RETWEAKED WX GRIDS THROUGH 15Z
THIS MORNING TO BEEF UP THE FOG WORDING ACROSS THE WESTERN HALF OF
ZONES WHERE SURFACE OBS AND MORNING COOP REPORTS TRICKLING IN ARE
INDICATING SOME AREAL COVERAGE OF DENSE FOG.
PREV DISCUSSION
SHORT TERM
TODAY THROUGH 00Z SUNDAY
MAIN FCST CHALLENGE FACING THE SHORT TERM IS PCPN CHANCES AGAIN
TODAY THROUGH FRIDAY MORNING.
LATEST MSAS ANLYS SHOWS SFC BOUNDARY DRAPED NW-SE ACROSS WRN PART
OF THE CWA...WITH ONLY TELLING DIFFERENCE IS THE L-M50 DWPTS
LOCATED ACROSS THE NW PART OF SD. AREAS OF LOW STRATUS/FOG IS
SETTING UP UNDER TROF AXIS WHERE MIXING WINDS ARE MINIMAL. HAVE
INSERTED SOME PATCHY FOG WORDING FOR THIS MORNING ACROSS ALL THE
CWA TO ACCOUNT FOR THIS.
ATTENTION THEN TURNS TOWARD THIS AFTERNOON. MODELS ALL AGREE ON
85H/925H BOUNDARY REMAINING PROGRESSIVE ACROSS THE NORTH...WHILE
HANGING UP ACROSS SRN SD BY 00Z. 5H WAVE THAT IS CURRENTLY
TRACKING ACROSS MT WILL INTERSECT THE SFC/LOW LEVEL BOUNDARIES
DURING PEAK HEATING ACROSS THE EAST...AND THERE SHOULDN'T BE THE
CONVECTIVE DEBRIS CLOUDS IN PLACE SIMILAR TO YESTERDAY...AND WITH
DWPTS ALREADY IN THE MID 60S...AND DWPTS IN THE LOWER 70S IN PLACE
ACROSS PARTS OF NERN NEB...THE MECHANISM SHOULD BE RESET FOR
CONVECTIVE DEVELOPMENT LATER THIS AFTERNOON. HOWEVER...WILL HAVE
TO SEE HOW MUCH OF A ROLE THE LOW CLOUDS/STRATUS PLAY UNDER TROF
AXIS...AND WHETHER OR NOT THEY CAN BE MIXED OUT. LATEST RUC SHOWS
THAT 7H THETA-E DOWNGLIDE REMAINS IN PLACE THROUGH 18Z FOR MUCH OF
THE CWA...WITH WAA RETURNING TO THE WEST LATER IN THE AFTN PER THE
06Z NAM12 SOLN. BY 00Z FRIDAY...NAM12 SHOWS AREA OF BEST LI'S
LOCATED ALONG AND JUST AHEAD OF NE-SW DRAPED SFC BOUNDARY...WITH
LI'S TO -8...ALONG WITH MOST UNSTABLE CAPES FROM 1500 TO 3000
J/KG. HAVE TRIED TO ORIENT POPS ALONG SFC BOUNDARY FOR LATER THIS
AFTERNOON THROUGH THE NIGHT. WITH RESPECT FOR THE OVERNIGHT
HOURS...MODELS AGREE ON PRESSURE RISES ON THE 305-315K
LAYERS...ALONG WITH SPEC HUMIDIES DECREASING ACROSS MY NW CWA.
THETA-E ANLYS POINTS TO DOWNGLIDE AND DRYING NOTED IN THE RH
FIELDS. HAVE REMOVED MENTION OF POPS ACROSS THE NW FOR THE
OVERNIGHT HOURS ON ACCOUNT OF THIS. OVERALL...VERY DIFFICULT AND
COMPLEX CONVECTIVE FCST SETTING UP FOR TODAY...AND WILL BE HIGHLY
DEPENDANT UPON LOCATION OF SFC BOUNDARY AND TIMING OF 5H/7H WAVES.
THERE IS SOME CONCERN FOR FRIDAY AS THE NAM SHOWS SFC BOUNDARY
REMAINING STALLED ACROSS SRN SD...ALLOWING MORE CONVECTIVE
DEVELOPMENT TO TAKE PLACE LATER IN THE AFN. THE GFS REMAINS MORE
PROGRESSIVE WITH THIS FEATURE...PUSHING IT OUT OF STATE DURING THE
DAY FRIDAY...WHICH ALLOWS COOLER/DRY CANADIAN HIGH PRESSURE TO
SETTLE IN FOR THE BEGINNING OF THE WEEKEND. GIVEN THE NEARLY ZONAL
FLOW SETTING UP ALOFT AND THAT FLOW REMAINS NEARLY CROSSWISE TO
SFC FRONTAL POSITION...HAVE OPTED WITH THE GFS SOLN AND KEPT PCPN
OUT OF FCST FOR FRIDAY.
TEMP WISE...THINK THAT TODAY WILL BE WARMEST DAY OF THE SHORT
TERM...WITH DECENT SUNSHINE PROVIDED THAT LOW CLOUDS/STRATUS BURN
OFF BY 15Z. DIDN'T GO REALLY WILD WITH HEATING AS AMPLE LOW LEVEL
MOISTURE WILL ABSORB SOME OF THE HEATING ENERGY...BUT SHOULD PROVE
TO BE A MUGGY DAY...ESPECIALLY ACROSS THE EAST.
LONG TERM
SATURDAY NIGHT THROUGH WEDNESDAY
00Z EC/GFS OPERATIONAL SOLUTIONS STILL SHOWING REASONABLY SIMILAR
UPPER LEVEL AND SURFACE SOLUTIONS. OVER THIS CWA...MUCH OF THE
EXTENDED FORECAST IS A PERIOD OF WEAK UPPER LEVEL RIDGING WITH
STEERING FLOW PREDOMINANTLY FROM THE WNW. IN THE LOW LEVELS...HIGH
PRESSURE IS PARKED OVER THE UPPER MISSISSIPPI RIVER VALLEY WITH
THE WESTERN HALF OF THE CWA IN SERLY RETURN FLOW WHILE THE EASTERN
HALF IS EITHER LIGHT AND VARIABLE WINDS OR WINDS OUT OF THE
NORTHEAST. BEST CHANCES FOR MEASURABLE PRECIP OVER THE CWA
CONTINUES TO EXIST SATURDAY NIGHT AND AGAIN MONDAY/MONDAY
NIGHT...SATURDAY NIGHT IN THE FORM OF AN MCC MEATBALL ORIGINATING
OVER EASTERN MONTANA/SWRN NODAK AND PROPAGATING SEWD THROUGH THIS
CWA...AND MONDAY/MONDAY NIGHT IN THE FORM OF CONVECTION GOING UP
ALONG AND AHEAD OF A SYNOPTIC SCALE COLD FRONTAL BOUNDARY PROGGED
TO WORK THROUGH THE NORTHERN PLAINS STATES. NO CHANGES MADE TO
MAX/MIN T GRIDS AS...THEY APPEAR SPOT ON WHEN COMPARED WITH 00Z
LOW LEVEL THERMAL PROGS OF THE EC AND GFS MODELS.
AVIATION
LOW LEVEL GULF OF MEXICO MOISTURE ABOUNDS IN THE LOWEST COUPLE
THOUSAND FEET OF THE ATMOSPHERE THIS MORNING. COUPLE THAT WITH
VACATING MID/HIGH CLOUDS AND LIGHT SOUTHERLY WINDS AT THE SURFACE
AND THE RESULT IS FOG AND LOW STRATUS CLOUDS DEVELOPING ACROSS THE
FORECAST AREA. BEEN MONITORING THE MOVEMENT OF A SURFACE TROF
ACROSS THE WESTERN AND CENTRAL DAKOTAS THIS MORNING. THE TROF AXIS
WILL BE POSITIONED OVER KMBG AND CLOSE TO KPIR THIS MORNING AT
SUNRISE. WINDS WILL BE LIGHTEST HERE...AND SURFACE OBS ARE
RESPONDING WITH IFR VISBIES IN GROUND FOG DEVELOPMENT. THIS IFR
VISBY CONDITION IN SHALLOW GROUND FOG ACROSS CENTRAL AND NORTH
CENTRAL SOUTH DAKOTA SHOULD BE SHORT-LIVED...DIMINISHING SHORTLY
AFTER SUNRISE.
FURTHER EAST ACROSS THE KABR AND KATY TERMINALS...SURFACE WINDS OF
5 TO 10 KNOTS SHOULD TRANSLATE TO MVFR VISBIES AND SOME IFR CIGS
IN LOW STRATUS THROUGH MID-MORNING. SHOULD NOT TAKE LONG FOR
DAYTIME INSOLATION TO MIX OUT THE LOW CLOUDS.
AFTER 15Z THIS MORNING...GOOD VFR SHOULD RESUME ACROSS ALL FOUR
TERMINALS. LATER THIS AFTERNOON...THIS PREVIOUSLY MENTIONED
SURFACE TROF WILL BECOME THE FOCUS FOR AFTERNOON AND EVENING
THUNDERSTORM ACTIVITY. THE BOUNDARY WILL BE ORIENTED ROUGHLY FROM
KPIR TO KATY...SO EXPECT THESE TWO TERMINALS TO BEGIN CARRYING
SOME SORT OF CONVECTION MENTION /EITHER CB OR VCTS/ IN THE LATE
AFTERNOON/EARLY EVENING TIMEFRAME.
ABR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
UPDATE...DORN
SHORT TERM...HINTZ
LONG TERM...DORN
AVIATION...DORN
WEATHER.GOV/ABERDEEN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page