000
FXUS63 KGID 272338
AFDGID
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
638 PM CDT WED AUG 27 2008
.AVIATION...00Z TAF. QUITE OF WEATHER CHANGES GOING THIS FORECAST
PERIOD. FIRST...GENERALLY EXPECT THE LOW VFR CIGS TO DISSIPATE
AROUND SUNSET AS WE LOSE DAYTIME HEATING. SOUTHEAST FLOW WILL
CONTINUE OVERNIGHT...BUT SHOW SIGNS OF SWITCHING AROUND 08Z. WITH
A PERIOD OF LIGHT WINDS...A BIT OF HAZE MAY DEVELOP DROPPING
LOCAL VSBYS TO 5SM...UNTIL THE FRONT BLOWS THROUGH BY SUNRISE AND
NORTHWEST WINDS START TO GUST OVER 20KTS THROUGHOUT THE DAY
THURSDAY. LOW LEVEL JET FOCUS TONIGHT IS WELL EAST/NORTHEAST OF
THE KGRI AREA...SO EXPECT STORM RISK OVER THERE. ONCE THE FRONT
PASSES EARLY THURSDAY ANOTHER 3 TO 5 HOUR PERIOD OF POST FRONTAL
MVFR CIGS IS LIKELY BEFORE SCATTERING OUT IN THE AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 310 PM CDT WED AUG 27 2008/
SHORT TERM...THIS EVENING THROUGH THURSDAY NIGHT. PRIMARY FORECAST
CONCERN CENTERS AROUND THUNDERSTORM CHANCES.
EARLY THIS AFTERNOON SFC OBSERVATIONS DEPICTED A NEARLY STATIONARY
TROUGH OF LOW PRESSURE OVER THE CENTRAL PLAINS. SATELLITE IMAGERY
SHOWED A SHORTWAVE UPPER LEVEL TROUGH TRACKING ACROSS THE
NORTHERN PLAINS. THE SFC TROUGH IS SOMEWHAT DETACHED FROM THE BEST
UPPER LEVEL FORCING ACROSS OUR AREA RESULTING IN ONLY MINIMAL
PRECIPITATION CHANCES. THE MOST FAVORED REGION FOR SHOWERS AND
THUNDERSTORMS TONIGHT INTO THURSDAY WILL ONCE AGAIN BE NORTHEAST
OF OUR CWA WITH ONLY AN OUTSIDE CHANCE OF AN ISOLATED STORM
BUILDING SOUTHWEST INTO OUR CWA. EVEN THEN...OUR MORE FAVORED
NORTHEASTERN ZONES ONLY HAVE A SLIGHT CHANCE OF SEEING
THUNDERSTORMS.
THE SFC TROUGH SLIDES SOUTHEAST OF OUR CWA DURING THE DAY ON
THURSDAY TAKING WITH IT ALL CHANCE OF RAIN. TEMPERATURES WILL BE
RIGHT AROUND NORMAL FOR THIS TIME OF YEAR WITH THURSDAY HIGHS IN THE
LOWER 80S.
LONG TERM...12Z FRIDAY THROUGH WEDNESDAY. MAIN FORECAST CONCERNS
INVOLVE PRECIPITATION CHANCES EARLY NEXT WEEK.
STILL LOOKS LIKE A PLEASANT HOLIDAY WEEKEND SHAPING UP FOR THE AREA
PARTICULARLY FRIDAY THROUGH SUNDAY...CHARACTERIZED BY PREDOMINANTLY
DRY CONDITIONS AND WARMING TEMPERATURES. THE DRY WEATHER BECOMES A
LITTLE MORE QUESTIONABLE BY LABOR DAY...BUT PRECIPITATION CHANCES
STILL LOOK QUITE LOW THROUGH THE DAYTIME HOURS. SURFACE HIGH
PRESSURE SLOWLY DRIFTS EAST ACROSS THE REGION ON FRIDAY UNDER WEST
TO SLIGHTLY NORTHWEST FLOW ALOFT AROUND AN ELONGATED AREA OF SURFACE
HIGH PRESSURE SPRAWLING EASTWARD ACROSS THE SOUTHERN CONUS. AFTER A
CRISP START TO THE DAY...ABUNDANT SUNSHINE SHOULD HELP TEMPERATURES
WARM INTO THE LOWER TO MID 80S FOR HIGHS. MODELS SHOW HINTS OF A
MID-LEVEL SHORTWAVE RIPPLE ROUNDING THE RIDGE AND POSSIBLY BRUSHING
THE SOUTHWEST CWA FRIDAY NIGHT. HAVE KEPT THE FORECAST DRY WITH
CONFIDENCE IN SUCH A FEATURE QUITE LOW EVEN ONLY A COUPLE DAYS
OUT...BUT WILL NEED TO KEEP AN EYE ON THIS POSSIBILITY.
THE SURFACE HIGH SHIFTS EAST ON SATURDAY WHILE THE LEE TROUGH
DEEPENS TO THE WEST...RESULTING IN INCREASED RETURN FLOW SATURDAY
AND SUNDAY. MEANWHILE THE UPPER RIDGE TRANSLATES ACROSS THE REGION
ON SATURDAY...FOLLOWED BY INCREASING SOUTHWEST FLOW ALOFT ON SUNDAY
BETWEEN THE EASTWARD SHIFTING RIDGE AND DIGGING TROUGH OVER THE
WESTERN CONUS. THIS WILL SPELL WARMING TEMPERATURES SATURDAY AND
SUNDAY...WITH HIGHS REACHING INTO THE UPPER 80S ON SUNDAY. AS THE
UPPER TROUGH CONTINUES TO PUSH EASTWARD THROUGH THE INTERMOUNTAIN
WEST SUNDAY NIGHT AND MONDAY...WEAK ISENTROPIC LIFT DEVELOPS OVER
THE CWA LATE SUNDAY NIGHT INTO MONDAY WHILE SUBTROPICAL MOISTURE
BEGINS TO FLOW NORTHEAST THROUGH THE PLAINS ON THE SOUTHWEST FLOW
ALOFT. HAVE SOME CONCERNS THAT SOME ISOLATED CONVECTION COULD
DEVELOP ON MONDAY WITH THE INCREASED MOISTURE TAP AND WEAK
ISENTROPIC LIFT...WHICH COULD BE SUPPLEMENTED BY ANY LEAD
SHORTWAVE ENERGY EJECTING AHEAD OF THE WESTERN TROUGH.
HOWEVER...OPERATIONAL GFS SEEMS TO BE THE OUTLIER WITH THIS
POSSIBILITY AT THIS POINT...WITH THE ECMWF/CMC GEM/GFS ENSEMBLES
SUGGESTING DRY CONDITIONS THROUGH THE DAYTIME HOURS...AND EVEN THE
OPERATIONAL GFS WOULD KEEP THE BETTER PRECIPITATION CHANCES WEST
AND SOUTH OF THE CWA UNTIL EVENING. THUS WILL HOLD OFF ON POPS FOR
THE DAYTIME HOURS ON LABOR DAY...BUT WILL NEED TO KEEP A CLOSE EYE
ON THIS OVER THE NEXT FEW DAYS.
PRECIPITATION CHANCES INCREASE MONDAY NIGHT AND TUESDAY AS THE UPPER
TROUGH LIFTS NORTHEAST INTO THE NORTHERN PLAINS...SENDING A COLD
FRONT THROUGH THE FORECAST AREA LATE MONDAY NIGHT INTO TUESDAY. MAIN
DYNAMICS WILL STAY WELL NORTH OF THE AREA...BUT SURFACE FRONT AND
LIKELY SOME MID-LEVEL FRONTOGENETICAL FORCING PUSHING THROUGH WILL
BRING A RETURN OF RAIN CHANCES TO THE AREA. MODELS DIFFER SOMEWHAT
WITH HOW PROGRESSIVE THE SYSTEM WILL BE...WITH THE ECMWF TRYING TO
CUT OFF THE UPPER LOW SOONER THUS MAKING IT LESS PROGRESSIVE OVERALL
VERSUS THE GFS WHICH IS SLOWER TO CUT OFF THE SYSTEM. FOR NOW
HAVE NOT LINGERED ANY POPS BEYOND TUESDAY...HEDGING TOWARD THE
SLIGHTLY MORE PROGRESSIVE SOLUTION. AFTER A WARM LABOR DAY...THE
FRONT WILL KNOCK TEMPS BACK DOWN TUESDAY AND WEDNESDAY.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
