282
FXUS63 KGID 090536 AAC
AFDGID
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HASTINGS NE
1236 AM CDT WED JUL 9 2008
AVIATION
FOR THE 06Z KGRI TAF. LOOKS AS THOUGH VFR TO MVFR
CONDITIONS WILL PERSIST FOR THE GRAND ISLAND TERMINAL THROUGH THE
NEXT 24 HOURS. HOWEVER...A FEW WEAK SHOWERS MAY SLIP INTO THE
TERMINAL AREA LATER TONIGHT WITH VISIBILITIES POTENTIALLY FALLING
TO 5 TO 6 MILES WHILE CEILINGS SHOULD STAY ABOVE 3 KFT. THE BIGGER
QUESTION FOR THE TERMINAL WILL BE THE POTENTIAL FOR THUNDERSTORMS
TOMORROW MORNING INTO THE EARLY AFTERNOON. THERE IS SOME EVIDENCE
THAT THUNDERSTORMS NEAR THE NEBRASKA/SOUTH DAKOTA BORDER
CURRENTLY...COULD PUSH INTO THE AREA BEFORE DISSIPATING. AT THIS
POINT THE COVERAGE OF STORMS LOOKS LOW ENOUGH TO KEEP THEM OUT
OF THE TERMINAL AIRSPACE BUT WILL INSERT VICINITY THUNDERSTORMS
TO INDICATE A FEW STORMS MAY MAKE IT INTO THE REGION.
PREV DISCUSSION
/ISSUED 1045 PM CDT TUE JUL 8 2008/
DISCUSSION...UPDATE TO THE FORECAST OVERNIGHT TO ADD A SLIGHT
CHANCE OF PRECIPITATION AND INCREASED SKY COVER AS WELL. COLD POOL
IS NOT GIVING UP SOON OUT TO THE WEST AS WEAK ATMOSPHERIC STEERING
ALLOWS THE COLD POOL TO HAVE ITS WAY...AND LOOKS LIKE IT COULD
SUPPORT CONVECTION FOR THE NEXT SEVERAL HOURS...ESPECIALLY ACROSS
THE NEBRASKA COUNTIES. ALSO...A PERTURBATION MOVING SOUTHEAST OUT
OF SOUTH DAKOTA MAY SWING BY CLOSE ENOUGH TO AFFECT OUR NORTHEAST
CWA WITH MORE SHOWERS AND THUNDERSHOWERS OVERNIGHT.
PREV DISCUSSION... /ISSUED 328 PM CDT TUE JUL 8 2008/
SHORT TERM...TONIGHT THROUGH 12Z THURSDAY. MAIN FORECAST CONCERN
WILL BE CHANCE FOR SHOWERS OR THUNDERSTORMS WEDNESDAY AFTERNOON AND
EVENING.
SHOWERS MOVED OUT OF THE FORECAST AREA EARLIER...BUT A WEAK BOUNDARY
HAS ALLOWED FOR A FEW THUNDERSTORMS TO DEVELOP IN THE SOUTHEAST PART
OF THE FORECAST AREA. DO NOT EXPECT THAT THERE WILL BE SEVERE
WEATHER WITH THESE...BUT THEY WILL LINGER INTO THE EVENING HOURS.
CURRENT ANALYSIS SHOWS THAT THE MAIN FRONT HAS ALREADY MOVED INTO
CENTRAL AND SOUTHERN KANSAS AT THIS TIME. THROUGH THE REMAINDER OF
THE NIGHT EXPECT LIGHT WINDS.IN THE SOUTHEAST THERE WILL BE
DECREASING CLOUDS WHILE IN THE NORTHWEST CLOUD COVER WILL REMAIN
NEARLY THE SAME.
ON WEDNESDAY ANOTHER WEAK UPPER LEVEL WAVE MOVES THROUGH THE
NORTHERN PART OF THE FORECAST AREA. EXPECT SOME SHOWERS AND
THUNDERSTORMS TO MOVE THROUGH THE NORTHEAST PART OF THE FORECAST
AREA DURING THE AFTERNOON AND LINGER INTO THE EVENING BUT MOST
EVERYTHING WILL BE LIGHT. THE SHOWERS AND THUNDERSTORMS SHOULD MOVE
OUT OF THE AREA LATE WEDNESDAY NIGHT.
LONG TERM...12 THURSDAY THROUGH TUESDAY. TEMPERATURES AND
WEEKEND PRECIPITATION CHANCES ARE THE MAIN FORECAST CONCERNS. NO
SIGNIFICANT CHANGES IN THE OVERALL SCHEME OF THINGS THROUGH THE
EXTENDED PERIOD...WITH A LOW AMPLITUDE PATTERN CONTINUING. THIS
BRINGS BASICALLY ZONAL FLOW ACROSS THE CONUS AS A FLATTENED RIDGE
SITS ACROSS THE SOUTH AND NUMEROUS PIECES OF WEAK AND QUICK MOVING
ENERGY PASS THROUGH THE CENTRAL AND NORTH.
LOOKING AT THE END OF THE WORK WEEK...KEPT DRY FORECAST GOING. ON
THURSDAY...OVER OUR CWA FLOW ALOFT IS SLIGHTLY NORTHWESTERLY AND A
SURFACE TROUGH DRAPED OVER THE HIGH PLAINS CONTINUES THE SOUTHERLY
FLOW. INTO THURSDAY NIGHT AND FRIDAY...A STRONGER MID/UPPER LEVEL
LOW PRESSURE SYSTEM MOVES EAST FROM THE WEST COAST OF CANADA...AND
MODELS IN GOOD AGREEMENT SHOWING THE CENTER OF THE LOW IN CENTRAL
CANADA BY 12Z FRIDAY. AT THE SURFACE AHEAD OF THIS UL SYSTEM...LOW
PRESSURE OVER THE NORTHERN ROCKIES/PLAINS DEEPENS. FOR BOTH
THURSDAY AND FRIDAY...THIS WILL CAUSE A TIGHTENING PRESSURE GRADIENT
ACROSS THE REGION...AND AN INCREASE IN SOUTHERLY WINDS TO NEAR 20
MPH. AS THE MAIN UL SYSTEM MAKES ITS WAY EAST ACROSS SOUTHERN
CANADA...SO MOVES THE MAIN SURFACE LOW ACROSS THE NORTHERN
CONUS...WHICH WILL HELP TO PUSH A COLD FRONT INTO OUR REGION LATE
FRIDAY AFTERNOON. SOME MODELS HINT AT DEVELOPING PRECIPITATION ALONG
THE FRONT...BUT DECIDED TO KEEP THE CWA DRY FOR NOW. ONE THING THAT
HURTS CHANCES FOR PRECIP IS WARM MID LEVEL TEMPERATURES SHOWN BY
MODELS...NEAR 14C AT 700MB...WHICH HELP TO KEEP THINGS CAPPED.
MODELS ARE ARE ALSO KEEPING THE BULK OF ACTION A BIT NORTHEAST OF
THE CWA WHERE THE UL SUPPORT IS BETTER AND THE CAP IS NOT QUITE AS
STRONG.
CHANCES FOR PRECIPITATION DO INCREASE FOR THE WEEKEND
TIME-FRAME...AND DID UP POPS A TOUCH. ALOFT...MAIN UPPER LEVEL LOW
HAS MOVED EAST...LEAVING SLIGHT NORTHWESTERLY FLOW OVER THE CENTRAL
PLAINS. AT THE SURFACE...THE FRONT WHICH HAD MOVED INTO THE REGION
LOSES ITS MAIN PUSH AS THAT UL LOW MOVES INTO EASTERN
CANADA...CAUSING IT TO STALL OUT THROUGH THE WEEKEND. THIS FRONT
WILL PROVIDE A FOCUS FOR PRECIPITATION DEVELOPMENT...AND HAVE LEFT
CHANCES IN ACROSS THE ENTIRE CWA FOR THE WHOLE WEEKEND. COOLER AIR
ADVECTING IN ALOFT HELPS TO LESSEN THE CAP...AND MODELS SHOW A SMALL
60ISH KT UPPER LEVEL JET STREAK CROSSING OVERHEARD. MODELS HAVE
SLIGHT DIFFERENCES WITH THE DETAILS OF WHERE EXACTLY THE FRONT
SITS...BUT DO KEEP BETTER CHANCES ACROSS THE SOUTHERN 2/3RDS OF THE
CWA. DID NOT MAKE SIGNIFICANT INCREASES TO POPS AS CONFIDENCE IS
NOT REAL HIGH...AS THE POSSIBILITY EXISTS THAT THE FRONT MAY GET
PUSHED FAR ENOUGH SOUTH SO IT HAS LITTLE IMPACT ON OUR CWA. WOULD
NOT EXPECT A CONTINUOUS FEW DAYS OF PRECIP...BUT WITH THE FRONT IN
CLOSE PROXIMITY AND WITH DETAILS YET TO BE IRONED OUT IN THE NEXT
FEW DAYS...CANT COMPLETELY RULE OUT ANY SPECIFIC TIME/LOCATION.
BETTER CHANCES EXPECTED DURING THE EVENING/OVERNIGHT HOURS...WHEN
THE SOUTHERLY LOW LEVEL JET/WAA INCREASE. DID COOL WEEKEND
TEMPERATURES A BIT...WITH PRECIPITATION POSSIBLE AND PLENTY OF CLOUD
COVER AND EASTERLY WINDS EXPECTED...KEPT HIGHS IN THE MID 80S WITH
NEAR 90 POSSIBLE ON SATURDAY ACROSS THE FAR SOUTH.
FOR THE FIRST PART OF NEXT WEEK...CONFIDENCE IS EVEN LOWER...AS HOW
THIS WEEKEND EVOLVES IS A MAJOR PART IN PRECIPITATION CHANCES. DID
KEEP SLIGHT CHANCES IN FOR THE DAYTIME HOURS ON MONDAY...AS THE
UPPER LEVELS BRING ANOTHER PUSH LATER IN THE DAY...ENOUGH TO MOVE
PRECIPITATION OUT OF THE CWA...AND LEFT MONDAY NIGHT/TUESDAY DRY.
WITH THE UNCERTAINTY...STAYED CLOSE TO HPC TEMPERATURES...BRINGING
HIGHS IN THE MID 80S TO NEAR 90 BY TUESDAY.
GID WATCHES/WARNINGS/ADVISORIES
NE...NONE.
KS...NONE.
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