000 FXUS63 KGID 240348 AAA AFDGID AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE HASTINGS NE 948 PM CST MON NOV 23 2009 .UPDATE...SFC TEMPERATURES ACROSS THE CWA RANGE FROM 37 TO 45 DEGREES AND CONTINUE TO BE TOO WARM FOR SNOW. THE COLD AIR IS SLOW TO WORK INTO THIS SYSTEM AND ALTHOUGH THERE COULD STILL BE A CHANGE OVER TO SNOW BEFORE ENDING...EXPECT LITTLE TO NO ACCUMULATION. THE DURATION OF SNOW AFTER CHANGE OVER WOULD BE VERY BRIEF...RIGHT AT THE TAIL END OF THE PRECIPITATION. THE RAIN COULD CHANGE OVER TO SNOW AS THE SFC TEMPERATURES FALL INTO THE 33 TO 36 DEGREE RANGE...BUT IT WOULD BE DIFFICULT FOR SNOW TO ACCUMULATE AT THESE TEMPERATURES. CONSEQUENTLY...THE EXPECTATION IS THAT WE WILL SEE LITTLE TO NO SNOWFALL ACCUMULATION ACROSS OUR CWA TONIGHT. && .PREV DISCUSSION... /ISSUED 557 PM CST MON NOV 23 2009/ AVIATION...00Z KGRI TAF. A BAND OF RAIN HAS DEVELOPED IN AND AROUND THE AIRPORT THIS EVENING AND WILL REMAIN NEARLY STATIONARY THROUGH LATE EVENING. PERIODS OF LIGHT RAIN CAN BE EXPECTED AT KGRI...WITH RAIN MIXING WITH SNOW BY AROUND MIDNIGHT. SFC TEMPERATURES WILL REMAIN ABOVE FREEZING SO ANY SNOW THAT DOES FALL SHOULD NOT ACCUMULATE TOO QUICKLY AND THEN END PRIOR TO DAYBREAK. NORTH NORTHWEST WINDS WILL INCREASE THROUGH THE OVERNIGHT HOURS AND BECOME GUSTY TOMORROW WITH GUSTS TO OVER 30 MPH. CLOUDS WILL GRADUALLY BREAK UP THROUGH THE MORNING WITH CLEAR TO MOSTLY CLEAR SKIES BY AFTERNOON. PREV DISCUSSION... /ISSUED 338 PM CST MON NOV 23 2009/ SHORT TERM...BIGGEST FORECAST CHALLENGE WILL BE DETERMINING WHEN AND IF PRECIPITATION CHANGES TO SNOW TONIGHT AND SUBSEQUENTLY HOW MUCH SNOW WILL FALL. UPPER LEVEL WATER VAPOR LOOP SHOWS A WELL-DEFINED UPPER LEVEL TROUGH LOCATED OVER THE ROCKY MOUNTAINS HEADING EAST INTO THE PLAINS...WITH A CLOSED LOW DEVELOPING WITHING THE TROUGH AXIS OVER THE CENTRAL PLAINS TODAY...MOST LIKELY TRACKING THROUGH CENTRAL KANSAS. SURFACE OBSERVATIONS REVEAL A COLD FRONT MOVING ACROSS THE STATE TODAY IN ASSOCIATION WITH THE AFOREMENTIONED UPPER LEVEL TROUGH. FOR TONIGHT...ENSEMBLES SUGGEST THAT GETTING PRECIPITATION IS PRETTY MUCH A SURE THING. DIVERGENT Q VECTORS IN UPPER LEVELS INDICATE VIGOROUS LARGE SCALE LIFT TONIGHT AND THAT GETTING WET IS AN ALMOST SURE THING...CONSIDERING THE AMPLE MOISTURE AVAILABLE. THIS LIFT TRANSLATES EAST AFTER MIDNIGHT...AND INDICATES THAT MOST PRECIPITATION SHOULD SHUT OFF AT THE END OF THE PERIOD. COULD BE SOME MODERATE MID-LEVEL FRONTOGENESIS ASSOCIATED WITH A DEFORMATION AREA MAINLY IN THE WEST AND NORTHWEST TONIGHT...WHICH SHOULD ENHANCE PRECIPITATION AMOUNTS SOMEWHAT...BUT TEMPERATURES ARE IN QUESTION WHEN IT COMES TO SNOW AMOUNTS. THAT THIS TROUGH SINCE THE BOUNDARY LAYER IS RELATIVELY WARM...A LOOK AT LEVELS NEAR 875 MB WOULD BE A BETTER INDICATOR OF CHANGEOVER TO SNOW. THE NAM SUGGESTS THIS WILL OCCUR IN THE FAR WEST/SOUTHWEST CWA ABOUT 00Z AND TRANSLATE EAST INTO THE TRI-CITIES AREA BY 06Z OR SO...AND WILL REMAIN BETWEEN 0 AND MINUS 1 DEGREE CELSIUS FOR THE REMAINDER OF THE NIGHT AS THINGS WIND DOWN. THE BEST SHOT AT MEASURABLE SNOW APPEARS TO BE CLOSER TO THE CLOSED LOW IN THE SOUTHWESTERN CWA WHEN TEMPERATURES WILL BE COLD ENOUGH FOR SNOW. FARTHER EAST...IT APPEARS TEMPERATURES WILL NOT COOL DOWN ENOUGH FOR MUCH SNOW. COULD GET UP TO A COUPLE OF INCHES OF SNOW IN THE FAR SOUTHWESTERN CWA...BUT MUCH OF THIS WILL MELT ON ROAD SURFACES...EXCEPT ON GRASSY SURFACES AND OVERPASSES WHERE IT MAY CLING A LITTLE BETTER. HIGHEST SNOWFALL TOTALS WILL BE NEAR 2 INCHES IN THE FAR SOUTHWESTERN CWA TOWARD ROOKS COUNTY. AS FAR AS WIND GOES...PRESSURE RISES AND LOW-LEVEL LAPSE RATES SUGGEST WE WILL NOT GET WIND ADVISORY CRITERIA...EVEN IN THE FAR SOUTHWEST. WOULD BE TOUGH TO ACHIEVE ANY SUSTAINED WIND SPEEDS MORE THAN ABOUT 23 KTS IN THE SOUTHWEST. WHERE THE THIS SUGGESTS A POSSIBLE RAIN/SNOW MIX OR WHEN IT DOES CHANGE TO SNOW...GETTING ANYTHING ABOVE AN INCH WOULD BE VERY DIFFICULT. MUCAPES AND MID-LEVEL LAPSE RATES SUGGEST POSSIBLE SOME ISOLATED THUNDER MAINLY TO THE EAST OF THE CWA TONIGHT AND DO NOT PLAN TO MENTION THUNDER AT THIS TIME. FOR TUESDAY...THE ISSUE WILL BE WIND SPEEDS. PRETTY GOOD SURFACE PRESSURE GRADIENT SETS UP ON THE BACK SIDE OF THE LOW AS IT TRANSLATES EAST AS WELL AS MIXING UP TO 850 MB WILL BE POSSIBLE ACCORDING TO THE NAM. THIS WOULD GIVE US WIND GUSTS TO NEAR 30 MPH FROM THE NORTHWEST. NOT WIND ADVISORY CRITERION...BUT STILL MUCH WINDIER THAN IT HAS BE FOR SOME TIME. FOR TUESDAY NIGHT...CONDITIONS SHOULD BE DRY AS A MID-LEVEL SHORTWAVE RIDGE WILL BE OVERHEAD IN ADVANCE OF THE NEXT WAVE DIVING SOUTH INTO THE NORTHERN PLAINS. LONG TERM...12Z WEDNESDAY THROUGH MONDAY. PRIMARY FORECAST CONCERN LIES WITH TEMPERATURES. KEPT FORECAST DRY AT THE START OF THE LONG TERM PERIOD...THOUGH MODELS IN PRETTY GOOD AGREEMENT SHOWING ANOTHER QUICK MOVING UPPER LEVEL LOW PRESSURE SYSTEM IN THE REGION. AT 12Z WEDNESDAY THIS SYSTEM IS NEAR THE EASTERN ND/SD BOARDER...AND THROUGH THE DAY SHIFTS TO THE SSE...ENDING UP CENTERED OVER NORTHERN IA BY 00Z THURSDAY. ASSOCIATED WITH THIS SYSTEM IS A REINFORCING SFC COLD FRONT...WHICH IS EXPECTED TO CROSS THROUGH THE CWA EARLY IN THE MORNING. MODEL OUTPUT SHOWING AT LEAST SOME LIGHT QPF DEVELOPING ACROSS PORTIONS OF THE CENTRAL PLAINS...EITHER ACCOMPANYING THE SYSTEM ITSELF...OR IN RESPONSE TO MORE FAVORABLE POSITIONING OF A STRONG +110KT UPPER LEVEL JET NOSING IN FROM THE NORTHERN PLAINS. DID KEEP FORECAST DRY...AS THE CWA SITS IN BETWEEN THOSE MORE FAVORABLE AREAS...AND FORECAST SOUNDINGS SHOW MUCH DRIER AREA MOVING IN BEHIND THE SFC FRONT. EXPECTING THE DAYTIME HOURS ON WEDNESDAY TO ALSO BE BREEZY...WITH PRESSURE RISES/INCREASED GRADIENT AND BETTER MIXING ACROSS THE CWA. THINK THAT WINDS WILL REMAIN BELOW ADV CRITERIA...WITH SUSTAINED SPEEDS NEAR 20KTS. THANKSGIVING DAY FORECAST REMAINS DRY...AS THE CWA SITS UNDER THE INFLUENCE OF NNW UPPER LEVEL FLOW ON THE BACKSIDE OF WEDNESDAYS SYSTEM. LOOKING AT THE SFC PATTERN...HIGH PRESSURE SETTLES IN ACROSS THE REGION DURING THE DAYTIME HOURS...BRINGING GRADUALLY DIMINISHING WINDS. AS FAR AS HIGH TEMPERATURES GO FOR WED/THURS...EVEN WITH A SFC COLD FRONT MOVING THROUGH...NO SIGNIFICANT CHANGES EXPECTED...WITH HIGHS REMAINING NEAR NORMAL GENERALLY IN THE 40S AND A FEW READINGS NEAR 50 IN THE SW ON THURSDAY. LOOKING TOWARD FRIDAY AND SATURDAY...MODELS IN GOOD AGREEMENT SHOWING AN AMPLIFYING UPPER LEVEL PATTERN...WITH RIDGING BUILDING IN OVER THE ROCKIES AS TROUGHS SIT NEAR BOTH COASTS. EXPECTING WARMEST DAY TO COME ON FRIDAY...WITH THE RIDGE AXIS SHIFTING OUT OF THE ROCKIES AND ONTO THE PLAINS. SFC WINDS BECOME SOUTHERLY AS HIGH PRESSURE SLIDES OFF TO THE SE AND LOW PRESSURE DEVELOPS ALONG THE FRONT RANGE. EXPECTING PLENTY OF SUNSHINE WITH HIGHS IN THE LOWER TO MID 50S. ON SATURDAY...THE RIDGE AXIS CONTINUES TO SHIFT EAST AND STARTS TO BREAK DOWN...WITH UPPER LEVEL FLOW BECOMING SOUTHWESTERLY AS THE NEXT TROUGH MOVES THROUGH THE ROCKIES. THIS BRINGS SLIGHTLY COOLER TEMPS...BUT ONLY INTO THE LOWER 50S. THINGS BECOME A BIT MORE INTERESTING AS WE GET INTO SUNDAY/MONDAY...BUT CONFIDENCE ALSO DROPS OFF. WHILE THE TIMING OF THIS NEXT SYSTEM IS ACTUALLY NOT TOO BAD BETWEEN MODELS...THERE ARE DIFFERENCE ON JUST HOW THE PATTERN EVOLVES AS THE TROUGH SHIFTS EAST AND AN AREA OF LOW PRESSURE DEVELOPS. BOTH THE GFS AND ECMWF DROP ENERGY DOWN INTO THE DESERT SW...BUT THE ECMWF DEVELOPS A CLOSED LOW AND KEEPS THE NORTHERN ENERGY AS AN OPEN TROUGH WHILE THE GFS CLOSES THE LOW IN THE NORTHERN PLAINS AND THEN DROPS IT SOUTH ACROSS THE CWA. OBVIOUSLY THIS CREATES ISSUES WITH WHETHER OR NOT TO MENTION POPS...AND DECIDED WITH THIS BEING DAY 6/7 TO LEAVE DRY UNTIL THERE IS BETTER AGREEMENT. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$