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000 FXUS63 KDVN 222213 CCA AFDDVN AREA FORECAST DISCUSSION...RETRANSMISSION WITH CORRECT SHORT TERM... NATIONAL WEATHER SERVICE QUAD CITIES IA IL 405 PM CST SUN NOV 22 2009 .SYNOPSIS... MID LEVEL CLOUDS ACROSS THE FORECAST AREA TODAY HAVE CAUSED AN INTERESTING SPLIT FROM WEST TO EAST TODAY. TO THE WEST UNDER THE CLOUDS...THERE ARE SCATTERED SHOWERS AND COOLER TEMPERATURES THAN THE AREA TO THE EAST...WHERE THE CLOUDS HAVE BROKEN OUT AND TEMPERATURES HAVE RISEN INTO THE UPPER 50S TO LOW 60S IN MANY AREAS. WE REMAIN IN SOUTHEAST FLOW WITH WEAK ANTICYCLONIC CIRCULATION IN THE MSLP PATTERN. A SURFACE LOW OVER SOUTHERN KANSAS HAS BEEN MOVING SLOWLY EAST TODAY AHEAD OF AN UPPER LEVEL SHORTWAVE EXITING THE ROCKIES THIS MORNING. AN INVERTED TROUGH EXTENDS FROM IT NORTH TO NORTHWEST MINNESOTA...WITH AT LEAST MID 40S DEWPOINTS OVER MUCH OF THE MIDWEST TO THE EAST OF THIS TROUGH. THE SCATTERED SHOWERS ARE AFFECTING MUCH OF IOWA...AS WELL AS ADJACENT AREAS OF NORTHERN MISSOURI...AND SOUTHERN MINNESOTA AND WISCONSIN. ON SATELLITE IMAGERY...THERE IS A SHORTWAVE MOVING ACROSS KANSAS IN THE SOUTHWEST UPPER LEVEL FLOW...AND IS LIKELY HELPING TO DRIVE THE SHOWERS CURRENTLY AFFECTING IOWA. ..LE.. && .SHORT TERM...TONIGHT AND MONDAY... TONIGHT I EXPECT THE SCATTERED SHOWER TO CONTINUE...ESPECIALLY THIS EVENING ACROSS CENTRAL IOWA WHERE THE MODELS SHOW A NICE AREA OF 850MB CONVERGENCE AND FRONTOGENESIS. THIS AREA WILL LIKELY SPILL OVER INTO THE WESTERN PORTIONS OF OUR CWA...AND HAVE KEPT SOME LOW END CHANCE POPS GOING THERE...TAPERING DOWN TO SLIGHT CHANCES BY THE MISSISSIPPI RIVER. AFTER MIDNIGHT WE START LOSING SOME OF OUR AMBIENT MOISTURE...AS THE SURFACE TO 850MB LAYERS ARE DRIER UPSTREAM OF THE FORECAST AREA THIS AFTERNOON. THIS MAY CAUSE A DIMINISHING TREND IN THE SHOWERS AFTER MIDNIGHT...AND A LOSS OF MORE OF THE CLOUDS. THESE DRIER DEWPOINTS MAY ALSO PLAY A ROLE IN FOG DEVELOPMENT. IF WE WERE TO KEEP OUR MID 40S DEWPOINTS ALL NIGHT... WOULD EXPECT VERY MILD TEMPERATURES OVERNIGHT...BUT LOTS OF FOG AND STRATUS DEVELOPMENT. HOWEVER...THE DEWPOINTS UPSTREAM OF THE AREA TODAY ARE ONLY IN THE UPPER 30S TO LOW 40S AT BEST...AND THIS SHOULD DIMINISH THE THREAT OF FOG. THIS SHOULD ALSO ALLOW OUR NORTHEAST COUNTIES TO DROP TO AROUND 40...WITH MID 40S TO THE SOUTHEAST. FOR NOW HAVE SOME REDUCED VISIBILITIES IN THE EAST AFTER MIDNIGHT ON THE TAFS...BUT NOTHING IN THE PUBLIC GRIDS. MONDAY OUR FLOW SHOULD TURN MORE SOUTHERLY...AND WE SHOULD GET A RESURGENCE OF LOW LEVEL MOISTURE FROM THE SOUTH DURING THE DAY. A WEAK AREA OF CONVERGENCE AGAIN SETS UP OVER THE WESTERN PORTIONS OF THE CWA AND CENTRAL IOWA...SO EXPECT SHOWERS THERE AGAIN...BUT SINCE THINGS APPEAR A LITTLE FARTHER WEST...HAVE PUT IN ONLY SLIGHT CHANCE POPS. MORE HIGH CLOUDS SHOULD KEEP US FROM BEING COMPLETELY SUNNY AGAIN TO THE EAST...AND WE WILL HAVE COOLER MID LEVEL TEMPS...SO EXPECT MAX TEMPS TO BE COOLER THAN TODAY. ..LE.. .LONG TERM... MONDAY NIGHT THROUGH TUESDAY NIGHT...STILL SOME VARIANCES BETWEEN THE 12Z RUNS IN HANDLING THE DEVELOPMENT OF THE TROF/CUT-OFF UPPER LOW ACRS THE SOUTHERN INTO CENTRAL PLAINS MON NIGHT BUT THE MODELS ARE COMING MORE INTO A GENERAL AGREEMENT FOR SOMEWHAT HIGHER CONFIDENCE THROUGH TUE NIGHT. LIKE THE WAY THE MODELS HAVE TRENDED SLOWER WITH ARRIVAL OF LEAD FORCING WING AND ADEQUATE LLVL SATURATION MON NIGHT AND WILL TRIM BACK POPS TO THE WEST THROUGH 06Z TUE...AND EVEN SOMEWHAT INTO TUE MORNING/12Z. MAYBE JUST A FEW NW-TO-SE ORIENTED BANDS OF LIGHT RAIN OR SPRINKLES SCOOTING ACRS THE CWA AS MON NIGHT PROGRESSES IN ELEVATED WAA REGIME. OVERNIGHT LOWS LOOK MILD AS WELL IN INCREASING SOUTHEASTERLY BOUNDARY LAYER FLOW AND MANY AREAS MAY HAVE TROUBLE DIPPING BELOW THE MID 40S. ON TUE... MOST MODELS INDICATE A NICE CONVERGENT WING OF LOW TO MID LEVEL FLOW AHEAD OF MAIN UPPER LOW UTILIZING PW IN-FEED OF .7 TO .9 OF AN INCH TO PRODUCE WIDESPREAD RAINFALL AND WILL RAISE TUE POPS TO CATEGORICAL ACRS THE SOUTHWEST 2/3S. A FEW AREAS COULD RECEIVE FROM A HALF TO THREE QUARTERS OF AN INCH OF RAINFALL BY 00Z WED. EXTENT OF LLVL SATURATION COMBINED WITH CLOUD COVER AND PRECIP ON TUE WARRANTS THE SIDING WITH THE COOLER OF GUIDANCE HIGHS/THE MAV/ OR EVEN UNDERCUTTING THOSE VALUES...BUT EVEN SO IT STILL WILL BE ONE MORE ABOVE NORMAL TEMP DAY. PREFER THE FURTHER NORTH PROPAGATION PATH BY THE 12Z GFS AND ECMWF OF THE NEAR STACKED SYSTEM ROLLING RIGHT ACRS THE DVN CWA TUE NIGHT. THIS PLACEMENT WOULD SUGGEST THAT THE MORE ORGANIZED BANDS OF RAIN WOULD MIGRATE NORTH AND EAST OUT OF THE DVN CWA DURING THE EVENING...JUST LEAVING LINGERING LIGHTER RAIN OR DRIZZLE IN IT/S PLACE ESPECIALLY SOUTH OF I80...UNTIL WRAP AROUND RAIN INCREASES AGAIN IN THE NORTHWESTERN CWA WELL AFTER MIDNIGHT. AS OPPOSED TO EARLIER RUNS...THERMAL PROFILES SUGGEST ALL LIQUID PRECIP TUE NIGHT THROUGH 12Z WED. LOWS BY WED MORNING WILL BE ADVERTISED IN THE UPPER 30S...BUT THIS MAY BE TOO COOL ESPECIALLY IN THE NORTH AND EAST AWAY FROM INITIAL IN-WRAPPING LLVL COOL CONVEYOR. IN THE EXTENDED/WED-SUN/...SOME LINGERING RAIN WED MORNING AGAIN WITH THERMAL PROFILES CWA-WIDE SUPPORTING ALL LIQUID UPON SFC ARRIVAL CWA-WIDE THROUGH 18Z WED AND WILL SPLIT UP THE DAY IN TWO HALVES. THIS TO TAKE INTO ACCOUNT THAT MOST MEDIUM RANGE MODELS ARE NOW COMING INTO MORE AGREEMENT IN HANDLING THE SECONDARY WAVE/SEEN NOW ON W/V IMAGERY OVER THE WESTERN GULF OF AK/ AND PIVOT IT DOWN ACRS TO THE WEST OF THE MAIN CYCLONE DEEPENING OVER THE GRT LKS WED INTO WED NIGHT. THIS SECONDARY WAVE ALMOST TO ACT AS A STRONG CLIPPER-LIKE FEATURE BUT MAYBE WITH A LITTLE MORE MOISTURE AND WARMER PROFILES TO GENERATE ANOTHER ROUND OF PRECIP INTO THE DVN CWA LATER WED AFTERNOON AND ESPECIALLY WED NIGHT. TAKING INTO ACCOUNT MEAN PLACEMENT OF VORT MAX AND INCOMING FORCING ON THE NORTH/NORTHEAST VORT GRADIENT...PRECIP WILL SPREAD IN ACRS THE NORTHWEST WED AFTERNOON AND BECOME WIDESPREAD ACRS THE NORTHEAST HALF BY WED EVENING. THIS PRECIP WILL COMBINE WITH INCREASING LLVL COLD CONVEYOR FOR RAIN POSSIBLY MIXING WITH SLEET AND SNOW AT CID AND DBQ BY 21Z WED...WITH PROFILES TOP-DOWN COOLING TO ALL SNOW BY 00Z THU ACRS THE NORTHWEST AND THEN FURTHER EASTWARD. EARLY INDICATIONS SUGGEST A GOOD CHANCE FOR 1-2 INCHES OF SNOW AND POSSIBLY A FEW AREAS OF 3 INCHES ALONG AND NORTH OF HWY 30 WED NIGHT...WITH THE ACCUMULATIONS OCCURRING ON ELEVATED AND GRASSY SFC/S. AN INCH MAY EVEN OCCUR DOWN TO THE I80 CORRIDOR...WITH STILL MILD GROUND TEMPS ERODING THE TRUE ACCUMULATIONS. ON THANKSGIVING...STILL LOOKS COLD...BLUSTERY WITH LINGERING SNOW SHOWERS AND FLURRIES AS THE SECONDARY WAVE DEEPENS ACRS SOUTHERN LK MICHIGAN FAVORING THE 12Z ECMWF SOLUTION. WILL TONE DOWN HIGH TEMPS FOR THU AGAIN WITH WIDESPREAD MID TO UPPER 30S EXPECTED. FRIDAY...WILL SLOW RETURN FLOW AND THERMAL RECOVERY WITH SLOWER STACKED LOW PROGRESSION ACRS THE GRT LKS AND TONE DOWN FRI HIGHS. AS RIDGE EDGES ACRS THE AREA FRI NIGHT WITH CLEARING...LOW TEMPS MAY DIP INTO THE LOWER 20S TO EVEN UPPER TEENS IN SOME LOCATIONS BY SAT MORNING. RETURN FLOW BEGINS ON SAT AND CONTINUED INTO SUNDAY FOR A THERMALLY MODERATING FCST. WILL KEEP THE WEEKEND DRY FOR NOW BUT THERE MAY BE A FRONTALLY FORCED PRECIP EVENT BY SUNDAY DEPENDING ON LLVL MOISTURE RETURN. ..12.. && .AVIATION... VFR CLOUDS AND VSBYS THIS AFTERNOON SHOULD CONTINUE INTO TONIGHT. SCATTERED SHOWERS MAY AFFECT KCID AND KDBQ THIS EVENING AND OVERNIGHT...BUT VSBYS STAYING ABOVE 6SM AND CIGS ABOVE 6KFT. FOG MAY DEVELOP AFTER 06Z TONIGHT...MOST LIKELY AFFECTING KMLI AND KBRL WITH 2-3SM VSBYS BY MORNING. MUCH DEPENDS ON HOW LOW DEWPOINTS GO WITH DRIER SOUTHEAST FLOW. SHOWERS REMAIN POSSIBLE FOR EASTERN IOWA ON MONDAY...BUT CIGS AND VSBYS SHOULD AGAIN REMAIN VFR. ..LE.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ LE/12
