000
FXUS63 KDMX 162122
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
422 PM CDT TUE MAR 16 2010
.SHORT TERM /TONIGHT/...
UPPER LEVEL WAVE SPINNING OVER WEST CENTRAL MINNESOTA...EXPECTED TO
DROP SOUTHWARD INTO CENTRAL MISSOURI BY LATE TONIGHT. WAVE HAS BEEN
RESPONSIBLE FOR PERSISTENT AREA OF SHOWERS ACROSS SE MN/NC AND NE
IOWA. THIS AREA OF SHOWERS SHOULD TRANSLATE TO THE SOUTH AND WEST
THROUGH THE EVENING INTO THE OVERNIGHT HOURS AS THE WAVE DROPS
THROUGH THE AREA. SHOWERS HAVE BEEN PRETTY SPOTTY ACROSS CWA...BUT
HAVE BEEN IN GREATER COVERAGE TO THE NORTH AND EAST. HOWEVER MODELS
INDICATING LIFT WANING SOME SO STUCK WITH ISOLATED TO SCATTERED
WORDING AT THIS TIME. LOW CLOUDS EXPECTED TO STICK AROUND...WITH FOG
POSSIBLE AGAIN LATE TONIGHT. MIN TEMPERATURES WILL BE MILD WITH THE
LOW CLOUDS/PRECIP HANGING AROUND...AND STUCK WITH TEMPS INTO THE 30S
TO AROUND 40.
.LONG TERM /TONIGHT THROUGH TUESDAY/...
THE FORECAST THROUGH THE WEEKEND LOOKS LIKE IT COULD THE GOOD...THE
BAD AND THE UGLY. FIRST WITH THE GOOD. HIGH PRESSURE WILL SETTLE
THROUGH THE WESTERN PLAINS ON WED WITH DECREASING CLOUD COVER
EXPECTED DURING THE DAY. HIGH TEMPERATURES IN THE UPPER 40S TO MID
50S SHOULD BE COMMON. AN EVEN WARMER DAY ON THURSDAY WITH THE
THERMAL RIDGE SETTLING THOUGH THE STATE. 850 MB TEMPERATURES OF 8C
WILL MOVE IN BY THURSDAY AND MAY HAVE MIXING UP TO THAT LEVEL. A
WARM SOUTHWEST TO WESTERLY FLOW AND SUN SHOULD PUSH READINGS INTO
THE MID 50S TO MID 60S.
THE BAD AND THE UGLY...STRONG SHORT WAVE ENERGY OVER THE GULF OF
ALASKA WILL OVERTOP THE WRN RIDGE AND DIVE INTO THE INTERMOUNTAIN
WEST. SOME UNCERTAINTY HOW THIS SYSTEM WILL EVOLVE AS IT LIFTS OUT
INTO MISSOURI FRIDAY INTO SATURDAY. CERTAINLY THE TRACK OF THE
SYSTEM IS GOING TO BE CONDUCIVE TO PULL COLD AIR DOWN FROM NORTHERN
CANADA AND WILL BRING THE CHANCE OF SNOW TO THE STATE. CURRENTLY
PREFER THE MORE NORTHERLY GFS/GEM SOLUTIONS OVER THE ECMWF. GIVEN
STRENGTH OF THE SYSTEM...WOULD EXPECT IT TO WRAP BACK TO THE
NORTHWEST FARTHER THAN THE ECMWF. IN ADDITION...LOW LEVEL WARM AIR
TENDS TO WRAP FARTHER NORTHWEST AS WELL AND DELAYS THE CHANGE OVER
FROM RAIN TO SNOW. EXPECT PRECIPITATION TO BEGIN OVER THE NORTHWEST
ON FRIDAY THEN SPREAD ACROSS THE REMAINDER OF THE AREA FRIDAY NIGHT
AND SATURDAY. THE PRECIPITATION TYPE OVER THE NORTHWEST WILL LIKELY
BE SNOW WITH THE SWITCH OVER LINE SOMEWHERE ACROSS CENTRAL
IOWA...WHICH IS QUITE DIFFICULT TO PIN POINT THIS FAR OUT.
EVENTUALLY WILL HAVE A CHANGE OVER TO SNOW ALL LOCATIONS. AT THIS
TIME...WOULD EXPECT AT LEAST MODERATE SNOW ACCUMULATIONS OVER THE
NORTHWEST. THIS PRECIPITATION WILL ALSO NEED TO BE MONITORED ON ITS
POTENTIAL IMPACT ON CURRENT FLOODING. LIQUID EQUIVALENTS OF ONE HALF
TO ONE INCH ARE POSSIBLE. MAINLY RAIN WOULD RESULT IN A MUCH QUICKER
PATH TO AREA STREAMS WHILE SNOW WOULD OFFER A SLOWER SOLUTION.
&&
.AVIATION...
16/18Z...IFR CIGS CONTINUES ACROSS THE AREA...AND ARE EXPECTED TO
REMAIN THROUGHOUT THE TAF PERIOD. AN UPPER LEVEL DISTURBANCE WILL
SPREAD ISOLATED TO SCATTERED SHOWERS ACROSS THE CWA FROM NORTH TO
SOUTH THROUGHOUT THE PERIOD. THESE SHOWERS ARE CURRENTLY IMPACTING
KMCW...AND WILL MOVE INTO KALO AND KFOD THIS AFTERNOON...AND KOTM
AND KDSM BY THIS EVENING. VSBYS RANGE FROM MVFR TO VFR...WITH A FEW
POCKETS OF IFR. VSBYS MAY DROP DUE TO FOG AGAIN AFTER THE SHOWERS
HAVE MOVED THROUGH THE AREA TONIGHT. SKIES ARE EXPECTED TO BEGIN
CLEARING FROM NORTH TO SOUTH THROUGH THE DAY WEDNESDAY...BUT FOR NOW
IT APPEARS TO BE JUST BEYOND THE FORECAST PERIOD.
&&
.HYDROLOGY...
WIDESPREAD MODERATE TO MAJOR FLOOD EVENT CONTINUES. THE FLOOD THREAT
IS MIGRATING FROM SOUTH TO NORTH WITH TIME. BASINS OF MOST CONCERN
ARE FIRST THE DES MOINES/RACCOON...FOLLOWED BY THE CEDAR/IOWA THEN
SKUNK. MODERATE TO MAJOR FLOODING EXPECTED AT MANY LOCATIONS IN THE
DES MOINES/RACCOON RIVER BASINS. ICE JAM PROBLEMS CONTINUE TO
DIMINISH.
SOME STREAMS ARE NEAR CREST NOW...WITH OTHERS EXPECTED THROUGH EARLY
NEXT WEEK. THERE IS A POSSIBILITY OF MODERATE TO HEAVY RAINFALL LATE
THIS WORK WEEK. LOOKING ON THE POSITIVE SIDE...IF THIS RAIN DOES
MATERIALIZE THEN IT WILL HAVE FALLEN AFTER THE CRESTS OCCUR...WHICH
MEANS IT WOULD HAPPEN DURING THE HYDROGRAPH RECESSIONS. ONCE THE
HYDROGRAPHS GO INTO RECESSION...IT TAKES A LOT OF EXTRA WATER TO
TURN THEM AROUND. WE WILL HAVE TO KEEP AN EYE ON THINGS.
MANY STREAMS WILL BE SLOWER THAN NORMAL TO RECEDE POST-CREST AND
FALL BELOW STAGE...AS THE RUNOFF FROM SNOW MELT AS WELL AS EXCESS
SOIL MOISTURE TAKES A WHILE TO FIND ITS WAY INTO THE STREAMS.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH UNTIL 7 AM CDT
WEDNESDAY FOR EMMET...HUMBOLDT...KOSSUTH...PALO ALTO...POCAHONTAS.
$$
SHORT TERM...BEERENDS
AVIATION...BEERENDS
LONG TERM...DONAVON
HYDROLOGY...ZOGG
