FXUS63 KDMX 111127
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
527 AM CST FRI DEC 11 2009
.SHORT TERM /TODAY/...
HI PRES RDG OVR IA WILL MOVE EWD SLOWLY TODAY AS A WEAK UPR LEVEL
RIPPLE SWEEPS ACRS THE CWA THIS MRNG. OTHER THAN SOME SCT
CLOUDS...DO NOT LOOK FOR ANY SIG WX WITH THIS FEATURE. TEMPS ARE
ALL OVER THE PLACE THIS MRNG WITH THE USUAL PLACES COOING OFF
SIG..WHILE READINGS REMAIN ABV ZERO ELSEWHERE. WENT AOA MOS IN MOST
AREAS AS MDLS ARE TOO COLD AT THE START AND WITH NEARLY FULL
SUN...WE DON'T HAVE ALL THAT FAR TO GO. COLD AREAS WILL JUMP QUICK
AS INVERSION BREAKS...SO THAT ISN'T MUCH OF AN ISSUE. SLOW WARMING
WITH LIGHT SWLY WINDS AND WAA TDA.
.LONG TERM /TONIGHT THROUGH THURSDAY/...
WARMING TREND CONTINUES OVER THE NEXT FEW DAYS AS BROAD SOUTHWEST
FLOW BEGINS TO DEVELOP. SNOW FIELD DEEPENS QUICKLY OVER IA AND ANY
SFC MOISTURE THAT ADVECTS NORTH OR EVAPORATES FROM MELTING WILL
QUICKLY PRODUCE FOG...THE LONGER THE SOUTHERLY WINDS PERSIST.
GUIDANCE HAS TEMPS WARMING TO THE 30S FOR SAT AND SUN. FEEL THAT SUN
MAY BE TOO HIGH THOUGH TREND IS CORRECT. WITH THE WEAK WARM FRONT
APPROACHING FOR SAT AFTERNOON/EVENING AND PERSISTENT SOUTH FLOW...
AND MOISTURE RETURN THE CHANCES FOR LIGHT SNOW OR ZL WILL INCREASE.
PREVIOUS SHIFTS HAVE ALREADY CARRIED MENTION FOR THIS TIME FRAME AND
SEE NO CHANGES TO CURRENT THINKING. HAVE ALSO INTRODUCED AREAS OF
FOG FOR THE PERIOD AS WELL BEGINNING SAT NIGHT AND CONTINUING
THROUGH SUNDAY NIGHT. THOUGH NOT A CERTAINTY...THIS IS GENERALLY A
GOOD SET UP FOR FOG...ESPECIALLY AFTER A STORM AND DEEP SNOW PACK.
THE FOG SHOULD BE A BIGGER PROBLEM THE FARTHER NORTH ONE GETS. FOR
NOW WILL INCLUDE AREAS/PATCHY WORDING FOR THE 3 PERIODS. ONCE LOW
MOVES THROUGH AND COLD AIR RETURNS THE FOG SHOULD BE SCOURED OUT OF
THE AREA. SYSTEM TO BRING LIGHT SNOW OR FLURRIES FOLLOWING THE LOW
ON MONDAY. ALONG WITH THAT THE MED RANGE GUIDANCE CONTINUES TO FORCE
RATHER COLD TEMPS BACK ACROSS THE REGION FOR A DAY OR TWO PRIOR TO
THE PATTERN ONCE AGAIN RETURNING TO ZONAL FLOW. THE GFS HAS H850
TEMPS TO -20C BY 12Z TUES WHILE THE WASHES A SWATH OF -12C AIR OVER
THE NORTH AND KEEPS THE BULK OF THE COLDEST AIR OVER THE NORTHERN
GREAT LAKES. THE EURO IS ALSO STRONGER WITH THE LOW ON SUNDAY NIGHT
WITH THE POTENTIAL FOR AN INCH OR TWO OF SNOW NORTH. WITH LESS
CERTAINTY BY DAY 4...WILL LEAVE IT TO SHIFTS FOLLOWING TO MAKE ANY
CHANGES IF THE TREND CONTINUES TO SHOW HIGHER QPF AND MORE
PROBABILITY OF SNOW. WARMER SIGNAL STILL REMAINS AFTER WED AFTERNOON
AND THURSDAY. GFS/GEM/EURO IN AGREEMENT TODAY THAT RIDGE WILL PASS
OVER THE STATE ON WED AM WHICH SUGGESTS A RATHER COLD OVERNIGHT AND
HAVE LOWERED MINS TO SUB ZERO CATEGORY FOR THAT PERIOD.
&&
.AVIATION...
11/12Z...VFR CONDS WILL HOLD THRU THE FCST PD. WK HI PRES RDG WILL
MOV EAST OF THE AREA WITH SW-SLY WINDS UNDER 10 KTS EXPECTED. GENLY
SWLY WINDS WILL HOLD THRU THE DAY WITH WINDS BCMG 160-180 DEG ARND
SNST.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE
&&
$$
SHORT TERM...MS DEC 09
AVIATION...MS DEC 09
LONG TERM...REV
