000
FXUS63 KDMX 032140
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
339 PM CST WED DEC 3 2008
.SHORT TERM.../TONIGHT THROUGH SAT/
EVEN AS THE BAND OF CLOUDS AND SNOW THAT AFFECTED OUR AREA TODAY
MOVES OUT TO THE SOUTHEAST LATE THIS AFTERNOON...A SUBTLE SECONDARY
SHORTWAVE/SURFACE TROUGH IS KICKING OFF STRATUS ACROSS MN/SD THAT
WILL MOVE INTO AT LEAST THE NORTHWESTERN THIRD OF OUR COUNTIES
TONIGHT. WHILE FLURRIES ARE PROBABLE WITHIN THIS STRATUS
FIELD...CHANCES OF MEASURABLE SNOW WILL LIKELY HOLD OFF UNTIL AFTER
12Z THURSDAY EXCEPT IN THE FAR NORTHWESTERN COUNTIES. OTHER PRIMARY
CONCERN FOR TONIGHT IS MIN TEMPS. IN THE NORTH/NORTHWEST THE
DEVELOPING CLOUD FIELD WILL HOLD TEMPS UP A BIT...BUT IN THE
NORTHEASTERN...CENTRAL AND SOUTHERN COUNTIES SKIES WILL BE CLEARER
AFTER SUNSET. IN ADDITION...HIGH PRESSURE SLIDING BY TO THE
SOUTHWEST WILL RESULT IN THE LIGHTEST WINDS BEING FOUND IN THE
SOUTHERN AND SOUTHWESTERN COUNTIES. THUS RADIATIONAL COOLING IS A
GOOD BET ACROSS MOST OF THAT AREA.
RELATIVELY SMALL...WEAK AND SHALLOWER LAYER OF DENDRITIC FORCING
DROPS INTO NWRN SECTIONS THU...DOWN TO AROUND H85 DUE TO COLD
AIRMASS. HAVE CONTINUED HIGH END CHANCE POPS...BUT MEASURABLE
AMOUNTS WILL BE SOMEWHAT SUSPECT...WITH LINGERING FLURRIES POSSIBLE
INTO THE EVENING. NEXT SYSTEM OF CONCERN IS FRI NIGHT/SAT FOR
NORTHEASTERN SECTIONS. ECMWF/GFS ARE IN GOOD AGREEMENT WITH SHORT
WAVE TOPPING GULF AK RIDGE AND DROPPING INTO UPPER MS VALLEY.
DENDRITIC LAYER FORCING IS RELATIVELY WEAK...BUT WIDESPREAD WITH
DEEP SATURATION SO HAVE HIGH END CHANCES TO LOW END LIKELIES GOING
NERN SECTIONS WITH AROUND AN INCH ACCUMS EXPECTED IF TRENDS CONTINUE.
HIGHS THU SHOULD BE ON THE LOW END OF GUIDANCE LOOKING AT SOUNDINGS
AND CONSIDERING SNOW COVER...WITH SIMILAR THINKING INTO THU NIGHT
AND FRI. WITH WARM ADVECTION INCREASE...EXPECTED NON-DIURNAL TREND
FRI NIGHT WITH STEADY OR SLOWLY RISING TEMPS FOLLOWING MAY FALLING
TEMPS SAT BEHIND ANOTHER COLD FRONT.
.LONG TERM.../SAT NIGHT THROUGH WED/
SIMILAR PATTERN EXIST DURING THIS PERIOD AS LONG WAVE TROUGH
CONTINUES TO RE-ESTABLISH ITSELF INTO CENTRAL CONUS BY EARLY NEXT
WEEK. DEEP MEAN TROUGH PASSES THROUGH MS VALLEY LATE MONDAY.
LATEST DETERMINISTIC AND ENSEMBLE SOLUTIONS INDICATE THAT SHORT WAVE
AND SURFACE REFLECTION SHOULD PASS TO OUR NORTH KEEPING MOST SNOW
ACCUMS NORTH OF IA. STRONG WARM ADVECTION SURGE COULD BRING SOME
PRECIP...AND MAY BE MIXED WITH WARM LAYER NUDGING ABOVE
FREEZING...BUT DEF ZONE AND PRIMARY KINEMATIC FORCING LOOK TO REMAIN
NORTH. THUS HAVE KEPT CHANCE POPS GOING IN THAT WINDOW. NOTHING
SIGNIFICANT ENOUGH TO CARRY POPS IN THE REMAINDER OF PERIOD AS OF
YET.
RAW TEMPS FROM RECENT GFS RUNS AND LATEST ECMWF SUGGEST GOING AT OR
BELOW COOLEST ENSEMBLE MOS NUMBERS THIS WEEKEND BUT WITH SOME
MODERATION POSSIBLE DAYS 5-7.
&&
.AVIATION...03/18Z
SNOW HAS CLEARED ALL TERMINALS EXCEPT KOTM...WHERE A BAND OF HEAVY
SNOW IS PRODUCING LIFR/VLIFR CONDITIONS ATTM. THIS BAND OF SNOW
SHOULD CLEAR KOTM BY AROUND 18Z...WITH LIGHT SNOW AND MVFR CIGS THEN
LINGERING UNTIL 19Z OR 20Z. OTHERWISE...MAINLY VFR CONDITIONS
EXPECTED NEXT 24 HRS. LOW CLOUDS WILL MAKE A RETURN AROUND MIDNIGHT
TONIGHT THROUGH THE MORNING...ATTM IT APPEARS THAT CIGS WILL REMAIN
AROUND FL035-045 HOWEVER IT SI POSSIBLE THAT AT THE NORTHERN SITES
THE STRATUS MAY BE BASED LOWER RESULTING IN MVFR CIGS.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
LEE/SMALL
