000
FXUS63 KDMX 301116
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
516 AM CST SAT NOV 30 2013

.SHORT TERM /TODAY/...
ISSUED AT 315 AM CST SAT NOV 30 2013

WEAK AREA OF LOW PRESSURE CURRENTLY LOCATED IN DAKOTAS WILL BEGIN TO
DROP SOUTHEAST THROUGH THE DAY TODAY. THIS WILL BRING A WEAK FRONTAL
BOUNDARY THROUGH CENTRAL IOWA TODAY. HOWEVER...THE FROPA WILL BRING
LITTLE WEATHER OF NOTE OTHER THAN A WIND SHIFT AS CONDITIONS REMAIN
DRY AND FORCING IS VERY WEAK. HOWEVER...WAA WILL INCREASE AHEAD OF
THE BOUNDARY WITH TEMPERATURES ABLE TO WARM NICELY THROUGH THE
DAY...ESPECIALLY ACROSS THE SOUTH AND WEST. GIVEN HOW WARM
TEMPERATURES WERE ABLE TO RISE ON FRIDAY...AND WITH LOWS ACROSS
CENTRAL IOWA REMAINING WARMER OVERNIGHT TONIGHT BY 10 OR MORE
DEGREES...HAVE INCREASED TEMPERATURES ACROSS THE CWA. AGAIN MAY SEE
SOME HIGH LEVEL CLOUDS INCREASING IN THE NORTH AS FRONTAL BOUNDARY
NEARS WHICH MAY AFFECT TEMPERATURES...KEEPING THEM COOLER.

.LONG TERM /TONIGHT THROUGH FRIDAY/...
ISSUED AT 315 AM CST SAT NOV 30 2013

A WEAK COLD FRONT WILL DROP SOUTH INTO THE AREA BY TONIGHT AND
EARLY SUNDAY. WITH LIGHT NORTHERLY WINDS AND COLD AIR ADVECTION
ALOFT...LIKELY THAT STRATUS WILL DEVELOP BY LATE SATURDAY NIGHT
AND CONTINUE FOR ALL OF SUNDAY AS COLDER AIR ALOFT LOWERS MID
LEVEL TEMPS TO NEAR SATURATION. THIS WILL RESULT IN COOL AFTERNOON
HIGHS FOR THE DAY. THE NEXT UPSTREAM TROUGH WILL APPROACH THE
REGION BY SUNDAY NIGHT AND MONDAY. THIS WILL AGAIN LACK MUCH
MOISTURE BUT THERE MAY BE ENOUGH LIFT ALONG THE APPROACHING WARM
FRONT OVER NORTHERN IOWA TO PRODUCE SOME LIGHT PRECIPITATION
BEGINNING FIRST AS LIGHT SNOW AND THEN BECOMING MIXED WITH LIGHT
RAIN AS TEMPS WARM DURING THE DAY. THE COVERAGE IS EXPECTED TO
EXPAND SOMEWHAT DURING THE EVENING HOURS AND THEN THE LIFT
GRADUALLY PULLS OFF TO THE EAST. OVERALL THE PATTERN BECOMES
ACTIVE NEXT WEEK AS ZONAL FLOW ALOFT CONTINUES TO CHANNEL A NUMBER
OF SHORT WAVES INTO THE REGION. A STRONG UPPER LEVEL LOW OFF THE
PACIFIC NORTHWEST WILL BEGIN TO EDGE EAST TUESDAY. AS IT DIGS
SOUTHEAST LEE SIDE TROUGHING WILL AGAIN INCREASE OVER THE PLAINS.
THIS WILL BRING ANOTHER ROUND OF PRECIPITATION TO THE REGION
TUESDAY NIGHT AND WEDNESDAY. CURRENTLY THE ENERGY FROM THIS SYSTEM
IS EXPECTED TO BE SPLIT INTO A NORTHERN AND SOUTHERN STREAM.
THOUGH CONFIDENCE IS BECOMING GREATER...THERE REMAINS SOME
UNCERTAINTY REGARDING THE TRACK OF THE ENERGY. THE MODELS HAVE FOR
NOW FOCUSED MOST OF THE ENERGY OVER THE NORTHERN PLAINS WITH THE
FIRST WAVE. THIS WOULD RESULT IN A DEEPER LOW OVER THE NORTHERN US
AND SOUTHERN CANADA. THE EURO IS SLOWER IN THE EVOLUTION OF THE
SYSTEM...ITS ARRIVAL AND EVENTUAL COLD FRONTAL PASSAGE LATE WED
AFTERNOON COMPARED TO THE GFS WHICH IS ABOUT 12 HOURS SOONER. WILL
SIDE WITH THE EURO FOR NOW...GIVEN THE EVER PRESENT BIAS THE GFS
GENERALLY EXHIBITS NEAR 120 HRS AND BEYOND. HAVE RAISED TMAX A FEW
DEGREES WED TO BLEND WITH SURROUNDING OFFICES. THE BEST CHANCES
FOR ANY MEASURABLE SNOWFALL WILL BE OVER CENTRAL AND NORTHERN MN
AND FAR OUT OF OUR AREA WITH THE PASSAGE OF THIS SYSTEM. AS THE
FRONT PASSES EAST SOME LIGHT SNOW OR FLURRIES WILL BE POSSIBLE.
THE MAIN THEME OF THE LARGE TROUGH WILL BE VERY COLD AIR. H850
TEMPS FALL FROM 5 TO 7C WED TO -17C SOUTH TO NEARLY -20C NORTH BY
FRIDAY AFTERNOON. THE MAGNITUDE OF THE COLD IS SUPPORTED BY THE
EURO...GFS...AND GEM THOUGH THE TIMING DIFFERS WITH THE GFS
ARRIVING SOONER. NO MATTER HOW YOU DO THE MATH...THIS TYPE OF
AIRMASS SHOULD SUPPORT HIGHS FALLING BACK INTO THE TEENS AND 20S
BY THURSDAY AND FRIDAY WITH LOWS FROM NEAR 0 TO 10 ABOVE AGAIN BY
THE END OF THE PERIOD. FOR NOW WILL NOT GO THAT COLD ONLY DUE TO
UNCERTAINTY OF EXTENT OF MIXING AS OLD LOW DEEPENS OVER SOUTHERN
CANADA AND ANOTHER ROUND OF ENERGY PASSES JUST SOUTHEAST OF
REGION...KEEPING SFC GRADIENT MORE ROBUST THAN USUAL WITH THIS
TYPE OF PATTERN CHANGE. WILL EXPECT TO SEE SOME RATHER COOL WIND
CHILLS BY THE END OF THE WEEK AT TIMES.

&&

.AVIATION...30/12Z
ISSUED AT 514 AM CST SAT NOV 30 2013

CEILINGS WILL REMAIN VFR THROUGH PERIOD. WINDS WILL SHIFT TO THE
NORTHWEST THROUGH 00Z AT SITES AS A FRONTAL BOUNDARY PUSHES
SOUTHEAST ACROSS CENTRAL IOWA. WINDS WILL BECOME LIGHT AND
BEHIND BOUNDARY FOR OVERNIGHT HOURS.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...AWB
LONG TERM...REV
AVIATION...AWB