000
FXUS63 KDMX 060529
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1129 PM CST THU DEC 5 2013

.SHORT TERM /TONIGHT/...
ISSUED AT 344 PM CST THU DEC 5 2013

MAIN FORECAST CONCERN FOR OVERNIGHT BECOMES TEMPERATURES AND
WINDCHILL VALUES. TEMPERATURES WARMED TODAY AS EXPECTED...THOUGH
HAVE ALREADY BEGUN TO FALL OFF ACROSS THE NORTHWEST WITH CLEAR SKIES
AND STRONGEST PUSH OF CAA. SHARP TEMPERATURES GRADIENT ACROSS THE
CWA WILL REMAIN DUE TO HIGH CLOUDS ACROSS THE SOUTH AND SOUTHEAST
THROUGH THE OVERNIGHT. HIGH PRESSURE WILL CONTINUE TO PUSH SOUTH
OVERNIGHT TONIGHT...THOUGH WILL REMAIN PRIMARILY NORTH OF IOWA.
AND...PRESSURE GRADIENT FROM RETREATING LOW WILL CONTINUE TO
WEAKEN...THOUGH WILL REMAIN IN PLACE ENOUGH TO KEEP WINDS UP
OVERNIGHT. WINDS WILL HELP TO KEEP LOWS SOMEWHAT WARMER.
HOWEVER...WINDS WILL COMPOUND ALREADY COLD LOWS LEADING TO FRIGID
WIND CHILL VALUES...ESPECIALLY AFTER 06Z AND NEAR SUNRISE. WITH
LOWS BELOW ZERO IN MUCH OF THE NORTH...HAVE EXPANDED WIND CHILL
ADVISORY SLIGHTLY FURTHER SOUTHWEST. HOWEVER...WIND CHILL VALUES
WILL BE WELL BELOW ZERO ACROSS THE ENTIRE CWA...WITH DANGEROUS
CONDITIONS POSSIBLE WITH PROLONGED EXPOSURE...ESPECIALLY ALONG AND
NORTH OF INTERSTATE 80.

.LONG TERM /FRIDAY THROUGH THURSDAY/...
ISSUED AT 344 PM CST THU DEC 5 2013

COLD AIR WILL CONTINUE TO ADVECT INTO THE STATE ON THURSDAY AHEAD
OF APPROACHING SURFACE RIDGE. IT WILL BE ANOTHER RELATIVELY SUNNY
DAY BUT QUITE COLD AS THE ARCTIC AIRMASS BECOME ENTRENCHED ACROSS
THE STATE. RIDGE AXIS TO BUILD INTO WESTERN IOWA ON FRIDAY NIGHT
WITH WINDS SLOWLY SUBSIDING. WIND CHILL VALUES ACROSS THE NORTH
WILL APPROACH ADVISORY CRITERIA BUT LEVEL OFF RIGHT AROUND 20
BELOW IN THE FAR NORTH. HAVE GONE WITHOUT HEADLINE FOR LATE FRIDAY
NIGHT/SATURDAY MORNING GIVEN THAT MOST LOCATIONS DO NOT MAKE
CRITERIA AND HAVE TIME TO REEVALUATE TONIGHT AND TOMORROW.

FOCUS THEN SHIFTS TO UPPER SYSTEM WHICH WILL DROP INTO THE
SOUTHWEST UNITED STATES BY SATURDAY EVENING BEFORE EJECTING TO THE
NORTHEAST INTO EARLY NEXT WEEK. WILL SEE A VERY BROAD AREA OF
ISENTROPIC LIFT INCREASE LATE SATURDAY NIGHT OVER IOWA AND PERSIST
INTO SUNDAY NIGHT BEFORE SYSTEM PASSES TO THE EAST AND SUBSIDENCE
INCREASES. THE LIFT WILL BE THROUGH A RELATIVELY DEEP DENDRITIC
LAYER THAT IS FULLY SATURATED. DESPITE RELATIVELY MODEST
LIFT...SNOW GROWTH SHOULD BE EFFICIENT WITH PLENTY OF FLUFF TO
THE SNOW. HAVE GONE WITH SNOW RATIOS OF 15:1 TO 20:1 ACROSS MUCH
OF THE AREA DURING THIS TIME WITH SNOW AMOUNTS GENERALLY FROM 3 TO
5 INCHES BY EARLY MONDAY MORNING ACROSS THE FORECAST AREA. WINDS
PRESSURE GRADIENT ISNT OVERLY TIGHT AND DONT ANTICIPATE WINDS TO
BE AN ISSUE AT THIS POINT. COLD AIR WILL REMAIN IN PLACE INTO
EARLY NEXT WEEK BEHIND THE WEEKEND SYSTEM WITH EDGE OF POLAR
AIRMASS NEAR IOWA INTO MID WEEK.

&&

.AVIATION...06/06Z
ISSUED AT 1129 PM CST THU DEC 5 2013

VFR CONDITIONS WITH BREEZY NORTHWEST WINDS WILL PERSIST THROUGH
THE PERIOD.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL NOON CST FRIDAY FOR CALHOUN-CERRO
GORDO-EMMET-HANCOCK-HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-SAC-
WINNEBAGO-WORTH.

&&

$$

SHORT TERM...AWB
LONG TERM...COGIL
AVIATION...DONAVON