Area Forecast Discussion
Issued by NWS Des Moines, IA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KDMX 180951
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
351 AM CST TUE NOV 18 2014

.SHORT TERM /TODAY/...
ISSUED AT 351 AM CST TUE NOV 18 2014

MAIN CONCERNS WILL BE EARLY MORNING WIND CHILLS ACROSS THE NORTH
ALONG WITH TEMPS AND CLOUD COVER OVER THE REGION FOR TODAY.
ALOFT...COLDEST AIR AT H850 ASSOCIATED WITH UPPER LEVEL TROUGH NOW
OVER THE AREA AND HEADING SOUTHEAST. WINDS HAVE BECOME MORE WESTERLY
OVER THE REGION SINCE MID EVENING AND CONTINUE IN THE 10 TO 15 MPH
RANGE. MEANWHILE...AN AREA OF MILDER AIR ALONG WITH CLOUD COVER IS
MOVING SOUTHEAST TOWARD THE STATE AND NOW ENTERING NORTHWEST IOWA.
THIS HAS ESSENTIALLY CAPPED THE TEMPERATURE FALL FOR NOW AND TEMPS
HAVE ACTUALLY RISEN IN SOME CASES. CLOUDS WILL SPREAD EAST SOUTHEAST
BY SUNRISE AND MUCH OF THE DAY OVER CENTRAL AND SOUTH WILL HAVE A
SUN CLOUD MIX. OVER THE NORTH...MORE CLOUDS ARE EXPECTED THROUGH THE
DAY. EARLY MORNING WIND CHILL VALUES MAY BE WARMER THAN EARLIER
ANTICIPATED...SO PLAN ON LETTING THE ADVISORY GO BECAUSE EARLY
MORNING TEMPS ARE MUCH WARMER THAN ANTICIPATED. THE REMAINDER OF THE
DAY WILL SEE WESTERLY WINDS MIXING TO ABOUT 16 TO 22 MPH IN THE
AFTERNOON. THIS...ALONG WITH WARM AIR ADVECTION ALOFT AT H850 WILL
PROMOTE WARMING THIS AFTERNOON... RELATIVE TO MONDAY. HIGHS WILL
CLIMB TO THE MID TEENS NORTH WHERE MORE CLOUDS ARE EXPECTED TO THE
MID 20S CENTRAL AND SOUTH DURING THE AFTERNOON HOURS. THERE MAY BE
SOME FLURRIES YET OVERNIGHT AND EARLY IN THE DAY WITH THE CLOUDS
HEADING EAST. OTHERWISE...A RELATIVELY QUIET FORECAST FOR MUCH OF
THE AREA.

.LONG TERM /TONIGHT THROUGH MONDAY/...
ISSUED AT 351 AM CST TUE NOV 18 2014

AN ALBEIT SHORT PERIOD OF WELL DESERVED WAA WILL BE ONGOING THIS
EVENING OUT AHEAD OF AN APPROACHING SHORTWAVE TROUGH. HAVE
LIKEWISE GONE WITH A NON-DIURNAL TEMPERATURE TREND DURING THIS
TIMEFRAME WITH READINGS SLOWLY RISING THROUGH THE NIGHT. THE FRONT
WILL QUICKLY PASS THROUGH THE CWA BETWEEN O6Z AND 12Z ON
WEDNESDAY. THE BEST DENDRITIC ZONE FORCING AND LIFT LOOKS TO GRAZE
THE NORTHERN CWA DURING THIS TIME. MOISTURE PROFILES DO SUPPORT A
SHORT BOUT OF SNOW FOR THE NORTHERN PARTS OF THE STATE AND HAVE
INCREASED POPS FOR THE NORTH BUT KEPT SNOW AMOUNTS TO ONLY A FEW
TENTHS OF AN INCH GIVEN THE TRANSIENT NATURE OF THE SYSTEM.

COLDER AIR WILL ONCE AGAIN STREAM IN BEHIND THE FRONT...
STEEPENING BL LAPSE RATES AND LEADING TO GUSTY WINDS DURING THE
DAY ON WEDNESDAY. NAM BUFR SOUNDINGS IN PARTICULAR FOR WESTERN AND
SOUTHERN IOWA SUPPORT SHALLOW UPRIGHT CONVECTION WEDNESDAY
AFTERNOON. ADDED SHSN WORDING TO THE FORECAST FOR THESE AREAS AND
ALSO PATCHY BLSN WITH WINDS OF 15 TO 20 KTS AND GUSTS TO 25 KTS. A
FEW GUSTS OVER 30 KTS ARE NOT OUT OF THE QUESTION OWING TO GOOD
DOWNWARD MOMENTUM TRANSPORT. SURFACE HIGH PRESSURE THEN BUILDS IN
FOR WEDNESDAY NIGHT INTO EARLY FRIDAY. LOWS ACROSS THE NORTH FOR
THESE TWO NIGHTS LOOK TO BOTTOM OUT JUST ABOVE ZERO GIVEN THE
CURRENT SNOW PACK AND MOSTLY CLEAR SKIES.

A DIGGING 500 MB TROUGH WILL PROGRESS ACROSS THE FOUR CORNERS
REGION LATE ON FRIDAY. GULF MOISTURE WILL STREAM NORTHWARD OUT
AHEAD OF THIS SYSTEM WITH 925-700 MB MIXING RATIOS RISING FROM
0.60 TO 4.20 G/KG BETWEEN 00Z FRIDAY AND 00Z SATURDAY. MULTIPLE
WAVES OF THETA-E ADVECTION LOOK TO DRIVE THE PRECIP DURING THE
WEEKEND. HOWEVER...THIS MOISTURE WILL BE CONFINED BELOW 850 MB
WITH A LARGE WEDGE OF DRY AIR ALOFT...INHIBITING ANY ICE
INTRODUCTION. THERE APPEARS TO BE A SMALL WINDOW LATE ON FRIDAY
WHERE FREEZING RAIN WILL BE POSSIBLE OVER PARTS OF CENTRAL AND
NORTHEASTERN IOWA. HOWEVER...THERE IS CONSIDERABLE UNCERTAINTY IN
THIS FORECAST AND THE DURATION OF THE ZR WILL LARGELY DEPEND ON
HOW QUICK THE WAA PUSHES SURFACE TEMPS ABOVE FREEZING. RAIN IS
FORECAST FOR THE REST OF THE WEEKEND BEFORE A RAPIDLY DEEPENING
SURFACE LOW LIFTS NORTHEAST OF THE CWA AND PULLS COLDER AIR BACK
ACROSS THE AREA ON MONDAY AND SWITCHES PRECIP BACK TO SNOW.

&&

.AVIATION...18/06Z
ISSUED AT 1130 PM CST MON NOV 17 2014

MAIN CONCERN THROUGH THE PERIOD WILL BE UPSTREAM...MAINLY LOW VFR
CIGS. THERE IS A MINIMAL POTENTIAL TO JUST DIP INTO MVFR...BUT
CONFIDENCE IN TIMING OR LOCATION IS NOT GREAT ENOUGH TO INCLUDE AT
THE MOMENT. VFR ANTICIPATED BY LATER TUE IS EXPECTED AS WELL...BUT
WITH NOTHING MORE THAN MID/HIGH CLOUDINESS. WIND SPEEDS SHOULD
REMAIN FAIRLY STEADY W TO SW IN THE 10-15KT RANGE UNTIL DIPPING
SLIGHTLY AS THEY BECOME MORE SLY TUE EVENING.


&&

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

&&

$$

SHORT TERM...REV
LONG TERM...SKOW
AVIATION...SMALL



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.