Severe Thunderstorm Warning 339, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
400 AM CST FRI NOV 10 2006

SHORT TERM (TODAY)...
PLENTY OF ISSUES FOR THE FIRST 12 HOURS AS SHORTWAVE PASSES THROUGH
THE REGION. CURRENTLY...FRONTOGENETICAL FORCING INCREASING ACRS THE
STATE AS UPPER WAVE APPROACHES.  STRONG THETA-E ADVECTION AND WEAK
INSTABILITY HAVE LED TO SOME CONVECTIVE SHOWERS OVER THE PAST FEW
HOURS WITH LIGHTNING NOTED IN BOTH OBS AND LIGHTNING DATA.
RELATIVELY DRY LOW LEVELS ACRS THE NORTH HAVE BEEN SATURATING AND
PULLING TEMPERATURES DOWN TOWARD FREEZING.  EST NOW INDICATING LIGHT
SNOW WITH A HEAVIER BAND ADVANCING TOWARD THE AREA.  EXPECT BANDED
FEATURES TO CONTINUE DURING THE MORNING AS STRONG FRONTOGENETICAL
FORCING PASSES THROUGH THE CWA.  SOME CONCERN AS TO THE EXTENT OF
THE CONVECTIVE POTENTIAL.  THE CROSS SECTION CERTAINLY SHOWS
NEGATIVE EPV ABOVE THE FRONTAL SURFACE ALOFT AND WITH SOME
CONVECTION ALREADY OCCURRING...LIKELY TO SEE SOME OF IT CONTINUE
INTO THE MORNING.  OTHERWISE...IT BECOMES A TIMING ISSUE OF SWITCH
OVER FROM RAIN TO SNOW ACRS THE CWA.  NORTHERN COUNTIES LIKELY TO BE
SNOW FOR ALMOST ENTIRE EVENT WITH SOME MIXTURE INDICATED IN A BAND
NEAR THE STATE HIGHWAY 3 TO HIGHWAY 20 CORRIDOR THIS MORNING BEFORE
TRANSITION TO ALL SNOW AS INDICATED BY BUFKIT SOUNDINGS.  FARTHER
SOUTH...WL SEE RAIN FOR MUCH OF THE MORNING PRIOR TO CHANGE OVER TO
SNOW DURING THE AFTERNOON AS CAA INCREASES BEHIND THE SYSTEM.
SNOWFALL AMOUNTS ACRS THE NORTH WL LIKELY BE ENHANCED BY SOME
CONVECTIVE ELEMENTS WITH HIGHEST AMOUNTS IN FAR NORTH CENTRAL BY
WORTH AND CERRO GORDO COUNTIES WHERE 4 TO 6 INCHES HAVE BEEN
FORECAST.  IF CONVECTIVE ELEMENTS CONTINUE FOR A TIME LONGER...MAY
PUSH WARNING CRITERIA IN THESE COUNTIES AND THIS WL HAVE TO BE
MONITORED.  MUCH OF THE REMAINDER OF THOSE NORTH CENTRAL COUNTIES WL
SEE 2 TO 5 INCHES AND SNOW ADVISORY HAS BEEN ISSUED FOR THIS AREA.
ON THE SOUTHERN EDGE OF THE SNOW ADVISORY...MAY SEE A BIT LONGER
PERIOD OF MIXED PCPN AND HAVE ISSUED A WINTER WX ADVISORY FOR
RAIN...SLEET AND SNOW FOR A PERIOD PRIOR TO A TRANSITION TO ALL
SNOW.  THESE LOCATIONS WL LIKELY SEE 1 TO 3 INCHES OF SNOW. COULD
ACTUALLY SEE SOME LGT SNOW ACCUMULATIONS DOWN TO THE INTERSTATE 80
WITH THE BEST THREAT IN THE WESTERN CWA WEST OF INTERSTATE 35. MAY
ALSO HAVE TO SEE IF WINDS KEEP UP AS FLOW OFF OF THE SFC REMAINS
NEAR 40KTS FM THE NORTHEAST AND HAVE SEEN SOME HIGHER GUSTS ACRS THE
FAR WEST.

COGIL

&&

LONG TERM (TONIGHT THRU THURSDAY)...
TONIGHT NAM TIMING FAVORED WITH LINGERING LIGHT SNOW BEFORE MIDNIGHT
THOUGH NOT EXPECTING ANYTHING MEASURABLE AND BEST DYNAMICAL FIELDS
MOVED OFF NORTHEAST AFTER 06Z/11.  NAM TEMPS ON LOW SIDE SO HAVE
LEANED MORE TOWARD HIGHER MAV GUIDANCE.  HIGH PRESSURE INTO STATE
SATURDAY LOOKING COLD SATURDAY NIGHT THOUGH WARM ADVECTION BEGINS
LATE SUNDAY EVENING AND IN FULL SWING BY SUNDAY MORNING.  HOWEVER
LOOK AT SOUNDINGS WOULD NOT EXPECT MOISTURE RETURN UNTIL LATE SUNDAY
NIGHT.  HAVE LEFT PREVIOUS FORECASTS CHANCE HOWEVER BECAUSE OF
TIMING ISSUES TOOK RAIN OUT FOR SUNDAY MORNING.  TEMPERATURE WISE
EXPECT RECOVERY FROM THAT COOL OVERNIGHT WITH GOOD WAA.

FORSTER

&&

DMX WATCHES/WARNINGS/ADVISORIES...SNOW ADVISORY TIL 18Z
IAZ004-005-015-023-024.
WINTER WEATHER ADVISORY TIL 18Z IAZ033>035.
SNOW ADVISORY TIL 22Z IAZ006-007-016-017.
WINTER WEATHER ADVISORY TIL 22Z IAZ025>028.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
518 AM CST FRI NOV 10 2006

IAZ004>007-015>017-023-024-111100-
EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-
POCAHONTAS-HUMBOLDT-
518 AM CST FRI NOV 10 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

AN ADVISORY IS IN EFFECT FOR THE AREA. PLEASE REFER TO THE
NATIONAL WEATHER SERVICE WEB SITE AT WEATHER.GOV/DESMOINES.
SNOW WILL CONTINUE MUCH OF THE DAY DIMINISHING OR ENDING DURING
THE AFTERNOON. SNOWFALL POTENTIAL IS FROM 3 TO 6 INCHES.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT NEEDED HOWEVER SNOWFALL REPORTS WOULD BE HELPFUL.

IAZ025>028-033>035-111100-
WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN-WEBSTER-
518 AM CST FRI NOV 10 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

AN ADVISORY IS IN EFFECT FOR THE AREA. PLEASE REFER TO THE
NATIONAL WEATHER SERVICE WEB SITE AT WEATHER.GOV/DESMOINES.
A MIX OF RAIN SLEET AND SNOW IS EXPECTED TO MAKE FOR DIFFICULT
DRIVING CONDITIONS.THERE IS THE LIKELIHOOD OF SNOW AND SLEET
ACCUMULATIONS OF 2 TO 4 INCHES BEFORE ENDING LATE THIS AFTERNOON.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT NEEDED HOWEVER PRECIPITATION REPORTS
WOULD BE HELPFUL.

IAZ036>039-044>050-057>062-070>075-081>086-092>097-111100-
HAMILTON-HARDIN-GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-GREENE-BOONE-
STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-DALLAS-POLK-JASPER-POWESHIEK-
CASS-ADAIR-MADISON-WARREN-MARION-MAHASKA-ADAMS-UNION-CLARKE-LUCAS-
MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE-DAVIS-
518 AM CST FRI NOV 10 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

RAIN AND ISOLATED THUNDERSTORMS ARE POSSIBLE ESPECIALLY THIS
MORNING BEFORE COLDER AIR FILTERS INTO THE AREA. SOME OF THESE
STORMS COULD PRODUCE SMALL HAIL. THE RAIN WILL BECOME MIXED
BRIEFLY WITH SLEET BEFORE CHANGING OVER TO ALL SNOW THIS
AFTERNOON. LITTLE SLEET OR SNOW ACCUMULATION IS EXPECTED.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NO SPOTTER ACTIVATION IS NEEDED AT THIS TIME.

FORSTER

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
829 AM CST FRI NOV 10 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0825 AM     HAIL             4 SE REASNOR            41.54N 92.97W
11/10/2006  E0.88 INCH       JASPER             IA   TRAINED SPOTTER

            HAIL WAS COVERING THE GROUND.

&&

CCOGIL