Freezing Rain Advisory 3, NWS Des Moines, IA

Adair County, IA, Adams County, IA, Appanoose County, IA, Audubon County, IA, Carroll County, IA, Cass County, IA, Clarke County, IA, Crawford County, IA, Dallas County, IA, Davis County, IA, Decatur County, IA, Greene County, IA, Guthrie County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Monroe County, IA, Polk County, IA, Ringgold County, IA, Taylor County, IA, Union County, IA, Wapello County, IA, Warren County, IA, Wayne County, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
910 PM CST SUN FEB 11 2007

.DISCUSSION...
HAVE LEFT SNOW ADVISORY IN THE NORTH AS S/W SLOW TO TRACK ACROSS
THAT AREA OF THE STATE THOUGH APPEARS BAND OF SNOW IN EXCESS OF 3
INCHES IS VERY NARROW PER CALLS.  OTHER PARTS OF THE STATE PCPN WAS
PLAYED DOWN AS CURRENT SHORT TERM MODELS FAVORING BEST DYNAMICAL
FIELDS NORTH THOUGH WILL NOT RULE OUT LIGHT FRZG PCPN.  TEMPERATURES
SLOW TO FALL SOME MINOR ADJUSTMENTS MADE THERE.

.PREVIOUS DISCUSSION...
PLENTY OF ISSUES IN THE FORECAST THROUGH TUESDAY WITH SYSTEM PASSING
THROUGH THE REGION.  WARM FRONT IS ACROSS NORTHERN IOWA THIS
AFTERNOON WITH READINGS RISING ABOVE FREEZING FOR THE FIRST TIME IN
JUST OVER TWO WEEKS...MAINLY SOUTH OF HIGHWAY 20.  THE WARMING WAS
AIDED BY A FEW HOURS OF SUNSHINE AS CLOUDS ERODED QUICKLY FROM THE
SOUTH THIS MORNING.  HOWEVER...CLDS RAPIDLY ADVANCING INTO THE WEST
AHEAD OF WEAK UPPER WAVE IN WESTERN NEBRASKA.  ISENTROPIC LIFT WL
INCREASE CONSIDERABLY THIS EVENING AHEAD OF THIS APPROACHING WAVE
WITH PDEF FALLING QUICKLY ACRS THE NORTH.  EXPECT A MIXTURE OF
RAIN/SNOW INITIALLY CHANGING TO ALL SNOW RATHER QUICKLY AS FORCING
INCREASES AND SOUNDING CRASH BELOW ZERO.  BOTH GFS AND NAM SUGGESTED
A RATHER INTENSE NARROW BAND OF FORCING IN NORTHERN IOWA THIS
EVENING INTO THE EARLY MORNING HOURS.  THIS WL PRODUCE A NARROW
SWATH OF ACCUMULATING SNOW IN NORTHERN IA WITH SOME MODERATE AMOUNTS
IN A SHORT PERIOD OF TIME.  HAVE OPTED TO GO WITH ADVISORY IN
NORTHERN THREE TIERS TONIGHT FOR THIS SNOWFALL WHERE 2 TO 5 INCHES
ARE POSSIBLE.

GFS AND NAM CONTINUE TO SLOW WITH PROGRESSION OF SYSTEM THROUGH THE
REGION.  MID LEVELS DRY ON MONDAY WITH LITTLE IF ANY FORCING PRESENT
THROUGH MUCH OF THE DAY.  SOUNDINGS INDICATIVE OF FZDZ FOR MUCH OF
THE DAY AND HAVE ADDED TO THE GRIDS.  WATCH IS QUITE BORDER LINE ON
MONDAY AND HAD THOUGHT OF BACKING IT UP TO 18Z OR 00Z.  HOWEVER...
THREAT REMAINS FOR HEADLINES IN CONSIDERATION OF THE PSBL FREEZING
DRIZZLE.  ISENTROPIC LIFT AND QG FORCING INCREASE BY LATE IN THE DAY
AS WAVE BEGINS TO CROSS THE PLAINS.  EXPECT SNOW RATES TO PICK UP
ACRS THE SOUTHWEST BY LATE AFTERNOON AND SPREAD NORTHEAST DURING THE
NIGHT.  FOCUS OF BEST FORCING REMAINS ACRS THE SOUTH WHERE HIGHEST
SNOW RATES ARE EXPECTED.  GFS AND NAM ARE NOT NEARLY AS HIGH WITH
AMOUNTS AS YESTERDAYS RUNS...BUT STILL APPROACH WARNING CRITERIA IN
THE SOUTHERN TWO OR THREE TIERS.  IN ADDITION...PRES GRADIENT REALLY
TIGHTENS BY LATER MONDAY NIGHT AND EXPECT BLOWING SNOW TO BECOME AND
ISSUE DURING THE EARLY MORNING HOURS.  THE SLOWING OF THE SYSTEM
EXTENDS THE PCPN INTO TUESDAY ACRS THE CWA AND THEREFORE HAVE
EXTENDED WATCH TIL 18Z ON TUESDAY.  BLOWING SNOW WL ALSO CONTINUE
INTO TUESDAY AS GRADIENT REMAINS TIGHT AROUND DEEPENING SFC LOW.
SO...WSW WL HIGHLIGHT FZDZ POTENTIAL FOR MONDAY THEN ACCUMULATING
SNOWFALL MONDAY NIGHT INTO TUESDAY MORNING ALONG WITH THE INCREASING
BLOWING SNOW PROBLEM AS WELL.

EXTENDED STILL REMAIN COLD THROUGH MID WEEK AS CANADIAN HIGH DROPS
INTO THE PLAINS.  SOME MODERATION EXPECTED TOWARD THE WEEKEND AS
UPPER RIDGING TRIES TO MOVE FROM THE WEST COAST TOWARD THE EAST AND
BROADEN.  APPEARS THAT A WAVE WL DROP DOWN BACKSIDE OF EASTERN TROF
BY LATE IN THE WORK WEEK WITH INCREASING THREAT OF SNOW.  CHANCES
HAVE BEEN INCREASED FOR FRIDAY NIGHT BUT LIKELY SOME ADJUSTMENT WL
BE NEEDED AS TIMING BECOMES BETTER DEFINED.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...SNOW ADVISORY 6 PM TO 6AM
TONIGHT.  IAZ004>007-015>017-023>028-039.
WINTER STORM WATCH ALONG AND SOUTH OF HIGHWAY 30 MONDAY THROUGH 12
PM TUESDAY.  IAZ044>050-057>062-070>075-081>086-092>097.

&&

COGIL/FORSTER/ 202/39

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
328 PM CST SUN FEB 11 2007

IAZ004>007-015>017-023>028-039-121145-
EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-
POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-BLACK HAWK-
328 PM CST SUN FEB 11 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHERN IOWA
ALONG AND NORTH OF HIGHWAY 20.

.DAY ONE...TONIGHT

PERIODS OF MODERATE SNOW WILL MOVE ACROSS THE AREA TONIGHT WITH
A BAND OF SNOW EXPECTED TO DEVELOP THIS EVENING THEN MOVE ACROSS
THE AREA OVERNIGHT. SNOWFALL ACCUMULATIONS UP TO 3 INCHES WILL BE
COMMON...THOUGH LOCALLY HIGHER AMOUNTS ARE POSSIBLE.

A SNOW ADVISORY IS IN EFFECT FOR THE AREA. PLEASE REFER TO THE
NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

ACCUMULATING SNOWFALL IS POSSIBLE LATE MONDAY AND MONDAY NIGHT
HOWEVER AT THIS TIME IT APPEARS THAT THE HEAVIER ACCUMULATIONS
WILL BE TO THE SOUTH OF THE AREA.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED BUT SNOWFALL REPORTS WILL
BE APPRECIATED.

IAZ044>050-057>062-070>075-081>086-092>097-121145-
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-
328 PM CST SUN FEB 11 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL AND
SOUTHERN IOWA ALONG AND SOUTH OF HIGHWAY 30.

.DAY ONE...TONIGHT

FOR AN AREA BOUNDED BY HIGHWAY 20 TO HIGHWAY 30...A PERIOD OF LIGHT
SNOW...POSSIBLY MIXED WITH LIGHT RAIN OR LIGHT FREEZING RAIN WILL
OCCUR THIS EVENING BEFORE CHANGING OVER TO LIGHT SNOW WITH LITTLE
ACCUMULATION EXPECTED. MINOR ICE ACCUMULATIONS ARE POSSIBLE BEFORE
THE MIXTURE BECOMES ALL LIGHT SNOW.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THE CHANCE FOR LIGHT FREEZING DRIZZLE MIXED WITH LIGHT SNOW WILL
CONTINUE MONDAY MORNING. SNOW CHANCES WILL INCREASE MONDAY
AFTERNOON AND MODERATE SNOW IS THEN LIKELY THROUGH TUESDAY MORNING.
SNOWFALL ACCUMULATIONS OF 4 TO 8 INCHES ARE EXPECTED BY TUESDAY
MORNING. IN ADDITION...INCREASING NORTHEAST WINDS OF 15 TO 25 MPH
WILL CAUSE BLOWING AND DRIFTING OF SNOW. VISIBILITY MAY DROP TO
ONE QUARTER OF A MILE OR LESS IN SNOW AND BLOWING SNOW
...ESPECIALLY MONDAY NIGHT AND TUESDAY MORNING. MINOR ADDITIONAL
ACCUMULATIONS ARE POSSIBLE TUESDAY MORNING BEFORE TAPERING TO
FLURRIES TUESDAY AFTERNOON.

A WINTER STORM WATCH IS IN EFFECT FOR THE AREA MONDAY MORNING
THROUGH TUESDAY MORNING. PLEASE REFER TO THE NATIONAL WEATHER
SERVICE WEBSITE AT WEATHER.GOV/DESMOINES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED BUT SNOWFALL REPORTS WILL
BE APPRECIATED.

IAZ033>038-121145-
SAC-CALHOUN-WEBSTER-HAMILTON-HARDIN-GRUNDY-
328 PM CST SUN FEB 11 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TONIGHT

LIGHT SNOW MIXED WITH LIGHT FREEZING RAIN IS POSSIBLE THIS EVENING
BEFORE THE MIXTURE CHANGES OVER TO LIGHT SNOW TONIGHT. LIGHT ICE
ACCUMULATIONS ARE POSSIBLE BEFORE THE MIXTURE CHANGES OVER TO ALL
LIGHT SNOW.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

ACCUMULATING SNOWFALL IS POSSIBLE LATE MONDAY AND MONDAY NIGHT
HOWEVER AT THIS TIME IT APPEARS THAT THE HEAVIEST ACCUMULATIONS WILL
BE TO THE SOUTH OF THE AREA.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED BUT SNOWFALL REPORTS WILL
BE APPRECIATED.

REV