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000
FXUS63 KDVN 250926
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
326 AM CST WED FEB 25 2015

.UPDATE...
ISSUED AT 324 AM CST WED FEB 25 2015

HAVE UPGRADED PORTIONS OF THE PREVIOUS ADVISORY TO A WINTER STORM
WARNING...AND ADDED SOME ADVISORY COUNTIES. LOOKING AT 3-6 INCHES
OF SNOW IN THE ADVISORY AREA...6-9 INCHES AND LOCALLY HIGHER IN
THE WARNING AREA. GRIDS/ZONES HAVE BEEN SENT. HEADLINES AND FULL
FORECAST DISCUSSION WILL BE OUT AROUND 4 AM.

&&

.SYNOPSIS...
ISSUED AT 326 PM CST TUE FEB 24 2015

LATEST SFC ANALYSIS WAS INDICATING STRONG SFC TROF ALMOST BISECTING
THE DVN CWA FROM NE-TO-SW...ACTING AS A WARM FRONT WITH GUSTY WEST
TO NORTHWEST WINDS DEEPLY MIXING ALONG AND BEHIND IT. MANY MID TO
UPPER 30S ACRS MUCH OF THE DVN CWA. WINDS IN THE NORTHERN CWA
FLIRTING WITH ADVISORY CRITERIA FROM TIME TO TIME AS WELL. SCTRD
SNOW SHOWERS AND FLURRIES DIMINISHING AS THEY MOVE OUT OF
NORTHEASTERN IA INTO THE NORTHERN AND NORTHEASTERN CWA ATTM...IN
LINE WITH DECREASING SNOW SQUALL PARAMETERS SEEN ON THE SPC WINTER
PAGE. ALOFT...STRONG JET FLOW ALL THE WAY UP IN STEEP NORTHWESTERLIES
FROM CENTRAL CANADA DOWN TOWARD THE MID MS RVR VALLEY...WEST OF
JAMES BAY CYCLONE CENTER. CUT-OFF UPPER LOW COMPLEX WAS NOTICED
ACRS THE SOUTHEASTERN GRT BSN...WHILE TOMORROW/S CLIPPER SYSTEM
SEEN PUSHING SOUTHEASTWARD ACRS B.C. TOWARD SOUTHERN ALBERTA ATTM.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 326 PM CST TUE FEB 24 2015

TONIGHT...TO BE A LULL PERIOD AS THE SFC TROF AND ASSOCIATED CLOUDS
CLEAR OFF TO THE SOUTHEAST AS THE EVENING PROGRESSES. WINDS TO VEER
TO THE NORTH AND NORTHEAST AND DECREASE INTO THE OVERNIGHT. DRIER
NORTHEAST FETCH/LOWER DPTS SHOULD ALLOW AREAS NORTH OF I80 TO COOL
DOWN INTO THE SINGLE DIGITS ABOVE ZERO ALONG AS SKIES REMAIN
REASONABLY CLEAR. LOW TO MID TEEN SOUTH OF I80. HIGH CLOUDS WILL
STEAM IN FROM THE NORTHWEST LATE TONIGHT AHEAD OF TOMORROWS WX
MAKING CLIPPER.

WEDNESDAY...ASSESSING SEVERAL OF THE 12Z MODEL RUNS IN HANDLING THE
INCOMING CLIPPER...THE TREND OF FURTHER NORTHEASTERN FORCING AND
DRAGGING ALONG MORE MOISTURE CONTINUE...ALONG WITH SOME TEMPORARY
MOISTURE DRAW FROM THE SOUTHERN PLAINS. BUT ASSESSING ISENTROPIC 290-
295K LAYER SATURATION AND LIFT...AS WELL AS ELEVATED WARM AIR
CONVERGENT ADVECTION TYPE FORCING PIVOTING AROUND VORT MAX DROPPING
SOUTHEAST ACRS NORTHWESTERN IA BY LATE AFTERNOON...SEEMS THAT THE
STRONGEST PARAMETERS PUSH SOUTH ACRS CENTRAL IA JUST TO THE WEST OF
THE DVN CWA THRU 00Z THU. BUT ENOUGH SECONDARY LIFT AND COLUMN
SATURATION SIDING WITH THE 12Z GFS TO ALLOW ACCUMULATING SNOW TO
STILL BUILD ACRS THE LOCAL AREA FROM WEST TO EAST FROM LATE MORNING
AND MAKING HEADWAY EAST-SOUTHEASTWARD MORE DURING THE AFTERNOON INTO
EARLY WED EVENING. LSR/S WILL BEGIN AT 16:1 TO 18:1...AND DECREASE
A BIT INTO THE EVENING BUT STILL REMAIN HIGH FOR A MORE FLUFFY
SNOWFALL. ACCEPTED FCST SOUNDINGS ALSO SHOW SOME SATURATION IN THE
DENDRITIC LAYER OF AT LEAST H2 MB DEPTH DURING THE AFTERNOON ALONG
AND ESPECIALLY WEST OF THE MS RVR.

LATEST THINKING HAS 0.5 TO 1 INCH OF NEW SNOW ACCUM ALONG AND
WEST OF MANCHESTER...TO IOWA CITY...TO FAIRFIELD BY NOON WED. FOR
THE AFTERNOON...HALF INCH TO NEAR 2 INCHES MORE ALONG AND WEST OF
THE MS RVR AND NORTH OF I80/HIGHEST AMOUNTS ALONG AND WEST OF
INDEPENDENCE...TO IOWA CITY. WESTERN IL HALF INCH EAST TO 1.5
INCHES ALONG THE MS RVR...AND 1.5 TO OVER 2 INCHES NEW WEST OF THE
MS RVR ACRS SOUTHEASTERN IA AN NORTHEAST MO. IN GENERAL...12 HR
TOTALS OF 1-3 INCHES ALONG AND WEST OF THE MS RVR BY EARLY WED
EVENING WITH THE 2-3 LIKELY ALONG AND WEST OF A CEDAR RAPIDS...TO
IOWA CITY TO WASHINGTON IA...TO KEOSAUQUA IA LINE. SYSTEM WILL
START TO SLOW LATE IN THE PERIOD WITH INTERACTION WITH PASSING
SOUTHERN STREAM SYSTEM ACRS THE LOWER MS RVR VALLEY/GULF STATES.
THESE AMOUNTS COMBINED WED EVENING AMOUNTS/SEE DETAILS IN
DISCUSSION BELOW/...WARRANT A SOLID WINTER WX ADVISORY FOR ROUGHLY
THE SOUTHWESTERN HALF OR A BIT MORE OF THE DVN CWA. WED HIGHS IN
THE UPPER TEENS NORTH OF HWY 30...TO THE LOW TO MID 20S SOUTH OF
I80.    ..12..

.LONG TERM...(WEDNESDAY NIGHT THROUGH NEXT TUESDAY)
ISSUED AT 326 PM CST TUE FEB 24 2015

THE WEATHER PATTERN WILL BE TURNING MORE ACTIVE STARTING THIS
WEEKEND AND CONTINUING INTO NEXT WEEK. THE TREND OF BELOW NORMAL
TEMPERATURES WILL CONTINUE INTO THE FIRST WEEK OF MARCH.

SNOW WILL BE WIDESPREAD ACROSS THE AREA WEDNESDAY NIGHT BUT THE
OVERALL FORCING WEAKENS WITH TIME. BASED ON FORCING/MOISTURE THE
HIGHER SNOW AMOUNTS WILL BE ACROSS THE SOUTHWEST HALF OF THE AREA.
AFTER MIDNIGHT SNOW WILL VERY SLOWLY END FROM NORTHWEST TO
SOUTHEAST.

BASED ON WHAT IS SUGGESTED BY THE VARIOUS MODELS...SNOWFALL AMOUNTS
BY SUNRISE THURSDAY SHOULD BE 3 TO 6 INCHES SOUTH OF A VINTON IA TO
ALEDO IL LINE WITH THE HIGHER AMOUNTS SOUTH OF I-80 AND WEST OF THE
MISSISSIPPI. AMOUNTS OF 1 TO 2 INCHES NORTH OF A VINTON TO ALEDO
LINE TO A DUBUQUE IA TO STERLING IL LINE LOOK POSSIBLE. NORTH OF A
DUBUQUE TO STERLING LINE AMOUNTS SHOULD BE AN INCH OR LESS.

LINGERING LIGHT SNOW/FLURRIES WILL PERSIST ACROSS THE SOUTHEAST HALF
OF THE AREA THURSDAY MORNING AND END BY MID DAY. ADDITIONAL SNOW
ACCUMULATIONS THURSDAY MORNING WOULD BE A DUSTING AT BEST.

QUIET AND COLD CONDITIONS WILL THEN BE SEEN THURSDAY NIGHT/FRIDAY AS
THE NEXT ARCTIC HIGH MOVES INTO THE MIDWEST. TEMPERATURES WILL BE
WELL BELOW NORMAL.

FRIDAY NIGHT ON...
THE QUIET AND COLD CONDITIONS WILL CONTINUE FRIDAY HIGH AS THE
ARCTIC HIGH SLOWLY MOVES INTO THE GREAT LAKES. ATTENTION THEN TURNS
TO THE WEEKEND STORM SYSTEM.

SATURDAY THROUGH SUNDAY...AS EXPECTED THE MODELS HAVE SLOWED DOWN
THE ARRIVAL OF THE STORM SYSTEM. CONFIDENCE THAT A WINTER STORM
WILL AFFECT THE MIDWEST IS STILL HIGH. CONFIDENCE REMAINS LOW
REGARDING THE TIMING...TRACK...AND POTENTIAL SNOWFALL AMOUNTS.

TRENDS WITH THE GLOBAL MODELS IS FOR A STRONGER ARCTIC HIGH ACROSS
THE OHIO VALLEY SATURDAY MORNING...THUS ADDITIONAL SLOWING OF THE
STORM SYSTEM IS POSSIBLE. THE CHANGING FLOW PATTERN ACROSS NORTH
AMERICA CONTINUES TO SHIFT THE POTENTIAL STORM TRACK. ONE MODEL HAS
ESSENTIALLY A MISS...ANOTHER MODEL GIVES A DIRECT HIT...AND ANOTHER
SUGGESTS SOME SNOWFALL. AS MENTION YESTERDAY...GIVEN THE WIDE RANGE
OF THE MODEL SOLUTIONS IT WOULD NOT BE PRUDENT TO CONSIDER
PRELIMINARY AMOUNTS THIS FAR OUT.

ANOTHER TREND WITH THE GLOBAL MODELS IS FOR MORE COLD AIR ACROSS THE
AREA FOR THE WEEKEND STORM SYSTEM. THUS THE PRECIPITATION TYPE IS
LOOKING TO BE MAINLY SNOW WITH POSSIBLY SOME SLEET MIXED IN ACROSS
THE FAR SOUTH.

SO...THE MODEL CONSENSUS INDICATES DRY CONDITIONS ACROSS THE AREA
SATURDAY MORNING WITH SLIGHT CHANCE POPS ACROSS THE SOUTHWEST HALF
OF THE AREA SATURDAY AFTERNOON. SATURDAY NIGHT THE MODEL CONSENSUS
HAS CHANCE TO LIKELY POPS WITH CHANCE POPS ON SUNDAY...AND SLIGHT
CHANCE TO CHANCE POPS SUNDAY NIGHT.

THE CHANGING FLOW PATTERN ALOFT ACROSS NORTH AMERICA SUGGESTS
ANOTHER POSSIBLE SNOW EVENT IN THE MONDAY/TUESDAY TIME FRAME. THE
RANGE OF MODEL SOLUTIONS VARY GREATLY WHAT WILL HAPPEN. AS SUCH THE
MODEL CONSENSUS HAS SLIGHT CHANCE TO CHANCE POPS MONDAY AND TUESDAY
WITH CHANCE POPS MONDAY NIGHT.    ..08..

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1138 PM CST TUE FEB 24 2015

A WINTER STORM SYSTEM DEVELOPING OVER THE NORTHERN PLAINS WILL
SPREAD SNOW ACROSS EASTERN IOWA AND NORTHWEST ILLINOIS WEDNESDAY
INTO WEDNESDAY NIGHT...RESULTING IN WIDESPREAD IFR TO LIFR
CONDITIONS. THROUGH THE REST OF TONIGHT INTO WEDNESDAY
MORNING...CONDITIONS WILL REMAIN VFR WITH LIGHT WINDS AND
INCREASING HIGH CLOUDS. SNOW AND LOWERING CIGS ARE EXPECTED TO
DEVELOP OVER CID BY MIDDAY AND REACH THE REST OF THE TERMINALS BY
MID AFTERNOON WITH WIDESPREAD IFR CONDITIONS BY LATE AFTERNOON.
ALL TERMINALS WILL HAVE THE POTENTIAL FOR LIFR OR EVEN VLIFR
PERIODS FROM LATE AFTERNOON INTO EARLY EVENING. WHILE NOT
ADVERTISED...SOME IMPROVEMENT IS POSSIBLE TOWARD LATE EVENING AT
CID AND DBQ AS THE SYSTEM BEGINS TO EXIT THE REGION.


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST THURSDAY FOR
     CLINTON-DELAWARE-DUBUQUE-JACKSON-JONES-SCOTT.

     WINTER STORM WARNING FROM NOON TODAY TO 6 AM CST THURSDAY FOR
     CEDAR-DES MOINES-HENRY IA-JEFFERSON-LEE-LOUISA-MUSCATINE-
     VAN BUREN.

     WINTER STORM WARNING FROM 9 AM THIS MORNING TO 3 AM CST THURSDAY
     FOR BENTON-BUCHANAN-IOWA-JOHNSON-KEOKUK-LINN-WASHINGTON.

IL...WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST THURSDAY FOR
     HENRY IL-MERCER-ROCK ISLAND.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 9 AM CST
     THURSDAY FOR HANCOCK-HENDERSON-MCDONOUGH-WARREN.

MO...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 9 AM CST
     THURSDAY FOR CLARK-SCOTLAND.

&&

$$

UPDATE...RP KINNEY
SYNOPSIS...12
SHORT TERM...12
LONG TERM...08
AVIATION...SHEETS