FXUS63 KDVN 050932
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
332 AM CST SUN FEB 5 2012

.SYNOPSIS...
IR SATELLITE IMAGERY INDICATED A LARGE AREA OF STRATUS SURGING
SOUTHEAST OUT OF THE EASTERN DAKOTAS AND MN INTO NORTHERN IA EARLY
THIS MORNING. SURFACE OBSERVATIONS UNDER THIS FIELD INDICATED VERY
LOW CIGS AND WIDESPREAD FOG WELL INTO LIFR CRITERIA. THIS LOW
LEVEL MOISTURE WAS TRAPPED IN A SUBSDINCE INVERSION ALONG THE
EASTERN HALF OF A SURFACE RIDGE AXIS THAT EXTENDED FROM EASTERN CO
INTO THE DAKOTAS AT 08Z. ALOFT...WV IMAGERY INDICATED THE
WEAKENING COMPACT CUT OFF UPPER LOW...REMNANT OF THE SYSTEM THAT
BROUGHT HEAVY SNOW NOT FAR TO OUR WEST YESTERDAY...CENTERED OVER
NW MO. A TROUGH AXIS EXTENDED WEST TO ANOTHER STATIONARY LOW OVER
THE GREAT BASIN. THIS WAS UNDERCUTTING AN UPPER RIDGE OVER MT INTO
SOUTHERN SASK AND ALBERTA. A RESULTING DEEP LOW TO MID LEVEL
NORTHERLY FLOW EAST OF THIS HIGH WAS HELPING PUSH THE
AFOREMENTIONED STRATUS DECK SOUTHWARD INTO IA.

&&

.SHORT TERM...TODAY AND TONIGHT...
PRIMARY CONCERN IS LOW CLOUDS AND FOG TRENDS THROUGHOUT.
OVERALL...FORECAST MODELS CONTINUE TO STRUGGLE WITH THE SHALLOW
LOW LEVEL MOISTURE...WITH THE EXCEPTION OF THE HRR IN THE VERY SHORT TERM
AND THE SREF A BIT FURTHER OUT. BOTH HAVE HAD A ROUGH HANDLE ON
THE COVERAGE AND EXTENT OF THE STRATUS AND FOG TONIGHT. BOTH
SUGGEST THIS WILL CONTINUE SOUTH-SOUTHEAST COVERING MOST OF
CENTRAL IA...AND STALLING OUT ROUGHLY ALONG A LINE FROM DBQ
THROUGH IOW TO SCOTLAND COUNTY MO BY LATE MORNING WITH BETTER
COVERAGE SUPPORTED ACROSS THE NORTHWEST THIRD OF THE FORECAST
AREA. SOME DISSIPATION IS THEN DEPICTED DURING THE AFTERNOON...
WHICH LINES UP WITH WHAT WAS SEEN ON VISIBLE SATELLITE IMAGERY
UPSTREAM YESTERDAY AND HAVE GENERALLY FOLLOWED THIS TREND. UNDER
THE CLOUDS...TEMPERATURES WILL STRUGGLE TO RISE MUCH PAST THE
LOWER TO MID 30S TODAY...WHILE FURTHER SOUTHEAST...WITH AT LEAST
PARTIAL SUNSHINE...A WARMER START...AND LACK OF SNOW COVER
TEMPERATURES SHOULD PUSH AT LEAST INTO THE LOWER 40S.

TONIGHT...THE HIGH PRESSURE RIDGE AXIS EXTENDING E-NE FROM THE
PLAINS DROPS SOUTH THROUGH AREA WITH LIGHT WESTERLY WINDS
DEVELOPING BY MORNING. THIS WILL LIKELY DRIVE HIGHER LOW LEVEL RH
ENHANCED TODAY BY MELTING SNOW OVER CENTRAL IA...EASTWARD INTO THE
FORECAST AREA. AS MENTIONED...THIS IS NOT HANDLED WELL BY
FORECAST MODELS OR MOS GUIDANCE...BEYOND AVIATION STATISTICAL FOG AND CLOUD
CIG OUTPUT FROM THE SREF. THUS CONFIDENCE REMAINS BELOW AVERAGE ON
BOTH THE EXTENT OR COVERAGE OF STRATUS AND FOG AND HAVE
INTRODUCED THIS POTENTIAL WITH PATCHY FOG WORDING AND 30 TO 50
PERCENT SKY COVERAGE. IN REALITY...IF THIS OCCURS...IT WOULD
LIKELY BE MORE WIDESPREAD OVERCAST. THIS WILL HAVE A LARGE IMPACT
ON MINIMUM TEMPERATURES...AS CLOUDS WILL HOLD TEMPERATURES NEAR
STEADY AND ANY CLEARING COULD RESULT IN MUCH COLDER
READINGS...WELL INTO THE LOWER 20S. FOR NOW HAVE COMPROMISED TOWARD
THE WARMER SIDE OF GUIDANCE WITH WIDESPREAD MID TO UPPER 20S.
..SHEETS..

.LONG TERM...MONDAY THROUGH SATURDAY...
THE EXTENDED FORECAST REMAINS DOMINATED BY TWO COLD FRONTAL
PASSAGES...ONE MONDAY NIGHT...AND ANOTHER TOWARDS THURSDAY NIGHT.
MONDAY WILL SEE WESTERLY FLOW...AND ASSUMING FULL SUNSHINE...A DEEP
MIXING DAY RESULTING IN HIGHS IN THE MID TO UPPER 40S. THIS STILL
LOOKS TO BE THE MOST LIKELY SCENARIO...THOUGH SOME DATA SUGGESTS
STRATUS MAY FIRE OVER THE SNOW PACK TO THE WEST TONIGHT...AND THAT
COULD AFFECT OUR REGION MONDAY...SO WE ARE NOT COMPLETELY CONFIDENT
IN MONDAYS MILD AND SUNNY FORECAST.

MORE CONFIDENT IS MONDAY NIGHT...WHERE A COLD FRONT WILL ARRIVE LATE
EVENING...BRINGING PLENTY OF LOW CLOUDS AND AND INCREASED NORTH
WINDS. TEMPERATURES MAY NOT FALL TOO MUCH GIVEN THE CLOUD
COVER...THUS LOWS IN THE MID 20S NORTH TO UPPER 20S SOUTH ARE
FORECAST. TUESDAY THROUGH EARLY WEDNESDAY SHOULD BE CLOUDY...WITH
HIGHS GENERALLY IN THE MID TO UPPER 30S. IF WE HAD SNOW COVER...20S
WOULD BE MORE ON TARGET...BUT WE DONT. WEDNESDAY SHOULD BE
COOL...BUT NOT WINDY...WITH SEASONAL HIGHS IN THE LOWER 30S.

THE COLD FRONT FOR THURSDAY NIGHT REMAINS TO LOOK STRONG...BUT THE
LINGERING COLD PUSH AFTERWARDS LOOKS MUCH LESS POTENT TONIGHT AS THE
PATTERN IS MORE PROGRESSIVE. THIS TREND WAS NOTED BY THE 12Z
ECMWF...AND CONTINUED ON THE 00Z ECMWF...AS WELL AS 00Z UKMET. THE
GFS IS THE LONE COLD MODEL OUT NOW FOR SATURDAY AND SUNDAY. SINCE WE
HAVE NOW SNOW COVER...AND SHOULD NOT GAIN MUCH IF ANY OVER THE UPPER
MIDWEST...IT IS UNLIKELY THAT THE COLDEST SOLUTION IS GOING TO BE
CORRECT. IN FACT...THE 00Z ECMWFT NOW SHOWS STRONG SOUTHERLY FLOW BY
SATURDAY NIGHT. IN THE END...OR FORECAST IS SLIGHTLY BELOW NORMAL
FOR HIGHS AND LOWS FRIDAY THROUGH SATURDAY...AS WELL AS DRY.
..4ANDYG/ERVIN..

&&

.AVIATION...
LARGE AREA OF STRATUS AND FOG WITH IFR TO LIFR CONDITIONS WAS
SURGING SOUTHEAST TOWARD EASTERN IA EARLY THIS MORNING. AS HIGH
PRESSURE OVER THE CENTRAL AND NORTHERN PLAINS SETTLES
SOUTHEAST...THIS AREA OF TRAPPED LOW LEVEL MOISTURE WILL LIKELY
SPREAD IFR...AND POSSIBLY LIFR CONDITIONS TO CID AND DBQ EARLY
THIS MORNING. AT THE CURRENT RATE...THE LOW CLOUDS AND FOG COULD
REACH MLI BEFORE 13Z...AND IF IT HOLDS TOGETHER...BRL TOWARD 15Z.
CURRENT EXPECTATIONS ARE FOR THE CLOUDS AND FOG TO BREAK UP DURING
THE DAYLIGHT HOURS...THEN POSSIBLY REDEVELOP OVERNIGHT. FORECAST
CONFIDENCE IS LOW ON THIS EVOLUTION...AND FORECAST MODELS OVERALL HAVE
A POOR HANDLE ON THIS SHALLOW LOW LEVEL MOISTURE. UPDATED TAFS
THIS MORNING WILL LIKELY INTRODUCE AT LEAST MVFR CONDITIONS FOR
SUNDAY NIGHT AT ALL SITES. ..SHEETS..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SHEETS/ERVIN


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