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000
FXUS63 KDVN 061720
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1120 AM CST THU MAR 6 2014

.UPDATE...
ISSUED AT 1008 AM CST THU MAR 6 2014

THE LOW LEVEL STRATUS CONTINUES TO SLOWLY ERODE WEST AND NORTH
BUT THE ARRIVAL OF HIGH LEVEL CLOUDS SHOULD SLOW DOWN OR STOP THE
DISSIPATION OF LOW CLOUDS. OTHERWISE...THE OVERALL FORECAST
GENERALLY LOOKS ON TRACK.

&&

.SYNOPSIS...
ISSUED AT 235 AM CST THU MAR 6 2014
THE EVENING UPPER AIR ANALYSIS SHOWED A SOUTHERN STREAM H5 TROF
OVER THE CENTRAL AND SOUTHERN PLAINS WITH ZONAL FLOW STILL IN
PLACE OVER THE NORTHERN TIER OF STATES. AT THE SURFACE EARLY THIS
MORNING HIGH PRESSURE WAS CENTERED OVER SOUTHERN ONTARIO WITH
RIDGING EXTENDING SOUTHWEST THROUGH IOWA AND ON INTO THE SOUTHERN PLAINS.
SOME CLEARING HAS OCCURRED ALONG AND EAST OF THE RIVER LIKELY DUE
TO SUBSIDENCE BEHIND THE MID LEVEL TROF. TO THE WEST STRATUS
EXTENDED FROM EASTERN IOWA INTO NEBRASKA WITH RECENT IR IMAGES
SHOWING SOME BREAKS DEVELOPING FROM NORTHWEST MO INTO NORTHWEST
IA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 235 AM CST THU MAR 6 2014

CLOUD TRENDS WILL BE TODAYS MAIN ISSUE WITH STRATUS STUCK IN AND
JUST WEST OF THE RIDGE AXIS OVER IOWA EARLY THIS MORNING. MODELS
SHOW SUBSIDENCE BEHIND THE DEPARTING WAVE DRYING OUT THE MID AND
LOWER LEVELS THIS MORNING WHICH SHOULD ERODE THE HIGHER BASED
CLOUDS OVER EASTERN IOWA AND NORTHEAST MO. THE CONCERN IS THAT VERY
LOW STRATUS IS DEVELOPING NEAR THE RIDGE AXIS AS THE HIGHER CLOUDS
DISSIPATE AND THE LOWER STRATUS MAY GET STUCK UNDER A STRONG
INVERSION AND LINGER WELL INTO THE AFTERNOON. HAVE SET UP THE SKY
GRIDS WITH MOSTLY CLEAR SKIES NEAR AND EAST OF THE RIVER AND A
SOMEWHAT OPTIMISTIC FORECAST OF CLEARING WEST. THE STRONG MARCH
SUN SHOULD HELP TEMPERATURES RECOVER INTO THE 30S SOUTH AND UPPER
20S NORTH TODAY. HOWEVER IF THE STRATUS HOLDS OVER THE WEST
TEMPERATURES THERE WILL PROBABLY STAY IN THE 20S.

TONIGHT MAINLY HIGH CLOUDS ARE EXPECTED OVER THE AREA WITH
INCREASING SOUTHERLY FLOW AHEAD OF A COLD FRONT MOVING INTO
NORTHWEST IOWA BY EARLY FRIDAY MORNING. THE SOUTH WINDS WILL LIMIT
THE DROP IN TEMPERATURES TONIGHT WITH LOW EXPECTED TO STAY IN THE
20S.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 235 AM CST THU MAR 6 2014

FRIDAY IS LOOKING INCREASINGLY WARM AND DRY AHEAD OF A COLD FRONT
THAT IS TRENDING SLIGHTLY SLOWER AND NOT EXPECTED TO PUSH THROUGH
UNTIL EVENING. ANTICIPATED POST-FRONTAL PRECIPITATION COVERAGE AND
TYPE REMAINS A CHALLENGE FOR LATE FRIDAY AFTERNOON THROUGH FRIDAY
NIGHT. CANADIAN HIGH PRESSURE THAT FOLLOWS TO RESULT IN COOLER
TEMPERATURES SATURDAY AND SATURDAY NIGHT...FOLLOWED BY SIGNIFICANT
WARMUP INTO EARLY NEXT WEEK. FURTHER OUT...AN ADVERTISED TRANSITION
BACK TO A MORE AMPLIFIED UPPER LEVEL PATTERN MAY RETURN TEMPERATURES
TO WELL BELOW NORMAL FOR LATE NEXT WEEK.

FRIDAY...THE GFS HAS BECOME SOMEWHAT OF AN OUTLIER WITH A FASTER
FROPA AND WILL STAY WITH A MORE CONSISTENT...SLIGHTLY SLOWER TIMING
AS FAVORED BY A NON-GFS MODEL CONSENSUS. THIS WOULD KEEP THE FRONT
AT BAY TO THE NW THROUGH AT LEAST NOON...PASSING THROUGH THE MS
VALLEY AROUND MID AFTERNOON...THEN ROUGHLY TO A CHICAGO TO QUINCY
LINE BY 00Z. THIS TIMING WOULD ALLOW A SIGNIFICANT PERIOD OF WARMING
ON SW WINDS...OVER ESPECIALLY THE SOUTH...WHERE UPPER 40S TO LOWER
50S LOOK ATTAINABLE...WHILE THE EARLIER FROPA AND THICKENING CLOUDS
HOLD THE NORTH TO THE UPPER 30S TO NEAR 40. MOISTURE PROFILES AND
FORCING CONTINUE TO INDICATE ONLY POST FRONTAL PRECIPITATION AND
HAVE LOW POPS DEVELOPING ACROSS THE NORTH IN THE AFTERNOON FOR WHAT
LOOKS TO BE MAINLY RAIN. BY EVENING...COLD AIR ADVECTION WILL
TRANSITION THE RAIN TO SNOW...AND STILL CANNOT RULE OUT SLEET IN A
PERIOD OF EVAPORATIVE COOLING. HOWEVER...CONFIDENCE IN THE VARYING
MODEL THERMAL PROFILES REMAINS TOO LOW...DUE TO CONTINUED POOR HANDLING
OF LOW LEVEL MOISTURE...TO NARROW THE SELECTION BEYOND A
RAIN/SLEET/SNOW MIX FRIDAY NIGHT...THAT WOULD TRANSITION TO ALL SNOW
OVER ALL BUT THE FAR SOUTH BY MORNING. HAVE FAVORED A
ECMWF/GEM/UKMET BLEND WITH THE HANDLING OF THE FRONT AND
PRECIPITATION FOR FRIDAY NIGHT...WHERE THE NAM SOLUTION PARTS WAYS
WITH A DISTINCT WAVE OF LOW PRESSURE OVER IL. THIS WOULD RESULT IN A
WIDER SHIELD OF PRECIPITATION FURTHER NORTH VS THE FAMILIAR LOOKING
WEST TO EAST AXIS OF FRONTOGENETICAL FORCING SHOWN BY OTHER MODELS
ACROSS NE MO...SE IA AND W CENTRAL IL OVERNIGHT INTO SAT MORNING. WITH
MODELS HONING IN ON THIS FEATURE OVER THE PAST SEVERAL RUNS...HAVE
INCREASED OVERNIGHT POPS TO LIKELY AND SNOWFALL AMOUNTS
CONSERVATIVELY IN A 1 TO 2 INCH BAND ACROSS THE SOUTH.

SATURDAY...WILL KEEP A POTENTIAL FOR A LINGERING BAND OF SNOW OVER
THE FAR SOUTH GOING IN THE MORNING BEFORE IT SWEEPS EASTWARD WITH A
SHORTWAVE PASSAGE. THIS WILL BE FOLLOWED BY HIGH PRESSURE DROPPING
SE OUT OF THE PLAINS WITH ITS RIDGE AXIS PASSING OVERHEAD IN THE
EVENING. COLD ADVECTION SHOULD LIMIT HIGHS TO THE UPPER 20S TO MID
30S SATURDAY...FOLLOWED BY CRASHING TEMPERATURES IN THE EVENING
UNDER CLEAR SKIES. KEPT LOWS FROM THE SINGLE DIGITS NW TO TEENS AND
LOWER 20S S AND SE...WITH A NON DIURNAL RISE POSSIBLE TOWARD SUNRISE
AS WINDS TURN SW AND INCREASE FOLLOWING THE RIDGE PASSAGE.

SUNDAY THROUGH MONDAY NIGHT LOOKS TO BE POTENTIALLY THE WARMEST
PERIOD OF THE YEAR SO FAR AS W-SW WINDS ADVECT A WARM AND DRY
AIRMASS SETTING UP IN THE ZONAL FLOW OVER THE PLAINS INTO THE AREA.
SUNDAY IS KEPT IN A RANGE FROM THE MID 30S TO MID 40S...THEN HAVE
BOOSTED MONDAY A FEW DEGREES TO THE LOWER 40S NE TO MID 50S IN THE
FAR S AND SW.

TUESDAY NIGHT ONWARD...ALTHOUGH THERE REMAIN CONSIDERABLE
DIFFERENCES IN THE TIMING...PLACEMENT AND PHASING ISSUES OF
SHORTWAVE FEATURES...THE OVERALL LARGE SCALE TREND IS TOWARD A
DEVELOPING...MORE AMPLIFIED PATTERN WITH A RIDGE BUILDING ALONG THE
WEST COAST AND A LONGWAVE TROUGH OVER THE CENTRAL OR EASTERN U.S.
THIS WOULD SEND A COLD FRONT THROUGH THE REGION MONDAY NIGHT OR
TUESDAY...FOLLOWED BY A PERIOD OF PRECIPITATION ADVERTISED
WITH LOW POPS TUESDAY INTO TUESDAY NIGHT. BASED ON THE CURRENT
SETUP...TEMPERATURES IN THESE PERIODS APPEAR TO BE SKEWED TOO
HEAVILY TOWARD CLIMATOLOGY AND MAY BE MUCH COOLER THAN THE
ADVERTISED HIGHS IN THE 30S AND 40S AND LOWS IN THE 20S TO LOWER
30S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1116 AM CST THU MAR 6 2014

VFR WX IS EXPECTED THROUGH 18Z/07 AS HIGH PRESSURE SLOWLY MOVES
EAST THROUGH THE GREAT LAKES. THE POSSIBILITY DOES EXIST FOR MVFR
VSBYS TO DEVELOP AFT 03Z/07 AS SOUTHERLY WINDS ADVECT WARMER AIR
INTO THE AREA. AFT 18Z/07 CONDITIONS WILL SLOWLY DETERIORATE TO
MVFR AS A FRONT MOVES THROUGH EASTERN IOWA AND ILLINOIS. THE
PROBABILITY OF IFR CONDITIONS ACROSS IOWA AND NORTHERN ILLINOIS
INCREASES SIGNIFICANTLY AFT 00Z/08.

&&

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

$$

UPDATE...08
SYNOPSIS...DLF
SHORT TERM...DLF
LONG TERM...SHEETS
AVIATION...08