Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 052100
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
300 PM CST THU MAR 5 2015

.SYNOPSIS...
ISSUED AT 300 PM CST THU MAR 5 2015

ARCTIC HIGH PRESSURE OVER THE REGION TODAY PROVIDING SUNNY SKIES
BUT COLD TEMPERATURES. 2 PM READINGS RANGED FROM 8 TO 14 ACROSS
THE DVN CWA...AND AT SOME LOCATIONS WIND CHILLS WERE STILL IN THE
SINGLE DIGITS BELOW ZERO.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 300 PM CST THU MAR 5 2015

FORECAST FOCUS ON THE BEGINNING OF A WELCOME WARMING TREND.

TONIGHT...WARM AIR ADVECTION DEVELOPS LATER TONIGHT AS WINDS TURN
SOUTHERLY ON THE BACK SIDE OF THE DEPARTING HIGH PRESSURE RIDGE. A
BAND OF MID LEVEL CLOUDS SHOULD ALSO MOVE ACROSS THE CWA LATER
TONIGHT IN ASSOCIATION WITH AN UPPER LEVEL TROUGH. THEREFORE...THE
COLDEST READINGS...MAINLY IN THE SINGLE DIGITS...SHOULD OCCUR
THIS EVENING FOLLOWED BY SLOWLY RISING TEMPERATURES AFTER MIDNIGHT.

FRIDAY...PARTLY CLOUDY SKIES AND SOUTH TO SOUTHWEST WINDS WILL BRING
WARMER TEMPERATURES INTO THE CWA. AFTERNOON HIGHS SHOULD RANGE FROM
AROUND 30 FROM DUBUQUE TO FREEPORT...TO THE LOWER 40S IN OUR FAR
SOUTHWEST COUNTIES. HOWEVER...WIND GUSTS IN THE 20 TO 25 MPH RANGE
ARE EXPECTED.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 300 PM CST THU MAR 5 2015

TRANSITION AWAY FROM A MID WINTER ARCTIC REGIME TO A MORE SPRINGLIKE
PATTERN IS THE PRIMARY FOCUS IN THE LONG TERM. MODELS CONTINUE TO
DIVERGE INTO SEPARATE CAMPS WITH REGARD TO THE AMOUNT OF SURFACE
WARMING EARLY IN THE WEEK AND THEN EVEN MORE SO LATE IN THE WEEK WITH
LARGE DIFFERENCES IN THE SOUTHWARD PENETRATION OF A STRONG COLD
FRONT. IN THE MEDIUM RANGE...A SERIES OF MID LEVEL SHORTWAVES AND AT
LEAST ONE CLIPPER-TYPE SYSTEM IN THE NW FLOW ALOFT WILL MOVE THROUGH
OVER THE WEEKEND.

FRIDAY NIGHT THROUGH SATURDAY...A CLIPPER IS PROGGED TO MOVE THROUGH
THE GREAT LAKES EARLY SATURDAY. OVER THE LOCAL AREA...WITH LOW LEVEL
MOISTURE LACKING...THIS IS EXPECTED TO RESULT IN LITTLE MORE THAN A
WIND SHIFT AND PERIOD OF MID LEVEL CLOUDS. SW WINDS AND INCREASING
CLOUDS SHOULD HOLD MINS IN THE MID TO UPPER 20S OVERNIGHT. WINDS
SHIFT TO THE NW FOLLOWING THE WEAK FRONTAL PASSAGE SATURDAY WITH MID
LEVEL SUBSIDENCE PROVIDING AFTERNOON SUNSHINE. MODEL BLEND HIGHS
FROM THE UPPER 30S NE TO UPPER 40S IN THE FAR SW LOOK REASONABLE.

LATE SATURDAY NIGHT INTO SUNDAY...THERE REMAINS POOR MODEL AGREEMENT
WITH THE TIMING...STRENGTH AND AVAILABLE MOISTURE WITH THE NEXT MID
LEVEL SHORTWAVE. THIS RESULTS IN LARGE DIFFERENCES IN QPF PLACEMENT
AND WHETHER A WEAK WAVE OF LOW PRESSURE MOVES ALONG AN ASSOCIATED
WEAK SURFACE FRONT. THE GFS AND ECMWF ARE MOST BULLISH WITH LIGHT
QPF...WHILE THE NAM IS ESSENTIALLY DRY. WITH BELOW AVERAGE
CONFIDENCE...WEAK FORCING... AND LITTLE MOISTURE FOR THE SYSTEM TO
WORK WITH ON...WILL LIMIT POPS TO SLIGHT CHANCES NORTH OF I-80. IF
THIS OCCURS...IT WOULD MOST LIKELY BE LIGHT SNOW OR FLURRIES...THEN
POSSIBLE LIGHT RAIN OR SNOW SHOWERS IN THE AFTERNOON MAINLY OVER NW
IL. TEMPERATURES SHOULD AGAIN REACH AT LEAST MID 30S NORTH...WITH
MID AND POSSIBLY UPPER 40S IN THE SOUTH...WHERE THE CURRENT EDGE OF
THE SNOW COVER WILL BE RETREATING RAPIDLY.

BEYOND...THE BIG QUESTION IS HOW THE LOW LEVEL THERMAL FIELDS AND
ASSOCIATED FEEDBACK FROM THE MELTING SNOW AND ICE WILL RESPOND TO
THE CHANGE TO A MORE ZONAL MID LEVEL FLOW AND LOW LEVEL S-SW WARM
ADVECTION REGIME. THERE REMAIN STARK DIFFERENCES IN HOW MODELS
DEPICT THIS...FALLING MAINLY INTO TWO DIFFERENT CAMPS. THE GFS AND
CANADIAN ARE CONSISTENTLY ON THE COLD SIDE...DEPICTING A GRADUAL
WARMING FROM HIGHS IN THE 30S MONDAY TO 40S AND 50S BY WED. AT THE
SAME TIME...THE ECMWF HAS 40S AND 50S MONDAY...REACHING WIDESPREAD
60S BY WED. OUR FORECAST FOLLOWS A BLENDED APPROACH...RESULTING IN
40S MONDAY...MAINLY 50S TUE AND 50S TO AROUND 60 WED WITH OVERNIGHT
LOWS IN THE 20S EARLY...THEN 30S BY MID WEEK. THIS IS A REASONABLE
COMPROMISE FOR NOW...AND HOPEFULLY TRENDS OVER THE NEXT FEW DAYS
WILL LEND A BETTER HANDLE ON HOW FAST THE SNOWMELT WILL OCCUR AND TO
WHAT EXTENT THE LOW LEVELS WILL BE ABLE TO TAP INTO THE LOW LEVEL
WARMING.

THURSDAY...THE GFS DRIVES A COLD FRONT THROUGH THE FORECAST AREA
WELL INTO MO AND IL...WHILE THE ECMWF HAS A PASSING SURFACE LOW AND
THE FRONTAL POSITION HOLDING UP WELL TO THE NORTH ACROSS MN AND WI.
OUR CURRENT FORECAST MAINTAINS 50S...BUT IT COULD ALSO BE EITHER THE
40S OR POTENTIALLY THE 60S DEPENDING ON THE FRONTAL POSITION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 300 PM CST THU MAR 5 2015

VFR CONDS THROUGH THIS TAF CYCLE. ARCTIC HIGH PRESSURE OVER THE
REGION THIS AFTERNOON WILL SHIFT OFF TO OUR EAST TONIGHT. NORTHWEST
TO WEST WINDS THIS AFTERNOON THEN SOUTH TONIGHT AND FRIDAY. WIND SPEEDS
WILL BE AROUND 10 KNOTS OR LESS.

&&

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

$$

SYNOPSIS...HAASE
SHORT TERM...HAASE
LONG TERM...SHEETS
AVIATION...HAASE








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