Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 230833
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
333 AM CDT MON MAR 23 2015

.SYNOPSIS...
ISSUED AT 330 AM CDT MON MAR 23 2015

CLIPPER SYSTEM DRIVEN BY A TIGHT THERMAL GRADIENT WAS LOCATED IN
FAR SOUTHWEST IA AND MOVING SOUTHEAST. JUST LOOKING AT THE DVN CWA
850 MB TEMPERATURES RANGE FROM -6C ALONG THE WI/IL BORDER TO +8C
IN EXTREME NORTHERN MO. STRONG WARM AIR ADVECTION IN THE ADVANCE
OF THE CLIPPER WAS PROVIDING STRONG FORCING OVER THIS TIGHT BAROCLINIC
ZONE. THE RESULT HAS BEEN CONVECTIVE BANDS OF SNOW/SLEET/FREEZING
RAIN AND RAIN ALONG WITH ISOLATED BRIEF LIGHTNING STRIKES. THIS IS
A TYPICAL MARCH SCENARIO. THE STRONG FRONTOGENESIS BAND OF HEAVY SNOW
WAS STILL NORTH OF THE DVN CWA WHERE 4 TO 9 INCHES OF SNOW HAS FALLEN
IN SOUTHERN MN INTO WESTERN WI. 3 AM TEMPERATURES IN THE CWA RANGED
FROM 26 AT DUBUQUE AND FREEPORT TO 39 AT KEOKUK.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT MON MAR 23 2015

HEADLINES...WILL CONTINUE WITH THE WINTER WEATHER ADVISORY FOR THE
HIGHWAY 20 CORRIDOR FROM DUBUQUE COUNTY TO STEPHENSON COUNTY UNTIL
10 AM THIS MORNING FOR 1 TO 4 INCHES OF SNOW. I WILL MONITOR AREAS
SOUTH OF THE ADVISORY FOR POSSIBLE EXPANSION IF NEEDED.

TODAY...OPERATIONAL MODELS INCLUDING THE RUC/HRRR MESO MODELS INDICATE
THE STRONGEST OMEGA AND THETA-E LAPSE RATES PUSH ACROSS OUR NORTHERN
CWA BETWEEN 3 AM AND 10 AM THIS MORNING. THIS IS WHEN MODERATE TO
LOCALLY HEAVY SNOW IS EXPECTED INCLUDING DURING THE MORNING COMMUTE
TIME. THIS SHOULD BE ALL SNOW IN THE NORTH WHILE A SLEET/SNOW MIX
SHOULD OCCUR AS FAR SOUTH AS THE INTERSTATE 80 CORRIDOR. FARTHER
SOUTH WHERE THE COLUMN IS ABOVE FREEZING THE PRECIPITATION WILL BE
IN THE FORM OF RAIN. PAVEMENT TEMPERATURES ARE JUST ABOVE FREEZING
SO MUCH OF THE SNOW SHOULD ACCUMULATE ON GRASSY OR ELEVATED SURFACES
WITH SOME SLUSH ON UNTREATED ROADS. ISOLATED THUNDERSTORMS CAN ALSO
BE EXPECTED ANYWHERE IN THE CWA INTO THE MORNING HOURS. AS THE FORCING
MOVES OFF TO OUR EAST LATER THIS MORNING THE PRECIPITATION WILL DIMINISH
FROM WEST TO EAST AND THEN END BY EARLY THIS AFTERNOON IF NOT SOONER.
IN THE WAKE OF THIS SYSTEM CLOUDY SKIES WILL REMAIN ALONG WITH A STIFF
EAST WIND MAKING FOR A RATHER CHILLY DAY. MAXIMUM TEMPERATURES WILL
RANGE FROM THE MID 30S NE TO THE MID 40S SW.

TONIGHT...CLOUDY EVENING BUT THEN THE NEXT STORM SYSTEM ALREADY TAKING
SHAPE IN THE ROCKIES WILL SPREAD WARM AIR ADVECTION RAIN INTO OUR SOUTHERN
CWA AFTER MIDNIGHT. TEMPERATURES WILL BE HOVERING NEAR FREEZING BUT
PAVEMENT READINGS SHOULD REMAIN ABOVE FREEZING. HOWEVER...FOR NOW I
WILL MENTION THE POTENTIAL FOR RAIN OR FREEZING RAIN AND LET LATER
SHIFTS MONITOR TEMPERATURE TRENDS. THE REMAINDER OF THE CWA SHOULD
REMAIN DRY THANKS TO THE DRY EASTERLY FEED FROM THE DEPARTING GREAT
LAKES HIGH PRESSURE. MINIMUM TEMPERATURES WILL RANGE FROM 23 AT
FREEPORT IL TO 33 AT MEMPHIS MO.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 330 AM CDT MON MAR 23 2015

AN UNSETTLED SPRING WEATHER PATTERN CONTINUES THIS WEEK. THE MAIN
FOCUS IS ON A STRONG UPPER LEVEL SHORTWAVE AND SURFACE LOW THAT ARE
STILL ON TRACK TO BRING WIDESPREAD RAIN AND POSSIBLE THUNDERSTORMS
TUE INTO TUE NIGHT. MAINLY DRY WEATHER FOLLOWS FOR MID TO LATE WEEK
WITH A COOLING TREND AS A DEVELOPING EASTERN U.S. TROUGH BRINGS
CANADIAN HIGH PRESSURE AND MUCH BELOW NORMAL TEMPERATURES BY FRIDAY.

TUESDAY MORNING...SHOWERS AND ISOLATED THUNDERSTORMS MAY BE ON-GOING
ACROSS THE FAR SOUTH. WITH TEMPERATURES STARTING OUT NEAR OR A FEW
DEGREES BELOW ZERO AT SUNRISE ACROSS THE SOUTH...THERE IS A
POTENTIAL SOME OF THIS INITIALLY FALL AS FREEZING RAIN BEFORE
TEMPERATURES BEGIN TO RECOVER. HAVE LEFT SUCH WORDING OUT FOR NOW
WITH LOW CONFIDENCE IN THE CRITICAL SURFACE TEMPERATURES AND
CONSIDERING THE WARM GROUND THAT WOULD MINIMIZE ANY IMPACTS. MODEL
CONSENSUS NOW SUPPORTS ANY SHOWERS OR THUNDERSTORMS BEING CONFINED
TO THE SOUTH UNTIL LATER IN THE AFTERNOON...AND HAVE SHIFTED POPS
ACROSS THE NORTH TO MAINLY THE AFTERNOON HOURS. BRISK EAST TO
SOUTHEAST WINDS...PRECIPITATION AND CLOUD COVER SHOULD LIMIT HIGHS
TO THE 40S...TO NEAR 50 IN THE FAR SOUTH.

THE 00Z MODELS HAVE COME INTO ROUGH AGREEMENT WITH THE SURFACE LOW
TRACKING NORTHEAST THROUGH EASTERN IA TUE NIGHT...REACHING EASTERN
WI OR LAKE MI BY 12Z WED. THE GEM/CANADIAN IS A SOMEWHAT STRONGER
AND SLIGHTLY SLOWER OUTLIER...SHOWING A DEEPER LOW LIFTING NE
THROUGH CENTRAL IA TO SW WI BY WED...WHICH WOULD SWEEP THE WARM
SECTOR THOUGH THE LOCAL AREA. FOR NOW...WILL KEEP THE FORECAST
TRENDED CLOSER TO THE BETTER CONSENSUS BLEND OF THE GFS/NAM/ECMWF
WITH THIS FEATURE. UPPER LEVEL FORCING AND THETAE ADVECTION WILL
INCREASE AND SPREAD SHOWERS OVER THE ENTIRE AREA BY MID TO LATE
AFTERNOON AS THE NEGATIVE TILT SHORTWAVE LIFTS INTO CENTRAL IA IA
AND NORTHERN MO...AND HAVE HIGHEST POPS IN THE AFTERNOON AND
EVENING.

STEEP MID LEVEL LAPSE RATES AND THE ENHANCE LIFT AHEAD OF THE STRONG
VORT LIFTING THROUGH WILL SUPPORT AT LEAST ISOLATED SHOWERS AND
THUNDERSTORMS ACROSS THE SOUTH AND SOUTHWEST IN THE AFTERNOON...AND
THEN OVER MOST OF THE FORECAST AREA TUE EVENING. THE QUICK SHOT OF
GULF MOISTURE AND SEASONABLY HIGH PW FORECAST INTO THE AREA WILL
SUPPORT RAINFALL AMOUNTS IN THE RANGE OF .50 TO POSSIBLY .75 INCHES
WITH ISOLATED HEAVIER AMOUNTS WITH CONVECTION. TEMPERATURES WILL BE
GREATLY DEPENDENT ON THE TRACK OF THE LOW...WITH THE WARM SECTOR
POSSIBLY HOLDING MINS IN THE UPPER 40S THROUGH THE NIGHT. FOR
NOW...HAVE A COMPROMISE OF UPPER 30S NORTH TO MID 40S SOUTHEAST.

MODELS DEPART FROM WED ONWARD...WITH THE GFS...AND TO A LESSER
EXTENT THE ECMWF...OUTLIERS IN THE 00Z RUN DEVELOPING A SEPARATE LOW
PRESSURE AND MCS ALONG THE MAIN FRONT TO THE SOUTH THAT MAY SEND
RAIN BACK INTO THE FAR SOUTH WED INTO WED NIGHT. WILL CARRY LOW
CONFIDENCE...LOW POPS FOR THIS POSSIBILITY IN THE SOUTH.
OTHERWISE...WED NOW LOOKS BREEZY AND SOMEWHAT MILD WITH HIGHS IN THE
50S TO LOWER 60S.

THURSDAY THROUGH SUNDAY...AN UPPER LEVEL TROUGH MOVES THROUGH AROUND
WED NIGHT...DIGGING INTO A LONGWAVE TROUGH OVER THE EASTERN HALF OF
THE COUNTRY BY FRIDAY. THE RESULTING PERIOD OF NEARLY MERIDIONAL
FLOW SENDS CANADIAN HIGH PRESSURE SOUTH INTO THE PLAINS WITH 850 MB
TEMPERATURES SHOWN PLUNGING TO A WINTER-LIKE -10 C TO -15 C RANGE
FRIDAY. THIS MAY LIMIT HIGHS TO THE 30S BY FRIDAY WITH LOWS IN THE
20S AND POSSIBLY TEENS. THE TROUGH IS SHOWN ADVANCING EASTWARD OVER
THE WEEKEND ALLOWING TEMPERATURES TO SLOWLY MODERATE TO RETURN HIGHS
TO THE 40S SATURDAY AND THEN AT LEAST 50S SUNDAY WITH OVERNIGHT LOWS
IN THE 30S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1128 PM CDT SUN MAR 22 2015

A SMALL...TIGHTLY PACKED STORM SYSTEM WILL SWEEP THROUGH SOUTHERN
IOWA TONIGHT THROUGH MONDAY MORNING. THE MAIN STORM WILL MOVE INTO
SOUTHERN IOWA...WITH RAIN SNOW AND SLEET DEVELOPING OVER MUCH OF
EASTERN IOWA AND NORTHWEST ILLINOIS. COLD AIR IS SPREADING IN
ALREADY AT LOW LEVELS...THUS...SNOW WILL BE LIKELY AT DBQ...AND
EVEN MLI OVERNIGHT...WITH CID AND BRL SEEING A MIX OF RAIN/SLEET
AND SNOW. THE LOWEST VISIBILITIES ARE FORECAST AT DBQ...WHERE
MODERATE SNOW IS POSSIBLE OVERNIGHT. HOWEVER...SOME CONVECTION MAY
ALLOW FOR BRIEF MODERATE OR HEAVY RATES/LOW VISIBILITIES FARTHER
SOUTH BETWEEN 09Z AND 14Z/23. AFTER 14Z...THE STORM WILL EXIT THE
REGION...WITH COLD EAST WINDS AND MVFR CONDITIONS THROUGH THE DAY
MONDAY.


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 10 AM CDT THIS MORNING FOR DUBUQUE.

IL...WINTER WEATHER ADVISORY UNTIL 10 AM CDT THIS MORNING FOR JO
     DAVIESS-STEPHENSON.

MO...NONE.
&&

$$

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












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