Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 281748
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1248 PM CDT SUN JUN 28 2015

.UPDATE...
ISSUED AT 1248 PM CDT SUN JUN 28 2015

ELEVATED CONVECTION OCCURRING IN THE WARM ADVECTION WING OF A
WEAK SHORTWAVE IN THE NW FLOW ALOFT HAS BEEN LIMITED TO THE
WESTERN HALF OF THE FORECAST THIS MORNING. CLOUD COVER FROM THE
SHOWERS AND THUNDERSTORMS HAS HELD TEMPERATURES DOWN
ELSEWHERE...WITH NOON READINGS MAINLY IN THE LOWER 70S. BASED ON
RADAR AND SOME SPOTTER REPORTS...THE STRONGEST SHOWERS/STORMS HAVE
PRODUCED RAINFALL AMOUNTS UP TO AN INCH IN THE THE CEDAR RAPIDS
AREA AND ALSO OVER FAR SE IA AND NE MO. AT NOON...MSAS PRESSURE
FIELDS INDICATED A SURFACE LOW OVER CENTRAL IA WITH PRESSURE FALLS
OVER S CENTRAL INTO SE IA...INDICATING CONTINUED SE PROPAGATION AS
SUGGESTED BY 12Z MODELS.

WITH A DIFFERENTIAL HEATING BOUNDARY SETTING UP ALONG THE LOW/S
TRACK IN CENTRAL IA INTO N CENTRAL MO AND THE OVERLAPPING AXIS OF
BETTER SHEAR MOVING INTO THE SAME AREA...THE GREATEST SEVERE
POTENTIAL LOOKS TO BE MAINLY OVER THE SW THIRD OF THE FORECAST
AREA FOR MID TO LATE AFTERNOON. UNTIL THEN...THE ELEVATED STORMS
MOVING ACROSS EASTERN IA...NE MO AND W CENTRAL MO WILL PRESENT
MAINLY A LIGHTNING RISK WITH LOCALLY HEAVY DOWNPOURS. THE
PROGRESSIVE STORM MOVEMENT SHOULD ELIMINATE ANY THREAT OF FLASH
FLOODING. HAVE UPDATED THE FORECAST FOR THESE TRENDS AND LOWERED
MAXES SOME DUE TO THE CLOUD COVER AND SLOW WARMING THIS MORNING.

&&

.SYNOPSIS...
ISSUED AT 410 AM CDT SUN JUN 28 2015

WING OF STRONG WARM AIR ADVECTION TRIGGERING AN AREA OF SHOWERS
AND SCATTERED THUNDERSTORMS FROM EASTERN MN/WESTERN WI INTO
NORTHERN/WESTERN IA. THESE SHOWERS AND STORMS WERE MOVING SOUTHEAST.
THIS PRECIPITATION WAS ALSO TIED TO THE AXIS OF HIGHER PWAT`S OF
GREATER THAN 1.30 INCHES. THERE WAS MINIMAL INSTABILITY SO THESE
STORMS WERE GARDEN VARIETY.

AT 3 AM TEMPERATURES IN THE DVN CWA RANGED FROM THE MID 50S TO
LOWER 60S WITH DEWPOINTS IN THE LOWER 50S TO LOWER 60S SO ANOTHER
COMFORTABLE EARLY MORNING IN PROGRESS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 410 AM CDT SUN JUN 28 2015

FORECAST FOCUS ON POTENTIAL FOR SEVERE WEATHER THIS AFTERNOON AND
EVENING.

TODAY...OPERATIONAL MODELS SEEM TO BE OVERDOING THE COVERAGE OF
THE INITIAL WARM AIR ADVECTION SHOWERS AND STORMS APPROACHING OUR
FAR NW COUNTIES. BASED ON THIS I BELIEVE THIS TREND OF OVERDOING
THE COVERAGE WILL CONTINUE IN THE MODELS IN THE SHORT TERM. THIS
WILL ALLOW FOR SOME SUNSHINE AT TIMES WHICH SHOULD PUSH TEMPERATURES
HIGHER THAN EARLIER FORECAST. I LIKE THE IDEA OF THE HRRR MODEL
BRINGING WEAKENING SHOWERS AND STORMS ACROSS THE CWA THROUGH MID
MORNING THEN SOMEWHAT OF A LULL LATE MORNING/EARLY AFTERNOON. THIS
SHOULD ALLOW AFTERNOON TEMPERATURES TO RISE INTO THE UPPER 70S TO
LOWER 80S...AND IF EVEN MORE SUN IS OBSERVED THAN EXPECTED THEN
SOME LOCATIONS MAY PUSH INTO THE MID 80S. POPS WILL BE LIKELY
THROUGH MID MORNING THEN CHANCE LATE MORNING/EARLY AFTERNOON...THEN
LIKELY AGAIN LATER THIS AFTERNOON INTO THE EVENING AS VIGOROUS UPPER
LEVEL TROUGH/EMBEDDED LOW DIVES INTO NORTHERN IL BY THIS EVENING.

SEVERE WEATHER DISCUSSION...SPC HAS A SLIGHT RISK OF SEVERE
THUNDERSTORMS THIS AFTERNOON AND EVENING FOR MUCH OF EASTERN IA...
WESTERN IL AND NORTHEAST MO. MLCAPES WILL INCREASE TO 1000-2000
J/KG WITH DEEP LAYER SHEAR AT 35 TO 45 KT WHICH IS SUFFICIENT FOR
SUPERCELLS DEVELOPING BY MID AFTERNOON. PARAMETERS ALSO COMING
TOGETHER FOR A FEW TORNADOES ESPECIALLY IN OUR FAR WESTERN
COUNTIES AND SOUTHEAST INTO WESTERN IL AND NORTHEAST MO. WITH
FREEZING LEVELS AT 12K LARGE HAIL IS LIKELY. LOCALLY HEAVY
RAINFALL WILL ALSO ACCOMPANY THESE STORMS WITH PWATS INCREASING TO
OVER 1.50 INCHES. NOTE...AS USUAL THE SEVERE THREAT WILL BE
CONDITIONAL ON AMOUNT OF SUNSHINE AND INSTABILITY. THE GREATEST
SEVERE THREAT APPEARS TO BE IN THE 3-10 PM TIME FRAME.

SHOWERS AND STORMS WILL DIMINISH BY LATE EVENING WITH CHANCE POPS
AFTER MIDNIGHT. MINIMUM TEMPERATURES TONIGHT WILL BE IN THE LOWER
TO MID 60S.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 410 AM CDT SUN JUN 28 2015

NORTHWEST FLOW WILL PERSIST THROUGH LATE WEEK WITH TEMPS NEAR TO BELOW NORMAL
(HIGHS 70S/LOWER 80S AND LOWS 50S/60S). THE FLOW PATTERN WILL REMAIN ACTIVE
WITH PERIODIC RAIN CHANCES WITH THE PASSAGE OF SEVERAL LOW AMPLITUDE
SHORTWAVES IN THE FLOW. WHILE IT WILL BE SOMEWHAT ACTIVE/UNSETTLED THE GOOD
NEWS FOR AREA FARMERS NEEDING SOME DRY WEATHER IS THAT THE THREAT
FOR WIDESPREAD ORGANIZED HEAVY RAINFALL IN THIS PATTERN IS VERY LOW... AND
OVERALL ANTICIPATE MAINLY LIGHT (0.25 INCH OR LESS)TO SOME AREAS OF MODERATE
(0.25-0.5+ INCH) RAIN AMOUNTS BY THE END OF THE WEEK. THE CHALLENGE REMAINS
OF TRYING TO TIME THESE SHORTWAVES AND ATTENDANT RAIN CHANCES GIVEN THE MODELS
GENERALLY POOR RESOLUTION AND SMOOTHING OF THESE SMALLER SCALE PERTURBATIONS.

MONDAY AND MONDAY NIGHT...BELIEVE OPPORTUNITY TO TRIM RAIN CHANCES AS MUCH OF
THE DAY WILL SEE LIMITED FORCING WITH ANY WRAP-AROUND FROM DEPARTING LOW
EXITING EASTERN SECTIONS EARLY ON... THEN MOST MODELS INDICATE WEAK SURFACE
RIDGING. LATE IN THE DAY ANOTHER DISTURBANCE AND MID LEVEL DIVERGENCE SIGNATURE
BEGIN TO APPROACH FROM NORTHWEST WITH RAIN CHANCES THEN INCREASING MONDAY NIGHT
AS THIS ENERGY AND ATTENDANT WEAK SURFACE LOW PASSES.

TUESDAY AND TUESDAY NIGHT...SUGGESTION OF BETTER RAIN CHANCES FAVORING THE
EASTERN CWA INTO EARLY EVENING BEING IN CLOSER PROXIMITY TO STRONGER CYCLONIC FLOW.

THEN MODEL TRENDS SEEM TO BE LEANING TOWARD DRYING ON EASTERLY FLOW POSSIBLY DURING
THE MIDWEEK PERIOD.

LATE WEEK LOOKS TO BRING RETURN OF RAIN CHANCES WITH ADDITIONAL SHORTWAVE ENERGY
RIPPLING DOWN IN NORTHWEST FLOW WITH MID LEVEL BAROCLINIC ZONE IN CLOSE PROXIMITY.

RIGHT NOW MOST OF THE MODELS APPEAR TO BE TRENDING TOWARD DRYING THINGS OUT FOR THE
4THOF JULY... BUT LOWER CONFIDENCE THIS FAR OUT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1248 PM CDT SUN JUN 28 2015

AN UPPER LEVEL DISTURBANCE AND WEAK SURFACE LOW MIGRATING THROUGH
THE REGION THIS AFTERNOON WILL SPREAD THUNDERSTORMS ACROSS THE
AREA. THESE STORMS WILL BE MAINLY THROUGH MID AFTERNOON AT CID AND
BRL...AND PERSIST UNTIL EVENING AT MLI AND BRL. WEAK WIND FIELDS
AND LINGERING LOW LEVEL MOISTURE FALLOWING THE PASSAGE OF THE LOW
TONIGHT WILL LIKELY LEAD TO WIDESPREAD MVFR IF NOT IFR
CONDITIONS. CONFIDENCE IS LOW AT THIS TIME WITH THESE TRENDS...BUT
HIGH ENOUGH TO WARRANT PERIODS OF IFR IN TEMPO GROUPS DUE TO FOG
AND LOW CLOUDS AT ALL SITES AROUND SUNRISE MONDAY. CONDITIONS
SHOULD THEN IMPROVE TO AT LEAST MVFR BY MID MORNING.

&&

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

$$

UPDATE...SHEETS
SYNOPSIS...HAASE
SHORT TERM...HAASE
LONG TERM...05
AVIATION...SHEETS



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