Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 302027
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
327 PM CDT THU JUL 30 2015

.SYNOPSIS...
ISSUED AT 324 PM CDT THU JUL 30 2015

THE LATEST SFC ANALYSIS WAS INDICATING HIGH PRESSURE CENTER SAGGING
SOUTH ACRS EAST CENTRAL KS INTO MO...WHILE A WEAK TROF WAS NOTED
SLIDING ACRS ND. SFC WINDS AND MIXING EXTENT NOT QUITE AS ROBUST AS
EARLIER ANTICIPATED...AS WELL AS SOMEWHAT HIGHER WESTERLY WINDS
UPSTREAM PRODUCING SOME MOISTURE CONVERGENCE ACRS THE LOCAL AREA
KEEPING SFC DPTS UP MORE IN THE LOW TO MID 60S OVER MOST OF THE
CWA/ALTHOUGH SOME 50 DPTS STILL OCCURRING IN NORTHWESTERN IL/.
CROP EVAPOTRANSPIRATION ALSO A FACTOR. ALOFT...12Z UPPER AIR
ANALYSIS AS WELL AS MID/UPPER LEVEL MOISTURE FLOW PATTERNS SEEN ON
THE CURRENT WATER VAPOR LOOP INDICATING SOME LARGE SCALE
AMPLIFICATION TAKING PLACE TO UPSTREAM RIDGE OVER THE ROCKIES.
THIS WILL EFFECTIVELY STEEPEN THE NORTHWESTERLIES DUMPING DOWN
ACRS THE UPPER MS RVR VALLEY THROUGH TOMORROW.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 324 PM CDT THU JUL 30 2015

TONIGHT...AS RIDGE SLIDES SOUTH...LIGHT WEST TO SOUTHWEST WINDS
OVERNIGHT AND MAINLY CLEAR SKIES ALLOWING FOR SFC TEMPS TO COOL
TOWARD THE AMBIENT DPTS FOR OVERNIGHT LOWS. A FEW MODELS IN VARYING
DEGREES SKIT A WEAK VORT INTO THE WESTERN CWA LATE TONIGHT IN
NORTHWESTERLY STEERING FLOW...BUT MAIN EFFECT SHOULD ONLY BE TO
INDUCE SOME PATCHY AC/MID CLOUDS IF EVEN THAT.

FRIDAY...UPSTREAM SFC TROF PROGRESSES ACRS THE CWA FROM NORTHWEST TO
SOUTHEAST DURING THE MORNING. A FEW HIRES MODELS EVEN GENERATE A FEW
SPOTTY TO ISOLATED SHOWERS ACRS SOUTHEASTERN IA INTO WEST CENTRAL IL
AT THIS TIME/MID FRI MORNING...BUT FORCING...MOISTURE CONVERGENCE
AND ANY INSTABILITY WEAK AT THAT TIME AND WILL KEEP THE FCST DRY
THRU EARLY AFTERNOON. DEEP UNIFORM NORTHWEST FLOW CONTINUES INTO THE
AFTERNOON...AND ADEQUATE HEATING AND MIXING WILL MAKE FOR WIDESPREAD
MID TO UPPER 80S ACRS THE CWA WITH A FEW SITES AROUND 90. AS FOR
AFTERNOON CONVECTION TAKING OFF...DEEP CONVECTIVE INDEX MAX/S...
RETURN FLOW CONVERGENT ZONES AND OTHER CONVECTIVE INDUCING PARAMETERS
IN A MODERATE CAPE BUT WEAK SHEAR REGIME ARE ALL POINTING AT THE
ACTIVE ZONE FOR SCTRD TO ISOLATED STORMS TOMORROW AFTERNOON FROM
ACRS SOUTH CENTRAL INTO SOUTHEASTERN NEB...INTO NORTHWESTERN AND
NORTH CENTRAL MO. BULK OF THE LATEST MODEL RUNS ARE ALSO PICKING
UP ON THIS TREND...SUGGESTING THE CWA WILL PROBABLY REMAIN DRY
THROUGH 00Z SAT WHILE STORM CLUSTERS BLOSSOM WEST-SOUTHWEST OF
OMAHA AND ISOLATED ACTIVITY TAILS OFF TOWARD THE NORTHWESTERN STL
AREA. FOR NOW WILL TRIM BACK SLIGHT CHC POPS TO THE FAR
SOUTHWESTERN CWA FROM MID TO LATE AFTERNOON...BUT IF TRENDS
CONTINUE THE NEXT FCST SHIFT MAY BE ABLE TO REMOVE THEM ALL
TOGETHER.   ..12..


.LONG TERM...(FRIDAY NIGHT THROUGH NEXT THURSDAY)
ISSUED AT 324 PM CDT THU JUL 30 2015

HAVE MAINTAINED LOW POPS ACROSS THE FAR SOUTH INTO FRIDAY EVENING...
ALTHOUGH IF RECENT TRENDS CONTINUE LATER SHIFTS MAY BE ABLE TO GO
DRY ALTOGETHER. THE INITIAL MAIN CHANCE FOR SHOWERS AND
THUNDERSTORMS STILL LOOKS TO BE SATURDAY NIGHT INTO SUNDAY. MODEL
INCONSISTENCY LINGERS REGARDING TIMING OF THE MAIN UPPER FORCING
AND FAVORED AREAS FOR STORMS. WRF MCS DIAGNOSTICS DO INDICATE SOME
POTENTIAL FOR A COMPLEX CLIPPING PORTIONS OF THE FORECAST AREA
SATURDAY NIGHT...BUT CONFIDENCE IN ANY PARTICULAR SCENARIO REMAINS
LOW. SPC HAS THE ENTIRE FORECAST AREA IN THE MARGINAL RISK AREA.
GENERAL SHEAR/INSTABILITY PARAMETERS DO SUPPORT SOME POTENTIAL FOR
ISOLATED SEVERE STORMS.

FOR SUNDAY AFTERNOON THROUGH THURSDAY...AT LEAST SLIGHT CHANCE POPS
CONTINUE EVERY PERIOD DUE TO TYPICAL ISSUES WITH SUBTLE SHORT WAVE
TIMING AND LOCATION. MONDAY NIGHT...AND AGAIN TUESDAY
NIGHT/WEDNESDAY LOOK A BIT MORE FAVORABLE AT THIS POINT.

TURNING TO TEMPERATURES THROUGH THE PERIOD...SATURDAY THROUGH MONDAY
SHOULD BE SEASONABLY WARM WITH AFTERNOON HIGHS FROM THE LOW 80S
NORTH TO UPPER 80S SOUTH. CONSENSUS BLENDED TEMP GUIDANCE CONTINUES
TO SUPPORT A COOLING TREND INTO THE 70S TUESDAY THROUGH THURSDAY.
SUNDAY AND MONDAY WILL LIKELY BE THE MOST HUMID PERIOD...WITH
DEWPOINTS FORECAST IN THE LOW 70S SOUTH...GOOD FOR AFTERNOON HEAT
INDEX VALUES IN THE LOW TO MID 90S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1230 PM CDT THU JUL 30 2015

HIGH PRESSURE ACRS THE CENTRAL PLAINS AND INTO THE MID MS RVR
VALLEY WILL MAINTAIN VFR CONDITIONS INTO TONIGHT AND MOST OF FRI
MORNING. WEST WINDS OF 8-12KTS THIS AFTERNOON WILL BECOME LIGHT
WEST TO SOUTHWEST OVERNIGHT AS THE RIDGE SINKS TO THE SOUTH. A
WEAK WAVE ALOFT EMBEDDED IN STEERING NORTHWEST FLOW MAY TRY TO
SCOOT INTO THE AREA/SOUTHEASTERN IA FRI MORNING BUT HOPEFULLY JUST
PRODUCE SOME MID LEVEL VFR CLOUDS IN THOSE AREAS...ALTHOUGH A FEW
MODELS TRY TO BREAK OUT ISOLATED TO WDLY SCATTERED SHOWERS FROM
13Z-16Z OR SO.    ..12..

&&

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

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...RP KINNEY
AVIATION...12



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