Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 211748
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1248 PM CDT THU AUG 21 2014

.SYNOPSIS...
ISSUED AT 315 AM CDT THU AUG 21 2014

ANALYSIS AT 3 AM SHOWS DEVELOPING MCS SYSTEM IN SW MN AND NW IA
MOVING EAST SOUTHEAST WITH SUPPORTING PRESSURE FALL CENTER AXIS AND
BACKING WINDS FOR A DECENT RAIN EVENT NEAR OR INCREASINGLY IN
NORTH SECTIONS OF FORECAST AREA WITH SOME DECENT RAINS SUGGESTED
NEXT 4 TO 8 HOURS. UPSTREAM ENERGY TO KEEP AREA NEAR THERMAL
BOUNDARY FOR EPISODES OF CONVECTION NEAR OR OVER FORECAST AREA
LASTING INTO THIS WEEKEND.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT THU AUG 21 2014

SHORT TERM FORECAST CONFIDENCE...FAIR TO POOR TO VERY POOR (AVERAGE
TO BELOW TO WELL BELOW AVERAGE). AS IN YESTERDAY...CLOUDS AND PRECIPITATION
RISKS APPEAR TO BE RISING NEXT 8+ HOURS THAT MAY REQUIRE LOWERING HIGHS
NORTH AND INCREASING POPS WITH HIGHER TO MUCH HIGHER QPF AMOUNTS. THE
MCS WILL TAKE ANOTHER 3 TO 5 HOURS TO BETTER ASSESS. ALONG AND SOUTH
OF HIGHWAY 34...LOOKS FAIRLY REASONABLE TODAY. TONIGHT RAIN POSSIBILITIES
WILL BE IMPACTED BY THE CONVECTIVE EVENT THIS MORNING INTO EARLY AFTERNOON.

TODAY...LARGE THERMAL GRADIENT FOR HIGH TEMPERATURES SUGGESTED WITH
HIGHS ALONG AND ESPECIALLY NORTH OF HIGHWAY 30 POSSIBLY 5 PLUS DEGREES
AGAIN TOO HIGH. THE MAGNITUDE OF THE MCS OUTFLOW BOUNDARY LATER THIS
MORNING WILL BE KEY. LOCATIONS NEAR HIGHWAY 20 AND POSSIBLY NEAR HIGHWAY
30 MAY PICK UP A HALF INCH OR 1+ INCH OR MORE OF RAIN IF TRENDS CONTINUE.
ALONG AND SOUTH OF HIGHWAY 34...HIGHS SHOULD REACH AROUND OR INTO THE
LOWER 90S WITH PARTLY TO MOSTLY SUNNY SKIES WITH HEAT INDEX VALUES INTO
THE UPPER 90S TO POSSIBLY AROUND 100F. POPS 20-50 PERCENT NORTH MAY
NEED RAISING DEPENDING ON TRACK OF MCS. STRONGEST STORMS TODAY MAY
BE STRONG WITH MARGINAL SEVERE RISKS OF GUSTY WINDS MAYBE UP TO NEAR
60 MPH THE MAIN THREAT AND .50 TO 1 INCH HAIL SECONDARY THREAT.

TONIGHT...AREA IN FAVORED CORRIDOR OF ANOTHER MCS EVENT NEAR OR OVER
THE REGION MID/LATE EVENING INTO OVERNIGHT. LATER SHIFTS DEPENDING ON
TODAY/S EVENT MAY NEED TO RAISE POPS AND QPF AMOUNTS OVER AGAIN NORTH
AND CENTRAL SECTIONS BASED ON FAVORED MCS TRACK METRICS. LOWS OF 70
TO 75 MAY BE TOO HIGH NORTH 1/2 IF ANOTHER DECENT CONVECTIVE EVENT
OCCURS. ASSESSMENT IS CENTRAL AND NORTH SECTIONS MOST AT RISK.  NICHOLS

.LONG TERM...(FRIDAY THROUGH NEXT WEDNESDAY)
ISSUED AT 315 AM CDT THU AUG 21 2014

FRIDAY THROUGH SUNDAY...ANOTHER ROUND OF MODEL RUNS GENERALLY
SUGGESTING THE UPPER RIDGE WILL LOOK TO AMPLIFY ACRS THE MID TO
UPPER MS RVR VALLEY REGIONS FRI INTO SAT WITH SUBSTANTIAL THERMAL
RIDGE/HEAT DOME SUSTAINING ALONG AND SOUTH OF THE CWA. BIG CONCERN
FOR FRI ANOTHER DAY WHERE CONVECTIVE DEBRIS OR ELEVATED WAA CLOUDS
SQUELCH THE HEAT UP POTENTIAL OVER PORTIONS OF THE DVN CWA...PROBABLY
NORTH OF I80. IF CLOUDS OR EVEN SHOWERS/STORMS FESTER LATE INTO THE
AFTERNOON...TEMPS COULD BE HELD WELL DOWN IN THE 80S OR EVEN IN THE
UPPER 70S IN THOSE AREAS...WHILE AREAS WITH MOSTLY SUNNY OR EVEN
PARTIAL SUNSHINE WITH A SOUTHWESTERLY BREEZE WARM INTO THE 90S WITH
NEAR HEAT ADVISORY OR HEAT ADVISORY CRITERIA INDICES. ONGOING
UNCERTAINTY INTO FRI EVENING AND OVERNIGHT IF MCS OR STORM CLUSTERS
CAN FIRE OVER PORTIONS OF...OR PROPAGATE INTO THE AREA FROM THE WEST
OR NORTHWEST. UPPER RIDGE AXIS ARC/S RIGHT UP THE UPPER MS RVR
VALLEY AND OBVIOUS BEST FORCED AND LLJ CONVERGENT ZONE TO PRODUCE
MCS/S OR EVEN AN MCC LOOK TO OCCUR ACRS THE WEST CENTRAL PLAINS UP
THROUGH THE DAKOTAS AND WESTERN MN. BUT A SECONDARY SWATH OF MCS
FORCING PARAMETERS BY THE NAM AND EVEN THE NEW 00Z ECMWF SUGGEST A
SECONDARY MCS OR STORM CLUSTER GENERATION AREA POSSIBLE FROM CENTRAL
IA EASTWARD TO NORTHEASTERN IL INTO WEST CENTRAL INDIANA LATE FRI
NIGHT. WILL KEEP LOW TO MODERATE CHC POPS ACRS MOST OF THE CWA.
SHEAR AND THERMODYNAMIC PROFILES SUGGEST HEAVY RAIN AND ISOLATED SVR
STORMS POSSIBLE WITH ANY CONVECTIVE SYSTEMS THAT CAN MAKE IT ACRS
THE LOCAL AREA FRI NIGHT INTO SAT MORNING. ONGOING RIDGE
AMPLIFICATION CONTINUES INTO SAT...AND THIS SHOULD FINALLY SHUNT
MOST OF THE RING OF FIRE POTENTIAL WEST/NORTH/NORTHEAST OF THE AREA.
BUT MANY OF THE MODELS NOW SUGGEST LK FRONT OR PORTION OF WARM
FRONTAL BOUNDARY STALLING ACRS THE NORTHEASTERN THIRD OF THE CWA
WITH LLVL EASTERLY FLOW INTO THESE AREAS. BESIDES BEING A BIG TEMP
BUST AREA WITH MUCH COOLER VALUES OCCURRING THAN WHAT WILL BE FCST...
THIS AREA COULD BE A FOCAL FOR NEW SHOWER/STORM DEVELOPMENT. WILL
LEAVE LOW TO MODERATE CHC POPS GOING NORTH OF I80 FOR SAT...WHILE
AREAS TO THE SOUTH OF THE INTERSTATE POSSIBLY WARM BACK UP INTO THE
LOW TO MID 90S WITH HEAT INDICES OF 100-105+. CONVECTIVE SPAWNING
GROUNDS CONTINUE ACRS THE NORTH HALF OF THE PLAINS INTO THE
NORTHWESTERN GRT LKS SAT NIGHT WITH BULK OF THE LATEST 00Z RUN
MEDIUM RANGE MODELS SUGGESTING THE LOCAL AREA DRY UNDER THE THERMAL
RIDGE. BUT WITH ONGOING MODEL MISTRUST WILL KEEP AT LEAST SLIGHT CHC
POPS GOING NORTH OF I80. UPPER TROF AND JET ENERGY REALLY DIG ACRS
THE NORTHERN ROCKIES AND INTO THE PLAINS THE SECOND HALF OF THE
WEEKEND WITH THE POTENTIAL FOR SOME OF THE CONVECTION INDUCED BY
THIS PROCESS BLEEDING IN FROM THE NORTHWEST AND CLIPPING PORTIONS OF
THE LOCAL AREA LATE SUNDAY OR SUNDAY NIGHT. OTHERWISE IF CONVECTIVE
DEBRIS CAN BE HELD AT BAY...SUNDAY COULD BE THE DAY WITH WIDESPREAD
LOW TO MID 90S IN ENHANCED SOUTHWESTERLY MIXING FLOW AHEAD OF
INCOMING LLVL BOUNDARY FROM THE NORTHWEST. ANOTHER HEAT ADVISORY
POTENTIAL DAY FOR AT LEAST PORTIONS OF THE AREA IF THIS UNFOLDS THE
WAY THE SOLUTIONS CURRENTLY ADVERTISE IT TO DO.

MONDAY THROUGH NEXT WEDNESDAY...LONG RANGE INDICATION SUGGEST MODELS
ARE HAVING TROUBLE RESOLVING INCOMING TROF ENERGY AND BATTLING WITH
UPPER RIDGING AND RIDGE PLACEMENT/BREAK DOWN. EARLY TO MID NEXT
WEEK COULD POTENTIALLY BE AN UNSETTLED PERIOD DEPENDING ON LLVL
FRONTAL STRENGTH AND PLACEMENT. SWEEPS THROUGH OR STALLS ACRS THE
REGION...ALONG WITH ORIENTATION. MORE CONFIDENCE ON SYNOPTIC FEATURE
EVOLUTION THIS PERIOD PROBABLY NOT GOING TO HAPPEN UNTIL THE WEEKEND
AS EASTERN PACIFIC AND GULF OF AK JET/WAVE ENERGY GETS BETTER
SAMPLED. UNTIL THEN...LOW CHC POPS ALMOST EVERY DAY AND GENERAL TEMP
TEND AT OR ABOVE NORMAL UNTIL THE RIDGE BREAKS.    ..12..

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1236 PM CDT THU AUG 21 2014

A MID LEVEL CLOUD ARE MOVING ACROSS EASTERN IOWA AHEAD OF A
DISTURBANCE MOVING INTO THE CENTRAL PART OF THE STATE. REGIONAL
RADAR SHOWED SCATTERED SHOWERS AND THUNDERSTORMS MOVING INTO
EASTERN IOWA AND NORTHWEST ILLINOIS MAINLY TO THE NORTH OF
INTERSTATE 80. CEILINGS AND VISIBILITIES WERE VFR AT ALL TAF SITES
WITH THE EXCEPTION OF KDBQ WERE MVFR CEILINGS WERE IN PLACE.

SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH APPROXIMATELY 21
UTC AHEAD OF THE CURRENT DISTURBANCE MOVING ACROSS THE IOWA.
CEILINGS SHOULD REMAIN VFR AT KCID AND KMLI BUT THERE MAY BE
PERIODS OF MVFR VISIBILITIES IN SHOWERS AND THUNDERSTORMS. KDBQ WILL
CONTINUE TO FLUCTUATE BETWEEN VFR AND MVFR AND DROP AS LOW AS LIFR
AS THE STRONGER SHOWERS AND THUNDERSTORMS MOVE THROUGH THE REGION.
ANOTHER ROUND OF THUNDERSTORMS WILL BE POSSIBLE OVERNIGHT
BEGINNING PRIOR TO 06 UTC BUT THE PLACEMENT OF THESE THUNDERSTORMS
IS A PROBLEM AS THEY MAY BE FARTHER TO THE NORTH AS THE WARM FRONT
LIFTS OUT OF THE AREA. EXPECT A MID LEVEL DECK TO OVERSPREAD THE
REGION FRIDAY MORNING AFTER 12 UTC DEPENDING ON WHERE THE
THUNDERSTORMS TRACK. WINDS WILL SHIFT FROM SOUTHERLY TO
SOUTHWESTERLY AFTER 12 UTC ON FRIDAY IN THE WAKE OF THE OVERNIGHT
DISTURBANCE.

&&

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

$$

SYNOPSIS...NICHOLS
SHORT TERM...NICHOLS
LONG TERM...12
AVIATION...COUSINS







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