Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 301128
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
628 AM CDT THU APR 30 2015

.SYNOPSIS...
ISSUED AT 330 AM CDT THU APR 30 2015

AT 3 AM...AREA RADARS SHOW WEAK SHOWERS THAT MOVED THROUGH NORTHERN
IL LAST EVENING WERE NOW MAINLY SPRINKLES OVER CENTRAL AND SOUTHERN
IL. THESE WERE LINKED WITH AN AREA OF UPPER FORCING OUT AHEAD OF A
DEEPENING UPPER LOW SEEN ON SATELLITE DROPPING SOUTH ACROSS WESTERN
LOWER MI. TO THE WEST...AN UPPER LEVEL LONGWAVE RIDGE AXIS REACHED
FROM THE FOUR CORNERS REGION NORTHEAST ACROSS THE PLAINS INTO ND.
THIS WAS REINFORCING A SURFACE RIDGE AXIS EXTENDING SW FROM ONTARIO
ACROSS MN INTO EASTERN NEB. THE LOW LEVEL ANTICYCLONIC FLOW WAS
RESULTING IN LIGHT E-NE WINDS OVER THE FORECAST AREA AND SEASONABLY
DRY AIR WITH DEWPOINTS IN THE 30S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT THU APR 30 2015

TEMPERATURES ARE THE PRIMARY CHALLENGE AS RIDGING...BOTH AT THE
SURFACE AND ALOFT...WILL BE THE MAIN WEATHER FEATURE. THIS WILL KEEP
THE SEASONABLY DRY AIRMASS IN PLACE UNDER MOSTLY CLEAR TO PARTLY
CLOUDY SKIES...WITH CONTINUED LARGER THAN NORMAL DIURNAL TEMPERATURE
SWINGS DUE TO THE DRY AIRMASS.

SKIES SHOULD START OUT CLEAR EARLY THIS MORNING. A LARGE AREA OF MID
LEVEL CLOUDS SEEN ON SATELLITE DROPPING SOUTH OUT OF EASTERN MN WILL
LIKELY DISSIPATE TO ONLY SCATTERED MID LEVEL CLOUDS OVER EASTERN IA
THIS MORNING AS THE WEAK MID LEVEL DISTURBANCE AND ENHANCED MOISTURE
TRANSITIONS INTO A MORE CONFLUENT AREA IN THE NEARLY MERIDIONAL
UPPER LEVEL FLOW. BY LATE MORNING INTO EARLY AFTERNOON CLOUD COVER
WILL BE LIMITED TO ONLY A FEW CU...AND THESE LIKELY CONFINED TO THE
EAST AND SOUTHEAST. DESPITE THE SUNSHINE...LIGHT NORTH WINDS AT THE
SURFACE THROUGH 850 MB ADVECTING IN A COOLER AIRMASS WILL LEAD TO
COOLER TEMPERATURES THAN THE PAST SEVERAL DAYS. LATEST MODEL
GUIDANCE AND MIX DOWN TOOLS BACK THE PREVIOUS FORECAST AND HAVE MADE
ONLY MINOR TWEAKS WITH HIGHS FROM AROUND 60 EAST TO THE MID 60S WEST.

TONIGHT...THE SURFACE RIDGE AXIS SHIFTING OVERHEAD WILL LEAD TO
CLEAR SKIES AND LIGHT WINDS. THESE NEARLY IDEAL CONDITIONS FOR
RADIATIONAL COOLING SUPPORTS LOW TEMPERATURES NEAR OR BELOW THE
COOLEST GUIDANCE...FROM THE MID AND UPPER 30S OVER NW IL INTO THE
EASTERN IA RIVER VALLEYS...TO THE LOWER 40S OVER THE SOUTH. CANNOT
RULE OUT LOCALIZED FROST...BUT CONSIDERING THE DRY AIRMASS AND
MARGINAL TEMPERATURES...WILL LEAVE OUT ANY MENTION IN THE FORECAST
AT THIS TIME.

.LONG TERM...(FRIDAY THROUGH NEXT WEDNESDAY)
ISSUED AT 330 AM CDT THU APR 30 2015

FRIDAY...LOOKING AT THE LATEST 00Z MODEL RUN SOLUTIONS AND
ESPECIALLY FORCING COMBINED WITH MOISTURE RETURN/CONVERGENCE...
SEEMS THE WEAKENING WAVE AND ANY TYPE OF SFC REFLECTION FRONT TRYING
TO MAKE IT INTO THE CWA BY FRI EVENING FROM THE WEST TO BE WASHING
OUT ENOUGH THAT ONLY A FEW LIGHT SHOWERS OR SPRINKLES TO MAKE IT
INTO THE FAR WESTERN CWA BY LATE FRI AFTERNOON/EVENING. THE RAM/S
DRY SOLUTION THRU 00Z PROBABLY MORE ON TARGET BUT WILL KEEP SLIGHT
CHE POPS IN THE FAR NORTHWEST FOR LATE FRI AFTERNOON...ARE-SYSTEM
RETURN FLOW TO MAKE FOR HIGHS IN THE UPPER 60S TO NEAR 70 IN MUCH
OF THE LOCAL CST AREA. NOT MUCH FOCUS LATER FRI NIGHT INTO EARLY
SAT MORNING FOR PRECIS TO DEVELOP OR FESTER...AGAIN LOW CHGE POPS
FOR MAYBE AN ISOLATED ELEVATED WARM AIR ADVECTION INDUCED
SHOWER...BETTER CHGE OFF TO THE SOUTHWEST WITH MORE ORGANIZED
RETURN FLOW ALONG A DEVELOPING LVL WARM FRONT.

SATURDAY AND SUNDAY...THE SAME THEME CONTINUES INTO THE DAY SAT WITH
CONVERGENT RETURN FLOW SWATHS LOOKING TO SET UP OFF TO THE NORTH/
NORTHWEST OF THE CWA...AS WELL AS MORE TO THE WEST AND SOUTHWEST
WITH JUST AN ISOLATED SHOWER/STORM POSSIBLE LOCALLY IN DIURNAL
HEATING OF THE DAY. A LOT OF DRY PERIODS OF THE DAY SAT TO ALLOW
TEMPS TO WARM INTO THE MID 70S. INCREASINGLY ACTIVE NEAR ZONAL FLOW
PATTERN ALONG WITH WARM AND MORE MOIST CONVEYOR STARTING TO STEAM UP
OFF THE WESTERN GULF...MAY FINALLY SHIFT A FOCUS FURTHER EAST INTO
THE LOCAL AREA FOR A NOCTURNAL WAN TYPE INDUCED SHOWER/STORM
CLUSTER SAT NIGHT INTO SUNDAY MORNING. BUT THERE ARE ALSO
CONTINUING SIGNS ON THE LATEST MEDIUM RANGE MODEL RUNS OF LAYING
OUT BETTER CONVERGENT FORCING ZONES FOR MORE ORGANIZED PRECIS
DEVELOPMENT TO THE NORTH OF THE AREA ACTS MN INTO WI...AND WELL
OFF TO THE SOUTH OF THE AREA OVER THE SOUTHERN PLAINS THAT PERIOD.
WILL KEEP MODERATE CHANCE POPS FOR NOW BUT LATER SHIFTS MAY HAVE
TO TRIM BACK. STRONGER RETURN FLOW WARMING AND MOISTURE ADVECTION
UP TO THE LEE OF DEVELOPING MAIN FRONTAL SYSTEM/THAT WILL LOOK TO
EXTEND FROM THE NW GRT LKS...SOUTHWESTWARD TO THE SOUTHWEST PLAINS
BY SUNDAY EVENING/ MAY PUSH TEMPS CLOSE TO 80 IN MUCH OF THE CWA
BY SUNDAY AFTERNOON. THAT/S IF PRECIS AND ASSOCIATED DEBRIS CAN
CONTINUE TO BE HELD TO A MINIMUM. DEPENDING ON HOW FAR EAST AND
SOUTHEAST THE MAIN LOW LEVEL BOUNDARY/BAROCLINIC RIBBON CAN
SAG...BATTLING A SFC RIDGE GETTING ESTABLISHING ACTS THE ATLANTIC
SEABOARD TO THE LOWER MS RVR VALLEY... A CONVECTIVE FOCAL ZONE MAY
SET UP INTO OR AT LEAST JUST OFF TO THE WEST AND NORTHWEST OF THE
DVN CWA LATER SUNDAY NIGHT INTO MON MORNING. MUCH WILL DEPEND ON
TIMING OF A POTENTIAL S/W TROF RIPPLING IN SOUTHERN EDGE OF
WESTERLIES TO IGNITE MORE WIDESPREAD SHOWERS/STORMS OR ENHANCE
FORCING THAT NIGHT FOR POTENTIALLY STRONGER CELLS AND LOCALLY
HEAVY RAINFALL. SOUTHERLY NOCTURNAL LLJ CONVERGENT FOCUS ALSO TO
BE A FACTOR.

MONDAY THROUGH NEXT WEDNESDAY...THE LATEST MREF SOLUTIONS SUGGEST
THAT ESTABLISHING WESTERN CONUS L/W TROFFINESS AND LVL SOUTHEASTERN
ATLANTIC TO WEST GULF STATES RIDGE AXIS...TO POTENTIAL SET UP A
TYPE OF EARLY SEASON PARTIAL RING OF FIRE ALONG CONVERGENT LVL
BOUNDARY AXIS. THE LATEST SOLUTIONS ARE TARGETING THE SOUTHWEST
PLAINS/ WESTERN GRT BSN...UP TO THE CENTRAL PLAINS AND THEN
EASTWARD ACTS NEB...IA AND INTO THE SOUTHERN GRT LKS. THESE ZONES
COULD GET REPEATED ROUNDS OF SHOWERS AND THUNDERSTORMS FOR AN
ACCUMULATIVE HEAVY RAIN IMPACT MON INTO EARLY WED...BEFORE ROCKIES
L/W UPPER TROF AMPLIFICATION POSSIBLY SHUNTS THE CONVECTIVELY
ACTIVE ZONES WEST AND NORTH OF THE AREA LATER WED INTO EARLY THU.
LIKE THE PREVIOUS SHIFT STATED...DEPENDING ON AMOUNT OF HEATING
AND FORCING...SOME STRONG TO SVR STORMS MAY BE POSSIBLE TO
ESPECIALLY IN THE SOUTHERN CST AREA SOMETIME EARLY NEXT WEEK...OR
BY NEXT THU WHEN A LARGER PIECE OF THE ROCKIES TROF POSSIBLY
SHEARS OUT ACTS THE UPPER MIDWEST. CONVECTIVE WINDOWS TO WATCH
OUT FOR ANYWAY. LARGE TEMP CONTRASTS FROM NORTH TO SOUTH PROBABLE
NEXT WEEK DEPENDENT ON SFC BOUNDARY LOCATION AND ROUNDS OF PRECIS.
..12..

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 635 AM CDT THU APR 30 2015

VFR CONDITIONS WILL RULE TODAY THROUGH TONIGHT AS THE REGION
REMAINS UNDER THE INFLUENCE OF HIGH PRESSURE.

&&

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

$$

SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...12
AVIATION...SHEETS



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