Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 030843
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
343 AM CDT WED JUN 3 2015

.SYNOPSIS...
ISSUED AT 343 AM CDT WED JUN 3 2015

THE LOCAL AREA REMAINS UNDER THE INFLUENCE OF HIGH PRESSURE OVER THE
GREAT LAKES. THIS...COMBINED WITH A BROAD UPPER LEVEL RIDGE REACHING
FROM TX TO THE WESTERN GREAT LAKES WAS PROVIDING CONTINUE QUIET
WEATHER WITH LIGHT WINDS...LOW HUMIDITY AND SEASONABLY COOL
TEMPERATURES EARLY THIS MORNING. SATELLITE IMAGERY SHOWED HIGH
CLOUDS FROM EARLIER PLAINS CONVECTION STREAMING OVER THE
AREA...WHILE FURTHER UPSTREAM...A LARGE MCS WAS RAPIDLY ADVANCING E-
SE ACROSS NEB. RADAR MOSAIC ALSO AN AREA OF SCATTERED...SLOW MOVING
THUNDERSTORMS OVER NORTHWEST MO.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT WED JUN 3 2015

THE MAIN CHALLENGE IS THE ONSET OF RAIN AND THUNDERSTORM CHANCES
TODAY AND TONIGHT. 00Z MODELS...AND MOST RECENT HIGH-RES
CONVECTIVE MODELS...WERE HAVING A DIFFICULT TIME WITH THE
LARGE...BOWING MCS OVER EASTERN NEB EARLY THIS MORNING. THE 00Z
ECMWF APPEARED TO BE BETTER INITIALIZED ON THE LOCATION OF THIS
COMPLEX...AND DEPICTION OVER THE PAST 6 HOURS...AND IS THUS THE
PREFERRED MODEL.

THE ECMWF CONTINUES THIS COMPLEX E-SE INTO WESTERN IA AND NW MO THIS
MORNING...BUT IT SHOULD GRADUALLY WEAKEN AS IT MOVES AWAY FROM THE
ELEVATED INSTABILITY AND THERMAL AXIS ALONG THE EDGE OF A BUILDING
HEAT DOME OVER THE SW U.S...AND ALSO AWAY FROM THE BETTER SURFACE
THROUGH 850 MB MOISTURE AXIS OVER THE CENTRAL PLAINS. AN ASSOCIATED
MID LEVEL VORT MAX WILL LIKELY MOVE THROUGH THE UPPER RIDGE AXIS
OVERHEAD FROM MIDDAY THROUGH EARLY AFTERNOON. AS IT MOVES AWAY FROM
THE BETTER MOISTURE FEED AND STEEPER MID LEVEL LAPSE RATES...INTO
A MORE STABLE ENVIRONMENT REMNANT FROM THE DEPARTING RIDGE...IT
IS NOT LIKELY TO TRIGGER ADDITIONAL CONVECTION. MODELS REFLECT
THIS...GENERALLY KEEPING QPF AND POPS CONFINED TO ONLY AS CLOSE AS
CENTRAL IA THROUGH THE DAY.

THUS HAVE KEPT ONLY LOW CHANCE POPS FOR SHOWERS AND THUNDERSTORMS
OVER THE FAR WEST AND SW FOR LATE THIS MORNING THROUGH AFTERNOON.
HIGH CLOUD COVER FROM THE UPSTREAM COMPLEX SHOULD KEEP SKIES
PARTLY TO MOSTLY CLOUDY PROVIDING ONLY FILTERED SUNSHINE TODAY...
LIMITING HIGH TEMPERATURES TO THE MID 70S TO NEAR 80. LIGHT SE
WINDS OUT OF THE DEPARTING SURFACE HIGH WILL KEEP DEWPOINTS IN THE
50S THROUGH MOST OF THE DAY...WITH LOWER 60S POSSIBLY ADVECTING
INTO THE FAR WEST LATE AS WINDS BEGIN TO VEER MORE SOUTHERLY.

TONIGHT...PARAMETERS FOR MCS GENERATION INITIALLY POINT TOWARD THE
MO RIVER VALLEY AND MODELS GENERALLY FOCUS RAIN AND THUNDERSTORMS
OVER WESTERN IA IN THE EVENING. A WEAKENING...VEERING 850 MB JET MAY
THEN SUPPORT ADVANCEMENT OF NON-SEVERE STORMS INTO THE LOCAL AREA...
ESPECIALLY AFTER MIDNIGHT. THUS HAVE LOW CHANCE POPS IN THE
EVENING...THEN SLIGHTLY HIGHER CHANCE POPS AFTER MIDNIGHT FOR MAINLY
THE WESTERN HALF OF THE FORECAST AREA. CLOUD COVER AND SLOWLY
INCREASING SURFACE MOISTURE LEVELS WILL LIMIT LOWS TO A RANGE
FROM AROUND THE UPPER 50S NORTHEAST TO THE LOWER 60S SW.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 343 AM CDT WED JUN 3 2015

THURSDAY MORNING...AN AREA OF CONVECTION WILL FORM OR BECOME
REINVIGORATED OVER SE NEBRASKA/NORTH-CENTRAL KANSAS/WESTERN IOWA
WEDNESDAY EVENING/NIGHT IN A ZONE OF ENHANCED MOISTURE FLUX-
CONVERGENCE ON THE NOSE OF A STRENGTHENING NOCTURNAL LOW-LEVEL JET.
THEN...THE MAJORITY OF MODEL SOLUTIONS BRING SCATTERED SHOWERS AND
STORMS INTO THE WESTERN PORTION OF THE CWA THU MORNING...ALTHOUGH
THE LLJ WILL BE WEAKENING WITH TIME AS SHOULD THE CONVECTION OR
POTENTIAL STORM COMPLEX.

850-300MB MEAN WINDS AND FORWARD PROPAGATING CORFIDI WIND
BARBS ARE LIGHT BUT BOTH HAVE A GENERAL WEST-TO-EAST ORIENTATION
HELPING GUIDE SOME OF THE STORMS INTO THE DVN CWA. MUCAPE VALUES ARE
FORECAST TO EXCEED 1000-1500 J/KG THROUGH THE MORNING TO THE SOUTH
OF I-80...COULD HAVE A FEW STRONG OR MARGINALLY SEVERE STORMS IN
THAT AREA. CURRENT FORECAST HAS 40-50 POPS ALONG AND WEST OF THE
MISSISSIPPI RIVER.

THURSDAY AFTERNOON...HIGHS SHOULD REACH TO AROUND 80 F. WINDS WILL
BE LIGHT AS PRESSURE GRADIENT REFOCUSES ACROSS THE PLAINS. ISOLATED
TO SCATTERED DAYTIME THUNDERSTORMS ARE POSSIBLE. GFS/ECMWF ARE
PROJECTING DECENT CONDITIONAL INSTABILITY OF 1000-2000 J/KG MUCAPE
BY THE AFTN. WIDESPREAD THUNDERSTORM ACTIVITY DOES NOT APPEAR LIKELY.

THURSDAY NIGHT...MODELS ARE DISPLAYING MANY DIFFERENT SCENARIOS IN A
WEAKLY FORCED SYNOPTIC REGIME. THE FAVORED ZONE FOR STORMS IS AGAIN
WEST OF THE MISSISSIPPI RIVER AND A LITTLE MORE LIKELY ALONG AND
SOUTH OF I-80. 850MB NOCTURNAL LOW-LEVEL JET IS FORECAST TO VEER TO
A MORE SW-NE ORIENTATION AND EXTEND FURTHER EAST COMPARED TO WED
NIGHT. AS SUCH...HAVE LIKELY POPS FOR AREAS ALONG/SOUTH OF I-80 AND
WEST OF THE RIVER.

PWAT VALUES AROUND 1.50 INCHES ARE SUPPORTIVE OF LOCALIZED HEAVY
RAINFALL IN ANY STORMS THAT FORM IN THE DVN CWA.

FRIDAY...DAYTIME INSTABILITY...A DISCERNIBLE MID-LEVEL LOW/VORT.
MAX...AND POSSIBLE LINGERING OUTFLOW BOUNDARIES WARRANT 50-60 POPS.
SFC WINDS WILL GRADUALLY DEVELOP OUT OF THE NE AS HIGH PRESSURE
BUILDS INTO THE GREAT LAKES. CONSEQUENTLY...HIGHS ARE FORECAST TO
RANGE FROM THE LOWER 70S OVER THE FAR NORTH TO THE LOWER 80S IN THE
FAR SOUTH.

SATURDAY AND SUNDAY...TEMPS LOOK SEASONAL IN THE 70S. BOTH THE GFS
AND ECMWF ARE FORECASTING A SHORTWAVE TROUGH TO DIVE SOUTHEASTWARD
INTO THE UPPER MIDWEST/GREAT LAKES SAT NIGHT INTO SUN DRAGGING A
COLD FRONT THROUGH THE AREA. THE ECMWF IS MUCH MORE ROBUST THAN THE
GFS AND HAS A MUCH BETTER CHANCE FOR SHOWERS/STORMS IN ASSOCIATION
WITH THE FRONT. ALL-IN-ALL SATURDAY LOOKS MAINLY DRY THEN HAVE 30-40
POPS SAT NIGHT/SUN.

MONDAY AND TUESDAY...THE ECMWF IS MOSTLY DRY WITH LARGE-SCALE
SUBSIDENCE ON THE WESTERN SIDE OF THE SHORTWAVE TROUGH.
HOWEVER...THE GFS BRINGS A SHORTWAVE AND SHOWER/STORM CHANCES INTO
THE UPPER MIDWEST. ONLY HAVE SLIGHT CHANCES FOR SHOWERS/STORMS AT
THIS TIME. FORECAST CURRENTLY FAVORS THE WARMER/DRIER SOLUTION OF
THE ECMWF THAT HAS 850MB TEMPS NEAR +16C AND 1000-500MB THICKNESSES
AROUND 572 DAM AND HIGHS IN THE LOWER 80S. THE GFS IS MUCH LOWER
WITH ITS THICKNESS VALUES AS IT BRINGS A COLD FRONT THROUGH E IOWA/W
ILLINOIS MONDAY NIGHT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1137 PM CDT TUE JUN 2 2015

JUST ROUNDS OF HIGH CLOUDS AND CIRRUS DEBRIS OFF CENTRAL PLAINS
INTO THE MO RVR VALLEY CONVECTION LATE TONIGHT INTO WED MORNING.
LIGHT SOUTH TO SOUTHEAST SFC WINDS OVERNIGHT...WITH THE
POSSIBILITY OF SOME LIGHT 5-6SM VSBY FOG AROUND THE TAF SITES
JUST BEFORE DAWN. SHALLOW INVERSION DEVELOPING OVERNIGHT MAY ALLOW
FOR A LOW STRATOCU DECK TO TRY AND FORM AROUND 1K FT AGL TOWARD
DAWN AS WELL...BUT LESS CONFIDENCE IN THIS PROCESS TO PUT A MVFR
OR EVEN AN IFR DECK IN THE TAFS FOR NOW. STILL FEEL MOST
CONVECTION ACRS CENTRAL IA WILL FALL APART AS IT TRIES TO HEAD
EAST TOWARD THE TAF SITES WED ON INTO WED EVENING. MAY BE JUST VFR
DEBRIS MAKING IT INTO THE VCNTY WITH SOUTH WINDS OF 8-12KTS. THE
CID TAF SITE WILL HAVE THE BEST CHC OF SOME DECAYING PRECIP
NEARING THE SITE FROM THE WEST WED MORNING THEN AGAIN WED
EVENING.

12
&&

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

$$

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


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