Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 050833
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
333 AM CDT SUN JUL 5 2015

.SYNOPSIS...
ISSUED AT 330 AM CDT SUN JUL 5 2015

THE LATEST SFC ANALYSIS WAS INDICATING BROAD RIDGE AXIS ACRS THE
WESTERN GRT LKS...WHILE SOUTHERLY RETURN FLOW GRADIENT WAS
ORGANIZING UP THE PLAINS AND MO RVR VALLEY. ALOFT...THE CURRENT
WATER VAPOR LOOP AS WELL AS 00Z UPPER AIR ANALYSIS WAS INDICATING
ELONGATED VORT COMPLEX OVER MN INTO WESTERN IA AND EASTERN KS...
WITH TN VALLEY UPPER LOW LOOKING TO WRAP UP AND EVENTUALLY CUT-OFF
TODAY.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT SUN JUL 5 2015

TODAY...WHILE UPPER LEVEL JET ENERGY CONTINUES TO DIG BROAD
TROFFINESS ACRS SOUTH CENTRAL CANADA INTO THE NORTHERN ROCKIES/
PLAINS TODAY...THE GRT LKS LLVL RIDGE WILL NUDGE EASTWARD ALLOWING
INCREASING SOUTHERLY RETURN FLOW TO SPILL ACRS THE REGION FROM THE
WEST. BESIDES GENERAL WARM AIR ADVECTION THRU THE COLUMN AND WARMING
VERTICAL PROFILES...LLVL MOISTURE WILL BE ON THE INCREASE AS WELL AS
SFC DPTS CLIMB AT LEAST INTO THE MID 60S...WITH SOME UPPER 60S IN
PORTIONS OF THE AREA. MIXING UP INTO THE BASE OF BUILDING H85-H7 MB
INVERSION ALOFT SHOULD TRANSLATE INTO WIDESPREAD LOW TO MID 80S ACRS
THE CWA TODAY FOR HIGHS...WITH A FEW SITES PUSHING THE UPPER 80S.
DON/T WANT TO GO TOO WARM WITH THE POTENTIAL OF THERMALLY ROBBING
CIRRUS STREAMING DOWN OFF NORTHERN PLAINS CONVECTION...AS WELL AS
ONGOING HIGH LEVEL HAZE/SMOKE.

TONIGHT...BULK OF THE 00Z RUN MODEL SOLUTIONS ADVERTISE DIGGING
UPPER TROF ACRS THE NORTHERN PLAINS...WITH ASSOCIATED SFC FRONT
PLOWING IT/S WAY EASTWARD ACRS THE NORTHERN PLAINS...NORTHERN MN
INTO THE WEST CENTRAL PLAINS BY MON MORNING. ONGOING WARM SECTOR
AHEAD OF THIS FEATURE TO ENGULF THE CWA AND MAKE FOR CONTINUED
SOUTHERLY SFC WINDS OVERNIGHT...AND HIGHER SFC DPT DRAW MAKING FOR
THE MILDEST NIGHT IN A WHILE WITH LOWS HELD UP IN THE MID 60S IN THE
EAST...TO NEAR 70 IN THE FAR WESTERN CWA. H85 MB TEMPS MAY WARM INTO
THE UPPER TEENS TO NEAR 20C BY 12Z MON. WILL KEEP THE LOCAL FCST
AREA DRY FRO NOW...BUT SOME SIGNS OF A POTENTIAL LEAD PRE-FRONTAL
WARM AIR ADVECTION WING AND MID LAYER HIGHER MUCAPE PLUME SKIRTING
NORTH ACRS THE CWA LATE THAT MAY TRY AND FUEL AN ELEVATED PRECIP
BAND IN PORTIONS OF THE CWA AFTER 08Z OR 09Z MONDAY MORNING.  ..12..


.LONG TERM...(MONDAY THROUGH NEXT SATURDAY)
ISSUED AT 330 AM CDT SUN JUL 5 2015

MAIN CHALLENGES ARE CENTERED ON THE MONDAY COLD FRONTAL PASSAGE THAT
SHOULD BRING WIDESPREAD THUNDERSTORMS TO THE AREA...THEN THE
UNCERTAIN MID TO LATE WEEK PERIOD WHERE MODELS ARE IN POOR AGREEMENT
WITH THE RETURNING WARM FRONT AND ASSOCIATED RETURN OF PRECIPITATION
CHANCES.

MCS FORECAST PARAMETERS ALL SUGGEST A LARGE MCS WILL LIKELY BE
ONGOING EARLY MONDAY MORNING OVER SOUTHERN MN. THIS IS EXPECTED TO
PROPAGATE NORTHEAST DURING THE DAY WITH WARMING ALOFT STABILIZING
MID LEVEL LAPSE RATES FURTHER SOUTH OVER THE FORECAST AREA...WHICH
ALONG WITH A DEVELOPING STRONG LOW LEVEL SOUTHERLY FLOW...SHOULD
NEARLY ELIMINATE THE POTENTIAL FOR OUTFLOW RELATED CONVECTION
SPILLING INTO THE LOCAL AREA. AS FAR AS THE COLD FRONT...FORECAST
MODELS ARE IN GOOD AGREEMENT WITH THE BOUNDARY NOT REACHING THE MS
RIVER UNTIL AROUND 00Z. WHERE THEY DO DIFFER IS IN LOW LEVEL
MOISTURE FIELDS AND RELATED LOW LEVEL INSTABILITY AND QPF AMOUNTS.
THE WRF/NAM STANDS OUT THE MOST AS IT DEPICTS WIDESPREAD SURFACE
DEWPOINTS SOARING INTO THE UPPER 70S AHEAD OF THE FRONT IN THE
AFTERNOON...WHICH LEADS TO BL CAPES PUSHING 4000 J/KG AND STREAKS OF
QPF IN THE 1.5 TO NEARLY 2.5 INCH RANGE OVER EASTERN IA INTO NW IL.
THE GFS AND ESPECIALLY ECMWF LOOK MORE REASONABLE SHOWING DEWPOINTS
RISING INTO THE LOWER 70S IN THE DEEP WARM...MOIST ADVECTION...WHICH
RESULTS IN CAPE VALUES MORE IN A 1500 TO 2000 J/KG RANGE AND 6 HOUR
QPF IN A HALF TO JUST OVER 1 INCH RANGE.

BASED ON A NON-WRF BLEND...MONDAY SHOULD BE BREEZY AND HUMID WITH
TEMPERATURES REACHING THE LOWER TO MID 80S AHEAD OF DEVELOPING
THUNDERSTORMS IN THE AFTERNOON. WITH THE ELEVATED CAPPING WARM
LAYER...HAVE FURTHER BACKED OFF ON MORNING POPS CONFINED TO THE FAR
NW...WITH MORE WIDESPREAD COVERAGE FROM MID TO LATE AFTERNOON AS
STORMS DEVELOP AHEAD OF THE APPROACHING COLD FRONT. ANTICIPATED
MUCAPE VALUES MAY BE ENOUGH FOR A FEW STRONG TO POSSIBLY SEVERE
STORMS...BUT EXPECTED BULK SHEAR VALUES BELOW 30 KTS WILL BE A
NEGATING FACTOR. SPC/S MARGINAL RISK FOR THE AREA IS PRIMARILY FOR
THE POTENTIAL FOR DAMAGING WIND AS HIGH FREEZING LEVEL WILL BE LESS
SUPPORTIVE OF LARGE HAIL. THE GREATEST THREAT WILL BE HEAVY
DOWNPOURS DUE TO THE HIGH MOISTURE LEVELS AS MODELS STILL SHOW PW
VALUES EXCEEDING 2 INCHES. WIDESPREAD QUARTER TO HALF INCH QPF
SHOULD BE REALIZED WITH AREAS OF 1 TO 1.5 INCHES OF RAIN POSSIBLE IN
THE STRONGER THUNDERSTORMS. AFTER SEVERAL DRY DAYS AND RIVERS WELL
INSIDE THEIR BANKS...FLOODING SHOULD NOT BE AN ISSUE.

BASED ON THE LATEST TIMING...CATEGORICAL POPS FOR THUNDERSTORMS ARE
CONTINUED INTO THE EVENING. MAINLY TO ACCOUNT FOR POSSIBLE FURTHER
SLOWING OF THE FRONT AND THE SLOWER ECMWF TIMING...WILL HAVE HIGHER
POPS HANGING ON IN THE EAST THROUGH THE NIGHT WHILE THE WEST SHOULD
SEE RAIN ENDING AFTER MIDNIGHT.

TUESDAY AND WEDNESDAY...THE FRONT SETTLES WELL TO THE SOUTH WITH
HIGH PRESSURE ROLLING ACROSS MN INTO THE GREAT LAKES PROVIDING
COOLER...DRIER WEATHER FOR MOST OF THIS PERIOD. RAIN AND
THUNDERSTORM CHANCES INCREASE OVER THE SOUTH ON WEDNESDAY BASED ON
THE CONTRIBUTION OF THE ECMWF SOLUTION WITH ITS DEPICTION OF A WAVE
OF LOW PRESSURE ADVANCING INTO NORTHERN MO BY AFTERNOON. THE GFS HAS
A SIMILAR WAVE FOLLOWING A MUCH MORE NORTHERLY TRACK ACROSS IA...BUT
NOT UNTIL THU NIGHT INTO FRIDAY.

FOR NOW...THE CONFIDENCE REMAINS LOW IN THE WED NIGHT THROUGH
SATURDAY FORECAST PERIODS WITH WHAT LOOKS TO BE OVERLY PESSIMISTIC
CHANCES FOR SHOWERS AND THUNDERSTORMS INCLUDED NEARLY EVERY PERIOD.
THESE WILL LIKELY BE NARROWED DOWN CONSIDERABLY IN LATER FORECASTS.
AFTER ONLY REACHING THE 70S TUE AND WED...THE NORTHWARD RETURNING
FRONT SHOULD RETURN HIGHS BACK TO THE LOWER AND POSSIBLY MID 80S BY
FRI AND SAT WHILE LOWS RECOVER FROM THE MID 50S TUE AND WED...CLOSER
TO NORMAL VALUES IN THE 60S TO NEAR 70 BY NEXT WEEKEND.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1122 PM CDT SAT JUL 4 2015

HIGH PRESSURE WILL STAY CENTERED OVER THE REGION TONIGHT AND WILL
MOVE EAST SUNDAY. THE WEATHER WILL BE MAINLY CLEAR THROUGH THIS
PERIOD...WITH A POSSIBLE MVFR LIGHT FOG EVENT IN THE PREDAWN HOURS
SUNDAY. IF THIS OCCURS...IT WILL BE SHORT LIVED. WINDS SUNDAY WILL
BECOME STRONGER FROM THE SOUTH...AROUND 10 KTS BY MID MORNING.
OTHERWISE...THE CLEAR/VFR WEATHER WILL CONTINUE.    ERVIN

&&

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

$$

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



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