Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KDVN 270510
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1210 AM CDT SAT JUN 27 2015

.SYNOPSIS...
ISSUED AT 330 PM CDT FRI JUN 26 2015

MOISTURE CONVERGENCE ALONG THE NORTHERN EDGE OF A DEVELOPING 850 MB
LOW OVER NORTH CENTRAL ILLINOIS...UPPER LEVEL VORT MAXIMA EMBEDDED
IN A CYCLONIC FLOW ALOFT...AND ENHANCED LOW LEVEL CONVERGENCE ALONG
LAKE ENHANCED LOW LEVEL BOUNDARIES WERE COMBINING TO PRODUCE BANDS
OF HEAVY RAINFALL OVER THE AREA TODAY. THIS MORNING...THESE WERE
PRIMARILY ACROSS FAR NORTHEAST MO...EXTREME SE IA INTO W CENTRAL
IL...WHICH RESULTED IN HEAVY RAINFALL AMOUNTS AND FLASH FLOODING.
MORE RECENT RADAR IMAGES INDICATED A NEW AXIS SETTING UP FROM THE
SOUTHERN SUBURBS OF CHICAGO SW ACROSS PUTNAM COUNTY TO NEAR
MACOMB...LIKELY AS A RESULT OF AN EASTWARD SHIFT OF THE AFOREMENTIONED
UPPER LEVEL FEATURES. ADDITIONAL LIGHTER RAIN SHOWERS HAVE BEEN
WIDESPREAD OVER THE FORECAST AREA IN A BROAD AREA OF LOW LEVEL
CYCLONIC FLOW AROUND A SURFACE LOW OVER FAR SOUTHERN IL...WHICH
WAS BEING ENHANCED BY LIFT AHEAD OF THE MAIN UPPER LEVEL VORT MAX
DROPPING SOUTH ACROSS MN AND WI IN THE NW FLOW ALOFT. THIS FEATURE
WAS PRODUCING WIDESPREAD THUNDERSTORMS IN CENTRAL MN...WITH AREA
RADARS AND LIGHTNING DATA INDICATING WIDELY SCATTERED THUNDERSTORMS
WELL OUT AHEAD OVER SOUTHERN MN INTO FAR NORTHERN AND WESTERN IA.
THE WIDESPREAD RAIN...CLOUDS AND NE SURFACE WINDS HAS KEPT
TEMPERATURES CONFINED TO THE UPPER 60S TO LOWER 70S.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 330 PM CDT FRI JUN 26 2015

SHOWERS WILL GRADUALLY WEAKEN AND END OVER THE AREA LATE THIS
AFTERNOON AND EARLY EVENING AS THE SURFACE AND 850 MB LOWS OVER IL
CONTINUE EASTWARD. RESULTING LOW LEVEL FLOW BACKING NORTHEAST TO A
TRAJECTORY OUT OF THE GREAT LAKES WILL CONTINUE TO ADVECT DRIER AIR
INTO ESPECIALLY THE EASTERN HALF OF THE FORECAST AREA. HOWEVER...AT
THE SAME TIME...UPPER LEVEL FORCING AHEAD OF THE UPPER LEVEL IMPULSE
ROTATING S-SE OUT OF MN WILL SPREAD INTO THE AREA FROM THE NORTH.
SCATTERED THUNDERSTORMS WITH THIS FEATURE MAY TRY TO PUSH INTO THE
FAR NORTH AND NW THIS EVENING...BUT THEY ARE NOT LIKELY TO HOLD
TOGETHER AS THEY MOVE INTO THE COOLER...MORE STABLE AIRMASS OVER THE
FORECAST AREA. WILL THUS HAVE ISOLATED THUNDERSTORMS IN THE NW
EARLY...WHILE CHANCE POPS FOR SHOWERS AND ISOLATED THUNDERSTORMS ARE
KEPT ACROSS THE SE UNTIL MIDNIGHT. THE WANING MOISTURE LEVELS SHOULD
PRECLUDE ANY ADDITIONAL HEAVY RAINFALL OR FLASH FLOOD THREAT. THE
INFLUX OF DRIER AIR SHOULD WILL LEAD TO A COOLER NIGHT WITH LOWS
FROM THE MID AND UPPER 50S NORTH TO LOWER 60S SOUTH.

SATURDAY STILL LOOKS LIKE A DRY BREAK FROM THE RECENT STRETCH OF WET
WEATHER. A PASSING SURFACE RIDGE AND MID LEVEL SHORTWAVE RIDGING
SHOULD RESULT IN MOSTLY SUNNY SKIES...WHILE LIGHT NORTH WINDS KEEP
HUMIDITY LEVELS RELATIVELY LOW FOR JUNE...WITH DEWPOINTS ONLY IN THE
50S BY AFTERNOON. HIGHS SHOULD TOP OUT IN THE MID TO UPPER 70S.

.LONG TERM...(SATURDAY NIGHT THROUGH NEXT FRIDAY)
ISSUED AT 330 PM CDT FRI JUN 26 2015

SATURDAY NIGHT AND SUNDAY...UNSEASONABLY AMPLIFIED NORTHWEST FLOW TO
CONTINUE THE FIRST HALF OF THE LONG RANGE PERIOD. VIGOROUS CLIPPER-
LIKE WAVE SEEN ON WATER VAPOR LOOP ACRS NORTHEASTERN B.C./ NORTHERN
ALBERTA...STILL ON TRACK TO DUMP DOWN INTO LARGE L/W TROF BASE
DIGGING ACRS THE EAST HALF OF THE CONUS AT THE TIME. LEAD ELEVATED
WAA WING OR WINGS OF SHOWERS AND SOME STORMS WILL LOOK TO SCOOT IN
ACRS THE NORTHWESTERN THIRD TO NORTHERN CWA BY SUNDAY MORNING. BUT
EXPECT COVERAGE AND INTENSITY TO BLOSSOM AS THE DAY PROGRESSES AND
ESPECIALLY THE AFTERNOON ACRS MUCH OF THE AREA WITH A COMBINATION OF
INCREASING DEEP LAYER SHEAR AND INSTABILITY UNDER STEEPENING LOW TO
MID LEVEL LAPSE RATE PLUME. WITH ADEQUATE HEATING AND IF LLVL
MOISTURE CAN IMPROVE ENOUGH TO PRODUCE 1000-2000+ J/KG MUCAPES ACRS
THE AREA...THE PROGGED 0-6KM BULK SHEAR PROFILES OF 30-50KTS WOULD
HAVE A GOOD CHANCE OF PRODUCING A NORTHWEST FLOW SEVERE WX EVENT.

THERMODYNAMIC PROFILES ARE FAVORABLE FOR LARGE HAIL IF THE FCST DEEP
LAYER SHEAR IS IN LINE...AS WELL AS DOWN BURSTS WIND POTENTIAL. WILL
HAVE TO ANALYZE ADDITIONAL FCST LCL HEIGHTS OVER THE NEXT FEW RUNS
FOR SUNDAY AFTERNOON...BUT COULD EVEN SEE AN ISOLATED TORNADO THREAT
DURING PRIME AFTERNOON AND EARLY EVENING HEATING. MUCH WILL DEPEND
ON SOME DECREASE IN MORNING ACTIVITY TO ALLOW FOR HEATING AND AIR
MASS DESTABILIZATION...ALSO TO GET THE PROJECTED HIGH TEMPS IN THE
UPPER 70S TO AROUND 80. LOCALIZED RAINFALL AMOUNTS OF GENERALLY UP
TO A HALF INCH IN MORE IN A SCTRD STORM MODE COVERAGE...BUT AREAS
THAT GET HIT REPEATEDLY MAY GET UP TOWARD AN INCH BY SUNDAY EVENING.
WILL WALK OUT ANY LINGERING CONVECTION TO THE EAST AND SOUTHEAST AS
SUNDAY EVENING PROGRESSES.

MONDAY THROUGH NEXT FRIDAY...LATEST SUITE OF 12Z RUN MEDIUM RANGE
MODELS AND MREF SOLUTIONS STILL PAINT A PICTURE DISCUSSED BY THE
PRIOR FCST SHIFT. GENERALLY WARM DOME RIDGE SETTING UP SHOP AND
CAMPING OUT ACRS THE WESTERN THIRD OF THE CONUS...EFFECTIVELY
TRAPPING NORTHWEST FLOW ACRS THE CENTRAL CONUS INTO PERSISTENT L/W
TROFFINESS ACRS THE GRT LKS AND APPALACHIA. THUS GENERAL CONTINUED
ACTIVE PATTERN WITH RIDGE-RIDING CLIPPER LIKE WAVES RIPPLING DOWN
ACRS OR NEAR THE FCST AREA ALMOST EVERY DAY. EVEN SUBTLE WAVES
COULD INDUCE ISOLATED TO WIDELY SCTRD AFTERNOON POP UP STORMS IN
DIURNAL DRIVEN INSTABILITY PLUMES NOT INDICATED BY THE MODELS EVEN
IN A NEAR TERM RUN. BUT ALSO LIKE THE PREVIOUS SHIFT MENTIONED...
PLENTY OF DRY HOURS MIXED IN WITH THOSE DAYS AS WELL...AND LACK OF
DEEP MOISTURE PROFILES TO PRECLUDE MUCH OF ANY THREAT FOR WIDESPREAD
FLOODING RAINS THROUGH THE PERIOD. ALMOST A DAILY CHC OF SHOWERS AND
SOME STORMS WILL HAVE TO RIDE FOR NOW. A MORE SUBSTANTIAL WAVE AND
SOMEWHAT DAMPENING PATTERN FLOW LATE IN THE WEEK OR NEXT WEEKEND MAY
BRING THE NEXT WIDESPREAD THREAT OF MORE SUBSTANTIAL SHOWER/STORMS
COVERAGE AND QPF POTENTIAL. BUT TIMING THAT FEATURE AT THIS POINT
WITH RECENT MODEL PERFORMANCE VERY PROBLEMATIC AND LACKING FOR
CONFIDENCE. IN GENERAL A BELOW NORMAL TEMP REGIME FOR MUCH OF THE
UPCOMING WEEK UNTIL PATTERN DE-AMPLIFICATION OCCURS LATE NEXT WEEK OR
TOWARD THE HOLIDAY.     ..12..

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1202 AM CDT SAT JUN 27 2015

RECENT TRENDS AND MODEL GUIDANCE SUPPORT SOME MVFR...AND POSSIBLY
IFR FOG DEVELOPING OVERNIGHT. KCID HAS ALREADY CLEARED OUT...AND
KBRL HAD SOME RECENT RAINFALL...SO I HAVE INCLUDED A TEMPO FOR 2SM
BR. KEPT VSBYS AT MVFR FOR KDBQ/KMLI. THERE IS A LOW PROBABILITY
OF ISOLATED STORMS DEVELOPING SATURDAY AFTERNOON AND EVENING IN
EASTERN IOWA...BUT WITH LOW CONFIDENCE...HAVE OPTED TO LEAVE OUT
OF TAF FOR NOW AND PASS ALONG FOR LATER SHIFTS TO MONITOR.

&&

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

$$

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.