National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KDVN 141746
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1246 PM CDT FRI JUN 14 2013

.UPDATE...
ISSUED AT 1212 PM CDT FRI JUN 14 2013

APPEARS THE MOIST AIR IS WINNING OUT AS THE SMALL MCS THAT WAS IN
SW IA EARLIER THIS MORNING HAS SHIFTED INTO SE IA AND EXTREME NORTHEAST
MO. HAVE MADE A QUICK UPDATE TO THE GRIDS TO INCREASE POPS TO
LIKELY IN OUR SOUTHWEST CWA INTO THIS AFTERNOON. NONE OF THE
MODELS INCLUDING THE MESO MODELS INDICATED THIS MCS MOVING INTO
THE DVN CWA SO WILL CONTINUE TO NOWCAST AND UPDATE AS NEEDED.

UPDATE ISSUED AT 1033 AM CDT FRI JUN 14 2013

THUNDERSTORMS WERE OCCURRING IN SW IA AND NW MO ON THE NOSE OF A
LOW LEVEL JET AND STRONG MOISTURE GRADIENT...AND ON THE EDGE OF A
STRONG CAP. 850 MB DEWPOINT AT KTOP WAS +18C BUT DRIER AIR WAS NOTED
FARTHER TO THE NORTHEAST WITH KMPX -4C AND KDVN +7. THE BETTER
FORCING WILL REMAIN WEST AND SOUTHWEST OF THE DVN CWA BUT ISOLATED
TO SCATTERED SHOWERS AND THUNDERSTORMS WILL OCCUR IN OUR WESTERN
CWA LATE THIS MORNING INTO THE AFTERNOON HOURS.

UPDATE ISSUED AT 642 AM CDT FRI JUN 14 2013

RADAR SHOWS THE CONVECTION IN CENTRAL IOWA CONTINUES BUT IS
RAPIDLY WEAKENING AS IT MOVES INTO DRIER AIR AND AWAY FROM THE
BETTER SUPPORT. RAP TRENDS CONTINUE TO SHOW A WEAK BUT RESPECTABLE
THETA E GRADIENT WHICH IS HELPING TO MAINTAIN THE CONVECTION.
BASED ON RADAR AND RAP TRENDS SOME OF THIS CONVECTION WILL GET
INTO THE WESTERN CWFA THIS MORNING AS LIGHT SHOWERS OR SPRINKLES
BEFORE DISSIPATING.

WATER VAPOR AND THE RAP SHOW TWO VORT MAXES CURRENTLY MOVING
ACROSS NEBRASKA. THESE FEATURES WILL DRIVE THE DIURNAL CONVECTION
THIS AFTERNOON THAT WILL EVENTUALLY EVOLVE INTO ANOTHER NOCTURNAL
MCS LATE TONIGHT.                   ..08..

&&

.SYNOPSIS...
ISSUED AT 308 AM CDT FRI JUN 14 2013

06Z SFC ANALYSIS HAS A HIGH RUNNING FROM LAKE SUPERIOR INTO THE
LOWER MISSISSIPPI VALLEY. LOWS WERE IN SOUTHEAST MONTANA AND
SOUTHEAST COLORADO. THE MAIN SYNOPTIC FRONT RAN FROM SOUTHWEST
KANSAS INTO THE DEEP SOUTH. DEW POINTS WERE IN THE 60S AND 70S FROM
THE CENTRAL PLAINS INTO THE DEEP SOUTH WITH 40S AND 50S ACROSS THE
GREAT LAKES AND UPPER MISSISSIPPI VALLEY.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 308 AM CDT FRI JUN 14 2013

THE MCS AND LIFT TOOLS INDICATE THE CURRENT CONVECTION FROM
SOUTHWEST MN INTO NORTHERN IOWA IS ASSOCIATED WITH A THETA E
GRADIENT AND VORT MAX. THIS CONVECTION WILL SLOWLY DISSIPATE AS IT
MOVES AWAY FROM THE BETTER MOISTURE AND INTO THE RIDGE. THUS THE
MORNING HOURS WILL BE DRY WITH AN INCREASE IN CLOUD COVER.
HOWEVER...THE CLOUD COVER WILL SLOWLY THIN AS IT HITS THE RIDGE SO
THERE SHOULD BE A RESPECTABLE AMOUNT OF SUNSHINE TO HELP WARM UP.

RAP TRENDS ALONG WITH THE MCS AND LIFT TOOLS INDICATE THE VORT MAX
MOVING THROUGH SOUTHERN NEBRASKA WILL PROBABLY BE THE MECHANISM TO
GENERATE DIURNAL CONVECTION THIS AFTERNOON. THIS CONVECTION SHOULD
DEVELOP OR MOVE INTO THE WESTERN CWFA AROUND MID AFTERNOON AND
SLOWLY OVERSPREAD THE WESTERN HALF OF THE CWFA THROUGH LATE
AFTERNOON.

TONIGHT...THE MCS AND LIFT TOOLS INDICATE THE DIURNAL CONVECTION IS
EXPECTED TO EVOLVE INTO ANOTHER NOCTURNAL MCS ACROSS THE AREA.
CONVECTION SHOULD REMAIN ISOLATED TO SCATTERED UNTIL CLOSER TO
MIDNIGHT WHEN THE LLJ VEERS INTO THE CWFA. AT THIS TIME UPSCALE
GROWTH AND AN INCREASE IN AREAL COVERAGE ACROSS THE CWFA WILL BE
SEEN. PWATS ARE EXPECTED TO BE OVER 1.5 INCHES SO THERE WOULD BE A
THREAT OF HEAVY RAIN IF STORMS MOVE OVER THE SAME AREA. THE GROUND
IS REASONABLY DRY SO THIS INITIAL ROUND OF RAIN SHOULD NOT CAUSE
MUCH IN THE WAY OF PROBLEMS.                      ..08..

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 308 AM CDT FRI JUN 14 2013

INITIAL FOCUS IS ON THUNDERSTORM POTENTIAL FOR SATURDAY THAT WILL
HAVE A RISK FOR BOTH SEVERE STORMS AND HEAVY RAINFALL. TRANSITION TO
NW FLOW TO THEN BRING COOLER AND DRIER WEATHER FOR AT LEAST THE
FIRST HALF OF NEXT WEEK.

NOCTURNAL MCS WILL LIKELY BE ON-GOING SATURDAY MORNING...WHERE
MODELS ARE IN GENERAL AGREEMENT DEPICTING LOW PRESSURE NEAR OMAHA
WITH A WARM...OR INITIALLY STATIONARY FRONT REACHING EAST ALONG THE
IA/MO BORDER. ALL ARE SUGGESTING A RIDGE TOPPING SHORTWAVE THAT WILL
PUSH THROUGH DURING THE DAY...WHICH SENDS THE SURFACE LOW
EAST-NORTHEAST ACROSS THE FORECAST AREA AND NUDGES THE SURFACE
BOUNDARY NORTHWARD. ON THE WARM SIDE OF THIS BOUNDARY...MODEL CAPES
ARE ROUGHLY IN THE RANGE OF 3500 TO OVER 4000 J/KG WITH BULK SHEAR
VALUES AROUND 40 TO 45 KTS...SUFFICIENT FOR SEVERE STORMS AND
SUPERCELLS ESPECIALLY ALONG THE BOUNDARY IN THE AFTERNOON INTO
EVENING. SPC HAS THE ENTIRE FORECAST AREA IN A SLIGHT RISK FOR DAY
2. MUCH WILL DEPEND ON THE TIMING OF THE EXITING OR DISSIPATING
OVERNIGHT MCS AND RELATED BOUNDARIES AND CLOUD COVER. FOR NOW...WILL
CONTINUE A BROAD-BRUSH APPROACH WITH LIKELY POPS FOR THUNDERSTORMS
OVER THE ENTIRE AREA. HIGHS WILL LIKELY BE LIMITED TO THE UPPER 70S
ACROSS THE NORTH...WHILE THE SOUTH SHOULD AT LEAST PUSH INTO THE 80S
WITH DEWPOINTS INTO THE 70S...DEPENDING ON TRENDS WITH CLOUD COVER AND
FRONTAL TIMING. ELEVATED SW FLOW OF 15 TO 30 KTS WILL ADVECT A HIGH
PW AIRMASS...AROUND 1.5 TO 1.8 OR 150 PERCENT OF NORMAL OVER THE
ENTIRE AREA...THAT WILL SUPPORT HEAVY RAINFALL IN HP TYPE SUPERCELLS OR
WHERE STORMS TRAIN ALONG BOUNDARIES. THE RESULTING FLASH FLOODING
THREAT WILL BE HIGHLY DEPENDENT ON RAINFALL COVERAGE AND AMOUNTS
FROM THE PREVIOUS EVENT. FOR NOW...HAVE WIDESPREAD QPF AMOUNTS OF A
QUARTER TO HALF INCH...BUT FULLY EXPECT STORM SCALE TOTALS OF 1 TO 2
INCHES.

SATURDAY NIGHT...A STRONGER SHORTWAVE...INITIALLY OVER THE TX BEND
REGION AT 00Z...IS SHOWN RIDING NORTH AND THEN SWEEPING EAST ACROSS
THE FORECAST AREA IN THE FIRST HALF OF THE NIGHT...PROVIDING RENEWED
FOCUS FOR LIKELY ANOTHER MCS AND POSSIBLE HEAVY RAINFALL AND LIKELY
POPS ARE MAINTAINED. THIS SYSTEM IS EXPECTED TO SUPPRESS THE FRONTAL
BOUNDARY BACK TO JUST SOUTH OF THE FORECAST AREA SUNDAY. THE CLOSE
PROXIMITY OF THIS BOUNDARY...AND A STRONG UPPER SHORTWAVE THEN
ADVANCING FROM THE NW WILL KEEP SHOWERS AND THUNDERSTORMS IN THE
FORECAST THROUGH MONDAY...BUT THE HEAVY RAINFALL THREAT WILL BE
DIMINISHED. A NW FLOW AND HIGH PRESSURE THEN SUGGESTS DRY CONDITIONS
THROUGH AT LEAST WED WITH NEAR TO SLIGHTLY BELOW NORMAL
TEMPERATURES. MODEL CONSENSUS HAS CHANCES FOR SHOWERS AND
THUNDERSTORMS RETURNING TO THE FORECAST THURSDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1242 PM CDT FRI JUN 14 2013

VFR CONDS THIS AFTERNOON WITH THUNDERSTORMS IN SOUTHEAST IA MOVING
TO THE SOUTHEAST. KBRL IS ON THE EDGE OF THE CLUSTER OF STORMS.
OTHERWISE...AT ALL TAF SITES SHOWERS AND THUNDERSTORMS WILL
ARRIVE THIS EVENING AND OVERNIGHT...THEN DIMINISH A BIT SATURDAY
MORNING. MVFR/BRIEF IFR CONDS CAN BE EXPECTED IN THE STRONGER
STORMS. SOUTHEAST WINDS AROUND 10 KNOTS OR LESS THIS AFTERNOON AND
TONIGHT THEN BECOMING SOUTH 10 TO 15 KNOTS ON SATURDAY.

&&

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

$$

UPDATE...HAASE
SYNOPSIS...08
SHORT TERM...08
LONG TERM...SHEETS
AVIATION...HAASE