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000
FXUS63 KDVN 191759
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1259 PM CDT SUN MAY 19 2013

.UPDATE...
ISSUED AT 1249 PM CDT SUN MAY 19 2013

CLUSTER OF STORMS MOVING THROUGH THE QUAD CITIES APPEARS TO BE
LINKED TO A SHORTWAVE TROUGH LIFTING NORTH ACROSS IA AND NW IL.
OVERALL...MAIN SEVERE WEATHER THREAT APPEARS TO BE TRANSITIONING
TO STRONG WINDS IN THE NEAR TERM AS THIS CONVECTION IS MOVING AWAY
FROM MORE FAVORABLE PARAMETERS UPSTREAM ACROSS S CENTRAL IA INTO
MO.

THIS AREA...SOUTH CENTRAL INTO SE IA AND NE MO WILL BE THE NEXT
FOCUS FOR POSSIBLE SEVERE STORMS FROM MID TO LATE AFTERNOON AS A
PROMINENT UPPER LEVEL DRY SLOT AND MID LEVEL PUNCH OF 50-60 KT MID
LEVEL WINDS OVER EASTERN KS INTO NW MO APPROACHES.

&&

.SYNOPSIS...
ISSUED AT 249 AM CDT SUN MAY 19 2013

06Z SFC ANALYSIS HAS SYNOPTIC LOWS SOUTH OF KABR AND IN SOUTHWEST
KANSAS. NUMEROUS MESO LOWS AND HIGHS WERE ACROSS NEBRASKA/KANSAS
BEHIND THE NOW DECAYING MCS IN WESTERN IOWA AND MISSOURI. THE MAIN
FRONT RAN FROM THE KABR LOW INTO SOUTHWEST WISCONSIN AND THEN INTO
THE OHIO VALLEY. DEW POINTS OVER MOST OF THE MIDWEST AND PLAINS WERE
IN THE 50S AND 60S WITH 40S AND 50S OVER THE GREAT LAKES.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 249 AM CDT SUN MAY 19 2013

NONLINEAR PROCESSES ARE DRIVING THE SENSIBLE WX. THUS ONE MUST LOOK
MORE CAREFULLY AT THE MODELS.

MCS AND LIFT TOOLS INDICATE THE CURRENT MCS OVER THE WESTERN PARTS
OF IA/MO WILL CONTINUE TO SLOWLY DECAY AS IT OUT RUNS THE BETTER
MOISTURE AND RUNS INTO THE UPPER RIDGE. OUTFLOW BOUNDARIES FROM THE
MCS WILL HELP FIRE NEW CONVECTION THROUGH SUNRISE WITH ISOLATED TO
POSSIBLY SCATTERED CONVECTION ENTERING THE WESTERN CWFA. THIS
CONVECTION WILL SLOWLY WEAKEN AFTER SUNRISE AS THE LLJ SHIFTS BACK
INTO THE PLAINS.

ISOLATED TO SCATTERED CONVECTION SHOULD LINGER THROUGH THE MORNING
ACROSS THE CWFA AS MESOSCALE INDUCED SHORTWAVES AND BOUNDARIES MOVE
THROUGH THE AREA.

THE MCS AND LIFT TOOLS INDICATE NEW CONVECTION SHOULD FIRE IN
CENTRAL IOWA AROUND MID DAY AND ENTER THE WESTERN CWFA BY MID
AFTERNOON. MESOSCALE BOUNDARIES WILL PLAY HEAVILY INTO THE OVERALL
EVOLUTION OF THIS CONVECTION BUT IT SHOULD EVOLVE INTO AN MCS BY
LATE AFTERNOON.

GIVEN THE MOISTURE/INSTABILITY SEVERE STORMS ARE A THREAT. THE MORE
SIGNIFICANT SEVERE STORMS SHOULD BE ACROSS EASTERN KS/WESTERN MO BUT
THERE SHOULD BE SOME THREAT OF SEVERE WIND/HAIL DURING THE AFTERNOON
AND EVENING HOURS.

TONIGHT...STRONG TO POSSIBLY SEVERE STORMS SHOULD BE SEEN ACROSS THE
AREA DURING THE EVENING. MCS/LIFT TOOLS SUGGEST AN MCS MOVING
THROUGH DURING THE EVENING. A MORE SUBSTANTIAL MCS SHOULD DEVELOP BY
SUNSET IN THE WESTERN PARTS OF IA/MO AND MOVE THROUGH THE AREA
OVERNIGHT. STRONG TO SEVERE STORMS MAY BE POSSIBLE WITH THIS MCS AS
WELL.

08

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 249 AM CDT SUN MAY 19 2013

SHOWERS AND THUNDERSTORMS INTO WEDNESDAY THEN COOLER AND DRY INTO
NEXT WEEKEND WITH ANOTHER RAIN EVENT BY SUNDAY.

OVERVIEW...ALL SOLUTIONS AGAIN ARE ADEQUATE ON KINEMATIC OR FLOW
FIELDS BUT AS IS NORMAL WITH CONVECTION ARE HAVING DIFFICULTIES.
VERIFICATION AT 06Z SUPPORTS A 70/30 MIX OF HI-RES ECMWF/GFS. THIS
SUGGESTS PERIODS OF SHOWERS AND THUNDERSTORMS WITH POOR CONFIDENCE
ON TIMING EXCEPT FOR LIKELY DECENT ROUNDS LATE PM TODAY AND ONCE
AGAIN LATE MONDAY. RUN TO RUN VARIANCE SUPPORTS BELOW AVERAGE TO POOR
CONFIDENCE OF TIMING AND SHOWERS AND STORMS TUE/WED WITH NEXT 36-48
HOURS KEYS TO HOW LAST UPPER WAVE PASSES. MOST LOCATIONS STILL ON
TRACK TO PICK UP 1 TO 3 INCHES OR RAIN BY TIME EVENT ENDS WEDNESDAY.

MONDAY...CHANCE POPS WITH LINGERING SHOWERS AND STORMS WITH ENOUGH
HEATING AND FORCING FOR THUNDERSTORMS TO FIRE MID TO LATE PM.
CONDITIONS CONTINUE TO SUPPORT GOOD CHANCE OF SEVERE STORMS WITH
SHEAR PROFILES AND MODERATE INSTABILITY. LOCAL TOOLS CONTINUE TO
SUPPORT GOOD UNIDIRECTIONAL SHEAR FOR MIXING DOWN WINDS ALOFT FOR
WINDS OF 60-70 MPH AND ALSO ENOUGH DRY AIR ALOFT WITH WBZ OF 10 TO
11K AGL FOR LARGE HAIL UP TO 1.75 INCHES. AN ISOLATED TORNADO MAY
BE POSSIBLE WITH SOME BACKING OF SURFACE WINDS BUT THIS DOES NOT
SUGGEST ANY STRONGER OR LONGER TRACK EVENTS UNLESS WINDS BACK MORE
ALLOWING FOR MORE SCL DIRECTIONAL SHEAR. TEMPERATURES AND POPS LITTLE
CHANGE WITH HIGHS ROUGHLY 80-85 AND LOWS IN THE MID 60S. CHANCE POPS
IN THE DAY WITH LIKELY AT NIGHT AS STORMS FIRE WELL INTO THE EVENING
HOURS. RAIN AMOUNTS COULD BE LOCALLY HEAVY WITH 1-2 INCH AMOUNTS IN
THE STRONGEST STORMS WITH PW/S OF 1.25 TO 1.5 INCHES AND SOME STORM
TRAINING POTENTIAL.

TUESDAY...MORE ENERGY TO PASS ACROSS AREA WITH LOTS OF CLOUDS AND
SHOWERS AND STORMS. POOR CONFIDENCE ON MAX TEMPS DUE TO CLOUD COVERAGE
AND HOW MUCH PRECIPITATION MOVES INTO AREA OR FIRES DURING THE DAY.
GENERALLY HIGHS OF 75-80 ARE SUGGESTED BASED ON CONVECTIVE TEMPS.
KEPT MOSTLY LIKELY POPS IN THE DAY WITH CHANCE POPS OVERNIGHT BUT
TIMING IS POOR WHEN THIS NEXT ORGANIZED EVENT OCCURS. MINS AT NIGHT
IN THE LOWER 60S. MARGINAL SEVERE POTENTIAL SUGGESTED DUE TO LIMITED
INSTABILITY.

WEDNESDAY...UPPER LOW ROTATES SLOWLY OVER AREA WITH POPCORN SHOWERS
AND ISOLATED TO SCATTERED STORMS WITH MOSTLY CHANCE POPS IN THE
NORTH AND EAST SECTIONS. HIGHS MOSTLY IN THE LOWER 70S WITH MINS
FALLING INTO THE 50S AS WINDS SHIFT TO THE NORTH AS COLD FRONT
PASSES MOST AREAS BY THURSDAY MORNING.

THURSDAY AND FRIDAY...CLEARING SKIES AND SEASONABLY COOL AND
COMFORTABLE WITH HIGHS UPPER 60S TO LOWER 70S AND MINS UPPER 40S
TO LOWER 50S. MINS SATURDAY MORNING WITH SURFACE CANADIAN HIGH
PRESSURE OVERHEAD MAY NEED LOWERING BY 3+ DEGREES WITH ISOLATED
LOWER 40S POSSIBLE IN LOW LYING LOCATIONS.

SATURDAY...WARM AND UPPER DISTURBANCE FROM WEST TO INTERACT WITH
COOL AIRMASS TO BRING CLOUDS AND AREAS OF RAIN AND RAINSHOWERS WITH
STRONG EVAPORATIVE COOLING BY LATE SATURDAY INTO SUNDAY. HAVE CHANCE
POPS THAT SHOULD BR RAISED IN THE NEXT DAY OR SO WHEN TIMING ISSUES
BETTER CLARIFIED. EVENT LOOKS LIKE ANOTHER MODERATE TO LOCALLY HEAVY
RAIN EVENT.

NICHOLS

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1249 PM CDT SUN MAY 19 2013

A WARM...HUMID UNSTABLE AIRMASS AND PERIODIC UPPER LEVEL
DISTURBANCES WILL RESULT IN SEVERAL ROUNDS OF STORMS WITH POSSIBLE
SEVERE WIND GUSTS AND LARGE HAIL TODAY THROUGH MONDAY. OUTSIDE A
CLUSTER OF STORMS MOVING THROUGH MLI AND POSSIBLE DBQ EARLY THIS
AFTERNOON...THE NEXT ROUND OF STORMS WILL LIKELY MOVE IN FROM LATE
AFTERNOON INTO THIS EVENING AND TEMPO GROUPS HAVE BEEN USED TO
COVER THIS POSSIBILITY. OTHERWISE...HAZE AND FOG WILL RESULT IN
MVFR VISIBILITIES. ADDITIONAL ROUNDS OF THUNDERSTORMS WILL BE
POSSIBLE LATE TONIGHT INTO MONDAY...BUT CONFIDENCE IN TIMING IS
TOO LOW TO PINPOINT IN THE TERMINAL FORECASTS AT THIS TIME.

&&

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

$$

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