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000
FXUS63 KDVN 180818
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
318 AM CDT SAT MAY 18 2013

.SYNOPSIS...
ISSUED AT 245 AM CDT SAT MAY 18 2013

06Z SFC ANALYSIS HAS A MESO WAKE LOW NEAR KPHP WITH A MESO HIGH
NORTH OF KONL. NUMEROUS OUTFLOW BOUNDARIES WERE ACROSS THE DAKOTAS
FROM THE MCS. THE MAIN FRONTAL BOUNDARY RAN FROM CENTRAL OHIO...
ACROSS NORTHERN ILLINOIS...AND THEN INTO SOUTHWEST MINNESOTA. DEW
POINTS SOUTH OF THE FRONTAL BOUNDARY WERE MAINLY IN THE 60S. NORTH
OF THE FRONTAL BOUNDARY DEW POINTS WERE IN THE 40S AND 50S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 245 AM CDT SAT MAY 18 2013

QUIET AND DRY CONDITIONS WILL BE SEEN ACROSS THE AREA TODAY AS THE
UPPER RIDGE MOVES EAST FROM THE PLAINS. CLOUDS FROM THE NORTHERN
PLAINS MCS SHOULD INITIALLY PROVIDE FILTERED SUNSHINE BEFORE
BREAKING UP DURING THE DAY.

TONIGHT...QUIET AND DRY CONDITIONS WILL BE SEEN DURING THE EVENING
AS THE UPPER RIDGE MOVES INTO THE WESTERN GREAT LAKES. AFTER
MIDNIGHT THE MCS AND LIFT TOOLS SUGGEST ELEVATED SHRA WITH POSSIBLY
SOME THUNDER SHOULD BEGIN DEVELOPING ACROSS THE WESTERN CWFA AS THE
LLJ BEGINS TO VEER SLIGHTLY INTO EASTERN IOWA WITH BETTER WAA ALOFT
AND MOISTURE.

08

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 245 AM CDT SAT MAY 18 2013

LOWER END SEVERE WEATHER RISKS LATE SUNDAY AND AGAIN MONDAY THE
MAIN FORECAST ISSUES WITH DECENT RAINS LASTING INTO WEDNESDAY.

OVERVIEW...INITIALIZATION AND VERIFICATION ADEQUATE ON SYNOPTIC
SCALES BUT POOR ON BL MOISTURE AND ESPECIALLY CONVECTIVE EVENTS.
THIS IMPACTS FORECAST WITH CONCEPTUAL FORCING TOOLS WEIGHTED
TOWARD HI-RES ECMWF BEST WITH GFS SERIOUS CONVECTIVE FEEDBACK AND
NAM-WRF NOT MUCH BETTER. D_PROG_DT SUPPORTS USE OF MORE STABLE
HI-RES ECMWF ENTIRE PERIOD WITH INPUTS FROM GEM-RH AND UKMET.

SUNDAY...TRENDS OF JET SUPPORT LOWER END SEVERE RISK MAINLY IN
THE LATE PM INTO EVENING HOURS. JET AXIS AND FORCING ARE DELAYED AND
BETTER FOCUSED WELL SW OF AREA WITH LITTLE SURFACE BASED FORCING
NOTED AT THIS TIME. PROBABLE STORMS AND SHOWERS TO MOVE INTO AREA
LATE PM AND MORE LIKELY IN THE EVENING. SBCAPES AOA 2000+ J/KG
SUGGESTED AND WBZ OF ~11K AGL WITH 35-45KT LOW LEVEL JET OF A
CONVECTIVE SYSTEM OR LINE WITH SOME BOWING SEGMENTS. IF SURFACE
TEMPERATURES/DEWPOINTS ARE AOA 78/65 THEN SOME WINDS OF 60 TO
POSSIBLY NEAR 70 MPH MAY OCCUR. LIMITED SCL SHEAR NOTED TO
PRECLUDE TORNADIC THREAT ATTM. STORMS THAT CAN ENTRAIN MID/UPPER
DRY LEVEL AIR MAY PRODUCE SOME LARGE HAIL UP TO 1.5 INCHES BUT
THIS MAY NOT OCCUR IF MCS IS IN MATURE STAGES AS SUGGESTED. HIGHS
SUNDAY WITH PARTLY SUNNY SKIES 83-88F NW TO SE. SUNDAY NIGHT TO BE
MILD WITH 64-68F READINGS FOR MINS. RAIN AMOUNTS MOST AREAS TO BE
LIGHT TO MODERATE WITH ISOLATED HEAVY AMOUNTS WITH ANY TRAINING OF
STORMS WHICH ARE MARGINAL ATTM WITH FAST FLOW ATTM. `POPS HIGH
CHANCE TO LOWER END LIKELIES AROUND 60 PERCENT.

MONDAY...FRONT NEARBY WITH FAST UPPER FLOW SUPPORTS PM SCATTERED
REDEVELOPMENT WITH POTENTIALLY HIGHER RISK OF SEVERE WEATHER IN PM
HOURS THAN SUNDAY AND ANY FORCING. T/TD PROFILES A FEW DEGREES
LOWER THAN SUNDAY BUT MORE FAVORABLE SHEAR PROFILES FOR SEVERE
WITH STRAIGHT LINE WINDS OF 60-70+ MPH DUE TO GOOD MOMENTUM
TRANSFER AND EVEN ISOLATED TORNADO AS JET AXIS IMPINGES IN WITH
DECENT SCL SHEAR. HAIL OVER 1.75" POSSIBLE IF MID LEVELS ARE AS
DRY AS CURRENTLY SUGGESTED. POPS 40-50 DURING DAY AND LIKELIES
MONDAY NIGHT WITH ANOTHER MCS PROBABLY TO MOVE ACROSS AREA. SEVERE
RISK SHOULD WANE BY MID TO LATE EVENING HOURS. MAX TEMPS 78-83
WITH MINS OF 60-65. RAIN AMOUNTS MOSTLY LIGHT TO MODERATE WITH
ISOLATED HEAVY AMOUNTS AND GREATER RISK OF TRAINING OF STORMS WITH
PARALLEL FLOW.

TUESDAY INTO WEDNESDAY...SHOWERS AND ISOLATED STORMS LIKELY WITH
WAVE TO ROTATE NORTH FROM SOUTHERN PLAINS. THIS SHOULD BE A
WIDESPREAD RAIN EVENT OF MODERATE TO HEAVY TOTALS BASED ON UPPER
FORCING. TOTAL RAIN AMOUNTS OVER THE NEXT 96 HOURS SHOULD BE 1-3
INCHES OVER THE FORECAST AREA. HIGHS IN THE 70S BOTH DAYS WITH
WEDNESDAY A FEW DEGREES COOLER THAN WEDNESDAY AS UPPER LOW MOVES
OVERHEAD. MINS MID 50S TO LOWER 60S.

THURSDAY AND FRIDAY...LARGE CANADIAN HIGH PRESSURE TO BRING COOL
AND DRY AIR INTO REGION WITH HIGHS UPPER 60S TO LOWER 70S AND LOWS
UPPER 40S TO LOWER 50S WITH LOWS FRIDAY AM POSSIBLY STILL AT LEAST
A CATEGORY LOWER SUGGESTED.

NICHOLS


&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 245 AM CDT SAT MAY 18 2013

A FRONTAL BOUNDARY FROM ROUGHLY KGYY TO KCID IS CREATING MVFR VSBYS
AT KCID/KMLI. THESE LOWER VSBYS WILL CONTINUE THROUGH SUNRISE AND
MAY AFFECT KDBQ. CIGS ARE EXPECTED TO REMAIN VFR BUT RECENT
SATELLITE TRENDS SHOW SPOTTY MVFR CIGS DVLPG ACROSS IOWA AND
ILLINOIS. AFT 12Z/18 VFR CONDITIONS ARE EXPECTED THROUGH 06Z/19. AFT
06Z/19 VFR CONDITIONS SHOULD CONTINUE BUT THE THREAT OF NOCTURNAL
SHRA/TSRA WILL BE ON THE INCREASE ACROSS EASTERN IOWA.

08

&&

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

$$

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