000
FXUS63 KDVN 242014
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
314 PM CDT FRI MAY 24 2013

.SYNOPSIS...
ISSUED AT 242 PM CDT FRI MAY 24 2013

LATEST SFC ANALYSIS WAS INDICATING LARGE COOL CORE RIDGE STARTING
TO PUSH EASTWARD ACRS THE WESTERN GRT LKS......WHILE RETURN FLOW
AND PRESSURE FALLS INCREASE ACRS THE PLAINS INTO WESTERN IA. 12Z
UPPER AIR ANALYSIS ALSO INDICATING ELEVATED MOISTURE FEED AT H85
MB AND WARM MOIST CONVEYOR ALSO BECOMING MORE PRONOUNCED UP THE
WESTERN PLAINS. DIFFLUENT SOUTHWESTERLIES WITH AN EMBEDDED VORT
ACRS THE NORTHWESTERN HIGH PLAINS PUSHING INTO WEAKENING OMEGA
RIDGE AND INDUCING AND INCREASING ELEVATED CONVECTIVE REGION ACRS
THE EASTERN DAKOTAS.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 242 PM CDT FRI MAY 24 2013

TONIGHT AND SATURDAY...VARIOUS SHORT RANGE HI-RES MODELS CONTINUE TO PICK
UP ON THE EASTERN DAKOTAS ACTIVITY...BUT STILL MOST ARE
LAGGING/TRYING TO CATCH UP IN SPEED...TIMING AND AREAL COVERAGE OF
WHAT IS OCCURRING. FEEL THE LEAD WAA WING OFF THIS ONGOING PROCESS
WILL INDUCE HIGH BASED SHOWERS AND POSSIBLY A FEW THUNDERSTORMS
INTO THE WESTERN CWA AFTER 02Z THIS EVENING...BETTER CHANCE OF
EVEN SPREAD EASTWARD TO THE MS RVR THROUGH 05Z-06Z IF EVEN IN A
WEAKENING MODE. BUT LLVL JET WITH THTA-E FEED FROM CENTRAL PLAINS
SOURCE REGION WILL BE INCREASING...NOTHING VERY STRONG BUT STILL
ENOUGH TO CONVERGE ON SLOWER FLOW AT THE SAME LEVEL AND ENHANCE OF
PROBABLY MCS DEVELOPMENT GENERALLY FROM NORTHWESTERN IA
SOUTHEASTWARD INTO THE WEST CENTRAL TO SOUTHWESTERN DVN CWA AFTER
MIDNIGHT AND INTO SAT MORNING. THE 12Z RUN UKMET AND NAM80 MCS
FORCING TOOLS BOTH SUPPORT THIS TRAIN OF THOUGHT AND AFTER THE
INTIAL WING OF ELEVATED SHOWERS/STORMS...WILL BLOSSOM POPS FROM
WEST TO EAST AFTER MIDNIGHT AND THROUGH AT LEAST 15Z SAT MORNING.
PW FEED OF 1-1.3 INCHES AND CONVERGENCE SUGGEST A FEW LOCATIONS
THAT GET HIT BY THE MAIN COMPLEX COULD GET AT LEAST AN INCH OF
RAIN BY MID SAT MORNING. BEFORE SOUTHEASTERLY FLOW INCREASES
OVERNIGHT...TEMPS TO DROP TO LOW VALUES OF LOWER 40S IN THE FAR
EAST...TO THE UPPER 40S OR NEAR 50 IN THE WEST CLOSER TO FASTER INCREASE
IN SFC/RETURN FLOW. AFTER MORNING MCS DECREASES...MCS SPAWNING
PARAMETERS START TO REFOCUS BACK ON NORTHWESTERN IA SAT
AFTERNOON...THUS HOPEFULLY SOME LULL IN THE ACTIVITY FOR MIDDAY
AND INTO THE AFTERNOON ESPECIALLY NORTH OF I80. BUT WILL KEEP CHC
POPS FOR ANY RENEWED CONVECTION ALONG OUT FLOW BOUNDARIES OR WARM
FRONT TRYING TO RETREAT OUT OF MO INTO THE SOUTHERN CWA. WILL PLAY
HIGHS ON THE COOL SIDE...BUT IF SUN BREAKS OUT AND MORE DRY
PERIODS OCCUR SAT AFTERNOON THAN CURRENTLY EXPECTED...ADVERTISED
TEMPS WILL BE TOO COLD IN MANY SPOTS.     ..12..


.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 242 PM CDT FRI MAY 24 2013

PROLIFIC RAINFALL IS EXPECTED THROUGH TUESDAY...AS A SERIES OF WARM
ADVECTION DRIVEN SHOWERS/THUNDERSTORMS...POSSIBLE FULL MCS ACTIVITY
MOVES ACROSS IOWA AND ILLINOIS.  THERE IS VERY HIGH PROBABILITY OF
THIS OCCURRING...AS STRONG LLJ CONVERGENCE IS INDICATED OVERHEAD ON
EVERY MODEL...AND THE PAST 2 DAYS HAVE SEEN QUITE A BIT OF ELEVATED
ACTIVITY...IN OKLAHOMA YESTERDAY...AND IN SOUTH DAKOTA TODAY. THIS
ELEVATED BOUNDARY LOOKS TO REMAIN OVER THE CWA THROUGH
TUESDAY...THUS A GROWING THREAT FOR SIGNIFICANT RAINFALL IS
EXPECTED. A HYDRO SECTION WILL BE ADDED TO THIS AFD.

IT IS HARD TO ARGUE AGAINST THE MODEL OUTPUT POPS FOR SATURDAY NIGHT
THROUGH MONDAY...WHICH SOLIDLY INDICATED LIKELY OR HIGHER. SINCE
THIS STRETCHES OVER MANY PERIOD...I WILL NOT GO CATEGORICAL ON ANY
PERIOD...AS THERE SHOULD BE SOME BREAKS IN THE RAIN/MCS ACTIVITY.
THUS...A PROLONGED PERIOD OF LIKELY POPS SHOULD COVER THE
UNCERTAINTY ON TIMING ROUNDS OF RAINFALL. IN GENERALLY IT APPEARS A
MAXIMUM IN COVERAGE IN RAINFALL SHOULD OCCUR IN THE OVERNIGHT AND
MORNING HOURS...WHICH IS TYPICAL OF MCS PATTERNS.

TEMPERATURES WILL CONTINUE TO COOL THROUGH SUNDAY...WITH HIGHS IN
THE 60S NORTH...LOWER 70S SOUTH...BUT BY MONDAY WE SHOULD SEE HIGHER
DEWPOINT AIR SURGE NORTH...THUS HIGHS IN THE UPPER 60S TO UPPER 70S
SHOULD BE MORE WIDESPREAD.  THE REMAINDER OF THE WEEK...WE SHOULD BE
IN THE WARM SECTOR...AND SHOULD SEE HIGHS IN THE UPPER 70S TO MID
80S. LOWS IN THE 60S CAN BE ANTICIPATED MUCH OF THE EXTENDED AFTER
SATURDAY NIGHT...WHICH WILL BOTTOM OUT IN THE UPPER 40S TO MID 50S
FROM NORTHEAST TO SOUTHWEST.
ERVIN

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1232 PM CDT FRI MAY 24 2013

VFR THROUGH THIS EVENING AND EVEN MIDNIGHT IN LINGERING PRESENCE
OF HIGH PRESSURE. BUT FORCING SWATH ALOFT/WARM AIR ADVECTION WING
TAKING SHAPE CURRENTLY ACRS EASTERN SD INTO THE MO RVR VALLEY WILL
LOOK TO BRING HIGH BASED SHOWERS/ROOTED ABOVE 4K FT AGL AND POSSIBLY
A THUNDERSTORM TO THE WESTERN VCNTY OF CID BY 1 AM CDT...AND INTO
DBQ AND MLI BY 3 AM CDT SAT MORNING. A ELEVATED SYSTEM OF SHOWERS
AND EMBEDDED THUNDERSTORMS STARTING TO ENCROACH MVFR CIGS MAY
BECOME MORE WIDESPREAD AND IMPACT MOST TERMINALS FROM 11Z-18Z SAT
MORNING. TEMPORARY BOUTS OF MVFR VSBYS BY HEAVIER RAIN POSSIBLE
SAT MORNING AS WELL EVEN IF CIGS REMAIN ABOVE 3K FT AGL. UNTIL
THEN...LIGHT EAST SOUTHEAST SFC WINDS THIS AFTERNOON TO BECOME
MAINLY SOUTHEASTERLY TONIGHT AT 5-10 KTS.    ..12..


&&

.HYDROLOGY...
ISSUED AT 242 PM CDT FRI MAY 24 2013

WIDESPREAD RAINFALL OF 1 TO 4 INCHES IS POSSIBLE THROUGH EARLY THIS
UPCOMING WEEK. IN SOME CASES WHERE TRAINING TAKES PLACE...AMOUNTS
OVER 4 INCHES ARE CERTAINLY POSSIBLE. WHILE THE HEAVIEST AXIS OF
RAINFALL IS FAR FROM CERTAIN...IT DOES APPEAR THAT THIS RAINFALL
WILL SUPPORT SIGNIFICANT NEW RISES ON MOST RIVERS...AND MAY CAUSE
NEW FLOODING OR PROLONGED FLOODING. THIS IS ESPECIALLY TRUE IN
EASTERN IOWA...WHERE THE CEDAR...IOWA...AND WAPSIPINICON RIVERS ARE
ALREADY RUNNING HIGH FROM RAINFALL UPSTREAM IN NORTH CENTRAL IOWA
LAST WEEK.
ERVIN

&&

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

$$

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