Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 261747
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1247 PM CDT TUE MAY 26 2015

.SYNOPSIS...
ISSUED AT 332 AM CDT TUE MAY 26 2015

SHOWERS ARE PERCULATING OVER NORTHEAST IA EARLY THIS AM IN WAKE
OF PASSING OUTFLOW BOUNDARY. OVERALL... RAIN CHANCES WILL BE
INCREASING TODAY AS A SHORTWAVE TROUGH OVER KS/OK LIFTS NORTHEAST
INTO THE UPPER MIDWEST WHILE MERGING WITH REMNANT UPPER LEVEL LOW
SHIFTING EAST FROM NE. ISENTROPIC ASCENT...VORTICITY ADVECTION...
INCREASING LOW LEVEL CONVERGENCE WITH PASSING MESO-LOW ALONG WITH
SURGE OF MOISTURE/THETA-E RIDGE WITH PW VALUES CLIMBING TO NEAR
1.5 INCHES WILL ALL RESULT IN FAIRLY GOOD COVERAGE OF SHOWERS AS
DAY PROGRESSES WITH A FEW STORMS AS WELL. WEAK COOL FRONT/SURFACE
TROUGH TO MOVE INTO THE AREA TONIGHT AND SHOULD RESULT IN TAPERING
RAIN CHANCES.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 332 AM CDT TUE MAY 26 2015

INCREASING COVERAGE OF SHOWERS AND A FEW STORMS EXPECTED THIS AM
WITH FORCING AND MOISTURE ADVECTION AHEAD OF APPROACHING SHORTWAVE
AND SURFACE MESO-LOW. LOCALLY HEAVY RAIN WILL BE THE MAIN
CONCERN... WITH THE FOCUS FOR HIGHER RAIN AMOUNTS (POTENTIALLY
POCKETS OF RAINFALL OF 1-2 INCHES) BEING OVER THE WESTERN CWA...
ESPECIALLY NORTHWEST OF REMNANT OUTFLOW BOUNDARY FROM NEAR IOW-
DBQ WHERE LIFT IS MAXIMIZED WITH INCREASING CONVERGENCE FROM
APPROACHING MES0-LOW AND UPPER LEVEL DIFFLUENCE AHEAD OF
SHORTWAVE. CANT RULE OUT SOME FLOODING ISSUES BEING POSSIBLE
ESPECIALLY WITH ANY TRAINING AND PROLONGED BOUTS OF HIGHER RAINFALL
RATES. THIS AFTERNOON IT WOULD APPEAR AS THOUGH GREATER COVERAGE
OF PCPN WILL MIGRATE NORTH OF I-80 AS SYSTEM LIFTS THROUGH THE
REGION AND MID LEVEL DRY INTRUSION ENVELOPS MUCH OF THE AREA.
THIS MAY ALLOW FOR SOME PARTIAL SUNSHINE WHICH COULD ALLOW FOR SOME
DESTABILIZATION AND DEVELOPMENT OF SCATTERED SHOWERS AND STORMS.
SUFFICIENT SHEAR WITH 0-6KM BULK SHEAR 30-35 KTS FOR POTENTIAL OF
A STRONGER STORM OR TWO SHOULD SUFFICIENT DESTABILIZATION OCCUR. AS
FOR HIGHS TODAY... AS THE CLOUDS/PCPN GO... SO GO THE TEMPS AND
THEREFORE A TRICKY TEMP FORECAST WITH BUST POTENTIAL. HAVE NUDGED
DOWN HIGHS 1-2 DEGS NORTHWEST CWA WHERE LIKELIHOOD OF MORE RAIN
AND LINGERING CLOUDS AND HAVE AROUND 70 OR LOWER 70S THERE WITH
MID/UPPER 70S ELSEWHERE.

TONIGHT... ANTICIPATE GRADUAL TAPERING OF RAIN CHANCES WITH FOCUS
SHIFTING MORE TO THE SOUTH IN TIME AS WEAK COOL FRONT/TROUGH
MOVES INTO THE REGION. LOWS COOLEST NORTHWEST (MID/UPPER 50S) TO
WARMEST SOUTHEAST (LOWER 60S) UNDER PARTLY TO MOSTLY CLOUDY SKIES
AND LIGHT SOUTHWESTERLY WINDS.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 332 AM CDT TUE MAY 26 2015

MAIN FORECAST CONCERN FOR THE LONG TERM FORECAST ARE
THE CHANCES FOR POPS AT THE BEGINNING OF THE PERIOD AND THEN THE
CHANCE FOR POPS THIS WEEKEND.  ACTIVE WEATHER PATTERN REMAINS IN
PLACE ACROSS THE AREA THROUGH THE LONG TERM WITH CHCS OF POPS
VIRTUALLY EVERY DAY WITH THE EXCEPTION OF A SHORT PERIOD WEDNESDAY
INTO THURSDAY.

WEDNESDAY...THE CURRENT TROF THAT HAS PLAGUED THE CENTRAL UNITED
STATES FOR THE PAST WEEK OR SO FINALLY EJECTS OUT OF THE PLAINS.
THIS OCCURS BECAUSE ANOTHER TROF IS BUILDING IN FROM THE NW.  THIS
GIVES US ONLY ABOUT 24 HOURS OF H5 RIDGING UNTIL THE NEXT TROF TURNS
THE FLOW TO THE SW ON THURSDAY.  WEDNESDAY AFTERNOON INTO THURSDAY
LATE AFTERNOON SHOULD BE QUIET AND PLEASANT.

THURSDAY THE FLOW TURNS SSW ACROSS THE AREA.  THIS SHOULD USHER
MOISTURE AND SHRTWVS INTO THE AREA AGAIN FOR THURSDAY NIGHT INTO THE
WEEKEND. THE MODELS...ESPECIALLY THE SPECTRAL MODELS WITH LARGER
GRID SPACING SEEM TO BE OVERDOING IT WITH COVERAGE OF THE POPS.
THEY HAVE DONE IT WITH THE CURRENT SYSTEM.  THIS COULD BE DUE TO THE
CONVECTION DOWNSTREAM SOUTH OF HERE OR ISSUES WITH PARAMETRIZATION
SCHEMES.  REGARDLESS...THEY DEPICT DIURNAL CONVECTION.  THE NAM
SEEMS TO BE THE BEST AS FAR AS COVERAGE OF POPS.  THIS SUGGESTS THAT
THURSDAY MOST OF THE SHOWERS AND STORMS WILL BE WEST OF THE AREA
UNTIL NEAR 00Z.  AFTER 00Z FRIDAY SHOWERS AND STORMS WILL ADVECT
INTO THE AREA AND LIKELY AFFECT NW ZONES THE MOST FRIDAY NIGHT.

OVERALL TIMING AND STRUCTURE OF THE FORCING APPEARS TO BE CONSISTENT
THROUGH 12Z SATURDAY.  THERE ARE SMALL DIFFERENCES BUT NOTHING THAT
WOULD AFFECT A FORECAST THIS FAR OUT.  THOSE DIFFERENCES WOULD
LIKELY AFFECT MESOSCALE FEATURES THAT ARE INHERENTLY DIFFICULT TO
FORECAST THIS FAR OUT.  THE OVERALL TROF IS SLOW TO LEAVE THE AREA.
COOLER AIR WILL BE PULLED INTO THE AREA SUNDAY...LEADING SUNDAY AND
SUNDAY NIGHT BEING CHILLY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1231 PM CDT TUE MAY 26 2015

WOUND UP SFC LOW WAS ROLLING NORTHEASTWARD JUST WEST OF DBQ
ATTM...WITH JUST A FEW SCTRD TO ISOLATED SHOWERS ROLLING ACRS THE
AREA. WILL WALK THOSE OUT THROUGH 2 PM...BUT WITH ANOTHER VORT MAX
OVER SOUTHEASTERN NEB PUSHING EASTWARD...THERE COULD BE ANOTHER
UPTICK IN ISOLATED TO SCTRD SHOWERS AND THUNDERSTORMS PUSHING
THROUGH THE AREA LATER THIS AFTERNOON AND EVENING. BUT WITH SOME
UNCERTAINTY IN EXTENT AND COVERAGE HAVE LEFT OUT MENTION IN TAFS
FOR NOW. OTHERWISE LINGERING MVFR DECKS SHOULD SCATTER OUT TO VFR
BY MID AFTERNOON AT MOST SITES. SOUTH OR VARIABLE WINDS NEAR THE
LOW CENTER WILL VEER SOUTHWEST AND INCREASE TO 12 TO 22 KTS WITH
HIGHER GUSTS INTO THE EARLY EVENING BEFORE DECREASING OVERNIGHT.
SOME CHC OF WRAP AROUND MVFR STRATUS LATER TONIGHT AFTER 10 PM AT
ALL TERMINAL SITES. IF WINDS GO LIGHT ENOUGH LATE TONIGHT...SOME
3-6SM FOG POSSIBLE IN RECENT RAINFALL AREAS. CLEARING CONDITIONS
WITH INCREASING WEST WINDS BY MID WED MORNING.   ..12..

&&

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

$$

SYNOPSIS...05
SHORT TERM...05
LONG TERM...GIBBS
AVIATION...12



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