Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KDVN 041758
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1258 PM CDT MON MAY 4 2015

.UPDATE...
ISSUED AT 1256 PM CDT MON MAY 4 2015

NEARLY STATIONARY FRONTAL BOUNDARY EXTENDED FROM CHICAGO TO ABOUT
THE QUAD CITIES AND THEN TO SAINT JOSEPH MO. TO THE NORTH OF THE
BOUNDARY...LOW CLOUDS...WINDS FROM THE NORTHEAST AND TEMPERATURES
WERE IN THE MID TO UPPER 60S. TO THE SOUTH OF THE BOUNDARY WINDS
WERE FROM THE SOUTH WITH TEMPERATURES IN THE MID 70S. DEWPOINTS
ACROSS THE CWA RANGED FROM THE UPPER 50S TO LOWER 60S.

VISIBLE SATELLITE SHOWED SOME BREAKS IN THE CLOUD COVER AND
MUCAPES WERE RISING TO 1000 J/KG AND ARE FORECAST TO 2500 J/KG
LATER THIS AFTERNOON. HOWEVER...SHEAR IS WEAK AND FREEZING LEVELS
ABOUT 10K. THIS SUGGESTS MULTICELL CLUSTERS PRODUCING NEAR SEVERE
HAIL AROUND 1 INCH. PRECIPITABLE WATERS INCREASE TO 1.50 INCHES SO
HEAVY RAINFALL WILL ACCOMPANY THE STRONGER STORMS.

OPERATIONAL MODELS...INCLUDING THE HRRR/ARW...INDICATE SCATTERED
THUNDERSTORMS DEVELOPING ALONG/SOUTH OF THE BOUNDARY BY LATE THIS
AFTERNOON...THEN ORGANIZING INTO A LARGER MCS OVER MUCH OF THE
CWA THIS EVENING AND OVERNIGHT.

&&

.SYNOPSIS...
ISSUED AT 313 AM CDT MON MAY 4 2015

SCATTERED STRONG THUNDERSTORMS WITH SMALL HAIL AND GUSTY WINDS
CONTINUE EARLY THIS MORNING ACROSS PARTS OF THE FORECAST AREA.
THE HEAVIER RAINS LAST EVENING AND OVERNIGHT OCCURRED NORTH OF
INTERSTATE 80S...WITH SOME LOCALIZED AMOUNTS AROUND 2 INCHES.
EARLY MORNING TEMPERATURES RANGED FROM THE MID 50S ALONG HIGHWAY
20...TO THE UPPER 60S NEAR AND SOUTH OF HIGHWAY 34.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 313 AM CDT MON MAY 4 2015

RAINFALL AMOUNTS/COVERAGE AND SEVERE WEATHER POTENTIAL ARE THE
MAIN FORECAST ISSUES IN THE SHORT TERM PERIOD.

A COLD FRONT HAS PUSHED INTO THE FORECAST AREA OVERNIGHT...AND
COMBINED WITH A SHORT WAVE TROUGH TO SUPPORT REPEATED THUNDERSTORM
DEVELOPMENT. THE STRONGEST STORMS THROUGH DAYBREAK MAY PRODUCE
SOME PEA TO HALF INCH DIAMETER HAIL AND WIND GUSTS TO 40 MPH...BUT
STORMS ARE EXPECTED TO STAY SUB-SEVERE. AFTER THE INITIAL SHORT
WAVE PASSES...AM EXPECTING A LULL IN MUCH OF THE SHOWER AND
THUNDERSTORM ACTIVITY THROUGH THE MORNING. THE FRONT IS EXPECTED
TO WAVER BETWEEN INTERSTATE 80 AND HIGHWAY 34 TODAY THEN START TO
LIFT NORTH LATE TONIGHT. ANOTHER SHORT WAVE CURRENTLY IN NEW
MEXICO WILL LIFT NORTH ALONG THIS BOUNDARY...SUPPORTING AN
INCREASE IN STORM COVERAGE...ESPECIALLY FROM LATE AFTERNOON ON. ONCE
AGAIN...DID NOT MAKE ANY DRAMATIC CHANGES TO PREVIOUS FORECAST. IN
ADDITION TO THE OVERNIGHT AND CURRENT RAINFALL...1/2 TO 1 INCH
ADDITIONAL AMOUNTS ARE POSSIBLE THIS AFTERNOON AND TONIGHT...WITH
THE INTERSTATE 80 CORRIDOR FAVORED FOR THE HIGHER END OF THAT
RANGE. SIGNIFICANT FLOODING SHOULD NOT BE A CONCERN...WITH THE
POSSIBLE EXCEPTION OF LOCALIZED ENHANCED RAIN IN URBAN AREAS. IN
TERMS OF SEVERE POTENTIAL...THE SOUTHWEST QUADRANT OF THE FORECAST
AREA IS IN SLIGHT RISK. ML CAPES AROUND 1500 J/KG ARE POSSIBLE BUT
DEEP LAYER SHEAR WILL BE MARGINAL. THE MAIN THREAT WILL LIKELY BE
HAIL AROUND QUARTER SIZE.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 313 AM CDT MON MAY 4 2015

A DECAYING THUNDERSTORM COMPLEX SHOULD BE OVER THE AREA AT SUNRISE
TUESDAY THAT SLOWLY MOVES EAST DURING THE MORNING ALLOWING
PRECIPITATION TO END FROM WEST TO EAST. THE BEST RAIN CHANCES WILL
BE OVER THE NORTH HALF WITH LOWER CHANCES ACROSS THE SOUTH.

CONVECTION THAT DEVELOPS TUESDAY AFTERNOON WILL BE DEPENDENT UPON
BOUNDARIES PRESENT AND OVERALL INSTABILITY ALONG WITH CLOUD
COVER/TEMPERATURE/MOISTURE DIFFERENCES. WHAT IS SUGGESTED BY THE
MODELS IS THAT SOME TYPE OF BOUNDARY WILL BE ACROSS THE FAR SOUTH
WHICH MAY BE LEFT OVER FROM THE MORNING THUNDERSTORM COMPLEX. THE
POSSIBILITY DOES EXIST THAT DRY CONDITIONS MAY BE SEEN OVER MUCH OF
THE AREA DURING THE AFTERNOON.

FLOW COMING OFF LAKE MICHIGAN SHOULD RESULT IN A FAIRLY LARGE
TEMPERATURE GRADIENT...POSSIBLY 15 TO 20 DEGREES...ACROSS THE AREA
ON TUESDAY WITH THE COOLEST READINGS ACROSS THE FAR NORTHEAST.

ANY DIURNAL CONVECTION THAT DEVELOPS TUESDAY AFTERNOON WILL
DISSIPATE WITH SUNSET LEAVING MAINLY DRY CONDITIONS ACROSS THE AREA
TUESDAY NIGHT.

MAINLY DRY CONDITIONS SHOULD BE SEEN ACROSS THE AREA WEDNESDAY
MORNING. DAY TIME HEATING SHOULD ALLOW ISOLATE TO SCATTERED
CONVECTION TO DEVELOP ACROSS THE WESTERN THIRD AS BETTER
FORCING/MOISTURE MOVE INTO THE AREA.

THE CONVECTION THAT DEVELOPS WEDNESDAY AFTERNOON WILL PERSIST INTO
WEDNESDAY NIGHT WITH THE WESTERN HALF OF THE AREA FAVORED.

THURSDAY ON...

THE ACTIVE WEATHER PATTERN WILL CONTINUE FROM THURSDAY THROUGH NEXT
WEEKEND. THERE WILL BE PERIODS OF DRY WEATHER FROM THURSDAY THROUGH
SUNDAY THAT MAY BE 6 OR MORE HOURS IN LENGTH. TIMING WHEN THESE DRY
PERIODS OCCUR IS DIFFICULT BECAUSE WHERE ONE THUNDERSTORM COMPLEX
DEVELOPS AND TRACKS WILL INFLUENCE WHERE THE NEXT STORM COMPLEX
DEVELOPS AND TRACKS.

AS SUCH THE MODEL CONSENSUS HAS CHANCE TO LIKELY POPS IN EACH PERIOD
FROM THURSDAY THROUGH SUNDAY. TEMPERATURES SHOULD GENERALLY AVERAGE
ABOVE NORMAL THROUGH THE PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1256 PM CDT MON MAY 4 2015

A NEARLY STATIONARY FRONTAL BOUNDARY NEAR I-80 WILL HAVE MVFR CIGS
ALONG AND NORTH OF THE BOUNDARY...ALONG WITH NORTHEAST WINDS 10 KNOTS
OR LESS. TO THE SOUTH OF THE BOUNDARY VFR CONDS AND SOUTH WINDS AROUND
10 KNOTS. SCATTERED THUNDERSTORMS WILL DEVELOP BY LATE THIS AFTERNOON
ALONG/SOUTH OF THE BOUNDARY AND THEN BECOME MORE WIDESPREAD THIS
EVENING AND OVERNIGHT. MVFR/LCL IFR CONDS IN THUNDERSTORMS PRODUCING
HEAVY RAIN AND POTENTIAL FOR AROUND 1 INCH HAIL.

&&

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

$$

UPDATE...HAASE
SYNOPSIS...RP KINNEY
SHORT TERM...RP KINNEY
LONG TERM...08
AVIATION...HAASE


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.