Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 061745 AAC
AFDDVN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1245 PM CDT WED MAY 6 2015

.UPDATE...
ISSUED AT 1052 AM CDT WED MAY 6 2015

A BAND OF ACCAS WAS MOVING NORTH THROUGH THE CWA LATE THIS
MORNING. AT THE SFC...WINDS WERE BACKING LEAD TO CONVERGENCE WITH
THE WARM FRONT. THE CLOUDS HAVE BROKEN OUT AND SUN HAS LEAD TO
TEMPS TO JUMP FAST ACROSS THE AREA. THESE THINGS HAVE MADE ME PUT
IN A SLIGHT CHANCE OF THUNDER THIS MORNING THROUGH EARLY AFTERNOON
ASSOCIATED WITH THE ACCAS. THIS CHANCE WILL MIGRATE NORTH WITH THE
ACCAS. THE REST OF THE PRECIP FORECAST IS ON TRACK. RAISED HIGH
TEMPS TODAY ACROSS THE SOUTHERN AND EASTERN ZONES. HIRES CAMS
DEPICT HIGHS IN THE 80S ACROSS THE AREA. WITH 80 ALREADY BEING
REPORTED AT SPRINGFIELD AT 10AM DECIDED THAT THIS IS NOT OUT OF
THE QUESTION. CONVECTIVE TEMP IS AROUND 82 AT DVN. WILL LIKELY
REACH THIS IN THE AFTERNOON. NO OTHER TWEAKS TO THE FORECAST WERE
MADE.

UPDATE ISSUED AT 704 AM CDT WED MAY 6 2015

UPDATE TO INCREASE COVERAGE OF FOG IN GRIDS. LOWER VISIBILITIES
HAVE EXPANDED MORE THAN PREVIOUSLY EXPECTED SINCE 630 AM...BUT THE
MORE WIDESPREAD FOG IS NOT EXPECTED TO LAST VERY LONG WITH AN
INCREASING E/SE WIND. HAVE OPTED TO HANDLE THE FOG WITH AN UPDATED
SPECIAL WEATHER STATEMENT RATHER THAN ISSUE A LATE ADVISORY.

&&

.SYNOPSIS...
ISSUED AT 310 AM CDT WED MAY 6 2015

LOW CLOUD AND FOG REMAINED IN PLACE DURING THE EARLY MORNING OVER
MUCH OF EASTERN IOWA AND WESTERN ILLINOIS. VISIBILITIES DROPPED
DOWN TO A QUARTER MILE AT TIMES.  ISOLATED THUNDERSTORMS WERE
PUSHING NORTH THROUGH CENTRAL IOWA. EARLY MORNING TEMPERATURES VARIED
FROM NEAR 50 DEGREES AT FREEPORT...TO THE MID 60S SOUTH OF HIGHWAY
34.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 310 AM CDT WED MAY 6 2015

THE MAIN FORECAST ISSUES ARE EARLY MORNING FOG AND CONVECTIVE
TRENDS/COVERAGE THIS AFTERNOON AND EVENING.

IN THE NEAR TERM...LOW CLOUDS AND FOG ARE IN PLACE ACROSS MUCH OF
THE FORECAST AREA. LOCALIZED DENSE FOG HAS BEEN OCCURRING...MAINLY
ALONG AND NORTH OF HIGHWAY 34. AFTER COLLABORATION WITH
SURROUNDING OFFICES...HAVE OPTED TO HANDLE FOG WITH A SPECIAL
WEATHER STATEMENT. VISIBILITIES SHOULD BEGIN TO IMPROVE BETWEEN 8
AM AND 9 AM. ISOLATED SHOWERS ASSOCIATED WITH A POCKET OF
ELEVATED INSTABILITY ARE PUSHING NORTH THROUGH CENTRAL IOWA...AND
MAY CLIP THE EXTREME WESTERN FRINGE OF THE FORECAST AREA PRIOR TO
SUNRISE.

THE MAIN CHANCES OF SHOWERS AND THUNDERSTORMS WILL BE THIS
AFTERNOON AND EARLY EVENING ACROSS EASTERN IOWA...AS SHORT WAVE
ENERGY LIFTS NORTH INTO THE REGION. FORECAST SOUNDINGS SUGGEST
MU CAPE LIMITED TO 1000 J/KG OR LESS...WITH WEAK DEEP LAYER SHEAR
AND MID LAYER LAPSE RATES LESS THAN 6C/KM. A FEW STORMS MAY
PRODUCE SOME PEA SIZE HAIL...BUT THAT SHOULD BE THE ONLY ISSUE.
COOLEST TEMPS WILL LIKELY BE LOCATED IN THE WESTERN COUNTIES WITH
MORE WIDESPREAD CLOUDS AND RAIN DURING PEAK HEATING. CURRENT
FORECAST HIGHS MAY BE A BIT TOO HIGH.

FOR TONIGHT...EXPECT DIMINISHING SHOWERS/STORMS IN THE
EVENING...WITH SOME REDEVELOPMENT POSSIBLE FAR WEST LATE.

ONE HYDRO NOTE...THE WAPSIPINICON RIVER NEAR DEWITT WILL LIKELY
CREST BELOW THE 11 FOOT FLOOD STAGE TODAY. NO OTHER ISSUES AT THIS
TIME.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 310 AM CDT WED MAY 6 2015

THURSDAY THROUGH TUESDAY

THE WEATHER PATTERN WILL REMAIN ACTIVE THROUGH THE END OF THE WORK
WEEK WITH SEVERAL CHANCES OF RAIN. THERE WILL BE PERIODS OF DRY
WEATHER THURSDAY AND FRIDAY THAT MAY BE 6 OR MORE HOURS IN LENGTH.

THE QUESTION ON THURSDAY IS HOW WIDESPREAD WILL PRECIPITATION BE.
THE BETTER FORCING/MOISTURE IS ACROSS CENTRAL AND WESTERN IOWA BUT
THE ATMOSPHERE IS UNSTABLE ACROSS THE AREA. THUS THERE SHOULD BE
SOME SHOWERS ACROSS THE AREA WITH THE BETTER CHANCES WEST OF THE
MISSISSIPPI. A FEW RUMBLES OF THUNDER CANNOT BE RULED OUT ACROSS THE
WESTERN HALF OF THE AREA.

THURSDAY AFTERNOON THE BETTER FORCING SHIFTS INTO EASTERN IOWA SO
AREAL COVERAGE OF CONVECTION SHOULD BE ON THE INCREASE.

THURSDAY NIGHT ANOTHER ROUND OF STRONG FORCING MOVES INTO THE AREA.
CONVECTION SHOULD PERSIST THROUGH THE NIGHT AND MAY GROW UPSCALE
INTO A LOOSELY ORGANIZED THUNDERSTORM COMPLEX.

IF SAID THUNDERSTORM COMPLEX DOES DEVELOP THURSDAY NIGHT...IT WOULD
SLOWLY EXIT THE AREA FRIDAY MORNING. THE COMBINATION OF BOUNDARIES
LEFT OVER FROM THIS STORM COMPLEX AND A FRONT MOVING THROUGH THE
AREA SHOULD RESULT IN SCATTERED CONVECTION DEVELOPING FRIDAY
AFTERNOON AND PERSISTING INTO FRIDAY EVENING.

FRIDAY NIGHT SOME MODELS ARE SUGGESTING ANOTHER THUNDERSTORM COMPLEX
DEVELOPING ACROSS THE AREA WHILE OTHERS DO NOT. IF ONE WOULD
DEVELOP...CONVECTION WOULD BE THE MOST WIDESPREAD UP THROUGH
MIDNIGHT WITH DECREASING COVERAGE AFTER MIDNIGHT AS THE BETTER
FORCING MOVES EAST OF THE AREA.

SATURDAY ON...

THE ACTIVE WEATHER PATTERN WILL CONTINUE OVER THE WEEKEND AND INTO
EARLY NEXT WEEK AS THE FRONT STALLS ACROSS THE MIDWEST. THUS
RAINFALL MAY BE MODERATE TO HEAVY IN ORGANIZED THUNDERSTORM
COMPLEXES. THERE WILL BE PERIODS OF DRY WEATHER FROM SATURDAY
THROUGH MONDAY NIGHT 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.

THE MODEL CONSENSUS HAS CHANCE TO LIKELY POPS IN EACH PERIOD FROM
SATURDAY THROUGH MONDAY. MONDAY NIGHT THE MODEL CONSENSUS HAS SLIGHT
CHANCE TO CHANCE POPS. TEMPERATURES DURING THIS TIME FRAME SHOULD
AVERAGE A LITTLE ABOVE NORMAL.

ON TUESDAY THE MODEL CONSENSUS HAS SLIGHT CHANCE POPS AS AN UPPER
LEVEL DISTURBANCE MOVES THROUGH THE AREA. TEMPERATURES SHOULD BE
COOLER THAN NORMAL.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1236 PM CDT WED MAY 6 2015

MAIN CONCERN FOR AVIATION IN THE TAF PERIOD ARE THE CHANCES FOR
CONVECTION AND POSSIBLE RESTRICTIONS TO MVFR DURING RAIN AND
POSSIBLY EVEN THUNDERSTORMS. PATTERN IS SUCH THAT DIURNAL
THUNDERSTORMS WILL DOMINATE THE AREA THIS AFTERNOON. HARD TO NAIL
DOWN ANY SPECIFIC TIMING OF CONVECTION...SO WENT WITH VCTS. WILL
TEMPO IF A BETTER IDEA IS ESTABLISHED OF CONVECTION. VSBYS AND
CIGS MAY CRASH TONIGHT...ESPECIALLY IF SITES PICK UP DECENT
RAINFALL. AT THIS TIME DECIDED TO HOLD OFF ON DROPPING CIGS OR
VSBYS UNTIL AFTER THE RAIN FALLS. FUTURE SHIFTS WILL NEED TO
MONITOR THIS.

&&

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

$$

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



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