Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 161153
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
653 AM CDT SAT AUG 16 2014

.SYNOPSIS...
ISSUED AT 230 AM CDT SAT AUG 16 2014

MAIN FEATURE ON THE WEATHER MAP THIS MORNING IS THE SLOW MOVING
VERTICALLY STACKED LOW PRESSURE SYSTEM/TROUGH OVER SOUTHWEST IA
AND NORTHWEST MISSOURI. THIS SYSTEM IS SPAWNING A LARGE AREA OF
SLOW MOVING SHOWERS AND THUNDERSTORMS WHICH ARE PRODUCING HEAVY
RAIN ACROSS SOUTHERN IOWA AND NORTHERN MISSOURI.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 230 AM CDT SAT AUG 16 2014

FORECAST ISSUE TODAY AND TONIGHT IS THE EVOLUTION OF THE LOW
PRESSURE SYSTEM AND ASSOCIATED PRECIPITATION.

SHORT AND LONG RANGE MODELS AGREE IN SLOWLY MOVING THE SYSTEM ACROSS
THE SOUTHERN PART OF IOWA/NORTHERN MISSOURI INTO WESTERN ILLINOIS
THROUGH THE DAY...THEN OUT OF OUR CWA BY TOMORROW MORNING. BOTH
OBSERVED RADAR AND MODEL TRENDS SUGGEST A WEAKENING OF THE
CONVECTION THIS MORNING...BUT A MODEST INCREASE IN CAPE DURING THE
AFTERNOON HOURS SHOULD HELP PARTIALLY REINVIGORATE THE STORMS.

DRY AIR TO THE NORTHEAST OF THE LOW WILL HAMPER THE PROGRESS OF
THE RAIN AREA...THUS SOME AREAS ALONG THE HIGHWAY 20 CORRIDOR
MIGHT NOT SEE ANY MEASURABLE RAIN AT ALL. ALONG THE I-80 CORRIDOR...
ANY AMOUNTS THAT OCCUR WILL GENERALLY BE LIGHT. HOWEVER...FURTHER
SOUTH ALONG THE IOWA-MISSOURI BORDER...LOCALLY HEAVY RAIN CAN BE
EXPECTED AS RADAR ESTIMATES IN SOUTH CENTRAL IOWA/NORTH CENTRAL
MISSOURI HAVE TALLIED 3-6 INCHES OVERNIGHT. WHILE THESE AMOUNTS
MAY BE OVERESTIMATED...HIGH PW VALUES AROUND 2 INCHES PER 00Z TOP
SOUNDING AND SPC MESOANALYSES CERTAINLY SUPPORT THE HEAVY RAIN
POTENTIAL. HOWEVER...RECENT DRY WEATHER IN OUR AREA SHOULD TEND
TO LIMIT ANY FLOODING ISSUES.

MAX TEMPS TODAY WILL BE HAMPERED BY THE EXTENSIVE CLOUD COVER AND
RAIN ESPECIALLY IN THE SOUTH. HAVE SOME CONCERNS LIKE YESTERDAY
THAT MAX TEMPS MAY BE TOO HIGH...ALTHOUGH WE ARE OFF TO A WARM
START THIS MORNING.  WOLF

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 230 AM CDT SAT AUG 16 2014

UNSETTLED PATTERN WITH ABOVE NORMAL TEMPERATURES BY LATE NEXT WEEK.

OVERVIEW...INITIALIZATION AND VERIFICATION TONIGHT VERY GOOD WITH
ONLY LIMITED BL TOO MOIST ISSUES IN AMERICAN SOLUTIONS AND PRECIPITATION
FIELDS HANDLED OK BOTH IN MIDWEST AND SW MONSOON MOISTURE UPSTREAM.
RUN TO RUN VARIANCE MOST SOLUTIONS GOOD PAST 24 HOURS WITH GFS A
BIT BETTER. THIS SUPPORTS A 70/30 MIX OF GFS TO A GEM-NH/HI-RES ECMWF.
TEMPERATURES AND DEWPOINTS OVERALL GOOD WITH MINOR TWEAKING FOR DIURNAL
RANGES DUE TO BL MIXING.

LONG TERM FORECAST ASSESSMENT CONFIDENCE...AVERAGE TO ABOVE AVERAGE
(GOOD TO VERY GOOD)...MAIN ISSUES ARE SPECIFIC TIMING AND COVERAGE OF
AREAS OF SHOWERS AND STORMS NEXT 7 DAYS. GENERAL PRECIPITATION ISSUES
ARE HANDLED WITH LITTLE OR NO PRECIPITATION INTO LATE MONDAY WITH MOSTLY
LIGHT TO MODERATE RAIN TOTALS TUESDAY AND WEDNESDAY INTO THURSDAY.

SUNDAY...CURRENT ONGOING CONVECTIVE COMPLEX TO MOVE EAST WITH NE WINDS
TO BRING IN SLIGHTLY DRIER AIR AND MOSTLY FAIR SKIES WITH HIGHS SLIGHTLY
BELOW NORMAL OF 77 TO 82 DEGREES AND DEWPOINTS MOSTLY IN THE MIDDLE
60S. ISOLATED SHOWERS IN SOUTH MAY BE ABLE TO BE PULLED BY LATER SHIFTS
IF TRENDS OF SUBSIDENCE AND DRIER AIR CONTINUE. SUNDAY NIGHT...LIGHT
NE WINDS AND FAIR SKIES SUPPORT ANOTHER COMFORTABLE NIGHT WITH LOWS
IN THE MID/UPPER 50S NE SECTIONS AND LOWER 60S ELSEWHERE.

MONDAY...WEAK SURFACE HIGH TO SLIDE EAST BY EVENING WITH LIMITED BL
MIXING SUPPORTING HIGHS 80 TO 85 DEGREES WITH DEWPOINTS RISING INTO
THE MIDDLE 60S BY PM.

MONDAY NIGHT AND TUESDAY...VIGOROUS NW FLOW SHORT WAVE TO BRING GOOD
CHANCES OF POPS WITH SHOWERS AND NON-SEVERE STORMS WITH LIKELY POPS
BY LATER SHIFTS TO CONSIDER. RAIN TOTALS MOSTLY IN THE MODERATE AND
LIGHT CATEGORY. TEMPERATURES NEAR NORMAL IN THE LOW/MID 60S AND HIGHS
LOWER 80S ONCE AGAIN.

WEDNESDAY THROUGH FRIDAY...SOUTH PLAINS HEAT TO BUILD WITH AREA NEAR
BOUNDARY AND ZONAL FLOW FOR RISK OF PRECIPITATION AND POSSIBLY STRONGER
CONVECTION. THIS ISSUE BETTER ASCERTAINED THE NEXT 24 HOURS. CHANCE
POPS REASONABLE WITH TEMPERATURES RISING TO AT LEAST A FEW DEGREES ABOVE
NORMAL WITH NEAR 90 DEGREES POSSIBLE IN SOUTH AND WEST SECTIONS BY FRIDAY.
LOWS UPPER 60S TO AROUND 70 DEGREES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 644 AM CDT SAT AUG 16 2014

SLOW MOVING UPPER LEVEL AND SURFACE LOW PRESSURE SYSTEM OVER SOUTH
CENTRAL IOWA AND ITS ASSOCIATED RAIN SHIELD ARE MAKING FOR A
COMPLEX AVIATION SCENARIO. OUTSIDE OF THE MAIN RAIN AREA...FOG HAS
DEVELOPED DROPPING VISIBILITIES...AND IN SOME CASE CEILINGS AS
WELL...TO RESTRICTIVE LEVELS. MEANWHILE RAINFALL AREAS ARE MAINLY
MVFR FOR BOTH CIGS AND VSBYS. THIS PATTERN WILL PERSIST MUCH OF
THE DAY WITH LITTLE IMPROVEMENT EXPECTED AS THE STORM SYSTEM
SLOWLY TRAVERSES THE REGION.

THE SYSTEM SHOULD BEGIN TO EXIT THE AREA WITH RAIN ENDING LATE THIS
AFTERNOON AND EVENING. BASED ON UPSTREAM OBSERVATIONS AND
ANTICIPATED RAINFALL...IT APPEARS A GOOD BET TO SEE IFR/LIFR FOG
AT ALL TAF SITES VERY LATE TONIGHT-EARLY TOMORROW MORNING. WOLF

&&

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

$$

SYNOPSIS...WOLF
SHORT TERM...WOLF
LONG TERM...NICHOLS
AVIATION...WOLF





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