Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 212312
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
612 PM CDT TUE OCT 21 2014

.SYNOPSIS...
ISSUED AT 320 PM CDT TUE OCT 21 2014

12Z UA ANALYSIS HAS AN 850MB COLD FRONT FROM THE EASTERN GREAT LAKES
INTO SOUTHWEST WISCONSIN. SATELLITE TRENDS THROUGH MID AFTERNOON
SHOW SYSTEM CLOUDS ASSOCIATED WITH THE GREAT LAKES SYSTEM SLOWLY
DISSIPATING WITH MINIMAL DIURNAL CLOUDS ACROSS THE PLAINS.

18Z SFC ANALYSIS HAS HIGH PRESSURE FROM THE GREAT LAKES INTO THE
LOWER MISSISSIPPI VALLEY WITH A DISSIPATING COLD FRONT FROM SOUTHERN
MISSOURI INTO THE TENNESSEE VALLEY. DEW POINTS WERE IN THE 30S AND
40S ACROSS THE GREAT LAKES AND NORTHERN PLAINS WITH 50S FROM THE
DEEP SOUTH INTO THE CENTRAL PLAINS.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 320 PM CDT TUE OCT 21 2014

QUIET AND DRY WEATHER WILL CONTINUE FROM LATE AFTERNOON THROUGH
WEDNESDAY AS HIGH PRESSURE SLOWLY MOVES INTO THE EASTERN GREAT LAKES.

WEAK FLOW WILL AGAIN COME OFF LAKE MICHIGAN LATE TONIGHT WHICH
SHOULD INDUCE SOME LAKE CLOUDS. AT BEST SOME OF THESE CLOUDS MAY
MAKE IT INTO THE FAR NORTHEAST AND EAST AREAS BY SUNRISE.

SOME PATCHY RIVER VALLEY FOG MAY DEVELOP ALONG THE MISSISSIPPI NORTH
OF LE CLAIRE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 320 PM CDT TUE OCT 21 2014

WED NGT-THU...PROGRESSIVE MID LEVEL SHORTWAVE TO BRING RAIN TO THE
AREA FROM WEST TO EAST MAINLY AFTER MIDNIGHT WED NGT AND MOSTLY
EXITING EASTERN CWA THU PM. PWATS SURGE TO AROUND 1.25 INCHES IN
NARROW RIBBON AHEAD OF SHORTWAVE...BUT FORCING PROGRESSIVE AND OF
FAIRLY SHORT DURATION OF LESS THAN 6 HOURS SUGGESTING MOSTLY LIGHT TO
SOME MODERATE AMOUNTS (0.1 TO 0.4 INCH) WITH SOME EMBEDDED THUNDER NOT
OUT OF QUESTION WITH 850 TO 500 MB THETA-E LAPSE RATES SLIGHTLY NEGATIVE.
IF FORCING AND MOISTURE TRENDS PERSIST... WITH HI-RES ECMWF THE MOST
CONSISTENT PER DPROG/DT AND THEREFORE THE FAVORED MODEL...THEN WILL NEED
TO RAISE POPS TO CATEGORICAL MANY AREAS. LOWS WED NGT COOLEST EAST (U30S)
WITH LIGHT E/SE WIND AND LATER ARRIVAL OF THICKER CLOUDS. HIGHS THU WILL
BE CHALLENGING AND DEPENDENT ON TIMING OF RAIN AND CLOUD TRENDS. OVERALL
HAVE RANGE ON HIGHS FROM THE MID 50S TO LOWER 60S...COOLEST EAST/NORTHEAST
PORTIONS AND WARMEST WEST/SOUTHWEST WHERE RAIN TO END EARLY THU PM AND MAY BE
FOLLOWED BY SOME BREAKS IN CLOUDS.

THU NGT-SUN NGT...GENERALLY DRY AND FINE STRETCH OF WX. POSSIBILITY OF SOME
RAIN LATE SUN NGT AHEAD OF NEXT FRONT AS MOISTURE IS DRAWN NORTHWARD ON
THE SOUTHERLY WINDS. OTHERWISE...WARMING TREND EXPECTED CULMINATING WITH
WARMEST DAY FOR MANY AREAS ON SUNDAY (WIDESPREAD HIGHS AROUND 70F TO NEAR 75F)
WITH GUSTY SOUTHERLY WINDS AND DEEP MIXING WITH 850 MB THERMAL RIDGE (15-18C)
MOVING THROUGH CWA.

MON-TUE...THIS PERIOD LOOKS TO HARBOR NEXT CHANCE OF RAIN AS SHORTWAVE
AND ATTENDANT FRONT MOVE THROUGH REGION. SOME POTENTIAL FOR FRONTAL WAVE
AND MODERATE TO LOCALLY HEAVY AMOUNTS 1+ INCHES PER GFS AND ECMWF...BUT
CONSIDERABLE UNCERTAINTY EXISTS WITH MODELS HANDLING OF ENERGY EJECTING FROM
THE WESTERN CONUS... WHICH WILL LIKELY TAKE ANOTHER 24-48 HRS TO CLARIFY.
TIMING OF FRONT... CLOUDS AND RAIN ALL TO HAVE BIG IMPACT ON HIGHS MON WITH
MAINLY 60S WITH SOME 70S POSSIBLE SOUTHEAST CWA WITH SLOWER TIMING. COOLING
OFF ON TUE BELOW SEASONAL NORMS AND MAINLY IN THE 50S... IF TIMING OF FRONT
IS UNCHANGED.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 609 PM CDT TUE OCT 21 2014

HIGH PRESSURE OVER THE GREAT LAKES WILL PROVIDE CLEAR AND VFR
WEATHER FOR ANOTHER 24 HOURS OR MORE AS IT SLOWLY SLIDES EAST.
WINDS WILL BE LIGHT EAST OVERNIGHT...BECOMING SOUTHEAST AROUND 10
KTS BY LATE MORNING WEDNESDAY. TOWARDS THE END OF THE
PERIOD...SOME CIRRUS MAY OCCUR...BUT OTHERWISE IT WILL BE CLEAR
WITH UNLIMITED VISIBILITIES.
ERVIN

&&

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

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...05
AVIATION...ERVIN






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