Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 180440
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1140 PM CDT WED SEP 17 2014

.SYNOPSIS...
ISSUED AT 343 PM CDT WED SEP 17 2014
12Z UA ANALYSIS HAS A WEAK UPPER LEVEL DISTURBANCE MOVING FROM THE
PLAINS INTO MISSOURI. BEHIND THIS DISTURBANCE A MUCH WEAKER
DISTURBANCE WAS OVER THE NORTHERN PLAINS. SATELLITE TRENDS THROUGH
MID AFTERNOON SHOW CLOUDS ASSOCIATED WITH THE MISSOURI DISTURBANCE
SLOWLY DISSIPATING ACROSS IOWA AND NORTHERN ILLINOIS.

18Z SFC ANALYSIS HAS A WEAK LOW NEAR KCNU WITH A WARM FRONT INTO
NORTHERN ARKANSAS. A WEAK FRONT/BOUNDARY RAN FROM A LOW NORTHERN
LAKE HURON WEST INTO CENTRAL MINNESOTA. DEW POINTS WERE IN THE 40S
AND 50S ACROSS THE GREAT LAKES AND NORTHERN PLAINS WITH 60S AND 70S
ACROSS THE CENTRAL AND SOUTHERN PLAINS.

&&

.SHORT TERM...(TONIGHT AND THURSDAY)
ISSUED AT 343 PM CDT WED SEP 17 2014

QUIET...DRY AND COOL CONDITIONS WILL BE SEEN ACROSS THE AREA TONIGHT
AND THURSDAY AS YET ANOTHER CANADIAN HIGH BUILDS INTO THE MIDWEST.
TEMPERATURES WILL AVERAGE A LITTLE BELOW NORMAL.

.LONG TERM...(THURSDAY NIGHT THROUGH NEXT WEDNESDAY)
ISSUED AT 343 PM CDT WED SEP 17 2014

THURSDAY NIGHT... HIGH PRESSURE SHIFTS EAST WITH LIGHT E/SE WINDS
FUNNELING IN DRIER AIR FROM THE DEPARTING HIGH. STRONG ELEVATED
MOISTURE ADVECTION ATTENDANT TO LOW LEVEL JET AIMED MAINLY TO
OUR WEST... THUS HAVE CONTINUED TO KEEP POPS BELOW MENTION. WITH
THE DRY AIR AND MAINLY CLEAR SKIES FOR MUCH OF THE NIGHT... I HAVE
SIDED TOWARD THE COOL SIDE OF GUIDANCE WITH LOWS MAINLY IN THE
UPPER 40S TO LOWER 50S.

FRIDAY-FRIDAY NIGHT... HAVE GONE WITH A SLIGHT CHANCE OF A SHOWER
FOR NW SECTIONS OF CWA DURING THE AM WITH VEERING LOW LEVEL JET
AND ATTENDANT STRONG MOISTURE TRANSPORT. WITH SUCH DRY LOW LEVELS
THOUGH MAY NOT BE MORE THAN ACCAS AND POSSIBLY SOME SPRINKLES.
AS FOR HIGHS ON FRIDAY... MODELS SHOW VEERED SOUTHWESTERLY WINDS
AROUND 850 MB WHICH DRAWS IN VERY WARM MID LEVEL AIR WITH 850 MB
THERMAL RIDGE OF 19-20C IN OR VERY NEAR NORTHWEST CWA FRIDAY
AFTERNOON. MODEL SOUNDINGS THOUGH DO NOT SUPPORT MIXING TO 850 MB
(WHICH WOULD YIELD WIDESPREAD LOWER TO MIDDLE 80S)... AND INSTEAD
ONLY SUPPORT MIXING TO AROUND 900 MB WHICH YIELDS HIGHS MAINLY
LOWER TO MIDDLE 70S. BASED ON INCREASING SOUTHERLY WINDS AND AMPLE
SUNSHINE I HAVE OPTED TOWARD BLEND OF THESE AND ADVERTISING
MAINLY UPPER 70S TO AROUND 80 WEST/SOUTHWEST CWA IN STRONGER GRADIENT
WITH MIDDLE 70S NORTHEAST CWA. FRIDAY NIGHT... MAY HAVE TO WATCH THE
FAR NORTH FOR SOME PCPN CHANCE IN THE EVENING WITH SHORTWAVE SKIRTING
MAINLY TO OUR NORTH. OTHERWISE... ANTICIPATE REDEVELOPMENT OF SHOWERS
AND STORMS TO OCCUR BACK TO OUR WEST/NORTHWEST LATE EVENING AND
PROPAGATING AND/OR DEVELOPING INTO NORTH/NORTHWEST PORTIONS OF THE
CWA BY SAT AT 7 AM. SOUTHERLY WINDS AND INCREASING CLOUDS WILL MEAN
LOWS AT OR JUST ABOVE WARMER SIDE OF GUIDANCE AND GENERALLY IN THE 60S.
WILL HAVE TO WATCH FOR WEAKENING GRADIENT AND DECOUPLING OF WINDS
MAINLY ACROSS THE EASTERN CWA WHICH WOULD RESULT IN LOWS INTO THE 50S.

SATURDAY-SATURDAY NIGHT... LIKELY TO HAVE SOME WEAKENING MORNING PCPN
AROUND ESPECIALLY ACROSS NORTH/WEST PORTIONS OF CWA. THEN LOOK TO SEE
SOME ADDITIONAL DEVELOPMENT ACROSS CWA DURING THE AFTERNOON AND EVENING
AHEAD OF THE FRONT...WITH EXTENT OF HEATING... AMOUNT OF FRONTAL
CONVERGENCE AND FORCING ALOFT PLAYING VITAL ROLES IN DETERMINING JUST
HOW MUCH PCPN OCCURS AHEAD OF THE FRONT. 12Z MODEL SUITE IS IN GENERAL
CONSENSUS ON KEEPING ODILE REMNANTS TO OUR SOUTH IN SOMEWHAT
WEAKER STEERING FLOW ON EDGE OF DIGGING UPPER MIDWEST TROUGH. STILL...
SOME OF THE MODELS SUGGEST THERE COULD BE SOME CONNECTING OF MOISTURE
FEED FROM ODILE WITH THE FRONT... BUT THIS WILL BE DEPENDENT ON FRONTAL
TIMING HOLDING FOR THE LATER AFTERNOON INTO EVENING. IF THIS OCCURS THEN
COULD SEE LOCALLY AREAS OF HEAVIER RAINS 1+ INCHES WITH PWATS SURGING IN
EXCESS OF 1.6-1.7 INCHES PRE-FRONTAL. SEVERE POTENTIAL LOOKS LOW ATTIM
WITH NON FAVORABLE RIGHT EXIT REGION OF UPPER JET COUPLED WITH
STRONGER BULK SHEAR 0-6KM OF 25-35 KTS MAINLY POST FRONTAL. HIGHS WILL
BE VERY CHALLENGING SATURDAY AND DEPENDENT ON HOW MUCH SOLAR INSOLATION
OCCURS... AND HAVE KEPT TOWARD PREVIOUS FCSTS OF UPPER 70S TO LOWER 80S
WHICH LOOKS REASONABLE AND ALLOWS FOR SOME SUNSHINE MIXED WITH CLOUDS.
SATURDAY NIGHT...RAIN CHANCES MAINLY DURING THE EVENING AND ACROSS THE
SOUTHEAST 1/3-1/2 OF CWA WITH THE FRONT. LOWS SATURDAY NIGHT WILL BE
COOLEST NORTHEAST IOWA WHERE MAINLY IN THE MID TO UPPER 50S... WHILE
AROUND 60 TO LOWER 60S ELSEWHERE.

SUNDAY-SUNDAY NIGHT... SECONDARY DIGGING SHORTWAVE AND ATTENDANT COLD FRONT
SHOWN TO SWEEP DOWN ACROSS THE GREAT LAKES REGION...AND THUS AREAS
FROM WI INTO MI FAVORED FOR VERY COOL AND PERHAPS SHOWERY CONDITIONS.
OUR REGION MORE DOMINATED BY INCOMING CANADIAN HIGH PRESSURE RIDING THUS
DRY AND COOLER... BEING USHERED IN BY GUSTY NORTHWEST WINDS ON SUNDAY.
LOWS SUNDAY NIGHT IN THE UPPER 40S TO LOWER 50S...BUT SHOULD WINDS DROP
OFF MORE THEN WITH 850 MB TEMPS AROUND 6-8C COULD SEE MORE WIDESPREAD
MID TO UPPER 40S WITH POSSIBLY LOWER 40S IN FAVORED DRAINAGE SITES.

MONDAY-WEDNESDAY... GENERALLY DRY AND SEASONABLY COOLER WITH CANADIAN
HIGH PRESSURE THE DOMINANT WEATHER FEATURE. DUE TO DRY AIR WILL LIKELY
NEED TO EXPAND THE DIURNAL RANGE FEW TO SEVERAL DEGS POSSIBLY
WARMER DURING DAY AND COOLER AT NIGHT... WHERE ONE OR TWO MORNINGS
HAVE POTENTIAL FOR LOWS IN THE 30S... MONDAY AND ESPECIALLY
TUESDAY MORNING BEING FAVORED SECOND MORNING AFTER FRONTAL PASSAGE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1129 PM CDT WED SEP 17 2014

QUIET VFR WEATHER SHOULD LAST ANOTHER 24 PLUS HOURS FOR MOST OF
EASTERN IOWA AND NORTHWEST ILLINOIS. WINDS WILL BE LIGHT EAST TO
SOUTHEAST...AND REMAIN UNDER 7 KTS. CLEAR SKIES MAY GIVE WAY TO
MVFR STRATUS AND LIGHT FOG LATE TONIGHT IN WISCONSIN AND EXTREME
NORTHERN ILLINOIS. THIS COULD IMPACT THE DBQ TERMINAL...AND A
TEMPORARY LOWER VFR CONDITION HAS BEEN PLACED INTO THE 11Z-15Z/18
TIME FRAME. THIS IS DUE TO POSSIBLE LAKE MICHIGAN ASSISTED STRATUS
ARRIVING ON NORTHEAST WINDS ALOFT. HOWEVER...WHILE COMPUTER MODELS
SHOW THIS OCCURRING...THEY ARE OVER ESTIMATING THIS STRATUS AT THIS
TIME AND WE WILL BE MORE CONSERVATIVE ON FORECASTING ITS ARRIVAL
COMPARED TO THE COMPUTER MODELS.
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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