Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 040831
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
331 AM CDT SAT JUL 4 2015

.SYNOPSIS...
ISSUED AT 330 AM CDT SAT JUL 4 2015

THE LATEST SFC ANALYSIS WAS INDICATING RIDGE AXIS OCCUPYING MUCH OF
THE CENTRAL PLAINS INTO THE SOUTHWESTERN GRT LKS/INCLUDING THE
ENTIRE DVN CWA WHICH CURRENTLY HAS CALM WINDS/...WITH A WEAK TROF
SAGGING ACRS EAST CENTRAL MN...NORTHWEST WI AND THE U.P. OF MI. TO
THE WEST OF THE RIDGE...RETURN FLOW WAS SEEN ORGANIZING ACRS THE
WESTERN PLAINS. ALOFT...AN UPPER RIDGE LOBE WAS PRESSING EASTWARD
TOWARD THE UPPER MS RVR VALLEY...WHILE FURTHER UPSTREAM A VORT MAX
WAS SEEN ON WATER VAPOR IMAGERY ACRS THE DAKOTAS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT SAT JUL 4 2015

TODAY...PATCHY FOG EARLY...THEN THE SFC RIDGE OVERHEAD WILL SLOWLY
MIGRATE EASTWARD ENOUGH TO ALLOW LIGHT RETURN FLOW TO TAKE OVER AS
THE DAY PROGRESSES. THE UPSTREAM UPPER RIDGE AXIS MENTIONED ABOVE
WILL CONTINUE TO PUSH EAST ACRS THE LOCAL AREA TODAY MAINTAINING
THE FAIR WX REGIME INTO THE EVENING. SOMEWHAT MODERATING THERMAL
PROFILES AND PROGGED MIXING DEPTH SUPPORT MODEL GUIDANCE
WIDESPREAD LOWER 80S TODAY...WITH A FEW LOCATIONS PUSHING THE MID
80S. SFC DPTS IN THE UPPER 50S TO LOWER 60S COMBINED WITH THE WARM
AMBIENT TEMPS WILL KEEP A LID ON THE HUMIDITY LEVELS. ANOTHER DAY
WITH ADVECTED SMOKE ALOFT MAKING FOR HAZY FILTERED SUNSHINE.

TONIGHT...THE ELONGATED VORT COMPLEX WILL LOOK TO PUSH OUT OF THE
NORTHERN PLAINS AND ACRS THE UPPER MS RVR VALLEY INTO SOUTH CENTRAL
IA BY SUNDAY MORNING. BUT FEEL NOT ENOUGH LLVL MOISTURE RETURN AND
CONVERGENCE ON IT/S INCOMING VORT GRADIENT TO FUEL MUCH OF ANY
PRECIP GENERATION IN OR JUST TO THE WEST OF THE LOCAL FCST AREA AND
WILL MAINTAIN A DRY FCST. LIGHT SOUTH TO SOUTHEAST SFC FLOW TO
CONTINUE... BUT THERE STILL MAY BE SOME PATCHY FOG OR VALLEY FOG
WITH THE CHC FOR THE SFC WINDS TO DECOUPLE FROM TIME TO TIME. A
CATEGORY MILDER LOW TEMP REGIME AS COMPARED TO PREVIOUS NIGHTS WITH
THE LIGHT RETURN FLOW AND LOWS IN THE UPPER 50S TO LOWER 60S.
  ..12..

.LONG TERM...(SUNDAY THROUGH NEXT FRIDAY)
ISSUED AT 330 AM CDT SAT JUL 4 2015

MAIN FOCUS IS ON THE FRONTAL PASSAGE THAT WILL BRING WIDESPREAD RAIN
AND THUNDERSTORMS MONDAY INTO MONDAY NIGHT. AHEAD OF THIS...WARM
ADVECTION SOUTHERLY FLOW WILL BRING MUCH WARMER AND CONSIDERABLY
MORE HUMID CONDITIONS FOR SUNDAY.

THE COMBINATION OF HIGH PRESSURE SHIFTING INTO THE EASTERN GREAT
LAKES AND A DEVELOPING LEE TROUGH OVER THE PLAINS WILL LEAD TO S-SE
WINDS THAT WILL ADVECT A MORE MOIST MID MS VALLEY AIRMASS NORTHWARD
INTO THE REGION. THIS SHOULD RESULT IN DEWPOINTS RISING INTO THE MID
60S TO NEAR 70 FOR NOTICEABLY MORE HUMID CONDITIONS SUNDAY. WARMING
ALOFT STILL SUPPORTS HIGHS IN THE MID 80S AND POSSIBLY UPPER 80S.
CLOUD COVER WILL BE INCREASING SUNDAY NIGHT AS BLOWOFF FROM UPSTREAM
MCS ACTIVITY OVERSPREADS THE AREA...WHICH COMBINED WITH INCREASING
LOW LEVEL MOISTURE WILL HOLD MINS IN THE MID 60S TO AROUND 70.

MONDAY...THE 00Z GFS CAME IN FASTER WITH THE COLD FRONTAL
PASSAGE...WHILE THE NAM...ECMWF AND CANADIAN WERE IN BETTER
CONSENSUS WITH A SLOWER FROPA WHICH WOULD NOT EXIT TO THE EAST UNTIL
WELL AFTER MIDNIGHT. HAVE TRENDED TOWARD THE MORE REASONABLE SLOWER
SOLUTIONS...WHICH DELAYS AND LOWERS POPS OVER THE EAST...WHILE
KEEPING LIKELY TO CATEGORICAL POPS GOING WEST FOR AFTERNOON INTO
EVENING...SPREADING EAST OVERNIGHT. THERE IS STILL A SUGGESTION OF
ELEVATED CONVECTION POPPING UP OVER THE AREA IN THE MORNING...WHICH
IS HANDLED WITH SLIGHT TO LOW END CHANCE POPS. FORECAST PW VALUES
WELL OVER 2 INCHES MAY BE OVERDONE...AND INFLUENCED BY PROGGED
DEWPOINTS SHOWN IN THE MID 70S AHEAD OF THE FRONT WHICH SEEM TOO
HIGH CONSIDERING THE LACK OF MOISTURE POOLING AND DEEP MIXING.
HOWEVER...MOISTURE LEVELS WILL STILL BE SEASONABLY HIGH...LEADING TO
A THREAT OF HEAVY RAIN. MUCAPES VALUES AT LEAST INTO THE 1500 TO
2000 J/KG RANGE WITH MODEST 0-6 KM SHEAR VALUES POSSIBLY AS HIGH AS
30 TO 35 KTS MAY SUPPORT ISOLATED SEVERE STORMS WITH PRIMARILY A
DAMAGING WIND THREAT ALONG AND AHEAD OF THE COLD FRONT IN THE LATE
AFTERNOON AND EVENING. THE INCREASED CLOUD COVER AND PRECIPITATION
WILL KEEP HIGHS A FEW DEGREES COOLER THAN SUNDAY.

TUESDAY THROUGH FRIDAY...WILL KEEP THUNDERSTORM CHANCES GOING
THROUGH THE NIGHT INTO EARLY TUESDAY MORNING TO COVER THE POSSIBLE
SLOWER FROPA. AFTER THIS...MUCH OF TUESDAY THROUGH WEDNESDAY SHOULD
BE DRY AND COOLER AS HIGH PRESSURE PASSING TO THE NORTH SETS UP
ANOTHER PERIOD OF EASTERLY WINDS. THIS WILL LIMIT HIGHS TO THE 70S
WHILE DRIER AIR LEADS TO MINS FROM THE MID 50S TO LOWER 60S. THE
LATE WED THROUGH FRI PERIOD REMAINS LOW CONFIDENCE AS THE ECMWF AND
GFS DIFFER IN THE HANDLING AND TIMING OF SUBSEQUENT MID LEVEL
SHORTWAVES AND PLACEMENT OF THE RETURNING WARM FRONT THAT WILL
INFLUENCE RAIN CHANCES. FOR NOW...OUR CONSENSUS BLEND APPROACH WILL
KEEP CHANCE TO SLIGHT CHANCE POPS FOR SHOWERS AND THUNDERSTORMS OVER
ESPECIALLY THE SOUTH THROUGH THIS PERIOD. CONFIDENCE IS HIGHER THAT
TEMPERATURES WILL BE BELOW NORMAL WITH HIGHS FROM THE MID 70S TO
LOWER 80S WITH OVERNIGHT LOWS IN THE 60S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1129 PM CDT FRI JUL 3 2015

GENERALLY VFR CONDITIONS NEXT 24 HOURS WITH FAIR SKIES OF A MILKY
COMPLEXION FROM CANADIAN WILD FIRES SMOKE AND LIGHT WINDS THE NEXT
24 HOURS AS HIGH PRESSURE OVERHEAD DOMINATES. SOME LIGHT AVIATION
FOG POSSIBLE LATE OVERNIGHT UNTIL EARLY SATURDAY DUE TO CALM WINDS.

&&

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

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...SHEETS
AVIATION...NICHOLS



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