Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 162030
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
330 PM CDT SAT AUG 16 2014

.SYNOPSIS...
ISSUED AT 330 PM CDT SAT AUG 16 2014

A WEAK AREA OF LOW PRESSURE AT THE SURFACE AND ALOFT WAS CENTERED
OVER SE IA/FAR NE MO AT MID AFTERNOON. WHILE THIS FEATURE PRODUCED
HEAVY RAINFALL AMOUNTS OVERNIGHT IN A STRIP ACROSS S CENTRAL IA AND
ADJACENT N CENTRAL AND NORTHEAST MO...IT HAS SINCE WEAKENED TO A
SMALL AREA OF RAIN SHOWERS CONFINED TO SCOTLAND AND CLARK COUNTIES
AS OF MID AFTERNOON. VISIBLE SATELLITE IMAGES SHOWED A RELATED
CLOUD SHIELD COVERING THE SOUTHEAST HALF OF IA AND MUCH OF
IL...WHILE CONVECTIVE LOOKING ELEMENTS WERE POPPING UP IN THE MORE
UNSTABLE WARM SECTOR OF THE SYSTEM OVER NORTHERN MO. 12Z ANALYSIS
INDICATED A RATHER MOIST AIRMASS OVER THE ENTIRE N CENTRAL U.S.
UNDER A WEAK CYCLONIC UPPER LEVEL NW FLOW. GULF MOISTURE PULLED
INTO THE REGION AHEAD OF THE CURRENT SYSTEM HAS RETURNED DEWPOINTS
TO THE UPPER 60S TO LOWER 70S...WHICH ARE MORE TYPICAL VALUES FOR
MID AUGUST THAN THOSE SEEN OVER THE PAST COUPLE WEEKS.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 330 PM CDT SAT AUG 16 2014

TRENDS WITH PRECIPITATION AND POSSIBILITY OF OVERNIGHT FOG ARE THE
PRIMARY FORECAST CONCERNS. SATELLITE LOOPS SUGGEST THE UPPER LEVEL
WAVE WILL CONTINUE DRIFTING/EVOLVING E-SE...WHILE AT THE SURFACE...AN
AXIS OF PRESSURE FALLS WAS DEVELOPING OVER THE MO BOOT HEEL. THIS E-SE
MOVEMENT...ALONG WITH NEW CONVECTION IN THE FORM OF THUNDERSTORMS...
LIKELY TO DEVELOP ALONG THE ASSOCIATED BOUNDARY TO THE SOUTH IN MO
LATE THIS AFTERNOON...SHOULD KEEP ANY LINGERING PRECIPITATION IN THE
FORM OF JUST LIGHT TO BRIEFLY MODERATE SHOWERS THIS AFTERNOON AND
EVENING LIMITED TO THE FAR SOUTH. WILL KEEP CHANCE POPS FOR THESE
LIGHT SHOWERS GOING IN THE EVENING...TRANSITIONING TO SLIGHT CHANCES
OVERNIGHT AS THE DEFORMATION AXIS NORTH OF THE DEPARTING SURFACE
SLOWLY TRANSITIONS SOUTHEAST OF THE REGION. OVER THE REST OF THE
FORECAST AREA...LIGHT...AND WEAKLY CONVERGENT WINDS...WEAK
SUBSIDENCE UNDER A MID LEVEL SHORTWAVE RIDGE...AND ABUNDANT LOW
LEVEL MOISTURE WILL LIKELY LEAD TO FOG AND LOW CLOUD DEVELOPMENT
OVERNIGHT. THIS FOG MAY BECOME DENSE...ESPECIALLY IF SIGNIFICANT
CLEARING OF MID AND HIGH LEVEL CLOUD COVER OCCURS TO ENHANCE
RADATIONAL COOLING. THIS WILL BE QUESTIONABLE...CONSIDERING THE
POTENTIAL FOR ADDITIONAL HIGH CLOUDS FROM UPSTREAM STORM COMPLEXES
IN THE NORTHERN PLAINS. FOR NOW...HAVE GONE WITH ONLY PATCHY FOG
WORDING...LEAVING ROOM FOR FINE TUNING LATER THIS EVENING.

SUNDAY...THE REGION WILL BE IN A WEAK LULL...AND ANTICYCLONIC LOW
LEVEL FLOW...BETWEEN THE CURRENT SYSTEM MOVING INTO SOUTHERN IL
AND THE WEAKENING SYSTEM FURTHER NORTH EXITING FROM THE DAKOTAS.
WILL KEEP SLIGHT CHANCES FOR SHOWERS GOING IN THE FAR SOUTH AND
SOUTHEAST THROUGH THE DAY CLOSEST TO THE WEAK CYCLONIC LOW LEVEL
FLOW. BASED ON THE THERMAL RESPONSE TO THE FILTERED SUNSHINE IN
THE NORTH TODAY...WILL GO WITH HIGHS AROUND 80 OVER MUCH OF THE
AREA AS CLOUDS SHOULD BE MUCH THINNER DURING THE DAY. THE
EXCEPTION WILL BE IN THE FAR NORTHEAST...WHERE THE STRONGER
EASTERLY FLOW OUT OF THE LAKES WILL HAVE A GREATER IMPACT AND HOLD
HIGHS IN THE UPPER 70S.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 330 PM CDT SAT AUG 16 2014

FORECAST FOCUS ON TEMPERATURES TRENDING TO ABOVE NORMAL.

MONDAY THROUGH TUESDAY...UPPER LEVEL TROUGH DIGS SOUTHEAST INTO THE
MIDWEST BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS. THE CURRENT
GRIDS WILL HAVE HIGH TEMPERATURES IN THE 80S BUT AS WE HAVE SEEN
LATELY WITH THESE SYSTEMS READINGS MAY STAY IN THE 70S...DEPENDING ON
AMOUNT OF CLOUD COVER AND COVERAGE OF RAIN.

WEDNESDAY THROUGH SATURDAY...OPERATIONAL MODELS SUGGESTING A MAJOR
PATTERN CHANGE TO HOTTER WEATHER. BUILDING HEIGHTS IN THE MIDDLE OF
THE COUNTRY WILL ALLOW FOR HOT AND HUMID WEATHER TO PUSH NORTHWARD
OUT OF THE SOUTHERN PLAINS. BY THE WEEKEND THE ECMWF/GFS INDICATE A
CLASSIC OMEGA BLOCK FORMING WITH DEEP TROUGHS IN THE EASTERN AND
WESTERN UNITED STATES...AND STRONG RIDGE IN THE MIDDLE. THE RING OF
FIRE SETS UP NORTH OF THE DVN CWA. BUT BEFORE THAT HAPPENS A STRONG
WARM FRONT MAY TRIGGER SOME THUNDERSTORMS ESPECIALLY IN OUR NORTH
WEDNESDAY NIGHT INTO THURSDAY. LATER NEXT WEEK AND INTO THE FOLLOWING
WEEKEND AFTERNOON TEMPERATURES SHOULD PUSH WELL INTO THE 80S TO
LOWER 90S...WITH POSSIBLY EVEN HOTTER READINGS BEYOND THIS PERIOD
THAT MAY LAST AT LEAST SEVERAL DAYS.

HAASE

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1250 PM CDT SAT AUG 16 2014

SLOW MOVING LOW PRESSURE SYSTEM OVER NORTHEAST MISSOURI WILL KEEP
LOW CLOUDS IN PLACE OVER MUCH OF THE AREA THROUGH THIS AFTERNOON
WITH CEILINGS HOLDING AT MVFR LEVELS OVER ALL BUT DBQ. THE
LINGERING MOISTURE IS LIKELY TO LEAD TO LOW CLOUDS AND FOG
OVERNIGHT AND THE LATEST FORECAST WILL MAINTAIN DETERIORATING
CONDITIONS WITH BOTH CIGS AND VISIBILITIES IN THE EVENING HOURS.
IFR CONDITIONS ARE EXPECTED TO BE WIDESPREAD AND AFFECTING ALL
TERMINALS LATE TONIGHT WITH PERIODS OF LIFR LIKELY OVERNIGHT INTO
SUNDAY MORNING. CONDITIONS WILL LIKELY IMPROVE TO AT LEAST MVFR AFTER
SUNRISE SUNDAY MORNING...BUT CONFIDENCE IS LOW IN THE TIMING AND
DETAILS OF THIS TRANSITION IN THE FINAL 6 HOURS OF THE FORECAST.


&&

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

$$

SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...HAASE
AVIATION...SHEETS





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