Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 051156
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
656 AM CDT WED AUG 5 2015

.SYNOPSIS...
ISSUED AT 330 AM CDT WED AUG 5 2015

SHORTWAVE OVER NE EARLY THIS AM WITH AREA OF CONVECTION ON
SOUTHERN FLANK INTO NORTH CENTRAL KS. BAND OF WIDELY SCATTERED
SHOWERS EXTENDS ROUGHLY FROM NORTHWEST IA (NEAR KSUX) TO SOUTHEAST
IA (NEAR KFFL) WITHIN ZONE OF WEAK ELEVATED THETA-E ADVECTION AND
ISENTROPIC ASCENT. AT THE SURFACE...A STATIONARY FRONTAL ZONE
MEANDERS FROM NORTHWEST KS TO SOUTHEAST NE THEN ACROSS CENTRAL MO.
DEEPER MOISTURE IS POOLING ALONG AND SOUTH OF THE BOUNDARY WITH
A LOW LEVEL MOISTURE GRADIENT NOTED ACROSS CWA WITH DEWPTS IN THE
LOW 60S SOUTH TO LOW 50S NORTH WHERE STILL UNDER INFLUENCE OF
WEAK RIDGING EXTENDING FROM THE UPPER MIDWEST TO THE OHIO VALLEY.
LINGERING NORTHWEST FLOW ALOFT ATTENDANT TO JAMES BAY UPPER LOW
LOOKS TO SHUTTLE PLAINS SYSTEM E/SE... AND INTERACTING WITH THE
FRONT AND DEEPER MOISTURE FOR MORE WIDESPREAD RAINS JUST SOUTH OF
THE CWA ACROSS PORTIONS OF KS...MO AND DOWNSTATE IL. STILL RAIN
CHANCES EXIST INTO THIS EVENING MAINLY IN SOUTHERN CWA RESIDING
IN CLOSER PROXIMITY TO FORCING AND WITHIN THE BETTER MOISTURE WITH
LAYER PWATS OF 1.2 TO 1.6 INCHES.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT WED AUG 5 2015

SHORTWAVE OVER NE TO SLIDE E/SE NEXT 24 HRS AND INTERACT WITH
STALLED FRONT FOR BEST RAIN CHANCES SOUTH OF THE CWA FROM KS
THROUGH MO INTO SOUTHERN IL. NORTHERN HALF TO POSSIBLY 2/3RDS OF
CWA LOOK TO REMAIN DRY BEING UNDER INFLUENCE OF SURFACE RIDGING
AND STRENGTHENING SFC TO 850 MB DRY EASTERLY FLOW AS SYSTEM SLIDES
TO OUR SOUTH. WHILE THIS IS GREAT NEWS FOR THE OUTDOOR ACTIVITIES
MANY AREAS ESPECIALLY ALONG/N OF I-80 ARE DRYING OUT PAST 2-3+
WEEKS... AND COULD USE SOME MOISTURE RECEIVING ONLY ABOUT 25-35
PERCENT OF NORMAL RAINFALL DURING THAT TIME. WILL MAINTAIN THE
RAIN CHANCES FOR AREAS MAINLY ALONG/S OF HWY 34... BUT EVEN THESE
AREAS NOT CONFIDENT ON SEEING MORE THAN JUST SPOTTY PRECIP WITH
WEAKENING ISENTROPIC ASCENT AND ADVECTION THIS AM... AND WITH THE
FORCING ATTENDANT TO SHORTWAVE SLIDING JUST SOUTH LATER TDY AND
TNGT. BY MID TO LATE EVE AND PRECIP CHANCES SOUTH SHOULD DIMINISH
WITH EAST TO NORTHEAST FLOW USHERING IN DRYING AS SYSTEM PULLS
INTO THE OHIO VALLEY.

AS FOR TEMPS... ANTICIPATE MORE OF THE SAME WITH HIGHS IN THE RANGE
OF 76-78 WHERE CLOUD COVER MORE OPAQUE AND LINGERS... WHILE AREAS
THAT SEE MORE IN WAY OF FILTERED SUNSHINE WILL BE AROUND 80 OR THE
LOWER 80S. STILL PLEASANT NORTH WITH DRIER AIR AND LOWER HUMIDITY
WHILE MORE HUMID SOUTH. LOWS TONIGHT MAINLY IN THE UPPER 50S TO
LOWER 60S... COOLEST READING NORTH 1/3-1/2 WHERE MORE CLEARING IS
ANTICIPATED.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 330 AM CDT WED AUG 5 2015

MAIN FORECAST FOR THE EXTENDED IS THE COMPLEX WEATHER PATTERN THE
NEXT COUPLE OF DAYS AND THEN A RETURN TO NW FLOW.  MODELS HAVE BEEN
VARYING WIDELY THE PAST FEW NIGHTS AND HAS LEAD TO LOW CONFIDENCE IN
THE FORECAST.  IT APPEARS AT THIS TIME WE WILL MISS MUCH OF THE BULK
OF ANY RAIN THE REST OF THE WORK WEEK.

THURSDAY THROUGH SATURDAY...

ANOTHER NEARLY STACKED SYSTEM WILL TRANSVERSE THE FLOW.  THE ECMWF
MOVES THIS SYSTEM AND LOW DUE EAST INTO A WEAK TROF.  THE GFS DIVES
SOUTH AND WITH IT THE LOW.  THE ECM KEEPS THE BULK OF THE PRECIP
NORTH AND THE GFS DEVELOPS PRECIP ACROSS THE AREA THURSDAY NIGHT.  I
LIKED HOW THE GFS MOVED THE WAVE SOUTH WITH THE FLOW BUT THINK THE
QPF AND DIVE SOUTH WITH THE LOW IS OVERDONE.  THE ECM DOESNT SEEM
REASONABLE WITH THE WAVE ADVECTING STRAIGHT EAST ACROSS THE FLOW.
THERE APPEARS TO BE A MOVING OMEGA BLOCK THAT THE TROF MOVES
THROUGH.  IF THIS IS THE CASE...THE WAVE MAY BE SLOWER...WHICH
SUPPORTS A SOUTHERN MOVEMENT TO THE WAVE.  AS A RESULT...WENT WITH A
BLEND BETWEEN THE TWO WHERE AREAS NORTH OF I80 ARE CHC TO HIGH CHC
POPS.  THE CHC OF POPS SHOULD MOVE THROUGH THE AREA IN THE LATE
AFTERNOON.  AFTER THIS...THE MODELS HAVE HIGH PRESSURE MOVING IN AT
THE SFC.  ALOFT...IT IS A DIFFERENT STORY.

A WAVE ACROSS THE PLAINS SHOULD MOVE INTO W IA NEAR 12Z FRIDAY.
WITH THIS WAVE A MCS IS LIKELY.  ALL THE PARAMETERS ARE IN PLACE
THAT IF THE WAVE IS SLIGHTLY FASTER...THE MCS WILL MOVE INTO OUR
AREA SATURDAY AM.  RIGHT NOW MODEL QPF LAGS THE WAVE.  THIS DOESNT
SEEM RIGHT.  AS A RESULT...IM STARTING TO THINK WE WILL SEE A MCS.
IF THIS OCCURS...OUR CHANCES OF SEEING RAIN THROUGH THE REST OF THE
WEEK WILL INCREASE DRAMATICALLY.  WILL BRIEF THE ONCOMING SHIFT OF
THIS AND SEE WHAT LATER MODELS DO.

SATURDAY ON...

THE MODELS TRY TO KEEP THE MCS ACROSS NE AT 12Z MOVING ACROSS IA.
AS A RESULT...SUPERBLEND HAS POPS IN FOR SATURDAY.  MY GUT IS THAT
THE BEST CHANCES FOR POPS WILL BE BETWEEN 06Z AND 18 SATURDAY.
AFTER THIS...THERE IS SHORT REPRIEVE BEFORE THE ANOTHER WAVE MOVES
THROUGH THE FLOW.  THIS WAVE BRINGS A CHANCE FOR POPS ON SUNDAY
NIGHT INTO MONDAY.  MODELS ARE IN DECENT AGREEMENT.  AFTER
THIS....HIGH PRESSURE BUILDS IN AS TEMPS REMAIN IN THE LOW 80S.  WE
ARE STILL IN NW FLOW SO ANY RIPPLES IN THE FLOW COULD LEAD TO POPS
ACROSS THE AREA NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 655 AM CDT WED AUG 5 2015

VFR CONDITIONS ARE EXPECTED THROUGH THE TAF CYCLE WITH EASTERLY WINDS
MAINLY BLO 10 KTS. A FEW SHOWERS WILL BE POSSIBLE LATE THIS AM THROUGH
EARLY EVENING...MOSTLY SOUTH OF KBRL.

&&

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

$$

SYNOPSIS...MCCLURE
SHORT TERM...MCCLURE
LONG TERM...GIBBS
AVIATION...05



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