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000
FXUS63 KDVN 171123
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
623 AM CDT MON JUN 17 2013

.SYNOPSIS...
ISSUED AT 330 AM CDT MON JUN 17 2013

RATHER WEAK SURFACE PRESSURE FEATURES WERE FOUND ACROSS THE REGION
THIS MORNING...FEATURING A BROAD AREA OF LOW PRESSURE FROM WESTERN
WI INTO NORTHERN MO AND HIGH PRESSURE EXTENDING FROM THE NORTHERN
HIGH ACROSS NEB INTO WESTERN IA. A WEAK SURFACE BOUNDARY...MAINLY
EVIDENT IN LOW LEVEL MOISTURE FIELDS...STRETCHED ACROSS SOUTHERN IA
AND NORTHERN IL JUST SOUTH OF THE I-80 CORRIDOR. DEWPOINTS WERE IN
THE 60S TO THE SOUTH...WHERE TEMP-DEWPOINT SPREADS WERE NARROWING
AND FOG WAS STARTING TO FORM OVER NORTHEAST MO. NORTH OF THE
BOUNDARY...DEWPOINTS WERE IN THE 50S UNDER MOSTLY CLEAR SKIES ACROSS
EASTERN IA AND NORTHERN IL. A SOMEWHAT STRONGER COLD FRONT WAS TO
THE NORTH...EXTENDING WEST FROM THE MN LOW PRESSURE COMPLEX.
TONIGHT/S MCS ACTIVITY HAS REMAINED WELL TO THE SOUTH ACROSS KS...OK
AND MO WHERE MID LEVEL SHORTWAVES IN THE UPPER LEVEL NW FLOW WERE
INTERACTING WITH DEEP LOW LEVEL MOISTURE. A WEAKER WAVE
MOVING ACROSS MN INTO WI WAS TRIGGERING MORE ISOLATED THUNDERSTORMS
ACROSS WI. UPSTREAM...A WEAK SHORTWAVE MOVING OUT OF NE WY INTO SD
WILL BE A FEATURE TO WATCH AS IT PROGRESSES E-SE THROUGH THE
FORECAST AREA DURING PEAK HEATING.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT MON JUN 17 2013

MAIN CHALLENGES CENTER AROUND THUNDERSTORM CHANCES THIS AFTERNOON
AND TONIGHT. TODAY COULD POTENTIALLY BE A BIT WARMER THAN THE PAST
COUPLE DAYS DEPENDING ON CONVECTIVE AND CLOUD COVER TRENDS.

00Z MODELS DID NOT APPEAR TO HAVE A GOOD HANDLE ON THE WEAK WY
IMPULSE THAT AT THE CURRENT RATE WILL REACH THE FORECAST AREA AROUND
MID AFTERNOON. THIS MAY BE ENOUGH TO TRIGGER THUNDERSTORMS ALONG THE
WEAK BOUNDARY THAT WILL LIKELY REMAIN IN PLACE SOMEWHERE ACROSS THE
SOUTH AND ALSO ALONG THE  SECONDARY NORTHERN PLAINS FRONT THAT WILL
BE RATHER DIFFUSE AT THE SURFACE AS IT ENTERS THE NORTH FROM MID TO
LATE AFTERNOON. WITH THESE WEAK TRIGGERS AND SOMEWHAT LIMITED
MOISTURE ALOFT...WILL CONTINUE WIDESPREAD SLIGHT CHANCE POPS FOR THE
AFTERNOON. DEEP LAYER UNIDIRECTIONAL SHEAR AROUND 40 KTS AND
INVERTED V TYPE FORECAST SOUNDINGS MAY SUPPORT STRONG WINDS IN WITH
THUNDERSTORMS...OTHERWISE...THE POTENTIAL FOR SEVERE STORMS IS LOW.
HIGH TEMPERATURES COULD POTENTIALLY REACH THE UPPER 80S IF MIXING IS
AS DEEP AS YESTERDAY...BUT WITH CONVECTION POSSIBLE DURING PEAK
HEATING...WILL STAY MORE CONSERVATIVE WITH WIDESPREAD HIGHS IN THE
MID 80S.

TONIGHT...THE MAIN UPPER SHORTWAVE THAT DRIVES THE COLD FRONT
THROUGH THE AREA IS SHOWN BY A NEAR CONSENSUS OF MODELS ENTERING THE
NORTHERN HALF OF THE FORECAST AREA TOWARD 12Z. WHETHER THIS WILL BE
ENOUGH TO TRIGGER CONVECTION IS QUESTIONABLE GIVEN THE DRY MID AND
UPPER LEVELS SHOWN AT THIS TIME...MARGINAL MID LEVEL LAPSE
RATES...AND DRY NE FLOW AT THE SURFACE DEVELOPING OFF LAKE MI.
WILL THUS KEEP A DRY FORECAST GOING. EARLIER...WILL MAINTAIN
SLIGHT CHANCE POPS IN THE EVENING TO HANDLE ANY LINGERING
CONVECTION FROM THE AFTERNOON. WILL KEEP LOWS FROM THE MID 50S
NORTH TO LOWER 60S SOUTH. THE FAR NORTHEAST COULD POTENTIALLY BE
COOLER AS DEWPOINTS IN THE 50S AND POSSIBLY UPPER 40S BEGIN
REACHING INTO THE AREA TOWARD MORNING.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 330 AM CDT MON JUN 17 2013

A RESPECTABLE SHORTWAVE WILL MOVE THROUGH THE AREA ON TUESDAY. THE
TRENDS WITH THE MODELS HAS BEEN TO MAKE THIS SHORTWAVE STRONGER OVER
TIME. MOISTURE IS LIMITED AND THE INITIAL WEAK THETA E GRADIENT
ACROSS THE AREA DISSIPATES DURING THE DAY. ADDITIONALLY...THE STEEP
MID LEVEL LAPSE RATES BECOME MORE STABLE WITH TIME. THUS SOME
SHOWERS SHOULD BE SEEN ON TUESDAY WITH POSSIBLY A FEW ISOLATED
THUNDERSTORMS.

TUES NIGHT/WED DRY CONDITIONS ARE EXPECTED AS THE NEXT HIGH MOVES
THROUGH THE MIDWEST. TEMPERATURES SHOULD BE NEAR NORMAL FOR HIGHS
BUT LOW TO MID 50S ARE POSSIBLE IN THE DRY AIR OVER THE NORTHEAST
HALF OF THE CWFA.

WED NIGHT RETURN FLOW BECOMES BETTER ESTABLISHED. HOWEVER...THE
BETTER MOISTURE RETURN REMAINS WEST OF THE AREA SO DRY CONDITIONS
SHOULD BE SEEN. THE MCS AND LIFT TOOLS SUGGEST THAT A WEAKLY
ORGANIZED MCS SHOULD DEVELOP IN THE PLAINS AND MOVE INTO
IOWA/MISSOURI BY SUNRISE.

THURSDAY ON...
CONCEPTUALLY...THE OVERALL PATTERN BECOMES MORE ACTIVE AND PLACES
THE CWFA CLOSE TO OR IN THE ACTIVE NOCTURNAL MCS TRACK. THE MODELS
GENERALLY AGREE THAT WEAK SHORTWAVES/VORT MAXES WILL BE TOPPING THE
RIDGE BUT DISAGREE ON THE OVERALL TIMING OF THESE SUBTLE FEATURES.
AS A RESULT...THERE IS A NEAR DAILY CHANCE OF RAIN FOR THE AREA.
THERE WILL BE DRY PERIODS BUT THEY WILL NOT BE KNOWN WITH ANY
CERTAINTY MORE THAN 12 HRS AHEAD OF TIME.

THE MODEL CONSENSUS HAS SCHC POPS OVER THE WESTERN CWFA ON THURSDAY
FOR THE FIRST DECAYING NOCTURNAL MCS. THE MODEL CONSENSUS GIVES
SCHC/CHC POPS FOR THURS NIGHT/FRIDAY FOR THE NEXT NOCTURNAL MCS.

FRIDAY NIGHT THROUGH SUNDAY THE MODEL CONSENSUS HAS CHC POPS FOR
EACH TIME PERIOD. THE MODELS AGREE ON AN ACTIVE WX PATTERN AND THAT
ATMOSPHERIC MOISTURE WILL BE ON THE INCREASE. THIS SIGNAL IMPLIES AN
INCREASED POSSIBILITY OF LOCALLY HEAVY RAINFALL.      ..08..

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 619 AM CDT MON JUN 17 2013

A COUPLE WEAK SURFACE BOUNDARIES OVER THE REGION AND AN UPPER LEVEL
DISTURBANCE MAY LEAD TO ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS. THERE REMAINS A LOW POTENTIAL THAT ANY STORMS WILL
IMPACT ANY PARTICULAR TAF SITE...AND NO MENTION IS INCLUDED IN THE
FORECASTS OUTSIDE OF VCSH WORDING AT CID AND DBQ. OTHERWISE...
CONDITIONS WILL BE VFR WITH LIGHT WEST SOUTHWEST WINDS...VEERING
TO THE NORTHWEST AND THEN NORTH TONIGHT WITH THE PASSAGE OF A WEAK
COLD FRONT. WINDS WILL BECOME NORTHEAST TUESDAY MORNING. &&

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

$$

SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...08
AVIATION...SHEETS