Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 270832
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
332 AM CDT WED AUG 27 2014

.SYNOPSIS...
ISSUED AT 331 AM CDT WED AUG 27 2014

AT 3 AM...MSAS SURFACE PRESSURE FIELDS INDICATED HIGH PRESSURE OVER
NORTHERN MN...WITH THE SURFACE FRONT WELL SOUTH ALONG THE I-70
CORRIDOR IN IL AND MO. AREA RADARS SHOWED SCATTERED...ELEVATED
WEAK SHOWERS STREAMING EAST ALONG THE I-80 CORRIDOR FROM DSM TO
THE QUAD CITIES WITH A ISOLATED SHOWERS OVER SE IA AND W CENTRAL
IL. A MORE SIGNIFICANT...AND SO FAR SLOW MOVING...MCS WAS ALONG
THE IA/NE/MO BORDER AREA...IN AN AXIS OF MORE SIGNIFICANT 850
THETAE CONVERGENCE. VERY LIGHT NORTH TO NORTHEAST WINDS OUT OF THE
MN HIGH WAS PULLING IN COOLER AND DRIER AIR AT THE LOW
LEVELS...WITH WIDESPREAD TEMPERATURES IN THE MID TO UPPER 60S AND
A FEW READINGS NEAR 70 IN THE FAR SOUTH.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 331 AM CDT WED AUG 27 2014

IN THE NEAR TERM...ELEVATED THETAE CONVERGENCE FIELDS IN THE
RAP...WHICH HAD A GOOD CORRELATION WITH THE STORMS IN SW IA...WOULD
SUPPORT THE STORM CLUSTER SLOWLY DRIFTING EAST THROUGH
SUNRISE...REACHING THE FAR SOUTHWEST AND SOUTH BEFORE DISSIPATING BY
MID MORNING. ELSEWHERE...THERE IS NOT MUCH SUPPORT OR MID LEVEL
INSTABILITY TO SUGGEST THE ELEVATED SHOWERS AND ISOLATED
THUNDERSTORMS OVER THE CENTRAL AND SOUTH WILL RAMP UP LIKE PREVIOUS
MORNINGS AND WILL MAINTAIN LOW CHANCE POPS. HIGHER CHANCE POPS ARE
MAINTAINED MAINLY SOUTH OF THE HIGHWAY 34 CORRIDOR IN SE IA...WHERE
WEAK MOISTURE CONVERGENCE AT 850 MB CONTINUES THIS MORNING.
BEYOND...RAIN CHANCES HAVE BEEN REMOVED OVER ALL BUT THE FAR SOUTH
FROM LATE MORNING THROUGH AFTERNOON AS A LOW LEVEL EASTERLY FLOW
CONTINUES TO ADVECT IN DRIER AIR UNDER A WEAK MID LEVEL RIDGE.
TEMPERATURES WILL BE SIMILAR TO A BIT COOLER THAN YESTERDAY DUE TO
THE EASTERLY FLOW AND LIKELY INCREASED CLOUD COVER.

TONIGHT...ALL MODELS HAVE THE NEXT MCS DEVELOPING OVER WESTERN OR NW
IA AROUND MIDNIGHT...EXPANDING EAST TOWARD MORNING. HAVE ADJUSTED
POPS ACCORDINGLY...WITH MUCH SLOWER TIMING RESULTING IN A DRY NIGHT
IN THE EAST AND LATER ONSET CENTRAL AND WEST. HEAVY RAINFALL DOES
NOT LOOK TO BE A MAJOR THREAT AS MCS GENERATION AND MAINTENANCE
TOOLS POINT TOWARD THE BEST FORCING NOT ADVANCING MUCH PAST NW OR
POSSIBLY N CENTRAL IA BY 12Z.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 331 AM CDT WED AUG 27 2014

THERE SHOULD BE A RESPECTABLE THUNDERSTORM COMPLEX ACROSS NORTHERN
IOWA THURSDAY MORNING WITH A WING OF CONVECTION MOVING ACROSS THE
AREA. THE NORTHWEST HALF OF THE AREA HAS THE BETTER CHANCES FOR
RAIN. BOUNDARIES LEFT OVER FROM THE MORNING STORM COMPLEX WILL
PROVIDE THE FOCUS FOR SCATTERED CONVECTION IN THE AFTERNOON AND
EVENING.

ALTHOUGH THE SIGNAL IS NOT AS CLEAR...ANOTHER ORGANIZED THUNDERSTORM
COMPLEX SHOULD DEVELOP WEST OF THE AREA THURSDAY EVENING AND MOVE
EAST NORTHEAST LATE THURSDAY NIGHT INTO FRIDAY MORNING. THE
NORTHWEST THIRD TO HALF OF THE AREA HAS THE BETTER CHANCES FOR RAIN.

BOUNDARIES FROM THE FRIDAY MORNING STORM COMPLEX WOULD AGAIN PROVIDE
THE FOCUS FOR SCATTERED CONVECTION THAT DEVELOPS FRIDAY AFTERNOON
AND EVENING.

LATE FRIDAY NIGHT ANOTHER FRONT OR BOUNDARY IS FORECAST TO BEGIN
MOVING INTO THE AREA. THE COMBINATION OF MOISTURE AND FORCING SHOULD
RESULT IN SCATTERED CONVECTION PERSISTING THROUGH SUNRISE SATURDAY.

SATURDAY ON...
THE OVERALL WEATHER PATTERN IS SUPPORTIVE OF NOCTURNAL THUNDERSTORM
COMPLEXES ACROSS THE MIDWEST. WHERE EACH DEVELOPS AND MOVES AFFECTS
SUBSEQUENT DEVELOPMENT. AS A RESULT...THERE WILL BE PERIODS OF DRY
WEATHER THAT MAY BE 6-12 HOURS IN DURATION.

TEMPERATURES SATURDAY THROUGH TUESDAY SHOULD BE NEAR NORMAL.

THE MODEL CONSENSUS HAS CHANCE TO LIKELY POPS FOR SATURDAY AND
SLIGHT CHANCE TO CHANCE POPS SATURDAY NIGHT.

THE MODEL CONSENSUS HAS SLIGHT CHANCE POPS FOR THE AREA
SUNDAY/SUNDAY NIGHT. SEVERAL MODELS ARE SUGGESTING HIGH PRESSURE
MOVING THROUGH THE AREA ON SUNDAY WHICH MAY RESULT IN DRY CONDITIONS.

MONDAY THROUGH TUESDAY THE MODEL CONSENSUS HAS CHANCE POPS FOR EACH
12 HOUR PERIOD.


&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1129 PM CDT TUE AUG 26 2014

VFR CONDITIONS WILL PREVAIL THROUGH AT LEAST ABOUT 27/10Z. ANOTHER
COMPLEX OF SHOWERS AND STORMS IS EXPECTED TO DEVELOP LATE OVERNIGHT
ACROSS THE REGION INTO EARLY WEDNESDAY MORNING. THIS IS HANDLED AS A TEMPO
GROUP OF MVFR CONDITIONS BETWEEN 10-14Z AT ALL SITES. VFR CONDITIONS
WITH PARTLY CLOUDY SKIES WILL THEN PERSIST THROUGH 28/00Z. AN INCREASING
CHANCE OF MORE SHOWERS AND THUNDERSTORMS IS POSSIBLE TOWARD 28/06Z...BUT
ARE LEFT OUT DUE TO UNCERTAINTY OF TIMING OF THE ARRIVAL. NORTHEAST
WINDS OF 3-7 KTS WILL SHIFT TO THE EAST AT 3-9 KTS ON WEDNESDAY MORNING.

&&

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

$$

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





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