Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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433
FXUS63 KDVN 271756 AAB
AFDDVN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1256 PM CDT WED APR 27 2016

...AVIATION UPDATE...

.SYNOPSIS...
ISSUED AT 322 AM CDT WED APR 27 2016

COLD...STABLE...DRY EAST TO NORTHEAST FLOW CONTINUES OVER THE
CWA...WITH TEMPERATURES HOVERING IN THE LOWER TO MID 40S NORTH OF I-
80 AND IN THE MID TO UPPER 40S FARTHER SOUTH. THIS HAS COMBINED WITH
THE NARROW RIDGE OF HIGH PRESSURE ALOFT OVER THE CWA TO COMPLETELY
LIMIT ANY ADVANCE OF RAIN AND THUNDERSTORMS FROM MISSOURI AND
CENTRAL IOWA THROUGH 2 AM...AND SHOULD CONTINUE TO DO SO THROUGH
AROUND 4 OR 5 AM.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 322 AM CDT WED APR 27 2016

AS SAID IN THE SYNOPSIS...THE UPPER RIDGE AND DRY LOW LEVEL FEED OF
COLD AIR WILL HOLD ANY SHOWERS AT BAY UNTIL THE UPPER RIDGE BEGINS
TO LIFT NORTHEAST THIS MORNING. ONCE THAT PROCESS IS UNDERWAY...A
BAND OF WAA ELEVATED SHOWERS AND THUNDER WILL LIKELY SWEEP NORTH AND
NORTHEAST THROUGH THE ENTIRE CWA. THIS CREATES A TRICKY POP
FORECAST...WHERE WE ARE POSSIBLY BEGINNING THE PERIOD WITH
CATEGORICAL COVERAGE SOUTHWEST AND 100 PERCENT DRY ELSEWHERE...AND
BY MID MORNING...MAY SEE A HIGH COVERAGE BAND LIFTING THROUGH WITH
CATEGORICAL POPS...WITH DRY CONDITIONS SOUTHWEST OF IT. IN
SHORT...IT WILL RAIN...BUT NOT ALL DAY. THERE IS A MEAGER
AMOUNT...500 J/KG...OF MUCAPE AVAILABLE TODAY FOR THIS BAND AS IT
LIFTS NORTHEAST...THUS THUNDER APPEARS TO BE MORE OF AN EMBEDDED
PHENOMENON. TEMPERATURES WILL STRUGGLE TO MOVE TODAY...AND MAY BE
SLOW TO REACH 50 IN MANY SPOTS...BUT A LATE DAY WAA REGIME COULD
ALLOW FOR HIGHS TO EVENTUALLY REACH THE LOWER 50S NORTH TO MID 60S
FAR SOUTH. THIS IS COUNTING ON AFTERNOON RAINS BEING NON-CONTINUOUS.

AFTER THE INITIAL BAND OF WAA RAIN/THUNDER LIFT NORTH...SCATTERED
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP NEAR THE WARM
FRONT IN NORTHERN MISSOURI AND ILLINOIS...AND LIFT NORTH IN A
GRADUAL STRATIFICATION PROCESS THIS AFTERNOON AND OVERNIGHT. THE
HIGHEST COVERAGE OF THIS CONVECTION SHOULD BE PRIOR TO
MIDNIGHT...BUT MAY LINGER IN WIDELY SCATTERED FASHION AFTER THAT.
SPC HAS OUR SOUTH IN SLIGHT RISK...BUT UNLESS OUR BOUNDARY LAYER CAN
UNEXPECTEDLY RECOVER TO THE LOWER 70S...I SEE LITTLE IN ANY
INTERACTION OF STORMS WITH THE BOUNDARY LAYER...THUS WINDS AND
TORNADOES SEEM UNLIKELY. HAIL WILL BE POSSIBLE...AND AN AFTERNOON
STORM WITH QUARTERS IS POSSIBLE IN OUR FAR SOUTH. WE WILL HIGHLIGHT
THAT THREAT IN OUR HWO TODAY.

TONIGHTS TEMPERATURES WILL ONCE AGAIN DROP TO THE LOWER 40S NORTH
WITH BLUSTERY CONDITIONS...WHILE OUR SOUTH REMAINS IN THE LOWER
50S...HELD UP BY INCREASING DEWPOINT VALUES.
ERVIN

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 322 AM CDT WED APR 27 2016

FORECAST FOCUS ON ANOTHER STORM SYSTEM THIS WEEKEND BUT THE LATEST
MODEL RUNS ARE INDICATING LESS RAINFALL.

THURSDAY...OCCLUDED SYSTEM TRACKS ACROSS IOWA AND INTO NORTHERN
ILLINOIS WITH A COLD POCKET ALOFT ALLOWING FOR STEEPENING LAPSE
RATES. SCATTERED SHOWERS CAN BE EXPECTED ALONG WITH ISOLATED
THUNDERSTORMS AS INSTABILITY WILL BE MARGINAL. A WEAK SURFACE LOW
SHOULD TRACK ACROSS OUR SOUTHERN CWA AS PERSISTENT CHILLY NORTHEAST
WINDS OFF THE GREAT LAKES KEEPS THE BOUNDARY SOUTH OF I-80. MAXIMUM
TEMPERATURES WILL RANGE FROM THE CHILLY UPPER 40S ALONG HIGHWAY 20
TO THE MID 60S IN OUR FAR SOUTHERN CWA.

FRIDAY...A DRY DAY AS HIGH PRESSURE BUILDS A BIT FARTHER SOUTH INTO
THE CWA. THIS SHOULD ALLOW FOR AT LEAST SOME SUNSHINE SO WILL CALL
IT PARTLY SUNNY. THIS WILL PUSH AFTERNOON TEMPERATURES TO 60 TO 65
BUT PERSISTENT NORTHEAST WINDS STILL KEEPING READINGS BELOW NORMAL.
IF THERE IS MORE CLOUDINESS THAN EXPECTED THEN TEMPERATURES MAY BE
TOO HIGH.

FRIDAY NIGHT THROUGH SUNDAY...WHAT LOOKED LIKE A REALLY WET WEEKEND
A COUPLE OF DAYS AGO MAY NOT TURN OUT THAT WAY. LARGE SPRAWLING HIGH
PRESSURE IN EASTERN CANADA/GREAT LAKES WILL CONTINUE TO FEED DRY
NORTHEAST WINDS INTO THE CWA. MODELS STARTING TO LATCH ONTO THE IDEA
OF A DRIER WEEKEND ESPECIALLY IN OUR NORTHERN CWA...WHILE
MAINTAINING THE SURFACE BOUNDARY ACROSS MO ALLOWING FOR PERIODS OF
SHOWERS AND ISOLATED STORMS IN OUR SOUTHERN CWA. THIS FORECAST IS
CERTAINLY NOT ETCHED IN STONE JUST YET AS MODELS STRUGGLE WITH THE
LOCATION OF THE BOUNDARY INFLUENCED HEAVILY BY THE DRY AND CHILLY
AIR OFF THE GREAT LAKES. THIS WILL IMPACT TEMPERATURES ALSO AND
THERE MAY BE MORE OF A GRADIENT FROM NORTHEAST TO SOUTHWEST THAN
INDICATED IN THE GRIDS. RAINFALL AMOUNTS OVER THE WEEKEND NOW
EXPECTED TO BE ABOUT 1/2 INCH OR LESS OVER MOST OF THE CWA EXCEPT
THE FAR SOUTH WHICH MAY STILL MANAGE TO RECEIVE AN INCH.

EARLY NEXT WEEK...WENT DRY AS THE STORM SYSTEM SHIFTS WELL TO OUR
EAST AND THE GREAT LAKES HIGH BUILDS EVEN FARTHER SOUTHWARD. THIS
SHOULD ALSO ALLOW FOR SKIES TO BE CLEAR TO PARTLY CLOUDY.
TEMPERATURES WILL BE AT LEAST GETTING CLOSER TO NORMAL WITH HIGHS IN
THE 60S AND LOWS IN THE 40S.

HAASE

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1250 PM CDT WED APR 27 2016

MESSY FORECAST FOR THE TAF PERIOD AS A WARM FRONT TRIES TO MOVE
NORTH INTO A STRONG HIGH PRESSURE OFF OF LAKE MICHIGAN. THE COOLER
AIR FROM THE LAKE ARE LEADING TO MVFR AND IFR CIGS ACROSS THE AREA
TODAY. CHANCES FOR THUNDER ARE POSSIBLE AT CID...MLI AND BRL WITH
AFTERNOON STORMS. THEN THE SLOW MOVING SYSTEM WILL LEAD TO MVFR
AND EVEN IFR CIGS AND VSBYS TOMORROW AM.

&&

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

$$

SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...HAASE
AVIATION...GIBBS



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