Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 241124
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
624 AM CDT THU APR 24 2014

.SYNOPSIS...
ISSUED AT 336 AM CDT THU APR 24 2014

THE SLOW MOVING STORM SYSTEM TO OUR WEST CONTINUES TO GAIN STRENGTH
AND MOISTURE OVER KS THIS MORNING. OUR CWA IS NOW MOSTLY SOUTH OF
THE ELEVATED WAA SHOWERS THAT AFFECTED OUR REGION LAST EVENING. THE
EXCEPTION IS THE FAR NORTH AND NORTHWEST...WHERE ACTIVITY FORMING IN
CENTRAL IOWA CONTINUES TO STREAM OVER THESE LOCATIONS. AS WAS THE
CASE YESTERDAY...THIS ELEVATED ACTIVITY IS NOT LEAVING MUCH QPF
BEHIND.

THE STRONGEST UPPER LEVEL VORTICITY CENTER/UPPER LOW OF THE TWO SET
TO MOVE THROUGH THE MIDWEST IS LOCATED NEAR AMARILLO THIS AS OF 230
AM. MODELS HAVE BEEN MAKING THIS FEATURE THE MORE DOMINANT LOW
TODAY...AND BY THE LOOKS OF WATER VAPOR THAT IS THE RIGHT CALL. I
WILL BASE MY FORECAST ON SEEING THAT FEATURE AS THE MAIN SYNOPTIC
ELEMENT THAT ALL OTHER FEATURES RELATE TO MOST.

ERVIN

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 336 AM CDT THU APR 24 2014

MODELS HAVE BEEN SPLIT ON SHOWING LOW PRESSURE CENTER LOCATIONS WITH
TODAYS FORECAST...WITH EITHER AN ELONGATED LOW FROM MISSOURI TO
MINNESOTA...OR A MORE DISTINCT LOW CENTER MOVING NORTHEAST FROM
KANSAS TO CENTRAL ILLINOIS TODAY INTO TONIGHT. GIVEN THE STRIKING
APPEARANCE OF THE UPPER LOW/VORT OVER THE TX PANHANDLE EARLY
TODAY...I AM CHOOSING TO BELIEVE IN THE MORE COMPACT 500MB LOW AND
STRONGER SURFACE LOW PRESSURE INDICATED BY THE MESO MODELS AND ALSO
THE HIGH RESOLUTION 00Z ECMWF. IN ADDITION...LOW LEVELS ARE
CONTINUING TO FEED IN DRY AIR FROM THE EAST...AND WILL CONTINUE TO
DO SO UNTIL WINDS BECOME MORE SOUTHERLY THIS MORNING. THE MORE
CLOSED LOW SCENARIO WILL FAVOR A SLOWER PROGRESSION EAST OF THE RAIN
TODAY...AND WITH IT PASSING SOUTHEAST OF THE CWA THIS AFTERNOON...IT
APPEARS THE VAST MAJORITY OF OUR PCPN WILL BE RAIN VS SHOWERS AND
STORMS. I CANT RULE OUT SOME EMBEDDED THUNDER TODAY...AND GIVEN THE
STRONG DYNAMICS ARRIVING TOWARDS AFTERNOON AND EVENING...WILL KEEP A
MENTION IN THE FORECAST. THE SLOWER ARRIVAL OF RAIN WILL POSSIBLY
LEAD TO A DRY DAY ALONG AND EAST OF THE MISSISSIPPI RIVER.
TEMPERATURES HAVE BEEN BUMPED UP SOMEWHAT AS WELL FOR HIGHS WITH
MORE OF THE DAY DRY IN THE EAST AS WELL. WILL MARCH CATEGORICAL POPS
EASTWARD FROM LATE MORNING WEST TO EVENING IN ILLINOIS. FOR THE
EASTERN HALF...MUCH IF NOT ALL OF THIS EVENTS RAIN MAY FALL DURING
THE EVENING HOURS. RAINFALL AMOUNTS OF 0.25 TO 0.75 SEEM MOST LIKELY
WITH MODERATE RATES.

TONIGHT...RAIN WILL END FROM WEST TO EAST DURING THE EVENING...WITH
COLD ADVECTION ONLY MODEST AFTER MIDNIGHT. LOWS WILL DROP TO THE
LOWER 40S WEST TO UPPER 40S EAST.

ERVIN

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 336 AM CDT THU APR 24 2014

DRY CONDITIONS WILL BE SEEN ACROSS THE AREA ON FRIDAY AS HIGH
PRESSURE QUICKLY MOVES THROUGH THE AREA. TEMPERATURES WILL AVERAGE
ABOVE NORMAL.

FRIDAY NIGHT A COLD FRONT WILL SLIDE DOWN LAKE MICHIGAN AND MOVE
INTO THE AREA FROM THE NORTHEAST. THE SLIGHT CHANCE POPS FOR THE
NORTHEAST AREA WERE KEPT BUT THERE ARE QUESTIONS ON WHETHER OR NOT
THERE WILL BE ENOUGH MOISTURE TO PRODUCE ANY RAIN.

DRY CONDITIONS WILL BE SEEN ACROSS THE AREA ON SATURDAY AS THE FRONT
STALLS OUT ACROSS THE AREA...LIKELY SOUTH OF I-80. SEVERAL MODELS
ARE SUGGESTING A SURGE OF DRIER AIR COMING OFF LAKE MICHIGAN DURING
THE AFTERNOON AND MOVING INTO THE AREA. FOR THOSE AREAS NORTH OF THE
FRONT TEMPERATURES SHOULD AVERAGE A LITTLE BELOW NORMAL. SOUTH OF
THE FRONT...TEMPERATURES WILL BE ABOVE NORMAL.

SATURDAY NIGHT A POTENT UPPER LOW APPROACHES THE AREA. THE EVENING
MAY START OUT DRY BUT SHOWERS WILL SLOWLY BREAK OUT ACROSS THE AREA
AND BECOME MORE NUMEROUS AFTER MIDNIGHT. SOME THUNDERSTORMS MAY ALSO
BE SEEN AS WELL AFTER MIDNIGHT.

SUNDAY ON...
THE GLOBAL MODELS ARE SLOWLY CONVERGING ON A SCENARIO THAT RESULTS
IN AN ANOMALOUSLY DEEP CUT OFF UPPER LOW OVER THE AREA FOR MUCH OF
NEXT WEEK. UNFORTUNATELY...THERE CONTINUES TO BE DISAGREEMENT
REGARDING PLACEMENT OF THE UPPER LOW...HOW IT MOVES OVER TIME...AND
WHERE A PERSISTENT LOW LEVEL BOUNDARY IS LOCATED. THESE FEATURES ALL
PLAY SIGNIFICANTLY IN THE DAILY SENSIBLE WEATHER AND RAINFALL
AMOUNTS. REFER TO THE HYDROLOGY SECTION FOR INFORMATION ABOUT
RAINFALL.

THE CURRENT MODEL CONSENSUS HAS LIKELY POPS FOR SUNDAY THROUGH
MONDAY ACROSS THE AREA. TEMPERATURES SHOULD BE NEAR NORMAL.

MONDAY NIGHT THROUGH WEDNESDAY...THE MODEL CONSENSUS HAS CHANCE POPS
IN EACH 12 HOUR PERIOD WITH TEMPERATURES AVERAGING BELOW NORMAL.

THE FORECAST OF DAILY RAIN CHANCES DOES NOT MEAN IT WILL RAIN
CONTINUOUSLY THE ENTIRE TIME PERIOD STARTING SUNDAY. THERE WILL BE
PERIODS OF DRY WEATHER FROM SUNDAY TO WEDNESDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 616 AM CDT THU APR 24 2014

A SLOWLY MOVING STORM SYSTEM WILL SWEEP WIDESPREAD RAIN AND A FEW
THUNDERSTORMS FROM CENTRAL IOWA INTO ILLINOIS BY THIS EVENING. AT
12Z...IT WILL ALREADY BE AFFECTING BOTH CID AND DBQ WITH SCATTERED
SHOWERS AND POSSIBLY A VERY BRIEF THUNDERSTORM...BUT WILL TAKE
UNTIL AROUND 18Z TO 20Z BEFORE IMPACTING MLI AND BRL
SIGNIFICANTLY. THIS WILL LEAD TO AT LEAST 4 HOURS OF MODERATE RAIN
AT MOST LOCATIONS AS IT PROGRESSES EAST. GENERAL MVFR CONDITIONS
SHOULD DEVELOP WITH THE PERIOD OF RAIN...AND WILL LAST UNTIL OUR
SOUTH WINDS OF 15 TO 25 KTS SWITCH TO NORTHWEST THIS
EVENING...ENDING THE RAIN. AHEAD OF THE RAIN...BOTH MLI AND BRL
CAN EXPECT MANY HOURS OF VFR WEATHER. AFTER THE RAIN ENDS
TONIGHT...A RETURN TO VFR WEATHER IS EXPECTED.
ERVIN

&&

.HYDROLOGY...
ISSUED AT 336 AM CDT THU APR 24 2014

THE GLOBAL FORECAST MODELS INDICATE THAT A CUT OFF UPPER LOW WILL
DEVELOP AND REMAIN OVER THE MIDWEST FOR MUCH OF NEXT WEEK WITH A LOW
LEVEL BOUNDARY NEARBY. SOUTH OF THE BOUNDARY...THERE WILL BE A
PERSISTENT FETCH OF MOISTURE MOVING UP FROM THE GULF OF MEXICO.

THE ABOVE SCENARIO SUGGESTS THAT RAINFALL WILL BE POTENTIALLY
HEAVIER THAN NORMAL FOR NEXT WEEK. THE AMOUNT OF RAIN WILL DEPEND
UPON THE LOCATION OF THE UPPER LOW AND THE LOW LEVEL BOUNDARY.

THE FACT THAT THE GROUND IS DRIER THAN NORMAL WILL INITIALLY HELP.
SOME OF THE RAIN WILL SOAK INTO THE GROUND AND NOT REACH AREA
RIVERS. HOWEVER...CONTINUED ROUNDS OF RAIN FOR MUCH OF NEXT WEEK
WOULD EVENTUALLY SATURATE THE GROUND AND CREATE MORE SUBSTANTIAL
RUN OFF INTO AREA WATERWAYS RESULTING IN RISES.

&&

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

$$

SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...08
AVIATION...ERVIN
HYDROLOGY...08






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