Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 242350
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
650 PM CDT FRI APR 24 2015

.SYNOPSIS...
ISSUED AT 247 PM CDT FRI APR 24 2015

AT 245 PM...SHOWER AND ISOLATED THUNDERSTORMS COVERED MUCH OF EAST
CENTRAL IOWA INTO FAR NORTHWEST ILLINOIS. A MEAGER AMOUNT OF
ELEVATED CAPE WAS SUPPORTING THE ISOLATED CONVECTION...BUT OTHER
THAN A FEW CLOUD TO GROUND LIGHTNING STRIKES...STORMS WILL NOT BE
A THREAT. LOW LEVEL MOISTURE RETURN WAS INCREASING IN THE FAR
WEST...WHILE THE FAR EAST REMAINED UNDER THE INFLUENCE OF DRY
EAST/SOUTHEAST FLOW. AREAS IMPACTED BY HEAVIER RAIN HAD
TEMPERATURES IN THE 40S...WHILE READINGS WERE IN THE LOW/MID 60S
SOUTH OF U.S. HIGHWAY 34.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 247 PM CDT FRI APR 24 2015

THE MAIN FORECAST ISSUES IN THE SHORT TERM PERIOD ARE PRECIP
TRENDS/COVERAGE/AMOUNTS.

IN THE NEAR TERM...ISOLATED THUNDERSTORMS HAVE CREPT INTO THE
WESTERN FRINGE OF THE FORECAST AREA...BUT ARE QUICKLY MOVING AWAY
FROM THE LITTLE ELEVATED INSTABILITY THAT IS AVAILABLE. EXPECTING
THIS WEAKENING TREND TO CONTINUE AS THE STORMS MOVE EAST. THE
EASTERN FRINGE IS TAKING LONGER TO SATURATE WITH DEWPOINTS STILL
IN THE 20S. HIGH RESOLUTION MODELS ARE HAVING VARYING LEVELS OF
SUCCESS IN CAPTURING THE CURRENT RAIN COVERAGE. IN GENERAL...THE
BULK OF THE ADDITIONAL RAIN THROUGH EARLY EVENING IS EXPECTED TO
BE ACROSS THE NORTHERN AND WESTERN COUNTIES.

LATER THIS EVENING...AM EXPECTING A DECREASE IN SHOWER
COVERAGE...AHEAD OF THE MAIN UPPER LEVEL ENERGY. THEN TOWARD
MIDNIGHT AND EARLY SATURDAY MORNING...SHOWERS SHOULD EXPAND IN
COVERAGE FROM SOUTH TO NORTH. MODEST ELEVATED CAPE POINTS TO AREAS
SOUTH OF INTERSTATE 80 AS MOST LIKELY TO SEE A FEW NON-SEVERE
THUNDERSTORMS.

ON SATURDAY...A CLOSED UPPER LOW WILL MOVE INTO THE AREA AND
LIKELY BECOME A MORE OPEN WAVE DURING THE AFTERNOON AS RAIN WANES
FROM NORTHWEST TO SOUTHEAST. THROUGH THE PERIOD...AVERAGE
RAINFALL AMOUNTS OF ONE HALF TO ONE INCH STILL LOOK DECENT...WITH
ISOLATED HIGHER AMOUNTS UP TO 1.5 INCHES NOT OUT OF THE QUESTION.

FOR TEMPERATURES...HAVE TIGHTENED UP THE DIURNAL RANGES A BIT.
AFTERNOON HIGHS ARE EXPECTED TO BE STUCK IN THE 40S NORTH OF
HIGHWAY 30...WITH READINGS IN THE UPPER 50S SOUTH.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 247 PM CDT FRI APR 24 2015

OVERVIEW...NORTHERLY MID-LEVEL WINDS ON SUNDAY WILL WEAKEN FOR
MONDAY AND TUESDAY AS MID-LEVEL RIDGE MOVES THROUGH THE MIDWEST AND
UPPER-LEVEL JET FOCUSES OVER THE SOUTHERN UNITED STATES. A SHORTWAVE
TROUGH WILL FOLLOW THE MID-LEVEL RIDGE AND BRING A CHANCE FOR LIGHT
SHOWERS TUESDAY NIGHT AND/OR WEDNESDAY.

SATURDAY NIGHT...500MB VORTICITY MAX OVER NE MISSOURI AND WEST-
CENTRAL ILLINOIS WILL CONTINUE TO SHEAR OUT AS IT ENTERS INTO A
CONFLUENCE ZONE SITUATED OVER THE OHIO VALLEY. ANY LINGERING SHOWERS
SHOULD END DURING THE EVENING OR EARLY NIGHTTIME HOURS.

SOME PATCHY FROST IS POSSIBLE NORTH OF I-80 WHERE LOWS ARE FORECAST
TO BE IN THE LOWER TO MIDDLE 30S.

SUNDAY...NICE END TO THE WEEKEND. MOSTLY SUNNY WITH HIGHS NEAR 60 F
AND STEADY NORTHEAST WINDS OF 10-15 MPH.

MONDAY AND TUESDAY...WEAK PRESSURE/HEIGHT GRADIENT FORECAST FROM THE
SFC UP TO 300MB AND RIDGING WILL BECOME MORE PRONOUNCED WITH HEIGHT
ABOVE GROUND LEVEL. 850MB TEMPS ARE NOT ALL THAT WARM AVERAGING NEAR
4C...BUT PLENTY OF SUNSHINE WILL HELP TEMPS REACH THE MIDDLE 60S.
SFC WINDS WILL BE LIGHT DURING THIS TIME.

WEDNESDAY...ECMWF/GFS DIFFER ON MID/UPPER LEVEL KINEMATICS AND ON
THE EVOLUTION OF A SHORTWAVE DROPPING SOUTHEASTWARD OUT OF
SASKATCHEWAN. THE GFS KEEPS THE 300MB JET MOSTLY TO THE NE/E OF IOWA
AND ILLINOIS. THE ECMWF HAS THE LEFT EXIT REGION OF A MERIDIONALLY
ORIENTED JET STREAK DIVING THROUGH THE PLAINS STATES AND WESTERN
IOWA...DIGGING A DEEPER TROUGH THROUGH THE MIDWEST.

THE ECMWF IS MORE AGGRESSIVE WITH RAINFALL POTENTIAL BUT SFC TEMP
PROJECTIONS ARE SIMILAR FROM BOTH MODELS. HIGHS ARE FORECAST TO BE
IN THE MID TO UPPER 60S. ALTHOUGH THICKNESSES ARE FORECAST TO BE
QUITE LOW...AROUND 546 DAM...SO TEMPS MAY HAVE TO BE KNOCKED DOWN IF
CLOUDS OR PRECIP ARE FORECAST TO BE MORE PREVALENT.

THURSDAY...COULD BE LOOKING AT A PATTERN CHANGE TO WARMER TEMPS AND
A MORE MOIST ATMOSPHERE FOR THE END OF THE WEEK. A MUCH MORE
EXPANSIVE MID/UPPER LEVEL RIDGE MAY BEGIN TO DEVELOP OVER THE
CENTRAL U.S. WITH STRONG TROUGHING APPROACHING THE PACIFIC NW. 1000-
500MB THICKNESS ADVECTION WILL COMMENCE DURING THE MORNING ON THU
BUT MAY NOT BECOME SIGNIFICANT UNTIL FRIDAY. HIGHS ARE FORECAST TO
BE IN THE LOWER 70S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 645 PM CDT FRI APR 24 2015

VFR CONDITIONS WILL DETERIORATE TO MVFR CONDITIONS BY 25/05Z WITH
INTERVALS OF IFR CONDITIONS POSSIBLE AFTER 25/08Z AS AREAS OF RAIN
DEVELOP THAT WILL LAST INTO THE LATE MORNING HOURS. ISOLATED THUNDER
MAY APPROACH THE BRL TERMINAL AND TO A LESSER EXTENT THE MLI TERMINAL
TOWARD DAYBREAK. THIS IS HANDLED AS A VCTS AT THE BRL TERMINAL. EAST
WINDS OF 10 TO 15 KTS WILL SHIFT TO THE NORTHEAST AND NORTH BY MID
DAY AND INCREASE TO 10 TO 20+ KTS AS THE SURFACE LOW PASSES SOUTH.
THE RAINS WILL END IN THE AFTERNOON WITH MVFR CONDITIONS LAST UNTIL
26/00Z WITH CLEARING SKIES AFTERWARD FROM THE NORTH.

&&

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

&&

$$

SYNOPSIS...RP KINNEY
SHORT TERM...RP KINNEY
LONG TERM...UTTECH
AVIATION...NICHOLS



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