Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 230837
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
337 AM CDT THU APR 23 2015

.SYNOPSIS...
ISSUED AT 330 AM CDT THU APR 23 2015

CLEAR AND COLD EARLY THIS AM WITH SUB-FREEZING TEMPS WIDESPREAD
NORTH OF I-80. TEMPS RANGE FROM THE MID TO UPPER 20S IN SEVERAL
VALLEYS AND LOW-LYING AREAS NORTH... TO THE MID 30S SOUTH.
SURFACE RIDGE AXIS EXTENDS FROM EASTERN ND THROUGH WESTERN IA AND
MO. STILL ENOUGH LOW LEVEL FRICTION WITH LINGERING GRADIENT
BETWEEN SURFACE RIDGE AND LOW PRESSURE OVER CANADA INDUCING WINDS
4-10 KTS TO LIMIT FROST POTENTIAL TO SHELTERED AREAS OR VALLEYS.
SURFACE HIGH PRESSURE RIDGE WILL BUILD IN OVER THE NEXT 24 HOURS
PROVIDING TRANQUIL WX AND CONTINUATION OF SEASONABLY COOL TEMPS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT THU APR 23 2015

SURFACE RIDGE AXIS WILL BUILD INTO THE REGION TODAY WHICH WILL
BRING GENERALLY SUNNY SKIES WITH SOME THINNING MID CLOUDINESS
POSSIBLE EARLY THIS AM WESTERN CWA ATTENDANT TO WEAKENING MID
LEVEL WARM ADVECTION. MOST NOTABLE THOUGH WILL BE MUCH LESS
WIND (10-15 MPH... WITH GUSTS TO 20 MPH EAST) COMPARED TO THE
PAST SEVERAL DAYS. VERIFICATION OF HIGHS YESTERDAY IN THE
VICINITY OF THE RIDGE AXIS SUPPORTS HIGHS TODAY MAINLY IN THE
MID TO UPPER 50S... WITH SOME AREAS AROUND 60F ROUGHLY OVER THE
SOUTHWEST THIRD OF CWA.

TONIGHT...THE MAIN CHALLENGE IS LOW TEMPS. THE SURFACE RIDGE AXIS
WILL BE OVER THE REGION THIS EVENING AND WITH LIGHT TO CALM
WINDS AND DRY AIR AND GENERALLY CLEAR SKIES SHOULD SEE TEMPS
QUICKLY RADIATE. LATE EVENING AND OVERNIGHT EXPECT SOME GRADUAL
INCREASE IN MID/HIGH CLOUDS AHEAD OF SHORTWAVE EMERGING IN THE
PLAINS. THESE CLOUDS AND DEVELOPING EAST/SOUTHEAST WINDS MAY BE
ENOUGH TO LIMIT THE TEMP DROP ESPECIALLY IN THE WESTERN CWA.
OVERALL... SIDED NEAR TO JUST BELOW GUIDANCE OVER FAR EASTERN
IA AND NORTHWEST IL WITH LOWS AROUND 30 OR LOWER 30S AND HAVE
INTRODUCED PATCHY FROST BUT MAY NEED TO BUMP UP TO AREAS OF FROST
WITH POTENTIAL FOR THIS PORTION OF CWA NEEDING ANOTHER FREEZE
WARNING. ELSEWHERE... WENT NEAR GUIDANCE BLEND WITH LOWS MID 30S
TO AROUND 40 FAR SOUTHWEST.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 330 AM CDT THU APR 23 2015

THE QUESTION ON FRIDAY IS HOW LONG WILL THE DRY AIR HOLD OUT BEFORE
PRECIPITATION BEGINS. IF WHAT IS BEING SUGGESTED BY THE MODELS IS
CORRECT...THE DAY WILL START OUT DRY BUT SPRINKLES/VERY LIGHT RAIN
WILL SLOWLY SPREAD EAST TO THE I-380/HWY 218 CORRIDOR BY LATE
MORNING. FRIDAY AFTERNOON THE SPRINKLES/LIGHT RAIN WILL CONTINUE
SLOWLY MOVING EAST AND OVERSPREAD NEARLY THE ENTIRE AREA BY EARLY
EVENING.

HOWEVER...IF THE DRY AIR IS DEEPER THAN WHAT THE MODELS SUGGEST THEN
PRECIPITATION COULD EASILY BE DELAYED BY AT LEAST 6 HOURS.

FRIDAY NIGHT INTO SATURDAY A SURGE OF BETTER MOISTURE MOVES INTO THE
AREA ALONG WITH MUCH STRONGER FORCING. THE TREND IS FOR THE CENTER
OF THE STORM SYSTEM TO MOVE FROM CENTRAL MISSOURI INTO SOUTHERN
ILLINOIS. THUS A GENERAL RAIN IS EXPECTED TO BECOME MORE WIDESPREAD
ACROSS THE AREA WITH THE MOST WIDESPREAD COVERAGE LATE FRIDAY NIGHT
INTO SATURDAY MORNING.

ALTHOUGH NOT A GIVEN...THERE MIGHT BE ENOUGH FORCING ALOFT TO RESULT
IN A COUPLE OF RUMBLES OF THUNDER ACROSS THE SOUTH THIRD OF THE AREA
LATE FRIDAY NIGHT INTO EARLY SATURDAY MORNING. CONFIDENCE ON THIS
HAPPENING IS QUITE LOW.

TEMPERATURES WILL AVERAGE BELOW NORMAL FRIDAY AND SATURDAY.
TEMPERATURES ON SATURDAY ARE NOT EXPECTED TO GET ABOVE 50 ACROSS THE
NORTH HALF OF THE AREA.

SATURDAY NIGHT THE STORM SYSTEM MOVES INTO THE OHIO VALLEY SO RAIN
WILL QUICKLY END FROM WEST TO EAST AS THE BETTER MOISTURE/FORCING
EXITS THE AREA.

SUNDAY ON...

THE MODELS HAVE TRENDED INTO BRINGING A SEASONABLY STRONG CANADIAN
HIGH INTO THE MIDWEST. THUS THE MODEL CONSENSUS HAS DRY CONDITIONS
WITH NEAR SEASONABLE TEMPERATURES SUNDAY THROUGH MONDAY NIGHT.

TUESDAY INTO WEDNESDAY THE MODELS SHOW SEVERAL WEAK UPPER LEVEL
DISTURBANCES MOVING THROUGH THE AREA. MOISTURE IS VERY LIMITED AND
THE FORCING IS NOT OVERLY GREAT BUT IT MAY BE ENOUGH TO GENERATE
SOME SHOWERS. AS SUCH THE MODEL CONSENSUS HAS SLIGHT CHANCE TO VERY
LOW CHANCE POPS. TEMPERATURES SHOULD BE CLOSE TO NORMAL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1127 PM CDT WED APR 22 2015

VFR CONDITIONS WILL DOMINATE THE PERIOD WITH LIGHTER WINDS TODAY
ACROSS THE AREA. SOME VERY ISOLATED CUMULUS CLOUDS COULD
DEVELOP...BUT NOTHING IS EXPECTED TO AFFECT VSBYS OR CEILINGS AT
THE TAF SITES. ANOTHER SYSTEM TO OUR WEST WILL LEAD THE WINDS TO
SHIFT TO THE EAST LATE IN THE PERIOD. WINDS WILL BE LIGHT AFTER
SUNSET TODAY AND MOST LIKELY FROM THE EAST AT ALL SITES.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...FREEZE WARNING UNTIL 8 AM CDT THIS MORNING FOR BENTON-BUCHANAN-
     CEDAR-CLINTON-DELAWARE-DES MOINES-DUBUQUE-HENRY IA-IOWA-
     JACKSON-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-LINN-LOUISA-
     MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.

IL...FREEZE WARNING UNTIL 8 AM CDT THIS MORNING FOR BUREAU-CARROLL-
     HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-MERCER-
     PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE.

MO...FREEZE WARNING UNTIL 8 AM CDT THIS MORNING FOR CLARK-SCOTLAND.

&&

$$

SYNOPSIS...05
SHORT TERM...05
LONG TERM...08
AVIATION...GIBBS


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