Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 112029
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
329 PM CDT THU SEP 11 2014

.SYNOPSIS...
ISSUED AT 326 PM CDT THU SEP 11 2014

LATEST SFC ANALYSIS WAS INDICATING LARGE RIDGE COMPLEX CONTINUING TO
BUILD DOWN THE PLAINS AND MID/UPPER MS RVR VALLEY REGIONS...WHILE
12Z UPPER AIR ANALYSIS WAS SUGGESTING TIGHTENING H85 MB BOUNDARY/
BAROCLINICITY FROM THE SOUTHWESTERN GRT LKS...SOUTHWESTWARD TO THE
WEST CENTRAL PLAINS/CO. A WEAK LEAD VORT EMBEDDED IN WESTERLIES
ALOFT NOTED ACRS CENTRAL NEB ATTM...WITH A MUCH STRONGER UPPER WAVE
NOTED ACRS EASTERN IDAHO INTO WESTERN MT/NW WY. THE NEB WAVE HELPING
IN SOME LEAD ISENTROPIC LIFT AND OVERRUNNING LIGHT SHOWERS/RAIN
ALONG THE LLVL BAROCLINIC RIBBON ACRS EASTERN NEB...WITH SOME OF
THIS TRYING TO FEED TOWARD THE WESTERN CWA THROUGH MID EVENING.
CLOSER TO HOME...LLVL COOL NORTH TO NORTHEASTERLY FETCH AND CLOUD
COVER KEEPING A LID ON TEMPS WELL DOWN IN THE 50S BUT WITH SOME
BREAKS STILL EXPECT LATE AFTERNOON HIGHS IN THE UPPER 50S TO LOWER
60S ACRS MUCH OF THE AREA. STILL WITH LATE AFTERNOON RISE...RECORD
COOL HIGHS FOR SEP 12TH MAY BE IN JEOPARDY FOR MLI/59 IN 1878/ AND
DBQ/58 IN 1878/.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 326 PM CDT THU SEP 11 2014

TONIGHT...EXPECT MUCH OF THE UPSTREAM LEAD LIGHT RAINS BANDS TO
DECREASE SOME AS THEY STREAK EASTWARD ACRS IA AND WILL KEEP THE FCST
DRY THROUGH MIDNIGHT...BUT WOULD NOT BE SURPRISED IF A FEW SPRINKLES
FALL ACRS PORTIONS OF THE WESTERN CWA THIS EVENING. STILL NOT WORTH
MENTION RAIN CHC WITH THIS OCCURRENCE. THEN AS THE MAIN UPSTREAM
UPPER WAVE DIGS ACRS THE NORTHEASTERN PLAINS/MO RVR VALLEY INTO EARLY
FRI MORNING...EXPECT AN UPTICK IN LEE-SIDE LOW TO MID LEVEL
FRONTOGENESIS AND ISENTROPIC LIFT ALONG AND UP OVER H85 MB BOUNDARY.
THIS PROCESS WOULD FUNNEL ELEVATED RAIN BANDS INTO THE NORTHWESTERN
THIRD OF THE DVN CWA THROUGH 12Z-13Z OR SO...BUT MODELS VARYING ON
ADEQUATE LOWERING OF CONDENSATION P-DEFS ENOUGH TO ALLOW FOR MUCH
PRECIP ARRIVAL AT THE SFC IN THESE AREAS...THUS WITH UNCERTAINTIES
MAY LIMIT THE HIGHER CHC POPS TO NORTHWEST OF A CID TO DBQ LINE
THROUGH SUNRISE. AFTER EARLY TO MID EVENING BREAKS START TO FILL BACK
IN WITH CLOUD INCREASE FROM THE WEST...CLOUDY OVERNIGHT WITH LOW
TEMPS IN THE MID TO UPPER 40S.

FRIDAY...RATHER VIGOROUS UPPER WAVE AND COOL CORE TROF TO CONTINUE
TO DIG ACRS MN/IA AND THE UPPER MS RVR VALLEY THROUGH FRI EVENING...
WHILE 100+ KT UPPER JET STREAKS FROM THE EAST CENTRAL PLAINS TO
NORTH OF THE GRT LKS. DECENT DEEP LAYER LIFT TO PRODUCE A WIDESPREAD
OVERRUNNING RAIN EVENT ACRS THE CWA FROM WEST TO EAST AS THE DAY
PROGRESSES...WITH MIDDAY THROUGH MID AFTERNOON THE PRIME LIFT WINDOW
ACRS THE HEART OF THE DVN CWA. BUT MOISTURE FEED LIMITED AND EXPECT
MOST OF THE CWA TO RECEIVE LESS THAN A QUARTER INCH OF RAIN BY
00Z SAT...SEVERAL AREAS ESPECIALLY SOUTH OF I80 PROBABLY LESS THAN A
TENTH OF AN INCH. WITH THICKENING CLOUD COVER/EVAPORATIVE COOLING
AND NORTH/NORTHEASTERLY BOUNDARY LAYER FLOW...IF PRECIP CAN
OVERSPREAD THE CWA QUICK ENOUGH IN THE MORNING...SFC TEMPS TO HAVE
TROUBLE RECOVERING OUT OF THE LOW TO MID 50S. THE FAR NORTHWESTERN
CWA COULD BE HELD IN THE 40S. WILL CONTINUE TO POST THE POSSIBILITY
OF MORE RECORD COOL MAX TEMPS NEARED OR SET.     ..12..


.LONG TERM...(FRIDAY NIGHT THROUGH NEXT THURSDAY)
ISSUED AT 326 PM CDT THU SEP 11 2014

BELOW NORMAL TEMPERATURES ARE LIKELY THROUGHOUT THE EXTENDED FORECAST
PERIOD WITH THE BEST CHANCES FOR RAIN EARLY NEXT WEEK.

FRIDAY NIGHT...RAIN WILL LIKELY BE ON-GOING OVER AT LEAST THE
EASTERN HALF OF THE FORECAST AREA AS FRONTOGENETICAL FORCING FROM
THE DEPARTING MID LEVEL SHORTWAVE EXITS TO THE EAST. WILL HAVE
LIKELY POPS IN THE FAR EAST AND CHANCE POPS ALONG AND EAST OF THE MS
RIVER CONFINED TO BEFORE MIDNIGHT. STRONG MID LEVEL SUBSIDENCE AND
DRY AIR AT THE MID AND UPPER LEVELS THEN FOLLOWS THROUGH THE REST OF
THE NIGHT WITH LIGHT NORTH WINDS AT THE SURFACE AS HIGH PRESSURE
BUILDS INTO SOUTHERN IA/NORTHERN MO FROM THE PLAINS. THIS WOULD
FAVOR CLEARING SKIES...AND SUBSEQUENT RADIATIONAL COOLING THROUGH
THE REST OF THE NIGHT. THE MOIST GROUND AND POSSIBLE LINGERING
SHALLOW LOW LEVEL MOISTURE FROM FRIDAY/S RAINFALL MAY LEAD TO AT
LEAST PATCHY FOG...WHICH HAS BEEN ADDED TO THE FORECAST. THIS
MOISTURE WILL ALSO COMPLICATE HOW LOW TEMPERATURES WILL GO ALONG
WITH THE POTENTIAL FOR FROST. MODEL CONSENSUS HAS 850 MB
TEMPERATURES ROUGHLY IN A 2 TO 4 DEGREE C RANGE BY 12Z. FOLLOWING
LOCAL FORECAST TECHNIQUES WITH THIS SYNOPTIC SETUP...MINS IN THE
LOWER 30S WOULD NOT BE OUT OF THE QUESTION ACROSS THE NORTHWEST AND
NORTH. HOWEVER...WITH THE LATE SEASON WARM GROUND AND UNCERTAIN
MOISTURE EFFECTS FROM THE RECENT RAIN...HAVE OPTED TO LEAVE OUT ANY
MENTION OF FROST AND STAY CLOSE TO A RANGE FROM THE MID 30S NORTH TO
LOWER 40S SOUTHEAST...ROUGHLY IN THE LOW TO MID RANGE OF FORECAST
GUIDANCE. THIS WOULD BE A FEW DEGREES ABOVE RECORD LOWS FOR
SEPTEMBER 13.

SATURDAY AND SUNDAY...HIGH PRESSURE OVERHEAD AND COLD 850 MB
TEMPERATURES POINT TOWARD WELL BELOW TEMPERATURES SATURDAY...
FOLLOWED BY SOME MODERATION SUNDAY AS WARM ADVECTION COMMENCES AHEAD
OF THE NEXT FRONTAL SYSTEM. EVEN WITH MOSTLY SUNNY SKIES
SATURDAY...THE MOIST GROUND AND LIGHT WINDS WILL MAKE IT DIFFICULT
TO CLIMB MUCH PAST THE LOWER 60S...WITH THE FAR NORTH POSSIBLY
LIMITED TO THE UPPER 50S. LIGHT SOUTHERLY FLOW DEVELOPING SATURDAY
NIGHT AND CLIMBING DEWPOINTS SHOULD LIMIT LOWS TO THE LOWER 40S OVER
MOST OF THE AREA. SUNDAY LOOKS TO BE ABOUT A CATEGORY WARMER...IN
THE MID AND UPPER 60S AS TEMPERATURES ALOFT MODERATE AND DEEPER
MIXING IS SUGGESTED.

SUNDAY NIGHT THROUGH MONDAY...A SHORTWAVE PASSING TO THE NORTH
PUSHES A WEAK COOL FRONT THROUGH THE AREA. RAIN CHANCES ARE GREATEST
FROM LATE SUNDAY NIGHT THROUGH ABOUT MIDDAY MONDAY. THERE IS AN
INDICATION THAT MID LEVEL TEMPERATURE AND THETAE LAPSE RATES WILL BE
STEEP ENOUGH TO REQUIRE A MENTION OF AT LEAST ISOLATED THUNDERSTORMS
IN THE CENTRAL AND SOUTH. THE FEED OF MOISTURE AND BRIEF SHOT OF
FORCING SHOULD LIMIT EVENT QPF TO A TENTH TO LESS THAN A QUARTER
INCH OVER MOST OF THE AREA. EVEN WITH CLOUDS AND RAIN...TEMPERATURES
SHOULD BE A BIT WARMER THAN SUNDAY WITH HIGHS FROM THE MID
60S TO AROUND 70.

TUESDAY THROUGH THURSDAY...NW FLOW ALOFT AND SLOWLY PASSING SURFACE
HIGH PRESSURE POINT TOWARD CONTINUED SOMEWHAT COOL AND DRY WEATHER.
TEMPERATURES WILL REMAIN BELOW NORMAL...BUT LIKELY TREND CLOSER TO
MID SEPTEMBER CLIMATE NORMALS BY LATE WEEK AS STRONGER WARM
ADVECTION DEVELOPS AHEAD OF THE NEXT SYSTEM THAT MODELS BRING IN
SOMETIME NEXT WEEKEND.    SHEETS

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1242 PM CDT THU SEP 11 2014

SOME SUBSIDENCE EROSION INTO MVFR CLOUD DECK...WITH DIURNAL
LIFTING OVER 3K FT AGL POSSIBLE AT ALL TAF SITES BY LATE AFTERNOON
AND EVEN PERIODS OF SCATTERING OUT FOR AWHILE AT CID AND DBQ
THROUGH EARLY EVENING. LOW VFR TO MVFR DECK TO SEEP BACK ACRS THE
TAF SITES FROM THE WEST OVERNIGHT ESPECIALLY AFTER MIDNIGHT AHEAD
OF NEXT UPPER TROF DIGGING ACRS THE NORTHERN PLAINS. THE WAVE WILL
EVENTUALLY INDUCE AN OVERRUNNING LIGHT RAIN EVENT THAT WILL GET
INTO THE VCNTY OF CID BY DAYBREAK FRI MORNING...AND DBQ/MLI BY MID
FRI MORNING WITH MVFR CIGS AND VSBYS. BRL PROBABLY DRY THROUGH
NOON FRI...BUT STILL A EXPERIENCING A LOWERING DECK TO MVFR. NORTH TO
NORTHEASTERLY SFC WINDS OF 6-12KTS FROM LATE AFTERNOON THROUGH FRI
MORNING.   ..12..

&&

.CLIMATE...
ISSUED AT 326 PM CDT THU SEP 11 2014

RECORD COOL HIGHS FOR FRIDAY SEP 12...

DUBUQUE... 53 SET IN 1902
MOLINE.... 55 SET IN 1902


RECORD LOWS FOR SEPTEMBER 13...

MOLINE.........36 IN 1902
CEDAR RAPIDS...35 IN 1975
DUBUQUE........35 IN 1953
BURLINGTON.....34 IN 1902

&&

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

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...SHEETS
AVIATION...12
CLIMATE...12/SHEETS






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