Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 042031
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
331 PM CDT WED MAY 4 2016

.SYNOPSIS...
ISSUED AT 330 PM CDT WED MAY 4 2016

THE LATEST SFC ANALYSIS WAS INDICATING A COLD FRONT PUSHING SOUTH
THROUGH THE OH RVR VALLEY ON LOWER MS RVR VALLEY...WITH STILL TIGHT
LLVL NORTHERLY GRADIENT BEHIND IT ACRS THE LOCAL AREA. NOT MUCH IN
THE WAY OF ANY PRECIP DEVELOPMENT IN THE MORE ENHANCED CU/STRATOCU
FIELDS EAST OF THE MS RVR...AND AT THIS POINT IT/S APPEARING THAT
THERE WON/T BE ANY IN OUR AREA OF CONCERN. ALOFT...MID/UPPER LEVEL
MOISTURE FLOW CHANNELS ON THE CURRENT WATER VAPOR IMAGERY LOOP WERE
INDICATING AN UPPER LOW OVER NORTHERN IND...WHILE A LARGE WELL
DEFINED OMEGA BLOCK UPPER RIDGE WAS REIGNING ACRS MUCH OF THE
WESTERN CONUS.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 330 PM CDT WED MAY 4 2016

TONIGHT...THE MORE CELLULAR CU ACRS THE CENTRAL AND WESTERN CWA WILL
DECAY DIURNALLY AROUND SUNSET...WHILE SOME OF THE STRATOCU IN THE
EAST LINGERS A BIT LONGER. BUT AS THE UPPER LOW ACRS IND ROLLS
FURTHER SOUTH-SOUTHEAST AND SOME OF THE UPSTREAM UPPER RIDGING
NUDGES IT/S WAY ACRS THE UPPER MS RVR VALLEY FROM THE WEST...SKIES
SHOULD CLEAR OUT CWA-WIDE OVERNIGHT. DEEP CYCLONIC/NEAR MERIDIONAL
FETCH TO THE LEE OF THE OMEGA RIDGE HAS BEEN AND WILL CONTINUE TO
COOL ADVECT CANADIAN SOURCE AIRMASS THRU TONIGHT. THE EXTENT OF THE
DRY COOL AIR MASS ALREADY IN PLACE WOULD SUPPORT WIDESPREAD LOWS IN
THE MID TO UPPER 30S WITH CALM WINDS AND CLEAR SKIES/OPTIMUM
TRANSLATION TO THE SFC OF H85 MB RIDGE COLD RULE. BUT THERE ARE
SIGNS THERE MAY BE ENOUGH OF A LINGERING LLVL PRESSURE GRADIENT TO
KEEP SFC WINDS AT 4-5 KTS EVEN TOWARD SUNRISE. THIS WOULD LIMIT MORE
OF A FROST DEVELOPMENT AND KEEP TEMPS MORE IN THE 37-39 DEGREE
RANGE. OTHER NOCTURNAL PROCESSES MAY GO INTO A HEAVY DEW FORMATION
AND RIVER VALLEY FOG TOWARD DAWN AS WELL...AS OPPOSED TO MORE OF A
TRUE WIDESPREAD FROST. BUT IN CASE THAT A BIT MORE OF A SFC WIND
DECOUPLE OCCURS THAN EXPECTED...WILL ADD PATCHY FROST TO THE GRIDS
FOR A FEW HOURS LEADING UP TO SUNRISE ALONG AND ESPECIALLY NORTH OF
I80. BUT THE ENTIRE CWA MAY HAVE SIMILAR LOWS OF UPPER 30S TO LOWER
40S...WITH SOME COOL AIR DRAINAGE LOCATIONS DIPPING TOWARD THE MID
30S. THUS SOME PATCHY FROST MAY ALSO BE POSSIBLE EVEN SOUTH OF I80.

THURSDAY...EASTERN EDGE OF PLAINS/MO RVR VALLEY SFC RIDGE COMPLEX
WILL LOOK TO SLIDE SOUTH/SOUTHEAST TOWARD THE LOW MS RVR VALLEY...
KEEP SOME LLVL NORTHERLY FLOW GRADIENT GOING ACRS THE CWA WITH A MID-
LATE MORNING WIND MIX OUT INCREASE TO 10-15 MPH. AIRMASS ALOFT WILL
ALREADY BE IN MODERATION MODE...AND A DAY OF JUST MARGINAL MIXING UP
CLOSE TO H9 MB WILL PRODUCE WIDESPREAD MID TO UPPER 60S FOR THU
HIGHS EVEN AFTER THE COOL START TO THE DAY. NORTHERLY FLOW ALOFT
WILL LOOK TO SHUTTLE A WEAKENING/INCREASINGLY CHANNELED VORT MAX DOWN
THE UPPER MS RVR VALLEY INTO NORTHEASTERN IA AS THE DAY PROGRESSES.
A FEW MODELS ARE BREAKING OUT ISOLATED TO SCTRD INSTABILITY SHOWERS
BY LATE MORNING ACRS THESE AREAS...BUT IF THEY DO FORM AND PERSIST
THEY SHOULD REMAIN OFF TO THE NORTH AND NORTHWEST OF THE LOCAL FCST
AREA THROUGH 00Z. CURRENT CU RULE PROGS SUGGEST CELLULAR CU
DEVELOPING TO SCTRD OR NEARING BROKEN COVERAGE IN THE FAR EAST TO
SOUTHEASTERN CWA BY MIDDAY..BUT THEN DECREASE AGAIN BY MID TO LATE
AFTERNOON. MOST OF THE DAY TO BE CHARACTERIZED AS SUNNY/MOSTLY
SUNNY.     ..12..


.LONG TERM...(THURSDAY NIGHT THROUGH NEXT WEDNESDAY)
ISSUED AT 330 PM CDT WED MAY 4 2016

FRIDAY...MID-LEVEL RIDGING WILL OVERSPREAD THE CENTRAL U.S. AS
CUT-OFF LOW MOVES UP THE EASTERN SEABOARD...EVENTUALLY WEAKENING
AND SHEARING OUT. LOCALLY THE UPPER MISSISSIPPI VALLEY...IS
FORECAST TO BE ON THE EASTERN SIDE OF THE 500MB RIDGE AXIS...SO
THE WARMEST TEMPS...UPPER 80S...WILL STAY OFF TO THE W/NW THROUGH
THE PLAINS AND UPPER MIDWEST INTO WESTERN ONTARIO.

FORECAST BUFKIT NAM/GFS SOUNDINGS INDICATE BOUNDARY LAYER MIXING
UP TO 850-800MB WHERE TEMPS ARE IN THE MID TEENS CELSIUS. FULL
SOLAR INSOLATION...DEWPOINTS IN THE UPPER 40S TO LOWER 50S...AND
COMPRESSIONAL MIX DOWN OF THE MILD TEMPS ALOFT SHOULD PUSH HIGHS
INTO THE LOWER 80S WITH A LOWER PROBABILITY OF MID 80S FOR SELECT
SITES. WINDS ARE NOT EXCEPTED TO BE VERY STRONG IN THE BOUNDARY
LAYER...WIND GUSTS WILL PROBABLY STAY BELOW 25 MPH.

SATURDAY...EASTWARD PROGRESSION OF THE 500MB RIDGE AXIS WILL BE
HALTED BY A SHORTWAVE TROUGH DIVING SOUTHEASTWARD THROUGH THE
UPPER MIDWEST AND GREAT LAKES. ANY SIGNIFICANT HEIGHT FALLS
ASSOCIATED WITH THIS SYSTEM ARE FORECAST TO REMAIN OVER THE GREAT
LAKES. AS A RESULT...LIFT OVER E IOWA/W ILLINOIS WILL BE WEAK AND
PRIMARILY RESTRICTED TO LOW-LEVEL CONVERGENCE ALONG A SOUTHWARD
MOVING COLD FRONT. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
ARE POSSIBLE ALONG AND SLIGHTLY AHEAD OF THE FRONT. QPF IS A TENTH
OF LESS FOR MOST LOCATIONS.

THUNDERSTORM POTENTIAL...THE BEST CHANCES FOR STORMS ARE SOUTH OF
I-80 WHERE MUCAPES MAY EXCEED 1000 J/KG AND 0-6 KM BULK SHEAR MAY
EXCEED 40 KTS. WITHOUT GETTING INTO THE DETAILS...THERE IS AT
LEAST THE POTENTIAL FOR A FEW STRONG STORMS.

SUNDAY THROUGH TUESDAY...SATURDAY/S COLD FRONT WILL BECOME QUASI-
STATIONARY SATURDAY NIGHT AND RETURN AS A NORTHWARD MOVING WARM
FRONT SUNDAY AND MONDAY AS IT IS FORCED BY A NEW AREA OF LOW
PRESSURE FORMING IN THE WEST-CENTRAL PLAINS. SHOWER AND
THUNDERSTORM CHANCES ARE HIGHEST FROM SUNDAY NIGHT INTO TUESDAY.
WIDESPREAD CLOUDS AND THE THREAT FOR RAIN TRANSLATES INTO NO BIG
WARM UPS WITH AVG HIGH TEMPS NEAR 70 F.

AS OF TODAY...THE THREAT FOR WIDESPREAD HEAVY RAIN WITH THIS
LOW PRESSURE SYSTEM IS HIGHLIGHTED...IN THE CPC 3-7 DAY HAZARDOUS
WEATHER OUTLOOK...OVER SOUTH-CENTRAL AND SOUTHWEST IOWA DOWN INTO
EASTERN TEXAS. UTTECH

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1241 PM CDT WED MAY 4 2016

MORE CELLULAR CU...SOME AT BKN COVERAGE BUT AT VFR LEVELS ALONG
AND EAST OF THE MS RVR THIS AFTERNOON. A LOW CHC FOR AN ISOLATED
SHOWER IN THESE CU FIELDS WHICH MAY GET INTO THE EASTERN VCNTY OF
DBQ/MLI/BRL. BRISK NORTHWEST WINDS GUSTING UP TO 25 KTS WILL
DIMINISH TO 5-10 KTS BY MID EVENING AS SKIES CLEAR. EXPECT ENOUGH
OF A NORTH BREEZE OF AT LEAST 4-6 KTS INTO EARLY THU MORNING TO
LIMIT ANY FOG DEVELOPMENT...ALONG WITH ONGOING DIURNAL DRYING
TODAY LOWERING SFC DPTS. VFR CONDITIONS ON THU WITH NORTH-
NORTHWEST SFC WINDS OF 8-13 KTS.   ..12..

&&

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

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...UTTECH
AVIATION...12


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