National Weather Service Raw Text Product

686 
FXUS63 KDVN 111746
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1146 AM CST WED NOV 11 2015

.SYNOPSIS...
ISSUED AT 320 AM CST WED NOV 11 2015

DYNAMIC AND CHALLENGING FORECAST WITH STRONG DEVELOPING SURFACE LOW
IN COLORADO INITIALIZING AS STRONG AS SOLUTIONS WITH MOISTURE MOVING
NORTH SLOWER THAN MOST SOLUTIONS. TRENDS ARE FOR BEST FORCING FOR
THIS EVENT TO ARRIVE SHORTLY AFTER SUNSET. TEMPERATURES NEARLY STEADY
ACROSS FORECAST AREA AT 2 AM WITH MID CLOUDS AND SOUTHEAST WINDS OF
5 TO 10 KTS HOLDING TEMPERATURES IN THE MID 40S TO LOWER 50S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CST WED NOV 11 2015

SHORT TERM FORECAST CONFIDENCE ASSESSMENT...POOR TO VERY POOR OR BELOW
AVERAGE TO WELL BELOW AVERAGE. THE ONE VERY BIG ISSUE IS SIMPLY CONFIDENCE
IN THE RISK OF SEVERE WEATHER. REASONS ARE A SLOWER SYSTEM...DELAYED
MOISTURE PLUS LIMITED INSTABILITY MAKE SEVERE STORMS A QUESTIONABLE
CHALLENGE FOR OUR AREA. THE REASONS WILL BE DISCUSSED MORE IN DEPTH
IN THE SECTION BELOW.

TODAY...HAVE DELAYED POPS IN MORNING AND EARLY AFTERNOON DUE TO SLOWER
MOISTURE ARRIVAL AND FORCING. HIGHS UPPER 50S NORTH TO LOWER TO MIDDLE
60S SOUTH. BEST FORCING APPEARS WILL ARRIVE FOR SHOWERS AND EMBEDDED
STORMS FROM THE WEST AROUND 22Z...OR 5 PM WHICH IS AFTER SUNSET (LOSS
OF ANY SURFACE HEATING) AND PASS RAPIDLY NORTHEAST WITHIN 3 HOURS WITH
A SPEED OF 45 TO 50+ MPH. TIMING AND LIMITED INSTABILITY OF MUCAPE AOB
600 J/KG MAKE FOR LOW CONFIDENCE FORECAST ON SEVERE WEATHER FOR REASONS
BELOW. THIS CONCERN IS NOW VOICED BY THE STORM PREDICTION CENTER AS
WELL. LARGE SCALE SYNOPTIC PROFILES SUPPORT DUE TO FORCING AND MOISTURE
ISSUES ABOVE FOR AREAS OF RAIN AND RAINSHOWERS WITH EMBEDDED STORMS
TO PASS ACROSS THE REGION. RAIN TOTALS FOR MOST OF THE REGION IN THE
.25 TO .75 INCHES RANGE SHOULD BE IN THE BALLPARK.

SEVERE WEATHER CHALLENGES...1.) LOW LEVEL INSTABILITY IN FORM OF LOW
LEVEL CAPE DOESN/T ARRIVE UNTIL AFTER BEST FORCING PASSES. 2.) SHALLOW
BUT SIGNIFICANT INVERSION LOWEST 2L AGL LIMITS BL MIXING FOR SEVERE
DAMAGING STRAIGHT LINE WINDS OR ISOLATED TORNADOES. 3.) TEMPERATURE
DEWPOINTS SPREADS OF 3 TO 7 DEGREES WITH BL RH VALUES AOA 80 PERCENT
IN INVERSION ALSO NOT FAVORABLE FOR MIXING FOR WINDS OR TORNADOES.
4.) CLOUD BASES WITH BEST FORCING WITH LARGE SCALE MOISTURE CONVERGENCE
NEAR TO AFTER SUNSET ARE SUGGESTED TO BE AOB 1500 FEET. THIS ALSO NOT
FAVORABLE FOR TORNADOES OR DAMAGING WINDS WHEN COMBINED WITH POINTS
1-3 ABOVE. ADD AGAIN...WILL OCCUR AFTER SUNSET IN MID NOVEMBER.

INTERNAL GRAVITY WAVE CONVECTION RISK WITH LINE...MAIN CHALLENGE IS
THE LARGE SCALE PROFILE THOUGH FAVORABLE...IF WE HAVE ENOUGH INSTABILITY
ALOFT WHICH DOES NOT APPEAR TO BE CASE AT THIS TIME. THE REASON IS
LIMITED INSTABILITY DUE TO DEEP MOIST TO NEAR MOIST ADIABATIC PROFILES
ARE THE ISSUE.

SIMPLY PUT...THIS IS A MARGINAL AND THUS LOW CONFIDENCE FORECAST FOR
SEVERE STORMS FOR THE REASONS ABOVE. 

LOCAL TOOLS CLEARLY DO SUGGEST SIGNIFICANT WINDS THOUGH MID TO LATE
AFTERNOON WITH AND AROUND HEAVIEST PRECIPITATION IN THE 30 TO 45 MPH
RANGE. AGAIN...WILL THE POINTS ABOVE BE OVERCOME TO RESULT IN STRONGER
WINDS OR ANY RISK OF A TORNADO. ONCE WINDS SHIFT TO SW THEN STRONG CAA...RESULTING
IN STRONG SUBSIDENCE. TIMING WINDOW FOR ANY RISK OF SEVERE WILL BE SHORT
IN THE 4 TO 7 OR 8 PM LATEST WITH FAR SW 1/3 OF FORECAST AREA MORE
SUSCEPTIBLE FOR REASONS OUTLINED.

TONIGHT...DRY SLOT AND STRONG ISALLOBARIC COMPONENT WITH LOW LEVEL
WINDS OF 50 TO 70 KTS WILL ARRIVE RAPIDLY. SIGNIFICANT PRECIPITATION
WILL EXIT NORTHEAST BY 9 PM CDT. LOCALS TOOLS AND TECHNIQUES CONFIRM
HIGH PROBABILITY OF WIND ADVISORY CRITERIA TO BE MET WITH 25 TO 30+
MPH SUSTAINED WINDS AND GUSTS OF 45 TO AT TIMES 50+ MPH BY MORNING.
LIGHT SHOWERS STILL REASONABLE NORTHERN 1/2 TO 2/3 AREA WITH
ADDITIONAL AMOUNTS OVERNIGHT OF A FEW HUNDREDTHS MOST PLACES. ANY
DRY AIR WOULD SUGGEST WIND GUSTS NEAR 55 MPH OR MORE ARE POSSIBLE.
THIS CONCERN WILL BE PASSED TO THE DAY SHIFT TO FURTHER EVALUATE.
HIGHEST WINDS SUGGESTED TO BE IN THE 2 AM TO 9 AM TIME PERIOD OR
LATER ON THURSDAY MORNING.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 320 AM CST WED NOV 11 2015

THURSDAY...THE WELL ADVERTISED SFC LOW WILL CONTINUE TO OCCLUDE AND
MOVE INTO WESTERN QUEBEC BY THE END OF THE DAY. A NOTABLE PRESSURE
GRADIENT OVER E IOWA/W ILLINOIS/NE MISSOURI WILL MAINTAIN THE STRONG
WEST-NORTHWEST WINDS OF 25-30 MPH WITH GUSTS BETWEEN 40-50 MPH ON
AVG INTO THE MID AFTN BEFORE WINDS SLOWLY DECREASE. THESE VALUES
SOLIDLY MEET WIND ADVISORY CRITERIA SO THE GOING WIND ADVISORY
ACROSS THE CWA THROUGH 6 PM CST REMAINS ON TRACK.

THERE ARE DIFFERENCES BETWEEN THE HEIGHT OF THE MIXED/DRY ADIABATIC
LAYER THAT DEVELOPS THURSDAY MORNING AND AFTN. BUFKIT GFS FORECAST
SOUNDINGS SHOW HIGHER MIXING INTO 50 KT WINDS...THE NAM MIXES UP TO
ABOUT 900-925MB WHERE WINDS ARE CLOSER TO 40 KTS. BUT THINKING THE
CURRENT FORECAST IS A GOOD COMPROMISE BETWEEN VARYING MODEL
SOLUTIONS AND DO NOT THINK HIGH WIND WARNING CRITERIA WILL BE MET
FOR GUSTS WHICH IS 58 MPH. HIGHS WILL RANGE FROM THE UPPER 40S
ACROSS THE FAR NORTH TO THE MID 50S FAR SOUTH.

FRIDAY...A SECONDARY VORT. MAX AND ATTENDANT SFC LOW IS FORECAST TO
MERGE INTO THE INITIAL UPPER LOW FROM THE WEST...THEREBY REINFORCING
THE SFC PRESSURE GRADIENT OVER THE MIDWEST. EXPECT SUSTAINED WNW
WINDS OF 20-25 MPH WITH GUSTS OF 30-35 MPH.

STRONG COLD AIR ADVECTION ON THE BACKSIDE OF THE OCCLUDED LOW WILL
DROP 850MB TEMPS TO NEAR -5 C. SFC TEMPS WILL RESPOND TO THE COOLER
AIR ALOFT ONLY REACHING THE LOWER 40S IN THE NORTHERN CWA TO UPPER
40S FAR SOUTH.

SATURDAY AND SUNDAY...SW RETURN FLOW EXPECTED ALONG WITH WARMING
TEMPS INTO THE MID 50S FOR SATURDAY AND UPPER 50S FOR SUNDAY.

MONDAY AND TUESDAY...THE NEXT NORTH PACIFIC JET WILL DIVE INTO THE
WESTERN U.S. AND ONCE AGAIN MERGE WITH A PRE-EXISTING SUBTROPICAL
JET OVER THE FAR SOUTHWEST. A NEWLY DEVELOPED UPPER-LOW IS FORECAST
TO MOVE INTO THE SOUTHERN PLAINS ON TUESDAY. AHEAD OF THIS
FEATURE...A SOUTHERLY 850MB LOW LEVEL JET WILL ADVECT PLENTY OF
MOISTURE NORTHWARD INTO THE MIDWEST WHICH SHOULD BRING ROUNDS OF
SHOWERS AND PERIODS OF RAIN TO THE UPPER MISSISSIPPI VALLEY THROUGH
WEDNESDAY. CONSENSUS HIGH TEMPS ARE IN THE MID/UPPER 50S...MILD BY
MID NOVEMBER STANDARDS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1130 AM CST WED NOV 11 2015

MESSY AVIATION WEATHER CONDITIONS ARE FORECAST THROUGH THE PERIOD
WITH STRONG WINDS GIVING WAY TO MVFR CIGS AND THE POTENTIAL FOR
STRONG TO SEVERE STORMS AT THE TAF SITES. AFTER THE STORMS A
WIND SHIFT AND THE POTENTIAL FOR GUSTS ABOVE 40KTS ARE POSSIBLE.
WILL UPDATE THE TEMPO GROUPS TO INCLUDE WIND GUSTS AS STORMS
APPROACH THEM. THOSE AIRPORTS WITHOUT A E-W RUNWAY WILL LIKELY
HAVE ISSUES WITH CROSSWINDS TOMORROW MORNING.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WIND ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST THURSDAY FOR 
     CLINTON-DES MOINES-JACKSON-LEE-LOUISA-MUSCATINE-SCOTT.

     WIND ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST THURSDAY FOR 
     BENTON-BUCHANAN-CEDAR-DELAWARE-DUBUQUE-HENRY IA-IOWA-
     JEFFERSON-JOHNSON-JONES-KEOKUK-LINN-VAN BUREN-WASHINGTON.

IL...WIND ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST THURSDAY FOR 
     BUREAU-CARROLL-HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-
     MCDONOUGH-MERCER-PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-
     WHITESIDE.

MO...WIND ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST THURSDAY FOR 
     CLARK.

     WIND ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST THURSDAY FOR 
     SCOTLAND.

&&

$$

SYNOPSIS...NICHOLS
SHORT TERM...NICHOLS
LONG TERM...UTTECH
AVIATION...GIBBS