Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KDVN 032341
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
641 PM CDT MON AUG 3 2015

.SYNOPSIS...
ISSUED AT 330 PM CDT MON AUG 3 2015

LATEST SFC ANALYSIS WAS INDICATING RIDGE AXIS MAINTAINING FROM
SASKATCHEWAN...DOWN ACRS THE DAKOTAS AND NOSING DOWN INTO CENTRAL IL.
MAIN LLVL BOUNDARY ORIENTED FROM WEST-TO-EAST AND SHUNTED TO THE
SOUTH OF THIS FEATURE...WITH BETTER RETURN FLOW CONVERGENCE NOTED ON
IT ACRS WESTERN AND CENTRAL KS. ALOFT...LARGE CLOSED OFF CYCLONE
CONTINUED ACRS THE JAMES BAY REGION...WITH BROAD CYCLONIC FLOW
PATTERN CURRENTLY ENGULFING MUCH OF THE UPPER MS RVR VALLEY AND GRT
LKS.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 330 PM CDT MON AUG 3 2015

TONIGHT...EMBEDDED/LARGELY CHANNELED VORTICITY AND SOUTHWEST EDGE OF
UPPER JET STREAK MAY COMBINE WITH SOME MARGINAL SOUTHWESTERLY LLJ
RUNNING UP AND OVER THE LLVL BOUNDARY TO PRODUCE A FEW ELEVATED
SHOWERS OR A STORM THAT MAY MAKE IT ACRS THE FAR SOUTHWESTERN CWA
OVERNIGHT. BUT MORE OPTIMUM SUPPORT ACRS EASTERN NEB AND
SOUTHEASTWARD DOWN TOWARD AND SOUTHEAST OF THE ST LOUIS AREA...AND
COULD SEE THE SCENARIO WHERE THE DVN CWA REMAINS LARGELY DRY THRU
12Z TUE MORNING. BUT WILL MAINTAIN LOW CHC POPS ACRS THESE SOUTHERN
AREAS. OTHERWISE MAINLY CLEAR SKIES/LIGHT WINDS FURTHER TO THE NORTH
AND WITH DRY DOWN-MIXED OR ADVECTED IN SFC DPTS...EXPECT A
SEASONABLY COOL NIGHT WITH MANY AREAS MAKING IT DOWN INTO THE 50S.

TUESDAY...WESTERN WAVE ENERGY COMPLEX TRYING TO UNDERCUT UPSTREAM
OMEGA RIDGE...AS WELL AS ONGOING LIFT MECHANISMS CLOSER TO HOME MAY
ALLOW FOR SOME NORTHWARD DRIFT/RETREAT OF THE BOUNDARY TO THE SOUTH
OF THE REGION ESPECIALLY ACRS THE CENTRAL PLAINS. THUS THERE MAY BE A
BIT MORE SUPPORT FOR SOME OVERRUNNING SHOWERS AND CLOUD DEBRIS
PUSHING UP ACRS THE SOUTHWESTERN CWA ON TUE...BUT AGAIN COULD EASILY
SEE THE SCENARIO WHERE THE CWA REMAINS MAINLY DRY THRU 00Z WED.
AREAS AWAY FROM THE THICKER CLOUD DEBRIS SHOULD BE ABLE TO WARM INTO
THE LOWER 80S AGAIN FOR HIGHS.     ..12..

.LONG TERM...(TUESDAY NIGHT THROUGH NEXT MONDAY)
ISSUED AT 330 PM CDT MON AUG 3 2015

OVERVIEW...TEMPS WILL AVG NEAR TO SLIGHTLY BELOW NORMAL THROUGH THIS
WEEK AS A 500MB NEGATIVE HEIGHT ANOMALY SLOWLY SHIFTS FROM THE
ONTARIO/HUDSON BAY REGION EASTWARD THROUGH QUEBEC...AND AS HIGH
PRESSURE OVER THE WESTERN GREAT LAKES RESULTS IN AN EASTERLY
COMPONENT IN THE LOW-LEVEL FLOW LOCALLY. FORECAST HIGHS ARE IN THE
UPPER 70S/LOWER 80S MOST DAYS WITH LOWER/MIDDLE 70S POSSIBLE FRIDAY.

A SERIES OF SHORTWAVE TROUGHS WILL BRING CHANCES FOR SHOWERS AND
THUNDERSTORMS...ESPECIALLY WEDNESDAY/WEDNESDAY NIGHT AND AGAIN ON
FRIDAY. THE EXTREME HEAT/HUMIDITY AND BETTER CHANCES FOR STRONG
STORMS SHOULD STAY SOUTH OF THE AREA THROUGH THE UPCOMING WEEKEND.

TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...RAIN CHANCES VARY BETWEEN 20-
50 PERCENT...LOWEST ALONG HIGHWAY 20...HIGHEST IN THE SOUTHERN TWO
TIER OF COUNTIES IN THE CWA. LOW INSTABILITY LEVELS WILL LIMIT
OVERALL THUNDERSTORM STRENGTH. MODEL CONSENSUS HAS THE BRUNT OF THE
MOISTURE GOING SOUTH OF THE FORECAST AREA WITH A MODERATELY STRONG
VORT. MAX TRAVERSING THROUGH CENTRAL MISSOURI. THEREFORE...MAY HAVE
TO LOWER POPS ACROSS A GOOD PORTION OF THE CWA IN FUTURE FORECASTS.

GFS IS AN OUTLIER TRACKING THE SFC LOW ACROSS NORTHERN IOWA
RESULTING IN STRONG WAA ACROSS E IOWA/W ILLINOIS AND WIDESPREAD RAIN
WED EVENING/NIGHT...THIS IS THE LEAST LIKELY OF SCENARIOS.

THURSDAY AND FRIDAY...THE SLOW COOL DOWN CONTINUES WITH HIGHS
FORECAST IN THE MID/UPPER 70S BY FRI. MODELS PROJECT 1000-500MB
THICKNESS VALUES BOTTOMING OUT NEAR 570 DAM AND 850MB TEMPS DOWN TO
14 C. ANOTHER SHORTWAVE TROUGH MAY CROSS THE UPPER MISSISSIPPI RIVER
VALLEY THU NIGHT INTO FRI PER THE ECMWF/GEM BUT IT DOES NOT APPEAR
TO HAVE MUCH INSTABILITY TO WORK WITH. THE GFS KEEPS THIS SECONDARY
DISTURBANCE ON A MORE SOUTHERLY TRACK SO IT IS AGAIN AT ODDS WITH
MODEL CONSENSUS WHICH IS LIKELY TIED TO THE INTERPLAY OF THE TWO
PRIMARY SHORTWAVES.

SATURDAY AND SUNDAY...TEMPS MAY BE A LITTLE WARMER INTO THE LOWER TO
MIDDLE 80S...850MB TEMPS CLIMB BACK UP INTO THE MIDDLE/UPPER TEENS
CELSIUS. SOUTHEASTERLY FLOW IS FORECAST TO DEVELOP IN RESPONSE TO
LEE-SIDE TROUGH FORMATION OVER THE WESTERN PLAINS AS STRONG 500MB
WINDS FLOW PERPENDICULAR TO THE ROCKIES. CHANCES FOR PRECIP ARE LOW
AT THE MOMENT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 640 PM CDT MON AUG 3 2015

VFR CONDS THROUGH THIS TAF CYCLE AS WEAK HIGH PRESSURE BUILDS INTO
THE AREA. ANY SHOWERS WILL REMAIN IN MO CLOSER TO A STALLED FRONTAL
BOUNDARY THERE. MAINLY NORTHWEST TO WEST WINDS LESS THAN 10 KNOTS
THROUGH THE PERIOD.

&&

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

$$

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.