Area Forecast Discussion
Issued by NWS Central Illinois

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 KILX 012016
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
316 PM CDT SAT AUG 1 2015

.SHORT TERM...(TONIGHT)
ISSUED AT 314 PM CDT SAT AUG 1 2015

A SHORT-WAVE TROUGH EVIDENT ON 19Z/2PM WATER VAPOR IMAGERY OVER THE
WESTERN DAKOTAS WILL BE THE PRIMARY TRIGGERING MECHANISM FOR
THUNDERSTORMS THIS AFTERNOON INTO TONIGHT.  AS THIS FEATURE TRACKS
EASTWARD...STORMS WILL INCREASE IN COVERAGE ACROSS THE EASTERN
DAKOTAS INTO MINNESOTA THIS EVENING...THEN WILL SPREAD INTO THE
GREAT LAKES BY SUNDAY MORNING.  FURTHER SOUTH...HIGH-RES MODELS SUCH
AS THE RAPID REFRESH ARE SUGGESTING ANOTHER AREA OF SCATTERED
CONVECTION WILL DEVELOP ALONG THE REMNANTS OF AN OLD FRONTAL
BOUNDARY ACROSS SOUTHERN IOWA/NORTHERN MISSOURI AFTER MIDNIGHT.
SOME OF THIS ACTIVITY MAY SPILL INTO WEST-CENTRAL ILLINOIS TOWARD
DAYBREAK.  HAVE ADJUSTED POPS TO GO WITH DRY CONDITIONS ACROSS THE
BOARD THIS EVENING...THEN HAVE INTRODUCED LOW CHANCE POPS ALONG/WEST
OF THE ILLINOIS RIVER WELL AFTER MIDNIGHT.  OVERNIGHT LOW
TEMPERATURES WILL RANGE FROM THE LOWER 60S SOUTH OF I-70 WHERE WINDS
WILL REMAIN LIGHTEST BENEATH A SLOWLY DEPARTING HIGH PRESSURE
SYSTEM...TO THE UPPER 60S IN THE ILLINOIS RIVER VALLEY.

&&

.LONG TERM...(SUNDAY THROUGH SATURDAY)
ISSUED AT 314 PM CDT SAT AUG 1 2015

FORECAST MODELS ARE COMING INTO A BIT BETTER AGREEMENT WITH THE
EVOLVING UPPER LEVEL PATTERN FOR NEXT WEEK AS WESTERN RIDGE AND
EASTERN TROUGH FLATTEN OUT INTO A SEMI-ZONAL FLOW BY LATE IN THE
WEEK. HOWEVER...AS THIS EVOLUTION TAKES PLACE...A PERIOD OF
UNSETTLED WEATHER WILL BE IN STORE FOR CENTRAL AND EASTERN IL IN THE
TUE-THU TIMEFRAME.

IN THE NEAR TERM...AN MCS/CLUSTER OF THUNDERSTORMS IS EXPECTED TO
DEVELOP IN SOUTHERN MN/NORTHERN IA OVERNIGHT...FARTHER NORTH THAN
PREVIOUSLY EXPECTED. THE REMNANTS OF THIS MAY BRING SCATTERED
SHOWERS AND T-STORMS TO AREAS NW OF THE UPPER IL RIVER VALLEY SUNDAY
MORNING. A WEAK COLD FRONT WILL ALSO GRADUALLY MOVE INTO NW IL
TOWARD EVENING. PLENTY OF WARM AIR AND MODERATE INSTABILITY SHOULD
LEAD TO SCATTERED T-STORMS NW OF A MACOMB-BLOOMINGTON LINE SUNDAY
AFTERNOON...REACHING A QUINCY-LINCOLN-DANVILLE LINE DURING THE
EVENING. AS THE FRONT CONTINUES TO MAKE PROGRESS THROUGH CENTRAL
IL SUNDAY NIGHT...THE POTENTIAL FOR SCATTERED T-STORMS WILL
INCREASE IN MOST AREAS NORTH OF I-70.

ON MONDAY THE FRONT WILL SLOW DOWN IN SOUTHERN IL. THE LOW LEVEL
WIND FLOW...HOWEVER...IS EXPECTED TO BECOME PARALLEL TO THE BOUNDARY
RESULTING IN A RAPID DROP IN LOW LEVEL CONVERGENCE. THIS COMBINED
WITH MARGINAL INSTABILITY SHOULD RESULT IN A FEW CLOUDS AND LITTLE
IN THE WAY OF CONVECTION IN SOUTHEAST IL.

THE GFS AND EUROPEAN MODELS ARE SIMILAR IN SHOWING A PIECE OF A
SHORTWAVE TROUGH CUTTING THROUGH THE UPPER RIDGE POSITION AND
APPROACHING THE MID MS AND LOWER OHIO VALLEY TUESDAY...WITH
ADDITIONAL SHORTWAVES EXPECTED TO FOLLOW THROUGH EARLY THURSDAY.
THIS UPPER LEVEL SUPPORT WILL COMBINE WITH THE NEARLY STATIONARY
FRONT IN SOUTHERN IL TO PRODUCE PERIODS OF SHOWERS AND T-STORMS.
WILL KEEP AN EYE ON THIS FOR A HEAVY RAIN POTENTIAL...BUT IT APPEARS
THAT THERE SHOULD NOT BE ENOUGH DEEP LEVEL MOISTURE FOR THIS TO
OCCUR. WITH MUCH OF THE FORECAST AREA EXPECTED TO BE ON THE COOL
SIDE OF THE FRONT...TEMPERATURES SHOULD BE BELOW SEASONAL NORMALS
MOST OF NEXT WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1237 PM CDT SAT AUG 1 2015

VFR CONDITIONS WILL PREVAIL THROUGH THE ENTIRE 18Z TAF PERIOD.
LATEST MODEL GUIDANCE SUGGESTS CONVECTION THAT DEVELOPS ACROSS THE
CENTRAL/NORTHERN PLAINS LATER THIS AFTERNOON/EVENING MAY REMAIN
WELL N/NW OF CENTRAL ILLINOIS OVERNIGHT INTO SUNDAY MORNING. AS
SUCH...HAVE MAINTAINED A DRY FORECAST AT THE TERMINALS WITH ONLY
BKN HIGH CLOUDS. WINDS WILL BE LIGHT/VARIABLE ACROSS THE EASTERN
HALF OF THE AREA THIS AFTERNOON...THEN WILL BECOME SW AT AROUND
5KT ACROSS THE BOARD TONIGHT.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...BARNES
LONG TERM...MILLER
AVIATION...BARNES


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