Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 300056
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
756 PM CDT MON JUN 29 2015

.SHORT TERM...(TONIGHT)
ISSUED AT 300 PM CDT MON JUN 29 2015

19Z/2PM SURFACE ANALYSIS SHOWS 1008MB LOW OVER EASTERN
INDIANA...WITH COLD FRONT EXTENDING SOUTHWESTWARD INTO THE OZARKS.
ALOFT...A DEEP TROUGH WITH SEVERAL EMBEDDED SHORT-WAVES REMAINS IN
PLACE ACROSS THE EASTERN CONUS.  WHILE ONE IMPULSE ASSOCIATED WITH
THE SURFACE LOW HAS PASSED WELL EAST OF ILLINOIS...TWO ADDITIONAL
FEATURES ARE NOTED ON UPSTREAM WATER VAPOR IMAGERY...ONE OVER
SOUTHERN LAKE MICHIGAN AND ANOTHER OVER EASTERN MINNESOTA/NORTHERN
WISCONSIN.  THE GREAT LAKES WAVE IS CURRENTLY TRIGGERING WIDELY
SCATTERED CONVECTION ACROSS MAINLY NORTHERN ILLINOIS INTO
NORTHERN/CENTRAL INDIANA.  A FEW SHOWERS ASSOCIATED WITH THIS
FEATURE WILL DRIFT SOUTHWARD INTO THE NORTHERN KILX CWA THIS
AFTERNOON INTO THE EARLY EVENING BEFORE DISSIPATING TOWARD SUNSET.
WILL INCLUDE LOW CHANCE POPS ALONG/NORTHEAST OF A RUSHVILLE...TO
DECATUR...TO PARIS LINE THROUGH MID-EVENING ACCORDINGLY. AFTER
THAT...THINK THERE WILL BE A LULL IN PRECIP CHANCES BEFORE THE
MINNESOTA WAVE APPROACHES FROM THE NORTH LATE TONIGHT.  HAVE
THEREFORE BROUGHT LOW CHANCE POPS AS FAR SOUTH AS I-70 WELL AFTER
MIDNIGHT TOWARD DAWN TUESDAY.  FURTHER SOUTHEAST...HAVE GONE WITH A
DRY FORECAST THROUGH THE ENTIRE NIGHT SOUTH OF THE I-70 CORRIDOR.

.LONG TERM...(TUESDAY THROUGH MONDAY)
ISSUED AT 300 PM CDT MON JUN 29 2015

THE 12Z EXTENDED MODELS ARE STARTING TO GIVE SOME HOPE TO LONGER DRY
PERIODS THIS WEEK, ESPECIALLY THE NORTHERN HALF OF ILLINOIS.

IN THE EARLY EXTENDED FOR TUESDAY, THE UPPER TROUGH IN THE EASTERN
CONUS AND THE RIDGE IN THE WEST WILL ALLOW A SHORTWAVE TO DROP SOUTH
THROUGH ILLINOIS LATE TONIGHT INTO TUESDAY, TRIGGERING SHOWERS AND A
FEW THUNDERSTORMS.

SOME WEAK RIDGING ALOFT MID WEEK OVER ILLINOIS COULD PUSH THE STORM
TRACK FOR THE WEDNESDAY NIGHT SYSTEM JUST SOUTHWEST OF OUR COUNTIES.
THE BETTER CHANCES FOR STORMS FROM THAT SYSTEM SHOULD REMAIN S OF I-
70, ALTHOUGH MODEL DIFFERENCES KEEP AT LEAST CHANCE POPS AS FAR
NORTH AS I-74. WE REMAIN IN THE SPC DAY 3 MARGINAL RISK FOR STORMS
SOUTH OF I-74, BUT OVERALL CHANCES OF SEVERE ARE RELATIVELY LOW.

THE NEXT STRONGER SHORTWAVE IS PROJECTED TO AFFECT OUR FORECAST AREA
ON FRIDAY, WITH THE ECMWF/GFS/CANADIAN HAVING RELATIVELY SIMILAR
TIMING AND LOCATION OF THAT SYSTEM. THE GFS IS THE OUTLIER WITH
PRECIP, GOING NEARLY DRY DURING THAT TIME. BETTER CHANCES FOR STORMS
FRIDAY APPEAR TO BE SOUTH OF I-74.

BEYOND THAT, MODEL DIFFERENCES BECOME MORE PROMINENT, WITH
VARIATIONS ON TIMING OF UPPER LEVEL RIDGING OR TROUGHING. GENERAL
CONSENSUS IS FOR SCATTERED SHOWERS/STORMS TO BE POSSIBLE AS THE
UPPER TROUGH AXIS REMAINS CLOSE-BY IF NOT DIRECTLY ACROSS ILLINOIS
FROM SW TO NE. FROM FRIDAY NIGHT THROUGH THE WEEKEND, WE TRENDED
DOWN WITH POPS TO SLIGHT CHANCE IN THE WEST, AND LOW CHANCE IN THE
EAST CLOSER TO THE POTENTIAL TRACK OF ANY SHORTWAVES.

IN THE FAR EXTENDED, THE GFS IS ADVERTISING A POTENTIAL SHIFT TO
LONG WAVE RIDGING ALOFT STARTING MONDAY, WHICH COULD TRANSLATE INTO
A SHIFT IN THE STORM TRACK NORTH OF ILLINOIS AND BUILDING OF SOME
HEAT IN OUR AREA. THE 12Z ECMWF HAS THE OPPOSITE SOLUTION, WITH
ANOTHER TROUGH PROGRESSING FROM THE NORTHERN PLAINS AND DIGGING INTO
ILLINOIS FOR THE FIRST HALF OF NEXT WEEK. HOPEFULLY THE DRIER GFS
PANS OUT SO WE CAN GIVE THE RIVERS A CHANCE TO RECEDE FROM NEAR
RECORD FLOODING IN SOME AREAS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 756 PM CDT MON JUN 29 2015

VFR CONDITIONS ACROSS CENTRAL IL TERMINALS WITH SCATTERED FEW-SCT
CLOUD COVER ABOVE 3.5 KFT AGL THIS EVENING WHILE ISOLATED
THUNDERSTORMS CONTINUE ACROSS NORTHERN IL. THUNDERSTORMS ARE
SHOWING SOME SLOW MOVEMENT TO THE SOUTH...BUT ARE STRUGGLING TO
MAINTAIN STRENGTH OVER CENTRAL IL WHERE GENERAL SUBSIDENCE ALOFT
CONTINUES. STORMS SHOULD TEND TO DISSIPATE AFTER SUNSET AS
WELL...SO HAVE NOT INCLUDED MENTION IN 00Z TAFS. SHORTWAVE TROUGH
CURRENTLY OVER SE MN/WI WILL DROP SOUTHWARD INTO THE AREA EARLY
TUESDAY MORNING...TRIGGERING SCATTERED SHOWERS/THUNDER. EXPECTING
LOW VFR CEILINGS AND VCTS SPREADING ACROSS TERMINALS
11-14Z...CONTINUING FOR MUCH OF REMAINDER OF TAF PERIOD. STRONGER
STORMS COULD PRODUCE LOCAL MVFR CIGS/VSBYS...ALTHOUGH
TIMING/LOCATION UNCERTAINTIES PREVENT EXPLICIT MENTION IN TAFS AT
THIS TIME. WINDS W-NW 5-10 KTS OVERNIGHT...VEERING SLIGHTLY NW AND
INCREASING TO 10-12 KTS AFTER 17Z.

&&

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

$$

SHORT TERM...BARNES
LONG TERM...SHIMON
AVIATION...ONTON



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