Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 171957
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
257 PM CDT FRI APR 17 2015

.SHORT TERM...(TONIGHT) ISSUED AT 256 PM CDT FRI APR 17 2015

QUIET WEATHER IS EXPECTED ACROSS CENTRAL AND SOUTHEAST ILLINOIS
TONIGHT WITH HIGH PRESSURE AND THE ASSOCIATED DRY AIRMASS IN
CONTROL. WE`VE HAD MORE INSOLATION TODAY THAT YESTERDAY, DESPITE THE
ROBUST CU FIELD, AND FORECAST SOUNDINGS SUGGEST THE LOW LEVEL
MOISTURE WILL BE FAIRLY WELL MIXED OUT. SO, DO NOT EXPECT FOG TO BE
AS MUCH OF PROBLEM LATER TONIGHT AS IT WAS IN SOME AREAS THIS
MORNING. OTHERWISE, LIGHT WINDS AND MINIMAL CLOUD COVER SHOULD ALLOW
FOR GOOD RADIATIONAL COOLING TONIGHT. EXPECTING OVERNIGHT LOWS
MAINLY IN THE MID 50S, WARMER THAN LAST NIGHT, THANKS TO AIRMASS
MODIFICATION/HIGHER DEW POINTS.

&&

.LONG TERM...(SATURDAY THROUGH FRIDAY) ISSUED AT 256 PM CDT FRI
APR 17 2015

THE CUTOFF UPPER-LEVEL LOW, CURRENTLY BEGINNING TO LIFT NORTHEAST
OUT OF THE FOUR CORNERS REGION, IS STILL EXPECTED TO GRADUALLY
SPREAD SHOWERS AND A FEW THUNDERSTORMS INTO THE REGION AS IT MOVES
THROUGH. HOWEVER, AS IS OFTEN THE CASE WHEN DEALING WITH CUTOFF
UPPER LOWS, THE MODEL GUIDANCE HAS BEEN TRENDING SLOWER WITH ITS
EXPECTED ARRIVAL (SOME SOLUTIONS ARE STILL FASTER THAN OTHERS).
GIVEN THE SLOWER EXPECTED ARRIVAL, HAVE PRETTY MUCH REMOVED POPS
FROM SATURDAY, AND GREATLY LOWERED THEM SATURDAY NIGHT. IF SLOWER
TRENDS PERSIST, THEY WILL NEED TO BE LOWERED FURTHER THROUGH AT
LEAST SATURDAY NIGHT. STILL LOOKS LIKE SUNDAY AND SUNDAY NIGHT
SHOULD END UP FAIRLY WET AS THE UPPER LOW REMNANTS GET ABSORBED IN
TO A DIGGING NORTHERN STREAM TROF. WHILE ONE MIGHT EXPECT THE
SURFACE LOW TO WEAKEN AS THE UPPER FEATURE IT IS TIED TO DIMINISHES,
THE LATEST MODEL RUNS SUGGEST THAT WILL NOT HAPPEN IN THIS CASE.
RECENT GUIDANCE DIGS THE NORTHERN STREAM TROF MORE THAN PREVIOUS
SOLUTIONS, AND THE JET STREAKS ASSOCIATED WITH THE DIGGING TROF AND
DISSIPATING UPPER LOW ARE WORKING IN CONCERT TO STRENGTHEN THE
SURFACE LOW. THAT BEING SAID, THE CONSENSUS TRACK UP THE EASTERN
BORDER OF ILLINOIS IS NOT CONDUCIVE TO US GETTING INTO THE WARM
SECTOR AND/OR SEVERE WEATHER ON SUNDAY.

SOME POST SYSTEM SHOWERS ARE POSSIBLE ON MONDAY, POSSIBLY A GREATER
RISK THAN BEFORE IF THE SYSTEM SLOWS MUCH MORE THAN CURRENT
INDICATIONS. HOWEVER, OTHERWISE MONDAY SHOULD BE THE FIRST DAY OF
WHAT LOOKS TO BE A PROLONGED PERIOD TEMPERATURES ON THE COOLER SIDE
OF NORMAL. THE WEEKEND SYSTEM CONTINUES TO EVOLVE AFTER IT LEAVES
THE AREA, TAKING UP A FAIRLY STEADY RESIDENCE AS A RELATIVELY DEEP
TROF OVER EASTERN NORTH AMERICA FOR THE REST OF THE WEEK. PERIODIC
DISTURBANCES MOVING THROUGH THIS TROF MAY POSE AN OCCASIONAL RISK OF
SHOWERS, BUT GUIDANCE AGREEMENT WITH RESPECT TO THESE DISCRETE
FEATURES IS POOR AT BEST. HAVE KEPT POPS ON THE LOW SIDE THROUGH THE
EXTENDED RANGE OF THE FORECAST AS A RESULT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1216 PM CDT FRI APR 17 2015

DIURNAL CU ACROSS THE REGION DEVELOPING AND VERY FEW OVER
CMI...BUT MORE BKN TO THE SOUTH FOR SPI AND DEC POTENTIALLY
THROUGH THE AFTERNOON. STILL VERY LIGHT AND VARIABLE WINDS
EXPECTED ACROSS THE REGION...WITH MAINLY WESTERLY FLOW ALOFT.
STILL PLENTY OF LLVL MOISTURE IN THE BOUNDARY LAYER TO LEND TO A
SLIGHT REDUCTION OF VISIBILITY OVERNIGHT AND IN THE EARLY MORNING
HOURS. HAVE CONTINUED THE TREND TO MAINLY MVFR VIS...BUT WILL HAVE
TO KEEP A CLOSE EYE ON THE XOVER TEMPS THIS AFTERNOON. NOT MUCH IN
THE WAY OF MIXING IS ANTICIPATED AGAIN WITH THE LIGHT FLOW...BUT
SINCE WESTERN TERMINALS WERE RELATIVELY LIGHT VIS DROPS THIS
MORNING...EXPECT SOME OF THAT WILL TRANSLATE EASTWARD.


&&

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

$$

SHORT TERM...BAK
LONG TERM...BAK
AVIATION...HJS



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