FXUS63 KILX 121621
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1021 AM CST FRI MAR 12 2010

.DISCUSSION...
ISSUED 1021 AM CST FRI MAR 12 2010

VIGOROUS UPPER SHORTWAVE/VORT MAX CENTERED OVER THE MISSOURI
BOOTHEEL WILL CONTINUE TO MOVE NORTHWARD...SPREADING RAIN OVER MOST
OF THE SOUTHERN 2/3RDS OF THE AREA TODAY. IT WILL TAKE SOME TIME FOR
THE AIRMASS TO MOISTEN UP AND ALLOW THE RAIN TO REACH THE SURFACE...
SO IT WILL BE LATER ON BEFORE RAIN IS OBSERVED WEST OF THE
INTERSTATE 55 CORRIDOR. HAVE ALREADY BUMPED UP POPS ACCORDINGLY TO
THE SOUTHEAST.

12Z MODELS INDICATE THE POTENTIAL FOR SOME HEAVY RAINFALL ACROSS
CENTRAL ILLINOIS TONIGHT. CURRENT COLD CLOUD TOP TEMPERATURES ON IR
SATELLITE IMAGERY OVER KENTUCKY AND SOUTHERN INDIANA WILL LIKELY
ROTATE CYCLONICALLY NORTHWESTWARD ON THE NORTHERN PERIPHERY OF THE
MISSOURI VORT MAX...SO THIS APPEARS REASONABLE. WILL EVALUATE THIS
POTENTIAL FOR THE AFTERNOON FORECAST PACKAGE.

04
$$

.AVIATION...
ISSUED 558 AM CST FRI MAR 12 2010

A COMPLEX AREA OF LOW PRESSURE CONTINUES TO SPIN ACROSS THE
MIDWEST...AND IMPACT THE CENTRAL ILLINOIS TERMINALS. MVFR
CONDITIONS SHOULD PREVAIL FOR MUCH OF THE 12Z TAF PERIOD.
HOWEVER...A BRIEF PERIOD OF CLEARING/VFR CONDITIONS IS POSSIBLE
THIS MORNING AS A REGION OF DRY AIR PINWHEELS AROUND THE LOW. A
DISTURBANCE LIFTING NORTH TOWARD THE REGION FROM THE LOWER
MISSISSIPPI VALLEY WILL SPREAD RAIN INTO THE TERMINALS AS EARLY AS
THIS AFTERNOON...BUT MORE LIKELY THIS EVENING. ONCE THE STEADIER
RAINS ARRIVE TONIGHT...EXPECT MVFR VSBYS AND IFR CIGS TO DEVELOP.
VARIABLE WINDS SHOULD PERSIST FOR MUCH OF THE DAY...BUT WINDS WILL
TREND NORTHERLY AND BECOME STRONGER TONIGHT AS THE LOW BEGINS TO
SHIFT EAST OF ILLINOIS.

BAK
&&

.PREV DISCUSSION...
ISSUED 320 AM CST FRI MAR 12 2010

NOT A LOT OF SHIFT TO THE GOING FORECAST FOR TODAY. A BRIEF BREAK IN
THE SHOWERS AND PRECIP TO CONTINUE THROUGH MUCH OF THE MORNING UNTIL
A WAVE ROTATES AROUND THE LARGER SCALE TROF....REDEVELOPING A SFC
LOW AND TROF FEATURE ACROSS THE STATE. MODELS HAVE BEEN ALL OVER THE
PLACE IN DISCERNING WHERE EXACTLY THE AXIS OF RAIN ASSOCIATED WITH
THE SYSTEM WILL SET UP. LATEST TREND SEEMS TO BE SQUARELY OVER
CENTRAL ILLINOIS...AND A BLEND OF MODELS SEEMS TO BE IN LINE WITH
KEEPING THE PRECIP IN THE FA THROUGH SATURDAY NIGHT. LONGER
TERM...MODELS SEEM TO BE COMING AROUND TO THE LATEST TRENDS IN THE
ECMWF...KICKING THE OLD LOW OUT TO THE AT COAST AND GIVING A PRECIP
FREE START TO THE WORK WEEK.

SHORT TERM...TODAY AND TOMORROW...
WAVE ON THE WAY FOR TODAYS PRECIP IS A LITTLE BIT AHEAD OF SCHEDULE
ON SAT IMAGERY AND FIRING PRECIP WELL AHEAD OF IT ACROSS THE SE. FOR
THIS REASON...NOT IN A HURRY TO DROP MORNING POPS IN THE SE. POPS
RISING THROUGH THE AFTERNOON AS THE WAVE MOVES AROUND THE BROADER
UPPER LOW THAT IS SLOW TO MOVE OVER THE MIDWEST. MUCH INCONSISTENCY
IN THE MODELS WITH THE LOCATION OF A SFC TROF FOR THE PRECIP TO
FOCUS ON. QPF IS ALSO WIDELY VARIED...AND WITH BOTH BEING A BIT
QUESTIONABLE...AM CONCERNED ABOUT POTENTIAL WATER IMPACTS SHOULD THE
AXIS OF PRECIP SET UP OVER THE FA...AS IT HAS IN PREVIOUS RUNS.
HOWEVER...WITH THE INCREASED SPEED OF THE WAVE ITSELF...THE
FRONTOGENETIC ZONE MAY BE DISPLACED A BIT NORTH. POPS CONTINUE
THROUGH SATURDAY AS THE UPPER LOW IS SLOW TO MOVE OUT.

LONG TERM...SUNDAY THROUGH TUESDAY...
RETURN TO A DRY PERIOD FOR THE FIRST PORTION OF THE WORKWEEK.
OPERATIONAL MODELS COMING INTO AGREEMENT WITH THE LAST FEW RUNS OF
THE ECMWF WITH THE LOW DIGGING IN OVER THE WRN PORTION OF THE CONUS
KICKING THE SLOW LOW OUT OVER THE ATLANTIC COAST. SOME HINTS IN THE
GFS AND ECMWF OF A WAVE FOR TUES...BUT THE AREAL DISPLACEMENT
BETWEEN THE TWO MODELS ENOUGH TO LEAVE OUT THE MENTION OF IT FOR NOW.

HJS
&&

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

$$