FXUS63 KILX 280524
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1124 PM CST FRI NOV 27 2009
.DISCUSSION...
ISSUED 833 PM CST FRI NOV 27 2009
EVENING SURFACE ANALYSIS SHOWS RIDGE OF HIGH PRESSURE EXTENDING
FROM THE GREAT LAKES TO THE GULF COAST...WITH WEAK RETURN FLOW
NOTED ACROSS CENTRAL ILLINOIS. SKIES ARE MOSTLY CLEAR...EXCEPT FOR
A BAND OF HIGH CLOUDS DRIFTING ACROSS THE CENTRAL AND SOUTHERN
KILX CWA. DESPITE S/SE FLOW...TEMPS HAVE BEEN STEADILY DROPPING
OFF SINCE SUNSET...PARTICULARLY ACROSS THE NE...WHERE MANY
READINGS ARE ALREADY IN THE LOWER 30S. BASED ON THE LATEST TEMP
TRENDS...HAVE DROPPED LOWS INTO THE UPPER 20S ALONG AND NORTHEAST
OF A BLOOMINGTON-NORMAL TO PARIS LINE. ELSEWHERE...LEFT LOWS IN
THE LOWER TO MIDDLE 30S. THINK LOW TEMPS WILL BE ACHIEVED BY
AROUND MIDNIGHT...WITH TEMPS RISING A COUPLE OF DEGREES TOWARD
DAWN AS SOUTHERLY FLOW BEGINS TO INCREASE.
&&
.AVIATION...
ISSUED 1124 PM CST FRI NOV 27 2009
VFR CONDITIONS WILL PREVAIL THROUGH THE ENTIRE 06Z TAF PERIOD.
LIGHT SOUTHEASTERLY WINDS OF AROUND 5KT TONIGHT WILL VEER TO
SOUTHWESTERLY AND INCREASE TO BETWEEN 10 AND 15KT ON SATURDAY
AHEAD OF THE NEXT APPROACHING FRONTAL BOUNDARY. SKIES WILL REMAIN
CLEAR THROUGH 06Z SUN.
BARNES
&&
.PREV DISCUSSION...
ISSUED 253 PM CST FRI NOV 27 2009
THE CURRENT UPPER PATTERN OF TROFS ON BOTH COASTS AND FLAT RIDGING
IN THE CENTRAL U.S. WILL UNDERGO A TRANSITION AS SHORTWAVE ENERGY
IN THE PACIFIC NW DIGS INTO THE MIDWEST. THIS WILL RESULT IN
COOLER WEATHER ACROSS CENTRAL AND SE IL...BUT MAINLY LIGHT
PRECIPITATION EVENTS AS THE DEEPER MOISTURE STAYS BOTTLED UP TO
THE SOUTH.
THE NAM...GFS AND EUROPEAN MODELS ARE ALL FAIRLY SIMILAR IN THEIR
SHORT TERM DEPICTION OF THIS EVOLVING PATTERN. HOWEVER...THE
EUROPEAN MODEL HAS MORE LOW LEVEL MOISTURE AND PRECIP THEN THE GFS
OR NAM IN THE 48-60 HOUR TIME FRAME. THE LATEST UPPER AIR
ANALYSIS AND WATER VAPOR LOOP DOES NOT SUPPORT THE HIGHER MOISTURE
AND QPF IN THE EUROPEAN...SO THE NAM/GFS FOLLOWED CLOSER.
THE 12Z EUROPEAN MODEL IS CLOSER TO THE GFS THAN THE 00Z RUN FOR
THE MIDDLE OF NEXT WEEK. HOWEVER...THERE IS NOT A LOT OF
CONSISTENCY FROM RUN TO RUN IN THE EUROPEAN AND THE GFS SEEMS TO
BE A BIT UNDERDONE WITH ITS DEPICTION OF PRECIP FOR LATE WED-THU.
THUS...THERE WILL ONLY BE LOW POPS INTRODUCED INTO THE FORECAST
IN PART OF THE FORECAST AREA FOR MIDWEEK.
SHORT TERM...TONIGHT THROUGH MONDAY
DEPARTING HIGH PRESSURE WILL GIVE US A LIGHT SOUTH WIND TONIGHT SO
LOWS SHOULD NOT BE AS COLD AS LAST NIGHT...ESPECIALLY IN WEST
CENTRAL AND CENTRAL IL. IMPRESSIVE LOW LEVEL WARM ADVECTION
OVERNIGHT AND TOMORROW...ALONG WITH A MOSTLY SUNNY SKY WILL RESULT
IN MILD TEMPERATURES ABOUT 15 DEGREES ABOVE NORMAL. WENT A LITTLE
ABOVE GUIDANCE WITH TEMPS IN THE 58-63 RANGE ACROSS THE REGION FOR
SATURDAY.
THE SHORTWAVE DIGGING INTO THE MIDWEST ON SUNDAY WILL RESULT IN
CLOUDIER CONDITIONS WITH AN APPROACHING COLD FRONT. TEMPS WILL BE
COOLER IN THE LOWER-MIDDLE 50S. LOW LEVEL MOISTURE WILL BE QUITE
SPARSE...WITH THE BEST MOISTURE NOT EXPECTED TO COME TOWARD THE
REGION UNTIL THE FRONT IS THROUGH CENTRAL IL. THIS WILL RESULT IN
THE BEST CHANCE FOR LIGHT RAIN EAST OF I-55...BEHIND THE FRONT
LATER ON SUNDAY. SURFACE RIDGING WILL NOSE INTO THE AREA BY
MONDAY...WITH GRADUAL CLEARING AND SEASONABLE TEMPS IN THE 40S.
LONG TERM...TUESDAY THROUGH FRIDAY
SURFACE RIDGING WILL KEEP CONDITIONS PARTLY CLOUDY AND COOL ON
TUESDAY BEFORE THE NEXT COLD FRONT AND UPPER LEVEL SHORTWAVE
APPROACH FOR MIDWEEK.
THE 12Z EUROPEAN MODEL IS A BIT CLOSER TO THE GFS SOLUTION THAN
ITS PREVIOUS RUN...BUT IT IS SLOWER WITH THE NORTHERN STREAM TROF
AND FURTHER NORTH WITH AN UPPER LOW EJECTING FROM THE SOUTHERN
PLAINS BY WED. THIS RESULTS IN THE EUROPEAN BRINGING PRECIP FARTHER
NORTH THEN THE GFS. CONVERSELY...THE GFS SEEMS TO BE UNDERDONE
WITH ITS DEPICTION OF PRECIP LATE WED-THU AS THE NORTHERN STREAM
SHORTWAVE SWINGS THROUGH. AS A RESULT WILL COMPROMISE...BUT LEAN
TOWARD THE GFS...AND PUT A CHANCE FOR RAIN IN THE FORECAST IN
EAST/SE IL FOR MIDWEEK.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
