FXUS63 KILX 222035
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
235 PM CST TUE DEC 22 2009
.DISCUSSION...
ISSUED 210 PM CST TUE DEC 22 2009
SHORT TERM...TONIGHT THROUGH FRIDAY
...LIGHT ICING POSSIBLE NORTH OF INTERSTATE 74 TONIGHT INTO
WEDNESDAY MORNING WITH AN INCREASING FLOOD THREAT OVER CENTRAL
EAST CENTRAL AND SOUTHEAST ILLINOIS LATE WEDNESDAY THROUGH THU
EVENING...
MAJOR WINTER STORM THE MAIN FORECAST ISSUE THIS PERIOD AND ITS
OVERALL AFFECT IN OUR AREA INTO FRIDAY. MODELS IN DECENT AGREEMENT
WITH THE DETAILS OF THE POTENT STORM SYSTEM FORECAST TO SLOWLY
PUSH OUT OF THE SOUTHERN PLAINS LATE TOMORROW INTO XMAS EVE.
PRIMARY CONCERN WL INITIALLY BE WITH SOME LIGHT ICING MAINLY NORTH
OF INTERSTATE 74 TONIGHT INTO WED MRNG...FOLLOWED BY A FLOOD THREAT
STARTING LATE TOMORROW THRU THU EVENING WITH MODELS CONTINUING TO
INDICATE CENTRAL ILLINOIS IN STORE FOR 2 TO 3 INCHES OF RAIN BY
THE TIME THE SYSTEM DRY SLOT PUSHES ACRS THE AREA LATER THU EVENING.
MODEL FORECAST SOUNDINGS LATER THIS EVENING INTO WED MRNG SUGGEST
AREAS NORTH OF A GALESBURG TO PEORIA TO DANVILLE LINE MAY SEE A
PERIOD OF FREEZING DRIZZLE AS SFC TEMPS WL BE AT OR JUST BELOW
FREEZING. DO EXPECT WITH STRONG LOW LEVEL WARM ADVECTION TO CONTINUE
ACRS THE AREA ON WEDNESDAY...THAT SFC TEMPS SHOULD RISE ABOVE
FREEZING IN OUR EXTREME NORTHERN AREAS DURING THE MORNING HOURS.
HOWEVER...INCREASING EASTERLY SURFACE WINDS WILL BE MAKING IT A
STRUGGLE TO SEE MUCH IN THE WAY OF ANY SIGNIFICANT RISE IN TEMPS
UNTIL LATER IN THE MORNING OR DURING THE AFTERNOON. WILL ISSUE A
WINTER WEATHER ADVSY FOR FREEZING DRIZZLE LATER THIS EVENING INTO
WED MRNG FOR THE AREAS MENTIONED ABOVE. 12KM NAM-WRF SOUNDINGS
CONTINUE TO SHOW NOT MUCH MOISTURE ABOVE 800 MB SUGGESTING A THREAT
MORE TWDS DRIZZLE/FREEZING DRIZZLE THRU MOST OF THE NIGHT...WITH
THE DEEPER MOISTURE TRANSPORT NOT EXPECTED UNTIL LATER WEDNESDAY.
STRONG MOISTURE TRANSPORT AND 850 MB THETA-E ADVECTION GETS GOING
TO OUR SOUTH TMRW MRNG AND SHIFTS INTO OUR AREA DURING THE DAY
BRINGING PERIODS OF MODERATE TO LOCALLY HEAVY RAINFALL INTO THU
AFTN AND EVENING. SOME THUNDER POSSIBLE AS WELL ACRS THE SOUTH
HALF OF THE FORECAST AREA WHICH WILL ONLY SERVE TO AGGREVATE THE
FLOOD POTENTIAL IN OUR AREA. PRECIP WATER VALUES UP TO 1.25 INCHES
TO OUR SOUTH WHICH IS WELL ABOVE NORMAL FOR THIS TIME OF YEAR.
FROST DEPTH OBSERVATIONS ACRS THE AREA INDICATE DEPTHS OF BETWEEN
3 TO 5 INCHES...THUS THE 2 TO 3 INCHES OF RAIN EXPECTED OVER THE
AREA WL ALL GO RUNOFF INTO AREA STREAMS AND RIVERS. INITIAL SFC
WAVE TO SHIFT INTO WRN IOWA BY THU MRNG WITH AN EVEN STRONGER
SURFACE LOW FORECAST TO DEVELOP OVR NRN LOUISIANA AND TRACK
STRAIGHT NWD INTO WRN IL BY THU NIGHT BRINGING ADDITIONAL MODERATE
TO LOCALLY HEAVY RAINS INTO OUR AREA. ISSUING A FLOOD WATCH FOR
ALL OF OUR AREA STARTING AT NOON ON WED AND CONTINUING THRU THU
EVENING WHEN MODELS CONTINUE TO INDICATE THE MID LEVEL DRY SLOT WL
SHUT DOWN THE SIGNFICANT RAINS IN OUR AREA.
MODELS SLOWING THE TRACK OF THE SFC AND UPPER SYSTEMS ON FRIDAY
RESULTING IN A CONTINUATION OF PRECIP CHANCES DURING XMAS DAY.
STRONG COLD ADVECTION...GUSTY WEST WINDS AND PERIODS OF SNOW
SHOWERS WILL BE THE STORY FOR XMAS DAY WITH FALLING TEMPERATURES.
LONG TERM...SATURDAY THROUGH TUESDAY
AS MENTIONED ABOVE...MODELS ADVERTISING A SLOWER SOLUTION TO THE
DEEP UPPER LOW AND ATTENDANT SFC LOW THIS PERIOD. WITH THE EXPECTED
UPPER LEVEL WAVES PIN-WHEELING AROUND THE LOW AND CONTINUED COLD
ADVECTION OVER AREA...SHOULD HAVE PERIODIC SNOW SHOWERS OVER
REGION FOR FRIDAY NIGHT INTO SUNDAY. HAVE THEREFORE ADDED POPS
FOR CHANCE OF SNOW SHOWERS THROUGH THAT TIME FRAME.
EXPECT THE UPPER LOW TO MOVE OFF BY MONDAY...WITH SOME POSSIBLE
BREAKUP OF CLOUDINESS...BUT STILL RATHER COLD. NEXT POTENTIAL SYTEM
TO WATCH MAY BE AFFECTS OF THE DEVELOPING LOW ALONG THE GULF...FOR
MID NEXT WEEK.
SMITH (SHORT TERM)/GOETSCH (LONG TERM)
&&
.AVIATION...
ISSUED 1135 AM CST TUE DEC 22 2009
LOW CEILINGS AND POOR VISIBILITIES WILL PREVAIL THROUGH THE ENTIRE
18Z TAF PERIOD...AS A STORM SYSTEM SLOWLY APPROACHES FROM THE
SOUTHWEST. CURRENT OBS INDICATE CEILINGS BELOW 1000FT AND VISBYS
LESS THAN 4SM...AND THESE CONDITIONS ARE EXPECTED TO PERSIST FOR THE
BALANCE OF THE AFTERNOON. AS LOW-LEVEL MOISTURE AND LIFT
INCREASES...DRIZZLE WILL DEVELOP AT THE TAF SITES AFTER 21Z. WITH
SURFACE TEMPS DROPPING TO AROUND 32F ACROSS THE NORTH TONIGHT...A
PERIOD OF FREEZING DRIZZLE WILL BE LIKELY AT BOTH KPIA AND KBMI
FROM 06Z THROUGH 13Z. FURTHER SOUTH...LIGHT RAIN WILL DEVELOP AT
KSPI AND KDEC WELL AFTER MIDNIGHT AND PERSIST INTO WEDNESDAY
MORNING. THE RAIN WILL SPREAD FURTHER NORTH AND IMPACT THE
REMAINING TERMINALS AFTER 13Z. WINDS WILL INITIALLY BE GUSTY FROM
THE E/SE THIS AFTERNOON...THEN WILL BECOME MORE EASTERLY AND
INCREASE LATER TONIGHT. BUFKIT DATA SUGGESTS GUSTS REACHING 25KT
BY WEDNESDAY MORNING.
BARNES
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY EVENING
FOR ILZ027>031-036>038-040>057-061>063-066>068-071>073.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO NOON CST
WEDNESDAY FOR ILZ027>031-037-038-045-046.
&&
$$
