000 FXUS63 KEAX 030359 CCA AFDMCI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1000 PM CST TUE DEC 2 2003 .DISCUSSION... EVENING SATELLITE IMAGERY AND OBJECTIVE ANALYSIS DEPICT VIGOROUS SHORTWAVE TROUGH DIGGING INTO SOUTHERN PLAINS WITH ELONGATED VORT LOBE EXTENDING NORTHWARD ACROSS CENTRAL KS/EASTERN NE. 50+KT LOW LEVEL JET EXTENDS AHEAD OF THIS TROUGH AXIS ACROSS CENTRAL OK INTO SOUTHERN KS. INTENSE UPWARD VERTICAL MOTION RESULTING FROM COMBINATION OF APPROACHING UPPER LEVEL TROUGH AND ISENTROPIC LIFT HAS ALLOWED WIDESPREAD RAIN TO DEVELOP ACROSS EASTERN KS INTO WEST CENTRAL AND NORTHWEST MO. 00Z TOPEKA SOUNDING INDICATED SUBSTANTIAL WEDGE OF AIR >0C BETWEEN 925-725MB. OBSERVATIONS NORTH OF CWA INDICATE RAIN/SNOW LINE CURRENTLY NEAR I-80...AND EXPECT THIS TO SLOWLY MIGRATE SOUTHWARD OVERNIGHT AS APPROACHING TROUGH CONTINUES TO AMPLIFY. HOWEVER THIS IS SLOWER THAN MODELS HAVE BEEN ADVERTISING...THUS HAVE GONE AHEAD AND SLOWED DOWN CHANGEOVER TO SNOW ACROSS NORTHERN MO UNTIL AFTER MIDNIGHT. HAVE SOME QUESTION AS TO WHETHER PRECIP WILL INDEED CHANGE OVER TO SNOW ALONG/SOUTH OF I-70 CORRIDOR ACROSS WEST CENTRAL MO BEFORE END OF EVENT WEDNESDAY MORNING...GIVEN VERY WARM TEMPS ALOFT AND STRENGTH OF LOW LEVEL WARM AIR ADVECTION. HAVE UPDATED FORECAST TO SLOW DOWN CHANGEOVER TO SNOW...AND REMOVED ANY ACCUMULATION FROM I-70 CORRIDOR. FURTHER EAST WEDGE OF DRY AIR AROUND KIRKSVILLE AND MOBERLY SHOULD SUBSTANTIALLY LIMIT ANY PRECIPITATION. HAVE KEPT POPS IN CHANCE CATEGORY ACROSS THIS AREA. SEAMAN && .PREV DISCUSSION... 315 PM... RADAR RETURNS ARE INCREASING OVER EASTERN KANSAS, EASTERN NEBRASKA, AND NORTHWEST MISSOURI DURING THE LAST HOUR. WITH SURFACE DEWPOINT DEPRESSIONS AROUND 25 DEGREES FAHRENHEIT, MOST OF THE RETURNS ARE VIRGA. THE TOPEKA OFFICE DID PASS ON A REPORT OF LIGHT RAIN/SNOW NEAR OSAGE CITY WITH ONE OF THE SHOWERS, BUT IT WILL BE SEVERAL HOURS BEFORE PRECIPITATION BEGINS TO HIT THE GROUND. AT THIS POINT VERTICAL MOTION AND RELATIVE HUMIDITY PROGS SUGGEST PRECIPITATION WILL BEGIN OVER NORTHWEST MISSOURI BETWEEN 6PM AND 8 PM, THEN SPREAD EAST SLOWLY OVERNIGHT. TEMPERATURES HAVE BEEN SLOW TO RISE TODAY WITH THICK CLOUDS IN THE REGION. THE MESOETA SOUNDINGS HAVE BEEN TRENDING COOLER AS A RESULT. WET BULB TEMPERATURES FROM THE SOUNDINGS SUGGEST THAT SNOW OR A RAIN SNOW MIX WILL BE AT THE ONSET OF PRECIPITATION FOR ALL OF MISSOURI EXCEPT THE FURTHEST COUNTIES ALONG THE KANSAS AND NEBRASKA BORDERS. A BIT OF WARM AIR AROUND 800MB INITIALLY WILL MOST LIKELY CAUSE PRECIPITATION TO BE RAIN THIS EVENING IN SAINT JOSEPH AND KANSAS CITY. PRECIPITATION AMOUNTS FROM THIS SYSTEM SHOULD BE THE HIGHEST OVER THE WESTERN PORTIONS OF MISSOURI WHERE ISENTROPIC LIFT WILL BE THE STRONGEST THIS EVENING. AS THE UPPER LOW TRACKS EAST, IT WILL TRACK INTO CONFLUENT FLOW. AS THE UPPER SYSTEM FILLS, ISENTROPIC LIFT DECREASES. THERE IS ALSO A POCKET OF VERY DRY AIR AT THE LOW LEVELS OVER ILLINOIS AND EASTERN MISSOURI THAT WILL CUT DOWN ON PRECIPITATION AMOUNTS IN THE KIRKSVILLE AREA. A VIRGA STORM IS ANTICIPATED TONIGHT IN NORTHEAST MISSOURI BEFORE THE COLUMN SATURATES. THE BEST CHANCE FOR ACCUMULATIONS WILL BE OVER THE NORTHWEST TIP OF MISSOURI AFTER MIDNIGHT. WITH TEMPERATURES REMAINING IN THE MID TO LOWER 30S FOR MOST OF THE NIGHT, ACCUMULATIONS WILL BE AROUND AN INCH AT MOST SINCE A LOT OF THE SNOW WILL MELT AS IT HITS THE GROUND. I EXPECT ACCUMULATIONS WILL BE LIMITED TO GRASSY SURFACES. KOCH BY FRIDAY THE MID AND EXTENDED RANGE MODELS AGREE THAT A DEEPENING LOW...IN THE UPPER MIDWEST...WILL BE EXITING MISSOURI. THE ONLY SENSIBLE WEATHER LEFT FOR OUR AREA BY FRIDAY WILL BE COOL TEMPERATURES. TEMPS ARE EXPECTED TO REBOUND INTO THE WEEKEND AS A DEEPENING EAST PACIFIC TROUGH PUSHES SOME SHORTWAVE RIDGING BACK INTO EAST KANSAS AND NORTHERN MISSOURI. BY HE END OF THE WEEKEND THE EAST PACIFIC TROUGH WILL BEGIN TO TRANSLATE ACROSS THE CONUS. THIS WILL COOL TEMPS AGAIN FOR THE START OF THE NEXT WORK WEEK. THERE IS A REASONABLE AMOUNT OF SPREAD IN THE MODELS WITH RESPECT TO THE TROUGHS POSITION FOR NEXT WEEK...WHICH WILL HAVE AN AFFECT ON THE PRECIPITABLE WEATHER CHANCE ASSOCIATED WITH THE TROUGH. I WENT AHEAD AND ADDED SOME CHANCE POPS FOR RAIN AND SNOW TUESDAY AND TUESDAY NIGHT AS A FIRST GUESS. THIS WILL HOWEVER REQUIRE MONITORING OVER THE WEEKEND AS WE GET A BETTER HANDLE ON THE APPROACHING SYSTEM. CUTTER && .PREVIOUS DISCUSSION... 234 AM... EMPHASIS FOR THIS PACKAGE HAS BEEN ON SHORT TERM. UPPER LOW HAS LANDED ON WEST COAST SO MODELS SHOULD BE GETTING A GOOD HANDLE ON SEQUENCE OF EVENTS. MAIN CHALLENGES ARE WITH TEMPERATURES AND RESULTANT PRECIP TYPE. HIGH CLOUDS TONIGHT HAVE TEMPERED THE DIURNAL DROP...WITH MOST LOCATIONS IN THE MID TO UPPER 30S. EVEN WITH CLOUDS...WAA SHOULD PUT HIGHS UP TO THAT OF YESTERDAY...EVEN A COUPLE DEGREES WARMER. HIGHS SHOULD RANGE FROM AROUND 50 IN THE SOUTHWEST TO THE MID 40S IN THE NORTHEAST. GOOD MOISTURE FETCH SHOULD EVENTUALLY PUT DEWPOINTS IN THE 30S...ALTHOUGH IT WILL TAKE A WHILE AS DEWPOINTS ARE CURRENTLY IN THE TEENS. DRY AIR IN BOUNDARY LAYER IS GOING TO HINDER A QUICK SATURATION SIGNIFICANTLY. DUE TO THAT...HAVE DELAYED CHANCES OF RAIN UNTIL AFTER 00Z TONIGHT. INVERTED SURFACE TROF BRINGS BEST LIFT AROUND 06Z. SOUNDINGS ARE SATURATED...SO PRECIP LOOKS LIKE A GOOD BET TONIGHT AND HAVE RAISED POPS TO DEFINITE IN CENTRAL CWA...LIKELY IN NORTHWEST AND EAST. GFS HAS SLIGHTLY FARTHER SOUTH TRACK...BUT HAVE MAINLY USED META TEMP PROFILES. BEST CHANCES FOR SNOW ARE IN 09Z-12Z TIMEFRAME. THE MAIN QUESTION IS SURFACE TEMPS. SURFACE WINDS ARE SOUTHEAST MOST OF THE NIGHT WHICH WILL NOT BRING TEMPS DOWN VERY FAST. IN SOUTHERN HALF OF CWA...PROBABLY LOOKING AT A SCENARIO OF 33-34 DEGREES AND WET SNOW. MIXED WITH RAIN AT ONSET. A LITTLE COLDER IN NORTHERN COUNTIES...AND WITH TREMENDOUS LIFT SNOW IS A GOOD BET. WE ARE CURRENTLY THINKING AMOUNTS FROM 1-2 IN NORTH CENTRAL TAPERING DOWN TO LESS THAN A HALF OUTWARD FROM THAT VICINITY. BOUNDARY LAYER REMAINS SATURATED IN FORECAST AREA ON WED. BEST LIFT IS GONE...SO HAVE ONLY GONE LOW CHANCE POPS IN THE MORNING FOR RESIDUAL. HAVE KEPT CLOUDS IN THROUGH THURSDAY WHEN NEXT WAVE APPROACHES. DUE TO CLOUD COVER HAVE ALSO LESSENED THE DIURNAL RANGE. NO OTHER CHANGES MADE. LVQ && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. $$