000
FXUS63 KTOP 032100
AFDTOP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
300 PM CST WED DEC 3 2008
.DISCUSSION...
COLDER AIR SPILLING INTO THE CWA TODAY...AS HIGH PRESSURE SLIDES
SOUTHWARD INTO THE CENTRAL PLAINS. LEADING EDGE BROUGHT BRISK WINDS
THIS AFTERNOON...WITH DEWPOINTS AND TEMPERATURES FALLING AS THE HIGH
MOVES IN. BROAD UPPER TROF PUSHING EASTWARD ACROSS THE CENTRAL US
IS MADE UP OF A SERIES OF IMPULSES...FROM MEXICO TO THE TEXAS
PANHANDLE TO NEBRASKA...THE LAST OF WHICH IS AIDING WITH THE
SOUTHERN PUSH OF THE COLDER AIR INTO OUR AREA.
CLOUDS AND FLURRIES WILL PUSH SOUTH AND EAST OF THE AREA BY
EVENING...WITH CLOUDS FOLLOWING SUIT SHORTLY AFTER. AS WINDS
DIMINISH AND SKIES CLEAR...EXPECT TEMPS TO DROP QUICKLY ESPECIALLY
GIVEN THE DEWPOINTS UPSTREAM REMAIN IN THE TEENS. ANOTHER IMPULSE
IS SLIDING ACROSS THE ROCKIES ATTM...AND WILL DRAW A MID LEVEL CLOUD
DECK TOWARD THE CWA BY EARLY MORNING HOURS. THIS MAY KEEP OVERNIGHT
LOWS UP SLIGHTLY IN THE WESTERN COUNTIES AND HAVE GRIDS AS SUCH.
HIGHS TOMORROW ALSO HINGE ON CLOUD COVER...WHICH AT THIS TIME
APPEARS TO INCREASE THROUGH THE DAY. HAVE KEPT COOLER HIGHS IN THE
MIDDLE 30S. 67
THURSDAY NIGHT...FIRST IN A SERIES OF WEAK SHORTWAVES SLIDES THROUGH
THE NORTHWEST FLOW. FORECAST SOUNDINGS INDICATE NEARLY SATURATED
MIDLEVELS...AND TEMPERATURE PROFILES FAVORABLE FOR SNOW. BUT...
LATEST MODEL RUNS CONTINUE TO DEPICT ONLY MEAGER ISENTROPIC LIFT
AHEAD OF THE SHORTWAVE TROUGH AND DRY LOWEST 5-7KFT OF THE ATM.
THEREFORE KEPT THE FLURRY MENTION GOING WITH NO CONVINCING
ARGUMENT TO INTRODUCE A CHANCE FOR MEASURABLE PRECIP.
NORTHWESTERLY FLOW ALOFT CONTINUES TO DOMINATE THE WEEKEND WEATHER
PATTERN. SHORTWAVE QUICKLY SLIDES THROUGH IOWA FRIDAY
NIGHT/SATURDAY MORNING. BRUNT OF FORCING LOOKS TO REMAIN NORTH AND
EAST...BUT WOULD NOT BE SURPRISED TO SEE FLURRIES IN THE
NORTHEASTERN PORTION OF THE FORECAST AREA...WHERE FORECAST
SOUNDINGS DEPICT PRIME SNOW GROWTH ZONE SATURATING...COINCIDENT
WITH ZONE OF WEAK LIFT. INHIBITING FACTOR WILL AGAIN BE DRY LOW
LEVEL ATMOSPHERE...AND ENERGY MAINLY OVER IA/MO. WILL LEAVE
PRECIP MENTION OUT FOR NOW DUE TO FORCING PLACEMENT AND LL DRY
AIR...BUT WILL HAVE TO KEEP AN EYE ON THIS PERIOD THE NEXT FEW
DAYS.
NEXT TROUGH SHIFTS INTO THE CENTRAL PLAINS MONDAY. 03/00Z RUN OF
THE ECMWF WAS MORE AMPLIFIED THAN THE GFS IN THE LONG LONG
TERM...BUT HAS COME MORE INTO LINE WITH THE GFS IN ITS 03/12Z
RUN. TIMING AND STRENGTH ISSUES STILL EVIDENT BETWEEN LONG RANGE
MODELS...AND THEREFORE MADE FEW CHANGES TO THE FORECAST. BEST TIME
PERIODS FOR PRECIP FIRST LOOKS TO BE MONDAY AFTERNOON IN WARM
ADVECTION REGIME AHEAD OF THE APPROACHING TROUGH. MAIN AREA
AFFECTED SHOULD BE EAST CENTRAL KANSAS WITH SOUTHWESTERLY
COMPONENT TO THE MIDLEVEL WINDS SHOVING MOISTURE INTO MISSOURI.
SECOND FAVORABLE PERIOD COMES MONDAY NIGHT/TUESDAY MORNING AS
SHORTWAVE TROUGH AND MIDLEVEL FRONTOGENETIC FORCING SLIDE THROUGH
THE PLAINS. PRECIP TYPE LOOKS TO START LIQUID SOUTH AND A MIX
NORTH...TRANSITIONING TO A MIX SOUTH...AND ALL SNOW NORTH. LUNDE
&&
.AVIATION...
FOR 18Z ISSUANCE...WEAK SNOW BAND MAKING QUICK EXIT TO THE
SOUTHEAST. MVFR CIGS REMAIN BUT ARE BECOMING THINNER IN COVERAGE.
WILL CARRY FOR ONLY A FEW HOURS THIS AFTERNOON THEN GO WITH VFR
SKY CONDITIONS. NORTHERLY WINDS TO LIGHTEN THROUGH THE DAY AND
OVERNIGHT...AND WHILE COULD HAVE ADDED A VRB GROUP
OVERNIGHT...SINCE WINDS RETURN TO NW IN THE MORNING LEFT OUT
ADDITIONAL CHANGE GROUP. 67
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
