FXUS63 KEAX 250018
AFDEAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
615 PM CST THU DEC 24 2009
...UPDATED FOR AVIATION...
.DISCUSSION...
/533 PM CST THU DEC 24 2009/
...BLIZZARD AND WINTER STORM WARNINGS IN EFFECT AS DANGEROUS WINTER STORM
SYSTEM APPROACHES...
POTENT WINTER STORM NOW ONGOING ACROSS PORTIONS OF THE CENTRAL AND
SOUTHERN PLAINS INTO THE MIDWEST WITH VERY IMPRESSIVE STRUCTURE EVIDENT
VIA LATEST WATER VAPOR IMAGERY. PV ANOMALY NOW DIVING SOUTH INTO THE
NORTHERN PLAINS WILL BEGIN TO MERGE WITH THE SOUTHERN STREAM FEATURE
OVERNIGHT AS IT LIFTS NORTHWARD INTO CENTRAL MISSOURI. HOWEVER...AS
THIS OCCURS SIGNIFICANT DEEPENING OF THE SOUTHERN STREAM SHORT WAVE
TROUGH WILL TAKE PLACE...LIKELY REACHING MAXIMUM INTENSITY AS IT
TRANSLATES ACROSS CENTRAL AND NORTHERN MISSOURI.
ATTM...LARGE SHIELD OF PRECIPITATION ONGOING FROM NORTHERN OKLAHOMA
AND ARKANSAS INTO PORTIONS OF IOWA AND NEBRASKA. DEFORMATION BAND
WHICH DEVELOPED EARLIER THIS AFTERNOON ACROSS EASTERN KANSAS IS
BEGINNING TO WEAKEN AS ADDITIONAL PRECIPITATION PUSHES NORTHWARD AND
NEW DEFORMATION BAND DEVELOPS THIS EVENING. BIG QUESTION IS WHERE
THIS AXIS OF HEAVIER PRECIPITATION ESTABLISHES. AT THIS TIME...IT
APPEARS THIS MAY BE TAKING PLACE ALONG THE KANSAS/MISSOURI STATE LINE
AND THIS MAY ULTIMATELY BE THE PIVOT POINT AS THE SYSTEM TURNS NORTH
ACROSS MISSOURI. FREEZING LINE HAS NOW PUSHED SOUTH OF A BETHANY TO
NEVADA LINE AND WILL CONTINUE SOUTH AND EASTWARD THIS EVENING AND
OVERNIGHT. HOWEVER...IMPRESSIVE TROWAL FEATURE TAPPING DEEP GULF
MOISTURE HAS LIMITED SNOW PRODUCTION THUS FAR AS WARM NOSE HAS
CONTRIBUTED TO MELTING THROUGH THE LOWER ATMOSPHERIC COLUMN. AS A
RESULT A MIXTURE OF FREEZING RAIN AND SLEET HAS BEEN THE DOMINANT
PRECIPITATION TYPE WITHIN THE SUBFREEZING SURFACE AIR MASS. WITH
HIGHER RADAR ECHOES SHOWING UP WITHIN LATEST NORTHWARD ADVANCING
PRECIP SHIELD...PERIODS OF HEAVY SLEET OR FREEZING RAIN WILL BE
POSSIBLE THIS EVENING WITH SLEET ACCUMULATIONS UP TO A HALF INCH WITH
ISOLATED HIGHER AMOUNTS. MID LEVEL COOLING SHOULD COMMENCE OVER THE
NEXT FEW HOURS FROM WEST TO EAST ALLOWING A CHANGEOVER TO
SNOW...ACROSS EASTERN KANSAS AND WESTERN MISSOURI. AREAS FURTHER EAST
ACROSS CENTRAL MISSOURI WILL LIKELY REMAIN WITHIN THE WARM AIR LONGER
AND THUS WILL HAVE A SLOWER TRANSITION PERIOD. LOCATIONS FROM
KIRKSVILLE TO BOONVILLE MAY NOT TRANSITION UNTIL LATE TONIGHT OR INTO
THE EARLY MORNING HOURS.
FURTHER HEIGHT FALLS WILL OVERSPREAD THE AREAS OVERNIGHT AS SOUTHERN
STREAM SYSTEM SLIDES NORTH ENHANCING LARGE SCALE ASCENT ACROSS THE
AREA LEADING TO CONTINUED PRECIPITATION THROUGH THIS TIME FRAME.
PERIODS OF MODERATE TO HEAVY SNOW CERTAINLY SEEM POSSIBLE WITH AREAS
OF ELEVATED INSTABILITY POSSIBLY DEVELOPING ABOVE LOW TO MID LEVEL
WARM NOSE. OF ADDITIONAL CONCERN IS THE LIKELIHOOD OF BLOWING SNOW AS
TIGHTENING PRESSURE GRADIENT LEADS TO SUSTAINED WINDS OF 20-30MPH. IN
ADDITION...WINDS AT OR JUST BELOW THE INVERSION LEVEL EXPECTED TO
REMAIN NEAR 45-50 KTS ACROSS EASTERN KANSAS AND WESTERN MISSOURI AS
STRONG H9 TO H8 JET SHIFTS OVERHEAD. THIS MAY EFFECTIVELY MIX DOWN AND
LEAD TO GUSTS OF 35-40 MPH AT TIMES. HAVE MAJOR CONCERNS THE HEAVY
SNOW WILL COINCIDE WITH THE STRONG AND GUSTY WINDS THIS EVENING AND
OVERNIGHT CREATING REDUCED VISIBILITIES AND FURTHER EXACERBATE HAZARDOUS
TRAVEL CONDITIONS. HAVE THEREFORE UPGRADED THE WINTER STORM WARNING
TO A BLIZZARD WARNING ACROSS THE EASTERN KANSAS AND FAR WESTERN
MISSOURI COUNTIES. OTHERWISE...MAINTAINED THE WINTER STORM WARNING
ELSEWHERE WHERE AND MIX OF SLEET FREEZING RAIN AND SNOW IS EXPECTED.
NORTHERN STREAM PV ANOMALY PINWHEELS AROUND SOUTHERN STREAM ANOMALY
AS IT OCCLUDES ACROSS CENTRAL IOWA. SYSTEM THEN BECOMES NEARLY
STATIONARY AND INCREASINGLY BAROTROPIC THROUGH THE MIDDLE OF THE
WEEKEND AND SHOULD LEAD TO PERIODIC SNOW SHOWERS WRAPPING ACROSS...AT
LEAST THE NORTHERN HALF OF THE CWA. WITH SLR ON THE ORDER OF 12-15:1
DURING THIS TIME...LIGHT FLUFFY ACCUMULATIONS MAY OCCUR FRIDAY AND
SATURDAY. OTHERWISE...COLD AIR WILL FILTER SOUTHWARD OVER THE NEXT
SEVERAL DAYS WITH COLDER READINGS EXPECTED OVER SNOW PACKED AREAS.
DEROCHE
MEDIUM RANGE (SUNDAY THROUGH THURSDAY)...
FOR THE LAST HALF OF THE FORECAST...HAVE NOT MADE TO MANY CHANGES.
DETERMINISTIC AND ENSEMBLES MODELS ALL INDICATE THAT THE WINTER
STORM WILL BE LIFTING CLEAR OF THE CENTRAL PLAINS BEGINNING
SUNDAY...AND BY MONDAY THE SYSTEM WILL HAVE SHIFTED FAR ENOUGH TO
THE NORTH AND EAST TO ALLOW A SHORTWAVE RIDGE TO MOVE ACROSS THE
CENTRAL PLAINS. SURFACE TEMPERATURES SHOULD STAY BELOW NORMAL AS A
COLD CANADIAN SURFACE HIGH OOZES ACROSS THE PLAINS STATES THROUGH
THE FORECAST PERIOD. ONLY MITIGATING FACTORS WOULD BE THE PARTLY
SUNNY SKIES AND LIGHT SOUTHEAST SURFACE WINDS. HAVE OPTED TO KEEP
TEMPERATURES HEDGED TOWARDS THE COLD SIDE AS THERE IS AN EXPECTATION
THAT WE WILL STILL HAVE SNOW ON THE GROUND ACROSS THE ENTIRE REGION
THROUGH AT LEAST THE MIDDLE OF NEXT WORK WEEK.
AS FOR ANY PRECIPITATION POTENTIAL...SUNDAY MAY STILL HAVE SOME
FLURRIES ACROSS THE REGION AS WE WILL STILL BE UNDER THE INFLUENCE
OF WRAP AROUND PRECIPITATION FROM THE WINTER STORM AS IT MOVES INTO
THE GREAT LAKES. HAVE KEPT THE GOING PUBLIC FORECAST DRY FOR THE
REST OF THE FORECAST...BUT HAVE HEDGED WITH SOME SILENT SLIGHT
CHANCE POPS FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT AS A OPEN AND
PROGRESSIVE SHORTWAVE MOVES THROUGH THE PLAINS. STILL RATHER FAR IN
THE FUTURE TO PIN DOWN DETAILS...BUT GIVEN RECENT WEATHER
TRENDS...THE MID TO LATE WORK WEEK PERIODS OF NEXT WEEK WOULD BE THE
PREFERRED PERIOD FOR OUR NEXT WINTER WEATHER SYSTEM.
CUTTER
&&
.AVIATION...
FOR THE 00Z TAFS...WINTER STORM IN FULL SWING AT ALL THREE
TERMINAL...WITH A MIXTURE OF SNOW AND SLEET BEING REPORTED. FEEL THE
THREAT OF SLEET WILL DIMINISH IN THE NEXT COUPLE HOURS AS THERMAL
PROFILE CONTINUES TO COOL AS EVAPORATIVE EFFECTS MITIGATED BY
INCREASING MOISTURE FLUX. BUFKIT SOUNDINGS AND COBB SNOW OUTPUT
CORROBORATE THIS TREND...THUS HAVE PRECIP TYPE CHANGING TO ALL SNOW
BETWEEN 01 AND 03Z AT ALL THREE TERMINAL SITES. SUSTAINED SURFACE
WINDS IN THE 20-25KT RANGE EXPECTED THROUGH THE NIGHT...WITH GUSTS
VACILLATING BETWEEN 27 AND 32KTS. WINDS HAVE ABATED SLIGHTLY FROM
HIGHER GUSTS EARLIER THIS AFTERNOON...BUT SURFACE PRESSURE WILL
CONTINUE TO STRENGTHEN OVERNIGHT AND H9/H8 JET AXIS IS EXPECTED TO
TRANSLATE EASTWARD...THUS EXPECT WINDS TO INCREASE AGAIN DURING THE
OVERNIGHT HOURS. ADDED BLOWING SNOW IN THE TERMINALS AFTER 06Z...AS
IT WILL TAKE SOME TIME FOR SNOWS TO ACCUMULATE AND SNOW-LIQUID
CONTENT TO DECREASE ENOUGH TO ALLOW SNOW TO BE LOFTED BY WINDS.
FORECAST GUIDANCE PROVIDING CONFLICTING INFORMATION ON CIG AND VSBY
TRENDS...SO FOR THE SHORT TERM FOLLOWED PERSISTENCE WITH TRENDS
TOWARD IFR CIGS AND LIFR VSBYS LATER IN THE TAF PERIOD. BASED ON
BLEND OF ECMWF AND 18Z NAM...LINGERED THREAT OF SNOW AND BLOWING
SNOW IN TERMINALS INTO THE AFTERNOON...IMPROVING CIGS AND VSBYS
AFTER 18Z.
24
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL 6 PM CST FRIDAY FOR MOZ007-008-016-
017-024-025-032-033-039-040-045-046.
WINTER STORM WARNING UNTIL 6 PM CST FRIDAY FOR MOZ003>006-014-
015-022-023-030-031-038-044-054.
BLIZZARD WARNING UNTIL 6 PM CST FRIDAY FOR MOZ001-002-011>013-
020-021-028-029-037-043-053.
KS...BLIZZARD WARNING UNTIL 6 PM CST FRIDAY FOR KSZ025-057-060-
102>105.
&&
$$
