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000
FXUS63 KEAX 100546
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1146 PM CST TUE FEB 9 2010

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...

WILL BE INCREASING CLOUD COVER FOR THIS EVENING AS UPSTREAM STRATOCU
DECK HAS FILLED IN SINCE LATE AFTERNOON. DID NOTICE CLOUDS CLEARING
OUT ACROSS NW IA AND THINK THAT WILL WORK ITS WAY SOUTH OVERNIGHT
BUT NOT TILL AFTER MIDNIGHT. WILL ALSO BRING FLURRIES/SNOW SHOWERS
FURTHER WEST AS WELL.

MJ

&&

.PREV DISCUSSION...
/318 PM CST TUE FEB 9 2010/
MAIN CHALLENGE IN THE VERY NEAR TERM CONTINUES TO BE LIGHT BANDING
OF SNOW AROUND THE BACK SIDE OF AN INTENSE PV ANOMALY. SECONDARY
CHALLENGES DEAL WITH TEMPERATURES WITH FRESH SNOW COVER AND SURFACE
RIDGE AXIS MOVING OVERHEAD.

TONIGHT:
A BAND OF LIGHT SNOW HAS PERSISTED ACROSS OUR SOUTHWESTERN ZONES
THROUGHOUT THE DAY. THIS BAND CORRESPONDS TO AN AREA OF FN
CONVERGENCE ASSOCIATED WITH THE WRAP AROUND REGION OF A PV ANOMALY
THAT HAD DESCENDED TO NEARLY 900 MB. THE FN CONVERGENCE IS EXPECTED
TO WEAKEN AS THE PV ANOMALY SHIFTS TO THE EAST/SOUTHEAST. WITH THE
FORCING WANING IN RESPONSE...SNOW SHOULD CONTINUE TO DIMINISH. BUT
WITH VERY COLD AIR ALOFT ANY CLOUDS WILL LIKELY STILL BE ABLE TO
PRODUCE SOME ICE CRYSTALS SO WILL KEEP MENTION OF FLURRIES GOING
THROUGH LATE THIS EVENING...ENDING FROM WEST TO EAST AS THE UPPER
SYSTEM MOVES AWAY. WINDS MAY STAY STRONG ENOUGH TONIGHT THAT
TEMPERATURES WOULD BE SLOW TO DROP OFF. IN FACT...MODELS ACTUALLY
WANT TO WARM THINGS THROUGH ABOUT MIDNIGHT...MAINLY ACROSS OUR
EASTERN ZONES...AND THEN START TO FALL OFF. HAVE TRIED TO DEPICT
THIS IN THE TEMPERATURE GRIDS BUT LOWS ARE STILL EXPECTED TO BE IN
THE SINGLE DIGITS ABOVE ZERO TO THE TEENS. KIRK HAS NOT REBOUNDED
MUCH AT ALL DURING THE DAY TIME HOURS WITH THE COLD CORE OF THE PV
ANOMALY SITTING OVERHEAD AND FAIRLY LIGHT WINDS. UPSTREAM TRENDS
SUPPORT WARMING THROUGH THE EVENING SO KIRK MAY HIT THEIR HIGH THIS
EVENING AND THEN TAPER OFF DURING THE OVERNIGHT.

WEDNESDAY - WEDNESDAY NIGHT:
QUIET WEATHER IS EXPECTED WITH A RIDGE BUILDING OVER THE REGION.
THIS SHOULD RESULT IN DRY CONDITIONS AND FEW(ER) CLOUDS. IT MAY ALSO
RESULT IN LIGHTER SURFACE WINDS WHICH IN TURN WOULD LIMIT HOW WARM
AFTERNOON TEMPERATURES GET. HIGHS SHOULD STAY BELOW FREEZING FOR ALL
AREAS AND LIKELY WILL NOT MAKE IT OUT OF 20S AS A RESULT OF THE
LIMITED MIXING. SURFACE RIDGE WITH CALM WINDS AND MOSTLY CLEAR SKIES
SHOULD BE POSITIONED ROUGHLY FROM THE UPPER MISSISSIPPI VALLEY
THROUGH NORTHERN MISSOURI BY THURSDAY MORNING. THIS WILL LEAD TO GOOD
RADIATIONAL COOLING SO VERY COLD OVERNIGHT LOWS ARE EXPECTED FOR
PARTS OF CENTRAL INTO NORTHERN AND NORTHEAST MISSOURI. FURTHER
WEST...ON THE BACKSIDE OF THE SURFACE RIDGE SLIGHTLY STRONGER
SOUTHERN/SOUTHEASTERLY WINDS AND INCREASING CLOUD COVERAGE SHOULD
LIMIT HOW COLD TEMPERATURES GET.

CDB


MUCH OF THE MEDIUM RANGE GUIDANCE AND PATTERN RECOGNITION SUGGESTS
A SUSTAINED PERIOD OF NEAR TO BELOW NORMAL TEMPERATURES THROUGHOUT
THE EASTERN HALF OF THE CONUS AS LONG WAVE TROUGHING OVER THE EAST
AND LONG WAVE RIDGING FORMS OVER THE WEST.

WILL BE KEEPING AN EYE ON A FEW CLIPPER SYSTEMS EMBEDDED IN THE NW
FLOW PATTERN HEADING INTO THE UPCOMING WEEKEND.  AS TYPICAL...MODELS
WILL HAVE POOR RESOLUTION OF THESE FEATURES IMPACTING TIMING AND
LOCATIONS UNTIL THEY ARE WITHIN A 24-48 HOUR WINDOW.  HOWEVER...ONE
SUCH S/W WILL ROTATE THROUGH THE AREA THU NIGHT INTO FRIDAY...WITH
A MUCH STRONGER WAVE APPROACHING FROM THE NW ON SATURDAY.  MODELS
DISAGREE WITH THE SPEED AND SWERN PUSH OF THIS SECONDARY WAVE HAVING
A SIGNIFICANT IMPACT ON THE TEMP FCST.  ECMWF REMAINS THE COLDEST OF
THE MODELS WITH A FASTER TRACK...WITH GEM/GFS SLOWER AND WARMER.
FEEL THAT GIVEN THE AMPLITUDE OF THE APPROACHING WAVE WILL FORCE
WARMER AIR NE EARLY SAT MORNING AND HAVE MAINTAINED A WARMER FCST.
HOWEVER THESE TEMPS MAY NEED TO BE LOWERED IN THE FUTURE.  GIVEN THE
LACK OF MOISTURE WITH ANY OF THESE SYSTEMS...FEEL HIGHEST POPS WOULD
BE TO THE NE OF THE CWA IN THE MORE TYPICAL CLIPPER ALLEY.
NEVERTHELESS...THE TRACK OF THIS S/W WILL BE CRITICAL TO OUR CHCS OF
ANY MEASURABLE PRECIP.

BEHIND THE STRONGER CLIPPER ON SATURDAY WILL BE ANOTHER STRONG
SOUTHWARD SURGE OF A CONTINENTAL POLAR AIRMASS.  TEMPS SHOULD FALL
WELL BELOW ZERO BY SUNDAY AND LINGER INTO MONDAY.  PRECIP CHCS LOOK
LOW INTO NEXT WEEK.

DUX

&&

.AVIATION...

FOR THE 06Z TAFS...UPSTREAM STRATUS DECK OVER SOUTHWEST AND WEST
CENTRAL IA HAS INCREASED SINCE 04Z. LATEST GUIDANCE NOT PARTICULARLY
USEFUL AS THEY TEND TO DISSIPATE THIS CLOUD COVER BY 09Z. 00Z GFS
COMES CLOSEST WHILE HOURLY LAMP DATA USING A MIX OF CURRENT
OBS/TRENDS/CLIMATOLOGY SUGGEST HOLDING ONTO CLOUDS WELL INTO
WEDNESDAY MORNING. WITH THE SURFACE RIDGE AXIS STILL WEST OF THE
TERMINALS AND CYCLONIC FLOW STILL DOMINATING THE REGION BELIEVE
THESE MVFR CEILINGS WILL LINGER UNTIL AT LEAST SUNRISE...AND
POSSIBLY INTO MID MORNING BEFORE SUFFICIENT SINKING MOITION FINALLY
SHIFTS EASTWARD.

AIR TEMPERATURES WITHIN THIS STRATUS DECK ARE AROUND -10C WHICH IS
SUFFICIENTLY COLD TO SUPPORT ICE CRYSTALS...AND THUS CARRIES THE
POTENTIAL FOR FLURRIES FOR MUCH OF THE NIGHT. SHOULD FINALLY SEE AN
END TO THE MVFR CLOUDS BY LATE WEDNESDAY MORNING AND THEN VFR FOR
THE REST OF THE FORECAST.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

$$