FXUS63 KDDC 060949
AFDDDC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
330 AM CST SUN DEC 6 2009
.DISCUSSION...
DAYS 1-2...
THE FORECAST TODAY IS VERY CHALLENGING WITH MULTIPLE OPPORTUNITIES
FOR ERROR. CONSIDERABLE UNCERTAINTY EXISTS REGARDING THE POTENTIAL
FOR LIGHT FREEZING DRIZZLE TODAY AS A PLUME OF MID TO UPPER 20
DEWPOINTS SPREADS NORTHWARD AND LIFTS OVER THE REINFORCING SURGE OF
ARCTIC AIR SPREADING SOUTHWARD INTO WESTERN KANSAS THIS MORNING. THE
PRECIPITATION TYPE AND QUANTITIES FARTHER NORTH ALONG I70 IN THE
REGION OF BEST FRONTOGENESIS AND ISENTROPIC LIFTING LATER TODAY ALSO
ARE SOMEWHAT UNCERTAIN. THE NEXT POWERFUL UPPER LEVEL TROUGH THAT
WILL APPROACH WESTERN KANSAS ON TUESDAY POSES A WHOLE FRESH SET OF
UNCERTAINTIES FOR PRECIPITATION TYPE AND QUANTITY. TEMPERATURES WILL
BE COLD TODAY AND MONDAY, BUT THE ARCTIC AIR COULD BE ERODED ALONG
THE OKLAHOMA BORDER ON TUESDAY.
A WELL DEFINED MADDEN-JULIAN OSCILLATION IS MOVING INTO THE WESTERN
HEMISPHERE AND LIKELY WILL ACCELERATE EASTWARD ACROSS THE PACIFIC
DURING THE NEXT WEEK. THE MADDEN JULIAN OSCILLATION WAS IN PHASE 7
OF THE WHEELER-HENDON PHASE SPACE DIAGRAM AND SHOULD BE MOVING
THROUGH PHASE 8 IN THE NEAR FUTURE. PHASE 8 FAVORS RIDGING IN THE
EASTERN PACIFIC INTO ALASKA AND TROUGHING IN THE WESTERN UNITED
STATES. THE NUMERICAL MODELS ALL ARE IN GOOD AGREEMENT IN
MAINTAINING A SHARP RIDGE NEAR 140W THROUGH THE FIRST PART OF THE
WEEK WITH A SLOWLY RETROGRESSIVE HIGH LATITUDE ANTICYCLONE
PROPAGATING WESTWARD TO NEAR THE DATELINE BY NEXT WEEKEND, AND THIS
SEEMS VERY REASONABLE. THE NET RESULT WILL BE CONTINUATION OF COLD
WEATHER THROUGHOUT THE CENTRAL UNITED STATES WITH REINFORCING SURGES
OF ARCTIC AIR SPREADING SOUTHWARD THROUGH THE PLAINS. SOME
MODIFICATION OF THE COLD REGIME APPEARS LIKELY BY NEXT WEEKEND.
A VIGOROUS UPPER LEVEL TROUGH THAT WAS OVER NORTHERN ARIZONA EARLY
THIS MORNING WILL MOVE EASTWARD QUICKLY AND SHOULD REACH WESTERN
KANSAS BY NOON. A REINFORCING SURGE OF MODIFIED ARCTIC AIR MOVING
SOUTHWARD BEHIND A NORTHERN BRANCH UPPER LEVEL TROUGH IN THE DAKOTAS
WILL CONTINUE TO SPREAD ACROSS WESTERN KANSAS THIS MORNING. A
SURFACE CYCLONE IN THE TEXAS PANHANDLE WILL CARRY LOW LEVEL AIR WITH
DEWPOINTS IN THE MID AND UPPER 20S NORTHWARD OVER THE ARCTIC
AIR...AND ISENTROPIC LIFTING MAY RESULT IN DEVELOPMENT OF VERY LIGHT
FREEZING DRIZZLE LATER THIS MORNING AS THE BOUNDARY LAYER SATURATES.
THE SOUNDING WILL BE BELOW FREEZING AT ALL LEVELS, BUT TEMPERATURES
IN THE MOIST LOWER LEVELS OF THE ATMOSPHERE ARE NOT LOW ENOUGH TO
GUARANTEE THE EXISTENCE OF ICE CRYSTALS. AS SUCH...MOST OF THE
PRECIPITATION WILL BE FREEZING DRIZZLE. WITH THE APPROACH OF THE
UPPER LEVEL TROUGH LATER TODAY...TEMPERATURES ALOFT WILL COOL ENOUGH
TO SUPPORT A TRANSITION TO SNOW IN NORTHERN KANSAS...AND AN INCH OR
SO OF ACCUMULATION IS POSSIBLE ALONG I70. EVEN THOUGH PRECIPITATION
AMOUNTS WILL BE LIGHT...THE GROUND IS COLD ENOUGH FROM THE ARCTIC
SURGE LATE LAST WEEK THAT ANY FREEZING DRIZZLE WILL STICK AND RESULT
IN SLICK PATCHES. WITH THE NUMBER OF PEOPLE GETTING OUT TO ATTEND
CHURCH SERVICES TODAY...A HEADLINE BASED ON THE IMPACT OF VERY LIGHT
PRECIPITATION IS JUSTIFIED.
SUBSIDENCE WILL DEVELOP BEHIND THE UPPER LEVEL TROUGH...AND MOST OF
THE PRECIPITATION WILL END BY LATE AFTERNOON. TEMPERATURES WILL DROP
INTO THE LOWER TEENS TONIGHT IN THE ARCTIC AIR EVEN WITH
CONSIDERABLE CLOUD COVER, AND TEMPERATURES MONDAY WILL PEAK IN THE
20S.
THE NEXT STRONG UPPER LEVEL TROUGH...JUST OFF THE WASHINGTON/OREGON
COAST THIS MORNING...WILL DIG THROUGH THE WESTERN UNITED STATES LONG
WAVE POSITION AND APPROACH THE CENTRAL PLAINS ON TUESDAY. LOW LEVEL
MOISTURE WILL BE CONSIDERABLY MORE ABUNDANT ALONG THE GULF COAST AND
SHOULD BE INGESTED BY THE SYSTEM AS CYCLOGENESIS OCCURS IN
SOUTHEASTERN COLORADO MONDAY NIGHT AND TUESDAY. THE COLD AIR WILL BE
FIRMLY ENTRENCHED...AND ISENTROPIC LIFTING OVER THE COLD AIR WILL
RESULT IN A CHANCE FOR LIGHT SNOW OR FREEZING DRIZZLE MONDAY NIGHT
WITH HEAVIER PRECIPITATION ON TUESDAY WITH THE APPROACH OF THE UPPER
LEVEL TROUGH. SUFFICIENT MOISTURE AND BAROCLINICITY WILL BE IN PLACE
TUESDAY TO SUPPORT HEAVY SNOWFALL IN NORTHERN KANSAS. STRONG WINDS
WILL PRODUCE NEAR BLIZZARD CONDITIONS. A WINTER STORM WATCH WAS
ISSUED COVERING THE AREA MOST LIKELY TO EXPERIENCE HEAVY SNOWFALL
FROM MONDAY NIGHT THROUGH TUESDAY NIGHT.
DAYS 3-7...
ABOUT THE ONLY DEFINITE FOR THE EXTENDED IS THAT THERE WILL BE
WINTER PRECIP SOMEWHERE IN THE CWA AT THE START OF THE PERIOD. THE
MAIN UPPER TROUGH EJECTS OUT INTO THE PLAINS ON TUESDAY, WITH SOME
SLIGHT DIFFERENCES BETWEEN THE MODELS ON EXACT TIMING. PRECIP WILL
BE ONGOING AT THE START OF THE PERIOD, AND ARCTIC AIR WILL BE IN
PLACE AT 12Z. MODEL SOUNDINGS FROM BOTH THE GFS AND HIGH-RES ECMWF
KEEP OUR NORTHERN COUNTIES COLD AND SATURATED, INDICATING A VERY
GOOD CHANCE FOR SNOW. THE GFS PUTS OUT 10-12 INCHES OF TOTAL SNOW
IN TREGO AND ELLIS COUNTIES BY 12Z WEDNESDAY, AND THE NAM IS ONLY A
COUPLE OF INCHES LIGHTER. OF COURSE, THESE MODEL FIELDS ARE
NOTORIOUSLY UNRELIABLE, BUT EVEN IF WE GET HALF OF WHAT THEY ARE
PREDICTING THERE WILL BE SIGNIFICANT SNOWFALL ALONG THE I-70
CORRIDOR. ADD TO THIS THE FACT THAT WINDS WILL GET VERY STRONG
TUESDAY AFTERNOON AS THE SFC LOW MOVES OUT INTO CENTRAL KANSAS,
WHICH SHOULD BRING BLOWING SNOW PROBLEMS. WILL GO WITH A WINTER
STORM WATCH FOR LATE MONDAY NIGHT INTO TUESDAY NIGHT FOR OUR FOUR
NORTHERN COUNTIES.
FURTHER SOUTH, PRECIP TYPE IS MUCH LESS CERTAIN. THE GFS, ECMWF,
AND CANADIAN ALL START STRONG WARM ADVECTION DURING THE DAY ON
TUESDAY. THIS SHOULD CREATE A SIGNIFICANT WARM LAYER ABOVE THE
SFC. THE MODELS EVEN ERODE THE ARCTIC AIR AT THE SFC, BRINGING
ABOVE FREEZING TEMPS AS FAR NORTH AS A SYRACUSE TO ST JOHN LINE, AND
PUTTING 2 M TEMPS NEAR THE OK BORDER AS HIGH AS 50 F. OF COURSE,
NONE OF THE MODELS HANDLE THE SCOURING OUT OF SHALLOW ARCTIC AIR
VERY WELL, AND IT MAY VERY WELL BE MUCH COLDER THAN THE MODELS
INDICATE. WILL STICK PRETTY CLOSE TO PREVIOUS SHIFT'S NOTION OF
TEMPS NEAR 40 F AT THE OK BORDER AND COLDER FURTHER NORTH. PRECIP
TYPE WILL BE VERY DIFFICULT, WITH THE WARM LAYER ALOFT BRINGING FZRA
AND IP. LIQUID RAIN WILL ALSO BE A POSSIBILITY NEAR THE OK BORDER
IF SFC TEMPS GET HIGH ENOUGH. TRIED TO SHOW FZRA AND IP MOVING INTO
OUR SOUTHERN AND CENTRAL COUNTIES TUESDAY MORNING AS THE WARM AIR
MOVES IN, THEN OUT AGAIN DURING THE LATE AFTERNOON AND EVENING AS
THE ARCTIC AIR SURGES BACK SOUTH BEHIND THE SFC LOW. ALL PRECIP
SHOULD TAPER OFF LATE TUESDAY NIGHT AS THE SYSTEM MOVES QUICKLY OFF
TO THE EAST.
FOR DAYS 4-7, MADE VERY LITTLE CHANGES TO THE GOING FORECAST. A
BROAD TROUGH FROM NORTHERN CANADA TO THE CENTRAL CONUS SHOULD KEEP
US WELL IN THE ARCTIC AIR WEDNESDAY. SINCE THE SOURCE LOW OF THIS
TROUGH IS CURRENTLY LOCATED OVER THE NORTH POLE, HAVE VERY LITTLE
PROBLEM KEEPING THE FRIGID HIGHS MID WEEK. THERE SHOULD START TO BE
SOME RECOVERY THURSDAY AS FLOW STARTS TO SPLIT OVER THE EASTERN
PACIFIC AND HEIGHTS RISE A BIT OVER THE SOUTHERN AND CENTRAL
PLAINS. THERE IS SOME QUESTION ABOUT HOW MUCH TEMPS WILL RECOVER,
AND THERE ARE SIGNS OF A REINFORCING COLD SURGE AROUND FRIDAY. WITH
A LOT OF UNCERTAINTY WILL KEEP TEMPS WITH THE BELOW AVERAGE READINGS
WE HAVE GOING.
&&
AVIATION...
MVFR CEILINGS HAVE BEGUN TO MOVE INTO THE NORTHWESTERN PORTIONS OF
THE FORECAST AREA AS OF 09Z ALONG WITH THE ARCTIC AIR. MOST ARE
AROUND 2000-3000 FT, ALTHOUGH THE MOST RECENT UPDATE AT HUGOTON
MUNICIPAL HAS BKN011. MVFR CEILINGS WILL SPREAD EASTWARD INTO THE
TAF SITES OVER THE NEXT COUPLE OF HOURS, AND COULD GO IFR OR LOWER
AFTER 14Z OR SO. THERE IS ALSO THE POSSIBILITY OF SOME FZDL OR EVEN
A BIT OF -SN. THE LOWEST CEILINGS WILL CONTINUE THROUGH 17Z OR SO
BEFORE RECOVERING TO MVFR DURING THE AFTERNOON AND OVERNIGHT HOURS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 27 13 24 21 / 40 0 20 50
GCK 26 14 22 20 / 40 0 20 50
EHA 27 14 27 23 / 10 0 10 20
LBL 28 15 26 22 / 20 0 10 40
HYS 26 11 21 19 / 70 10 20 90
P28 35 19 27 22 / 30 10 10 50
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 8 AM THIS MORNING UNTIL 6 PM THIS
EVENING FOR KSZ030-031-043>046-063>066-077>081.
WINTER STORM WATCH LATE MONDAY NIGHT THROUGH TUESDAY EVENING FOR
KSZ030-031-045-046.
&&
$$
FN01/26/26
