FXUS63 KDDC 262139
AFDDDC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
339 PM CST SAT DEC 26 2009
.DISCUSSION...
DAYS 1-2...
PAST MORNING UPPER AIR DATA ALONG WITH RECENT WATER VAPOR IMAGERY
REVEALS A HIGHLY AMPLIFIED PATTERN ACROSS THE CONUS WITH A DEEP
UPPER CYCLONE SITTING OVER THE UPPER MIDWEST WHILE UPSTREAM AN OMEGA
BLOCK RIDGE IS IN PLACE OVER THE WEST. ALTHOUGH THE CYCLONE IS
VERTICALLY STACKED/OCCLUDED ACROSS THIS AREA AND STRONG MID LEVEL
HEIGHT RISES ARE SEEN BEHIND THE UPPER LOW ACROSS THE REGION, IT
REMAINS A PROMINENT FEATURE IN THE ONGOING AND FORECAST WEATHER FOR
SOUTHWEST AND WEST CENTRAL KANSAS. RECENT SURFACE ANALYSIS DISPLAYS
A FILLING LOW TRACKING VERY SLOWLY ACROSS SOUTHERN IOWA WITH
MULTIPLE WEAK SURFACE TROUGHS OR POSSIBLE WEAK FRONTAL BOUNDARIES
SEEN RIPPLING THROUGH THE BACK SIDE OF THE CYCLONE.
AS THE AREA HEADS INTO TONIGHT...THE INDIRECT CIRCULATION ASSOCIATED
WITH THE EXIT REGION OF A 70-80KT UPPER JET STREAK SEEN ON THE BACK
SIDE OF THE CYCLONE, WILL CONTINUE TO AID IN PRODUCING A MODEST BAND
FRONTOGENESIS IN THE 850-750MB LAYER THIS EVENING STRETCHING FROM
SOUTHERN NEBRASKA INTO EXTREME SOUTHWEST TO SOUTH CENTRAL KANSAS.
ALTHOUGH THE ATMOSPHERE IS VERY DRY ACROSS THE AREA AND THE FORCING
LIMITED TO BELOW 750MB, SOUNDINGS REVEAL THE DENDRITIC LAYER AS LOW
AS 850MB, WHICH SHOULD SUPPORT AT SOME ISOLATED TO SCATTERED SNOW
FLURRIES GENERALLY NORTH OF A SYRACUSE TO PRATT LINE. THE LEFT EXIT
REGION OF THE JET STREAK ALONG WITH THE ASSOCIATED FRONTOGENESIS IS
THEN SHOWN TO SLIP EAST OF THE CWA BY AROUND MIDNIGHT AND SUSPECT
THE THREAT FOR FLURRIES WILL DIMINISH QUICKLY DURING THE LATE
EVENING HOURS WITH DRY CONDITIONS THEN EXPECTED THE REMAINDER OF THE
NIGHT. HOWEVER, ANTICIPATE A TIGHT GRADIENT IN CLOUD COVER WITH
AREAS NORTH OF HIGHWAY 50 REMAINING MOSTLY CLOUDY TO OVERCAST WHILE
AREAS ALONG THE OKLAHOMA BORDER SEE A PARTLY CLOUDY TO MOSTLY CLEAR
SKY AS TEMPERATURES LOWER INTO A 15 TO 20 DEGREE RANGE. IN ADDITION,
WINDS WILL BE ON THE BRISK SIDE THROUGH THE EVENING HOURS BUT THE
PRESSURE GRADIENT SHOULD CONTINUE TO EASE TONIGHT AS THE LOW TRACKS
EAST OF THE REGION.
THE PATTERN WILL SLOWLY TURN MORE QUIET SUNDAY INTO SUNDAY NIGHT FOR
SOUTHWEST TO WEST CENTRAL KANSAS AS THE UPPER CYCLONE OPENS UP AS IT
PHASES WITH A STRONG HUDSON BAY VORTEX. THIS WILL ALLOW THE BLOCKING
RIDGE OVER THE WESTERN CONUS, TO ALSO SLIDE EAST INTO THE ROCKIES TO
HIGH PLAINS REGION BY LATE SUNDAY NIGHT. ALTHOUGH SOME REMNANT LOW
CLOUD COVER WILL SLIDE ACROSS THE NORTHEASTERN HALF OF THE CWA
THROUGH MOST OF THE DAY, THE MID LEVELS AND ESPECIALLY THE DENDRITIC
LAYER WILL DRY OUT AS SUBSIDENCE BEGINS TO INCREASE IN RESPONSE TO
CONFLUENT UPPER FLOW AND ASSOCIATED SUBSIDENCE. THIS WILL ALSO ALLOW THE
PRESSURE GRADIENT TO DROP QUICKLY BY LATE AFTERNOON ON SUNDAY AS
SURFACE HIGH PRESSURE BUILDS INTO THE REGION VIA THE INCREASING
SUBSIDENCE. AFTERNOON TEMPERATURES WILL BE TRICKY GIVEN THE VARYING
CLOUD COVER AND REMNANT SNOW COVER ACROSS TREGO AND ELLIS COUNTIES,
BUT STEEP LAPSE RATES ARE SHOWN IN THE LOWER 3-4 KFT OF THE
ATMOSPHERE WHICH SUPPORTS MIXING FROM AROUND 800-850MB AND RESULTANT
HIGHS IN THE UPPER 20S NEAR HAYS AND THE MID 30S NEAR THE OKLAHOMA
LINE.
MONDAY IS THEN LOOKING LIKE A PLEASANT DAY ACROSS THE REGION AS THE
UPPER RIDGE IS KICKED EAST INTO THE PLAINS IN ADVANCE OF A DEEP
UPPER TROUGH BEING CARVED OUT OVER THE WESTERN CONUS. ALTHOUGH THE
SURFACE HIGH WILL REMAIN ACROSS MOST OF THE AREA DUE TO MODEST
SUBSIDENCE LINGERING OVER THE AREA, INCREASING WESTERLIES ACROSS THE
SOUTHERN TO CENTRAL ROCKIES, WILL ALLOW THE LEE TROUGH TO BEGIN
DEEPENING ALONG THE FRONT RANGE REGION OF COLORADO INTO NEW MEXICO.
THIS SHOULD EFFECTIVELY PUSH THE DEEPER MORE ENTRENCHED ARCTIC AIR
EAST OF THE FORECAST AREA BY EARLY AFTERNOON. ALTHOUGH SOME CIRRUS
WILL ALSO BEGIN TO SPILL INTO THE REGION BY AFTERNOON, EXPECT DECENT
INSOLATION AND MIXING UP TO 875-900MB TO BRING HIGHS IN THE MID 30S
TO LOWER 40S FOR MONDAY.
THE NEXT SOUTHERN BRANCH S/W TROF IS STILL PROGGED TO MOVE OUT INTO
THE SRN PLAINS ON TUESDAY AS AN OPEN WAVE. GIVEN IT CURRENT TRACK
THIS WOULD CONTINUE TO SUPPORT AT LEAST SLT CHANCE POPS IN OUR
CWA...ESPECIALLY IN OUR S/SE. THE CURRENT FORECAST APPEARS TO HAVE A
DECENT HANDLE WITH THIS SYSTEM SO NO MAJOR ADJUSTMENTS TO THE
PREVIOUS FORECAST PLANNED FOR MID WEEK.
CYCLONIC FLOW ALOFT REMAINS IN PLACE ACROSS THE CNTL PLAINS THROUGH
THE END OF THE WORK WEEK AS A COLD CORE NORTHERN BRANCH S/W TROF
BEGINS TO TAKE AIM ON WRN KS THURSDAY NIGHT. DESPITE THE LACK OF
GOOD LOW LVL FORCING BOTH THE GFS AND ECMWF WERE SHOWING SOME MID
LVL MOISTURE AND 7-5H INSTAB OVER WRN KS THURSDAY NIGHT AND/OR
FRIDAY. AT THIS TIME IF PCPN DOES DEVELOP WITH THIS NEXT SYSTEM IT
DOES NOT APPEAR THAT IT WILL AMOUNT TO MUCH, IF AT ALL. AS A RESULT
GIVEN THE LOW PROB OF ANYTHING MEASURABLE HAVE OPTED TO LEAVE THE
FORECAST DRY ON FRIDAY BUT DID INCREASE CLOUD COVER AND INTRODUCED
SOME SILENT POPS INTO THE GRIDS.
ONCE THIS WAVE PASSES ANOTHER ROUND OF COLD ARCTIC AIR WILL SURGE
SOUTH INTO PLAINS. AS FOR WRN KS...GIVEN THE PROGGED LOCATION OF THE
UPPER LVL RIDGE AXIS AND NW DOWNSLOPE FLOW THAT IS EXPECTED TO
DEVELOP BY EARLY SATURDAY AM UNSURE HOW FAR WEST THIS COLD AIR WILL
BE BY LATE FRIDAY. AT THIS TIME WILL BE FAVORING THE COOLER MEX
NUMBERS AS A START FOR FRIDAY AND THEN KEEPING TEMPS ON THE COOL
SIDE ACROSS OUR ERN CWA ON SAT.
&&
AVIATION...
GUSTY NORTHWEST WINDS ARE EXPECTED TO CONTINUE TO DECREASE LATE THIS
AFTERNOON AND EARLY TONIGHT AS A WEAK SFC RIDGE AXIS STARTS TO BUILD
INTO THE AREA FROM THE NORTHWEST. ALSO SHOULD SEE A FEW FLURRIES
LATE TODAY AND EARLY TONIGHT BUT GIVEN HOW WIDELY SCATTERED THIS
PCPN WILL BE HAVE OPTED TO LEAVE MENTION OF PCPN OUT OF TAFS AT THIS
TIME.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 17 32 15 39 / 10 0 0 0
GCK 17 33 13 39 / 10 0 0 0
EHA 18 35 17 40 / 0 0 0 0
LBL 17 36 13 41 / 0 0 0 0
HYS 18 29 12 34 / 10 10 0 0
P28 19 35 18 42 / 10 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN23/18/18
