AREA FORECAST DISCUSSION
NWS DODGE CITY KS
AFDDDC 133 PM CST MON JAN 20 2003
DAYS 1-2...
MAIN PROBLEMS TODAY WILL BE TEMPERATURES AND STRATUS AND FOG TONIGHT
AND TUESDAY NIGHT.
THE 12Z DIAGNOSTIC DATA SHOWS THE MEAN WESTERN CONUS UPPER RIDGE
STILL IN PLACE WITH A RELATIVELY WEAK CLOSED UPPER LOW NEAR SOUTHERN
CALIFORNIA. THE SOUTHERN BRANCH POLAR JET WAS ACROSS MEXICO AND THE
NORTHERN GULF WITH THE SOUTHERN BRANCH POLAR FRONT WELL SOUTH ACROSS
THE CARIBBEAN. A STRONG NORTHERN BRANCH JET STREAK NORTH OF THE
UPPER RIDGE EXTENDED FROM WESTERN CANADA EAST SOUTHEAST ACROSS THE
UPPER MISSISSIPPI VALLEY TO THE SOUTHERN ATLANTIC SEABOARD. THE
POLAR FRONT ALONG THIS JET STREAK HAD ACROSS MOST OF NEBRASKA AND
NORTHEAST KANSAS WITH A STRONG REINFORCING ARCTIC SURGE CLOSE ON ITS
HEELS. OVER THE CENTRAL HIGH PLAINS THIS MORNING A POOL OF VERY WARM
AND WELL MIXED AIR WAS IN PLACE ABOVE THE MORNING INVERSION WITH H8
TEMPERATURES AROUND +18C ON THE SOUNDINGS. INDEED IF THE SHALLOW
RADIATION INVERSION AT DDC MIXES OUT EARLY, TEMPERATURES MAY QUICKLY
SOAR WELL OVER THE FORECAST HIGHS FOR TODAY NECESSITATING AN QUICK
UPDATE OF THE FORECAST. AT THE SURFACE A BROAD AREA OF LOW PRESSURE
ASSOCIATED WITH THE WARM POOL ALOFT WAS WORKING SLOWLY EASTWARD
ACROSS KANSAS SHIFTING SURFACE WINDS WEST TO NORTHWEST IN DOWNSLOPE.
NORTH OF THE POLAR AND ARCTIC FRONTS ACROSS THE NORTHERN PLAINS
THERE WAS A GOODLY AMOUNT OF MOISTURE DUE TO SATURATION OF THE LOW
LEVEL AIR THROUGH COOLING AND MOISTURE MOVING THROUGH THE UPPER
BAROCLINIC ZONE.
IN VALIDATING THE MODEL INITIALIZATIONS THIS MORNING, MASS FIELDS
APPEARED TO BE QUITE GOOD WITH ALL THE SYNOPTIC SCALE FEATURES. THE
MESOSCALE MODELS WERE ALL STRUGGLING A BIT WITH THE WARM SURFACE LOW
OVER KANSAS IN THE EARLY PERIODS OF THEIR FORECASTS, BUT ALL OF THE
MODELS SEEM TO HAVE CAPTURED THE SATURATION THROUGH COOLING ALONG
AND NORTH OF THE FRONTS, AND ALL HAD INITIALIZED WELL WITH THEIR
MASS FIELDS OVER THE EASTERN AND CENTRAL PACIFIC PER THE AIREP AND
ACARS DATA AVAILABLE. WILL EXPECT THEM ALL TO DO A REASONABLE JOB
WITH SYNOPTIC SCALE FEATURES ASIDE FROM THEIR USUAL BIASES. OVER THE
CENTRAL HIGH PLAINS WILL THEREFORE GENERALLY FOLLOW THE HIGHER
RESOLUTION MESOETA WHICH IS ALSO MORE MOIST IN THE BOUNDARY LAYER.
THE SURFACE WARM TROUGH SHOULD CONTINUE TO WORK SLOWLY EAST TODAY
WITH NORTHWEST BOUNDARY LAYER FLOW LIMITING HIGH TEMPERATURES AT
LEAST A LITTLE. BY LATE TODAY, AN UPPER LEVEL SHORT WAVE DIVING
SOUTHEAST OUT OF CANADA ALONG THE UPPER BAROCLINIC ZONE WILL BEGIN
DRIVING THE ARCTIC REINFORCED POLAR BOUNDARY SOUTHWEST ACROSS
KANSAS. THE FRONT SHOULD ARRIVE IN MY NORTHEAST ZONES SHORTLY AFTER
6PM THIS EVENING. IT WILL THEN WORK ITS WAY ACROSS THE FORECAST AREA
THROUGH THE NIGHT BRINGING CONSIDERABLE UPSLOPE AND SATURATING THE
BOUNDARY LAYER. DUE TO THE UNCERTAINTY OVER THE AMOUNT OF SATURATION
WILL FORGO ANY ADVISORY FOR DENSE FOG, BUT WILL KEEP MENTION OF FOG
IN THE ZONES.
THE DEPTH OF THIS MOISTURE IS A HUGE UNKNOWN AT THE MOMENT WITH ALL
THE MODELS HAVING DIFFERENT IDEAS. GIVEN THE AMOUNT OF LOW CLOUD
ASSOCIATED WITH THIS SYSTEM THIS MORNING OVER THE NORTHERN PLAINS
HAVE TO BELIEVE THERE WILL BE FOG AND STRATUS IN THE STRONG UPSLOPE
AFTER MIDNIGHT TONIGHT AND LASTING WELL INTO THE DAY ON TUESDAY.
WILL PLAY TEMPERATURES ACCORDINGLY. AS THE BOUNDARY LAYER FLOW
TURNS MORE SOUTHEAST TUESDAY NIGHT INTO WEDNESDAY WILL LIKELY SEE A
REPEAT OF THE FOG AND STRATUS LATE TUESDAY NIGHT INTO WEDNESDAY WITH
THE ARCTIC AIR INFILTRATING MY NORTHERN ZONES WEDNESDAY AFTERNOON
AND CONTINUED COLD AIR ADVECTION OVER THE FORECAST AREA ON WEDNESDAY
ENHANCING THE CLOUD COVER.
DAYS 3-7...
AFTER REVIEWING THE LATEST RUNS OF THE AVN, GFS, ETA AND UKMET, AND
COMPARING THEM TO THE MORE STABLE ECMWF, HAVE DECIDED TO LEAVE MOST
OF GOING FORECAST AS IS. HOWEVER, WILL TRIM A SECTION OF
NORTHEASTERN CWA COUNTIES TO INCLUDE A SLIGHT CHANCE FOR SNOW
WEDNESDAY NIGHT INTO THURSDAY. AS MENTIONED FROM PREVIOUS SHIFT'S
DISCUSSION, THERE COULD BE SOME FREEZING DRIZZLE SOMEWHERE IN CWA
WITH THE PROLONGED UPSLOPE FLOW. BUT, THE AVAILABLE MOISTURE IS THE
QUESTION. THE SURFACE FRONT WILL SINK STEADILY SOUTH WEDNESDAY NIGHT
THROUGH THURSDAY NIGHT, WITH THE COLDEST AIR STAYING OFF TO OUR
EAST. THEREFORE, ANY MOISTURE WHICH PRECIPITATES OUT WILL HAVE TO
COME WITH THE SYSTEM; THE GULF SOURCE IS CUT OFF. ONE SMALL SCALE
WAVE ORIGINATES OVER SOUTHWEST CALIFORNIA, MOVES THROUGH THE
SOUTHERN ROCKIES TUESDAY THROUGH WEDNESDAY, AND THEN PHASES WITH A
LARGER WAVE CENTERED OVER THE GREAT LAKES NEAR THE DDC CWA WEDNESDAY
NIGHT. MOST OF THE MID AND LOW LEVEL MOISTURE IS WELL TO OUR NORTH,
OVER NEBRASKA AND SOUTH DAKOTA. SO AS THE SURFACE FRONT DIVES
FARTHER SOUTH WEDNESDAY NIGHT, UPSLOPE FLOW COULD SATURATE LOWER
LAYERS ENOUGH FOR A FEW FLAKES TO FLY IN NORTHEAST PART OF CWA.
WITH WITH ONLY A SLIGHT CHANCE FOR SNOW.
A SLIGHT WARMING TREND SET IN SATURDAY INTO MONDAY, WITH BOTH HIGHS
AND LOWS ABOVE NORMAL VALUES. DO NOT SEE MUCH CHANCE FOR ANY PRECIP,
EVEN THROUGH DAY 10. WILL HAVE TO WAIT FOR CHANGE IN PATTERN WITH
LARGE SCALE UPPER LOW OVER SOUTHEAST CANADA TO GET KICKED OUT,
BEFORE ANY STRONGER LOW PRESSURES CAN MAKE IT THROUGH THE ROCKIES
AND MEET ANY MOISTURE RETURNING FROM GULF.
PRELIMINARY GUIDANCE FOR COORDINATION ONLY. OFFICIAL FORECASTS ARE
CONTAINED WITHIN THE DODGE CITY ZONE FORECAST.
DDC 22 38 20 33 / 0 0 0 0
GCK 23 39 21 34 / 0 0 0 0
EHA 28 43 26 42 / 0 0 0 0
LBL 27 41 24 38 / 0 0 0 0
HYS 19 36 18 25 / 0 0 0 0
P28 25 38 23 33 / 0 0 0 0
.DDC...NONE.
JOHNSON/BURKE