AREA FORECAST DISCUSSION
NWS DODGE CITY KS
AFDDDC 230 PM CST MON JAN 6 2003
DAYS 1-2...
MAIN FORECAST CONCERN FOR TODAY AND TOMORROW WILL BE TEMPERATURES.
12Z UPPER AIR ANALYSIS SHOWS CUTOFF LOW OVER THE SOUTHWESTERN U.S,
WITH RIDGING NOSING IN ABOVE IT OVER THE PACIFIC NORTHWEST AND
NORTHERN ROCKIES. 500 MB CHART SHOWS 60 M HEIGHT FALLS JUST TO THE
WEST OF THE LOW, SO THE SYSTEM LOOKS LIKE IT WILL CONTINUE TO DRIFT
TO THE SOUTHWEST, A TREND SUPPORTED BY THE RECENT WATER VAPOR LOOP.
OVER THE PLAINS, NORTHWESTERLY FLOW ALOFT DOMINATES WHILE A CENTER
OF SURFACE HIGH PRESSURE SLIDES INTO CENTRAL KANSAS.
DESPITE SOME DIFFERENCES IN THE INITIALIZATION OF JET STREAKS IN THE
PACIFIC, THE SHORT TERM MODELS ALL ARE IN FAIRLY GOOD AGREEMENT FOR
THE FIRST 36 HOURS OR SO. THE GFS, ETA, NGM, AND UKMET ALL BRING
THE CENTER OF HIGH PRESSURE INTO TX OVERNIGHT, WITH WINDS SHIFTING
TO A MORE WESTERLY COMPONENT. WITH CLOUDS ALREADY ERODING OVER THE
CWA THIS AFTERNOON, IT DOESN'T LOOK LIKE THERE WILL BE A REPEAT IN
CLOUD COVER TONIGHT WITH DRIER DOWNSLOPING FLOW. WINDS SHOULD BE
STRONG ENOUGH TO KEEP TEMPERATURES FROM DROPPING ALL THE WAY DOWN TO
THE DEWPOINT OVERNIGHT. THE WEST WINDS WILL CONTINUE THROUGH
TOMORROW, SO SUNNY SKIES AND DOWNSLOPING WINDS SHOULD ALLOW HIGHS TO
CLIMB INTO THE LOWER 60'S. THE UPPER LEVEL RIDGE OVER THE WEST WILL
BEGIN TO PUSH EASTWARD INTO THE PLAINS TOMORROW NIGHT. THE GFS AND
ETA PRODUCE 850 MB TEMPERATURES IN THE MID TEENS BY WEDNESDAY
AFTERNOON. WITH A 14 C READING IN CENTRAL ALBERTA THIS MORNING,
THAT FORECAST DOESN'T LOOK TOO UNREASONABLE. THUS, WITH THE WARM
850 MB TEMPS, SUNNY SKIES, AND CONTINUING DOWNSLOPE, WILL KEEP THE
GOING HIGH OF NEAR 70 FOR WEDNESDAY.
DAYS 3-7...
THE LATEST GLOBAL DIAGNOSTICS INDICATE THE STRONG MOIST PHASE OF THE
MJO NOW BEGINNING TO WANE OVER THE CENTRAL PACIFIC AS EVIDENCED BY
THE LARGE AREA OF TROPICAL CONVECTION ALONG THE ITCZ WHICH IS NOW
NEARLY STATIONARY AND FEEDING SUBTROPICAL MOISTURE INTO THE SOUTHERN
HEMISPHERE. THE PNA PATTERN OVER WESTERN NORTH AMERICA SHOULD THUS
LINGER A FEW MORE DAYS BEFORE THE CROSS PACIFIC WESTERLIES BREAK
SOUTHERN BRANCH ENERGY THROUGH INTO THE CONUS. GLOBAL AVERAGE
ANGULAR MOMENTUM ANOMALIES IN THE WESTERLIES HAD BEGUN GRADUALLY
INCREASING AGAIN AND REMAINS ABOVE NORMAL. THE BASE CIRCULATION
STATE CONTINUES TO BE A NORTHERN HEMISPHERE WAVE 5 PATTERN WITH THE
AFOREMENTIONED PNA PATTERN OVER WESTERN NORTH AMERICA INTERRUPTING
WHAT WOULD OTHERWISE SUGGEST A PROGRESSIVE REGIME.
MORNING MODEL VALIDATION INDICATES THAT THE AVN, GFS, AND ETA HAVE A
PROBLEM WITH THE MASS FIELDS IN MID PACIFIC AS A 145KT JET STREAK
SEEN IN THE AIREPS AND ACARS DATA NEAR 160W WAS MISSED ENTIRELY BY
THESE MODELS. THE NGM, UKMET AND ECMWF HAD A MUCH BETTER
INITIALIZATION WITH THIS FEATURE AND WILL THUS FOLLOW THEIR SOLUTION
OF BRINGING A SOUTHERN BRANCH WAVE TO THE SOUTHERN CALIFORNIA COAST
LATE WEDNESDAY RATHER THAN SHUNTING THE WAVE OVER THE UPPER RIDGE AS
THE AVN, ETA AND GFS DO.
THE CURRENT UPPER LOW OVER THE DESERT SOUTHWEST CONTINUES TO DIG TO
A LOCATION OFF THE NORTHERN BAJA BY TOMORROW AND THIS FEATURE WILL
THEN BE KICKED OUT INTO THE PLAINS WEDNESDAY NIGHT BY THE
APPROACHING SOUTHERN BRANCH PACIFIC WAVE. THEREAFTER, A PROGRESSIVE
WAVE CHAIN ON THE SOUTHERN BRANCH OF THE WESTERLIES WILL DOMINATE
THE WEATHER REGIME OVER THE CENTRAL HIGH PLAINS WITH LITTLE MOISTURE
AND FEW DAYS OF DOWNSLOPE WARMING. BY THE WEEKEND ANOTHER SOUTHERN
BRANCH WAVE WILL CROSS THE PLAINS. THE AVN AND GFS BOTH ATTEMPT TO
PRODUCE PRECIPITATION WITH THIS FEATURE ALTHOUGH IT IS STILL UNCLEAR
HOW SUFFICIENT MOISTURE CAN BE HAD IN SUCH A PROGRESSIVE REGIME. FOR
NOW PREFER TO MAINTAIN A DRY FORECAST THROUGH THE WEEKEND. THE GFS
IS ALSO ADVERTISING A CANADIAN COLD SURGE THURSDAY NIGHT AHEAD OF
THE NEXT PACIFIC WAVE. THIS COLD SURGE SEEMS REASONABLE AS A
NORTHWEST FLOW WAVE DIVES INTO THE MEAN EAST COAST UPPER TROUGH. THE
GFS SEEMS WELL INITIALIZED FOR THE NORTHERN BRANCH WESTERLIES IN
SPITE OF ITS DIFFICULTIES WITH THE SOUTHERN BRANCH ENERGY. WILL HOLD
OFF ON ADDING PRECIPITATION OVER TOP OF THE COLD DOME FOR NOW AS THE
MOISTURE SOURCE REMAINS UNCLEAR. ANOTHER SUCH NORTHWEST FLOW WAVE IS
FORECAST THROUGH THE AREA ON MONDAY AND SEEMS REASONABLE AS WELL SO
WILL GO WITH BELOW NORMAL TEMPERATURES AND NEAR NORMAL PRECIPITATION
IN THE OUTLOOK PERIOD.
PRELIMINARY GUIDANCE FOR COORDINATION ONLY. OFFICIAL FORECASTS ARE
CONTAINED WITHIN THE DODGE CITY ZONE FORECAST.
DDC 27 61 33 70 / 0 0 0 0
GCK 26 60 30 69 / 0 0 0 0
EHA 29 61 31 69 / 0 0 0 0
LBL 28 60 30 70 / 0 0 0 0
HYS 26 59 29 68 / 0 0 0 0
P28 28 63 35 70 / 0 0 0 0
.DDC...NONE.
RITTERLING/JOHNSON