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000
FXUS63 KDDC 212020
AFDDDC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
320 PM CDT TUE MAY 21 2013

...UPDATED LONG TERM DISCUSSION...

.SYNOPSIS...
ISSUED AT 116 AM CDT TUE MAY 21 2013

THE UPPER LEVEL FLOW ACROSS THE CENTRAL UNITED STATES WAS DOMINATED
BY A DEEP UPPER LEVEL CYCLONE CENTERED IN SOUTHEAST NORTH DAKOTA.
NORTH OF THE UPPER LEVEL CYCLONE, A BLOCKING UPPER LEVEL HIGH WAS
CENTERED IN SASKATCHEWAN. ANOMALOUSLY STRONG MID LEVEL FLOW WITH
WIND SPEEDS ABOVE 50KTS AT H5 PREVAILED FROM NEW MEXICO ACROSS
OKLAHOMA TO THE UPPER MIDWEST. VERY COLD AIR ALOFT COVERED THE
CENTRAL PLAINS AND ROCKIES WITH H5 TEMPERATURES AT OR BELOW -16C
ACROSS A WIDE AREA. A VIGOROUS UPPER LEVEL TROUGH WAS EVIDENT ON
SATELLITE IMAGERY IN CENTRAL NEW MEXICO, AND CONSIDERABLE MID AND
HIGH LEVEL CLOUDINESS IN THE REGION OF UPWARD VERTICAL MOTION EAST
OF THE TROUGH COVERED EASTERN NEW MEXICO AND THE TEXAS PANHANDLE.

A MINOR TROUGH ROTATING AROUND THE GYRE CENTERED IN THE NORTHERN
PLAINS EXTENDED FROM CENTRAL NEBRASKA INTO SOUTHEAST COLORADO AT
00Z, AND A REINFORCING SURGE OF COLD AIR IN THE LOWER LEVELS OF THE
ATMOSPHERE WAS SPREADING ACROSS WESTERN KANSAS. THE LEADING EDGE OF
THE COLD AIR ADVECTION EXTENDED FROM SOUTHEAST NEBRASKA TO THE
CENTRAL OKLAHOMA PANHANDLE AT 04Z. AN INCREASE IN NORTHWEST WINDS
AND RISING PRESSURES WAS EVIDENT BEHIND THE SUBTLE BOUNDARY. VERY
RICH LOW LEVEL MOISTURE COVERED THE SOUTHERN PLAINS IN ADVANCE OF A
DRYLINE IN WEST TEXAS, AND A WARM ELEVATED MIXED LAYER WAS EVIDENT
IN THE MID LEVELS FROM WEST TEXAS TO THE UPPER MIDWEST.

UPSTREAM IN THE PACIFIC, A DEEP OCCLUDED CYCLONE OVER THE ALEUTIAN
ISLANDS NEAR 175W WAS FEEDING WARM AIR NORTH INTO AN UPPER LEVEL
RIDGE NEAR 150W, AND A DOWNSTREAM TROUGH NEAR 130W WAS DIGGING
TOWARD THE PACIFIC NORTHWEST.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 207 AM CDT TUE MAY 21 2013

A PERIOD OF QUIESCENT WEATHER WILL PREVAIL IN WESTERN KANSAS THROUGH
WEDNESDAY, AND TEMPERATURES WILL PROVIDE THE BIGGEST FORECAST
CHALLENGE. CONSIDERABLE HIGH LEVEL CLOUDINESS WILL SPREAD NORTHWARD
INTO SOUTHWEST KANSAS THIS MORNING AS THE VIGOROUS UPPER LEVEL
TROUGH IN NEW MEXICO MOVES EAST INTO THE TEXAS PANHANDLE. THE HIGH
CLOUDINESS WILL THIN THIS AFTERNOON AS THE TROUGH PROPAGATES EAST
INTO CENTRAL OKLAHOMA. VERY COLD AIR ALOFT WILL PERSIST, AND
AFTERNOON HEATING WILL SUPPORT DEVELOPMENT OF HIGH BASED CUMULUS
CLOUDINESS AGAIN TODAY. COLD AIR ADVECTION BEHIND THE SUBTLE FRONTAL
BOUNDARY WILL CONTINUE THIS MORNING, AND THE LOW LEVELS OF THE
ATMOSPHERE WILL BE A LITTLE COOLER THAN YESTERDAY. TEMPERATURES AT
H7 ARE CONTINUING TO COOL, AND MID LEVEL INSTABILITY WILL BE NEARLY
ABSENT THIS AFTERNOON. AS A RESULT, THERE SHOULD BE FEW IF ANY HIGH
BASED SHOWERS THIS AFTERNOON. A SUBTLE UPPER LEVEL TROUGH IN EASTERN
UTAH WILL DROP INTO NEW MEXICO AND SOUTHEAST COLORADO THIS
AFTERNOON, AND THE ENTRANCE REGION OF THE JET STREAK WITH THE MINOR
TROUGH MAY PROVIDE SOME UPPER LEVEL DIVERGENCE IN SOUTHEAST COLORADO
LATE IN THE DAY. MODEL SOUNDINGS TO HAVE SOME SLIGHT MID LEVEL
INSTABILITY IN FAR SOUTHWEST KANSAS, AND A FEW VIRGA SHOWERS MAY
SPREAD FROM COLORADO INTO MORTON COUNTY BEFORE DYING THIS EVENING.
TEMPERATURES TODAY WILL BE SLIGHTLY COOLER THAN MONDAY AS A
CONSEQUENCE OF THE INVASION OF COOLER AIR LATE MONDAY AND MONDAY
NIGHT.

WEAK HIGH PRESSURE WILL COVER WESTERN KANSAS TUESDAY NIGHT, AND
WINDS WILL DIMINISH QUICKLY THIS EVENING AS THE BOUNDARY LAYER
STABILIZES. DEWPOINTS IN THE 30S, MOSTLY CLEAR SKIES AND COLD AIR
ALOFT WILL FAVOR STRONG RADIATIONAL COOLING, AND TEMPERATURES WILL
DROP INTO THE 40S DURING THE NIGHTTIME HOURS.

THE UPPER LEVEL ANTICYCLONE IN SASKATCHEWAN WILL BUILD INTO THE
NORTHWEST TERRITORIES AS THE DEEP TROUGH NEAR 130W CLOSES OFF OVER
THE PACIFIC NORTHWEST ON WEDNESDAY. A TROUGH ROTATING AROUND THE A
LOBE OF THE POLAR VORTEX NORTHEAST OF HUDSON BAY WILL DIG SOUTH TO
JAMES BAY WEDNESDAY, AND THE NORTHERN PLAINS UPPER LEVEL LOW WILL
OPEN UP AND MOVE EAST WEDNESDAY AND THURSDAY. UPPER LEVEL RIDGING
WILL BUILD OVER THE CENTRAL PLAINS WEDNESDAY, AND ANOTHER DAY OF
MILD, QUIET WEATHER CAN BE EXPECTED IN WESTERN KANSAS.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 319 PM CDT TUE MAY 21 2013

AT THE START OF THE LONG TERM PERIOD, THE REMAINS OF THE UPPER LOW
OVER THE MIDWEST WILL BE MOVING EAST INTO THE GREAT LAKES AND
PHASING WITH A STRONG SHORTWAVE DIGGING SOUTH OUT OF THE HUDSON`S
BAY REGION. AT THE SAME TIME, A WEAK UPPER LEVEL RIDGE WILL BE
BUILDING OVER THE CENTRAL PLAINS TO THE EAST OF A DEEP CLOSED LOW
SPINNING OVER THE PACIFIC NORTHWEST.

AS THE MIDWEST SYSTEM MOVES EAST, SURFACE HIGH PRESSURE WILL BUILD
SOUTHWARD INTO THE CENTRAL HIGH PLAINS WITH COOL UPSLOPE FLOW
OCCURRING ACROSS WESTERN KANSAS.  A WEAK UPPER LEVEL DISTURBANCE
MOVING UP OUT OF THE SOUTHWEST TOWARD THE CENTRAL PLAINS COULD BRING
SOME ISOLATED LATE AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS
TO AREAS ALONG THE OKLAHOMA BORDER WEDNESDAY EVENING. THE COOL
AIRMASS WILL KEEP HIGH TEMPERATURES AT OR BELOW SEASONAL AVERAGES ON
THURSDAY. ON FRIDAY THE UPPER RIDGE MOVES A LITTLE FARTHER EAST INTO
THE PLAINS WITH THE SURFACE RIDGE LOOSENING ITS GRIP AND ALLOWING
WARMER TEMPERATURES TO MOVE BACK INTO WESTERN KANSAS INTO THE
WEEKEND. THE MODELS SHOW A SHORTWAVE TROUGH ROTATING AROUND THE
UPPER LOW IN THE PACIFIC NORTHWEST AND LIFTING INTO THE NORTHERN
ROCKIES AND ADJACENT HIGH PLAINS BY FRIDAY MORNING. THE SOUTHERN
FRINGES OF THIS WAVE COULD BRING SHOWERS AND THUNDERSTORMS TO
WESTERN KANSAS THURSDAY NIGHT. MODEL SOUNDINGS INDICATE SOME CAPPING
IN THE MID LEVELS THURSDAY EVENING SO AM NOT OVERLY EXCITED ABOUT
THUNDERSTORM CHANCES AT THIS TIME. HAVE DECREASED POPS SOMEWHAT FROM
THE PREVIOUS FORECAST THROUGH THURSDAY NIGHT.

THROUGH THE REMAINDER OF THE WEEKEND INTO EARLY NEXT WEEK, THE UPPER
FLOW PATTERN REMAINS FAIRLY STATIC WITH THE RIDGE AXIS CONTINUING
OVER THE CENTRAL PART OF THE COUNTRY AND AN UPPER TROUGH AXIS
CONTINUING OVER THE WESTERN STATES. WEAK SOUTHWESTERLY FLOW ALOFT
WILL BE IN PLACE OVER THE CENTRAL HIGH PLAINS WITH A LEE SIDE TROUGH
AT THE SURFACE SOMEWHERE NEAR THE KANSAS/COLORADO BORDER. THERE WILL
BE AT LEAST SLIGHT CHANCES FOR AFTERNOON THUNDERSTORMS OVER WESTERN
KANSAS THROUGH THE MEMORIAL DAY WEEKEND WITH ANY WEAK DISTURBANCES
MOVING OUT OF THE SOUTHWEST HELPING TO FOCUS AND SUSTAIN
THUNDERSTORMS INTO THE LATE EVENING HOURS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1254 PM CDT TUE MAY 21 2013

NORTHWEST WINDS WILL GRADUALLY DIMINISH THIS AFTERNOON TO 10 KTS BY
22Z AND THEN BECOME LIGHT NORTHERLY TONIGHT AS WEAK SURFACE HIGH
PRESSURE MOVES INTO KANSAS. WITH THE LACK OF LOW LEVEL MOISTURE, VFR
CONDITIONS WILL PERSIST.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  45  84  51  73 /   0   0  10  20
GCK  44  84  51  72 /   0   0  20  20
EHA  49  89  54  78 /   0  20  20  30
LBL  47  90  53  75 /   0  10  20  30
HYS  44  77  50  71 /   0   0  10  20
P28  49  82  54  73 /   0   0  10  20

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...RUTHI
SHORT TERM...RUTHI
LONG TERM...GERARD
AVIATION...FINCH