FXUS63 KOAX 140051
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
751 PM CDT SUN MAR 13 2011
.UPDATE...
UPDATED TO INCLUDE SOME LIGHT SNOW/SLEET ACCUMULATIONS FAR
SOUTHWESTERN ZONES.
&&
.DISCUSSION...
PRECIPITATION AREA CONTINUES TO SHIFT NEWD INTO SOUTHEAST NEBRASKA
MOSTLY AROUND AND SOUTHWEST THROUGH SOUTH OF BIE. ALTHOUGH UPPER
DISTURBANCE DRIVING PRECIPITATION WAS DROPPING SSE ACROSS OK/TX
PANHANDLES AS OF 0030Z...88D IMAGERY SHOWED PRECIP AREA STILL
TRYING TO LIFT NEWD INTO SERN NEBR. THIS TREND COULD LAST SEVERAL
MORE HOURS UNTIL UPPER SYSTEM DROPS FAR ENOUGH SOUTH SO THAT BULK
OF PRECIP WILL BE SOUTH OF NEBRASKA. HOWEVER...PER TELCO WITH
EMERGENCY MANAGEMENT IN JEFFERSON COUNTY SOME LIGHT SNOW/SLEET
ACCUMULATIONS WERE TAKING PLACE NEAR KS BORDER. UPDATED TO
INCREASE POPS BEFORE 06Z AND TO MENTION SOME LIGHT SNOW/SLEET
ACCUMULATIONS MOSTLY AROUND THE BIE/FBY AREAS. CHERMOK
&&
.PREV DISCUSSION... /ISSUED 317 PM CDT SUN MAR 13 2011/
SHORT TERM...TONIGHT THROUGH WEDNESDAY
POTENT PIECE OF SHORTWAVE ENERGY CURRENTLY MOVING ACROSS WESTERN
NEBRASKA AND KANSAS HAS LED TO SCATTERED PRECIPITATION ACROSS MUCH OF
CENTRAL NEBRASKA THIS AFTERNOON. AT THE SFC...COOL HIGH PRESSURE
IS CURRENTLY CENTERED OVER THE ND/SD/MN BORDER. THIS HAS ALLOWED
DRIER AIR TO WORK ITS WAY ACROSS MUCH OF OUR NORTHERN AND EASTERN
COUNTIES. THIS ALONG WITH OVERCAST SKIES HAS LIMITED HEATING FOR
TODAY AND WE CONTINUE TO STRUGGLE TO MAKE IT OUT OF THE LOWER 30S
OVER MUCH OF THE AREA.
WL CONTINUE POPS INTO THE EVENING HOURS FOR OUR SOUTH AS SHORTWAVE
ENERGY CONTINUES TO DIG SEWD INTO THE OVERNIGHT HOURS. LIMITING
FACTOR ON ACCUMULATING PRECIPITATION WILL BE LACK OF MOISTURE TO
WORK INTO THE SYSTEM SO WL KEEP QPF VALUES VERY LOW. AS SFC TEMPS
CONTINUE TO COOL THIS EVENING...WL TRANSITION FROM RAIN OVER TO A
MIX OF SNOW AND RAIN...THEN EVENTUALLY OVER TO SNOW.
AGAIN...ANY ACCUMULATIONS SHOULD REMAIN MINOR.
THIS SYSTEM EVENTUALLY CLOSES OFF AND MOVES WELL TO OUR SOUTHEAST
ON MONDAY. HAVE LOWERED MONDAYS HIGHS SLIGHTLY AS WARMER LOW LEVEL
SOUTHERLY FLOW IS SLOW TO SET UP WITH DEPARTING UPPER SYSTEM.
ANOTHER PIECE OF SHORTWAVE ENERGY WILL PUSH THROUGH ON TUESDAY AND
MOVE A WEAK COLD FRONT THROUGH THE REGION. LATEST MODEL GUIDANCE
HAS GREATLY REDUCED THE AMOUNT OF MOISTURE ASSOCIATED WITH THIS
SYSTEM SO HAVE REDUCED POPS SLIGHTLY TO ACCOUNT FOR THIS LACK OF
MOISTURE. STRONG RETURN FLOW SETS UP BY WEDNESDAY WHICH SHOULD
PUSH HIGH TEMPS INTO THE 60S.
LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
THE PRIMARY CONCERNS DURING THIS TIMEFRAME ARE TEMPERATURES AND THE
POTENTIAL FOR PRECIPITATION. 12Z OPERATIONAL RUNS OF THE ECMWF AND
GFS MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE MID TROPOSPHERIC
PATTERN...AND GENERALLY A BLEND OF BOTH WAS USED. THE 12Z CANADIAN
MODEL IS NOT QUITE AS PROGRESSIVE WITH THE FLOW FROM THE EASTERN
PACIFIC INTO THE MID PART OF THE CONTINENTAL UNITED STATES. THE 12Z
CANADIAN MODEL 500 MB PATTERN STARTS TO BECOME SIGNIFICANTLY
DIFFERENT THAN THE REST OF THE MODELS BY FRIDAY.
A COLD FRONT WILL BE MOVING ACROSS OUR AREA WEDNESDAY NIGHT AND
THURSDAY MORNING...SO KEPT SOME MENTION OF SHOWERS GOING ALONG AND
AHEAD OF THE COLD FRONT. WEAK HIGH PRESSURE AT THE SURFACE BUILDS
IN FOR THE THURSDAY NIGHT THROUGH FRIDAY NIGHT PERIODS. EVEN THOUGH
THE MODELS HINT AT POTENTIAL FOR LIGHT PRECIPITATION...DECIDED TO
KEEP THE THURSDAY NIGHT THROUGH FRIDAY NIGHT PERIODS DRY FOR NOW.
THE 12Z GFS SHOWED A TROUGH DIGGING OVER THE WESTERN UNITED STATES
BY SATURDAY...WITH SOUTHWEST FLOW ALOFT AND ISENTROPIC UPGLIDE
INCREASING ACROSS THE PLAINS. THE GFS SOLUTION MAY BE JUST A LITTLE
FAST...BASED ON THE GFS ENSEMBLE MEAN AND THE 12Z ECMWF. HOWEVER...
EVEN THE 12Z ECMWF SHOWED SOME LIGHT PRECIPITATION ACROSS OUR LOCAL
AREA SATURDAY. USING A BLENDED SOLUTION...FELT THAT A 20-30 PERCENT
CHANCE OF SHOWERS WAS JUSTIFIED FOR DAYS 6/7 (SATURDAY AND SUNDAY).
AT THIS TIME...THERMAL PROFILES WOULD SUPPORT LIQUID PRECIPITATION
ONLY...BUT THE GFS IS SUGGESTING COLDER CONDITIONS BY SUNDAY NIGHT
FOR NORTHEAST NEBRASKA.
AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
A SHORTWAVE TROF IS OVER NEBRASKA AND KANSAS AND WILL CONTINUE TO
MOVE ACROSS THE REGION DURING THE TAF PERIOD. SKY CONDITIONS WILL
AGAIN BE VARIABLE WITH VFR CONDITIONS AND PERIODS OF MVFR
CONDITIONS. ALTHOUGH SNOW AND RAIN/SNOW MIXED IS FALLING OVER
CENTRAL NEBRASKA...THIS AREA WILL HAVE A HARD TIME MAKING IT
EASTWARD TO THE TAF SITES DUE TO THE DRY AIR THAT IS PRESENT IN THE
BELOW 1.5-7K FEET LAYER. IN ADDITION...THE SUPPORT FOR THE
PRECIPITATION SPLITS...IT WEAKENS OVER NORTHEAST NEBRASKA...THEN
RE-FOCUSES OVER KANSAS AND MISSOURI SOUTHWARD. DID INCLUDE AN HOUR
OR TWO OF RAIN/SNOW MIX OR SPRINKLES EARLY THIS EVENING WITH MVFR
CIGS. THINK THERE WILL BE PERIODS OF MVFR CIGS OVERNIGHT AT
KOFK/KLNK...HOWEVER KOMA IS MORE QUESTIONABLE AND LEFT OUT FOR NOW.
SKY CONDITIONS SHOULD IMPROVE AFTER 12-15Z MONDAY. NORTHEAST
SURFACE WINDS GENERALLY UNDER 10KTS WILL BECOME SOUTH BETWEEN 12-15Z
MONDAY.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
KERN/MILLER/ZAPOTOCNY