FXUS63 KOAX 210854
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
354 AM CDT MON MAR 21 2011
.DISCUSSION...
FORECAST CONCERNS OVER THE NEXT COUPLE OF DAYS WILL CONTINUE TO BE
PRECIPITATION CHANCES...POTENTIAL FOR SEVERE WEATHER AND TEMPERATURES.
THE LATEST SURFACE MAP HAD HIGH PRESSURE CENTERED OVER EASTERN
SOUTH DAKOTA WITH A STALLED SURFACE FRONT FROM KANSAS INTO
NORTHERN MISSOURI. SURFACE TEMPERATURES WERE IN THE 40S AND
50S...AND SURFACE DEWPOINTS WERE IN THE 30S NORTH TO THE LOWER 50S
SOUTH. SFC DEWPOINT DEPRESSIONS ALONG WITH LIGHT WINDS EARLY THIS
MORNING TO RESULT IN SOME FOG AND WILL MENTION EARLY UNTIL THE
WINDS PICK UP. ON THE UPPER AIR CHARTS...AT H5...THERE WERE 90M
HT FALLS AROUND SOUTHERN CALIFORNIA WITH THE SHORTWAVE TROF. AT
H3...THERE WAS A BROAD 80-100KT JET FM SRN CA INNTO NRN NEB AND
IOWA.
AS THE MID TROPOSPHERIC TROF MOVES FARTHER INTO THE WEST...SFC LOW
PRESSURE WILL RESPOND BY LOWERING AND BY MOVING INTO NORTHEAST
COLORADO. A WARM FRONT THAT EXTENDS TO THE EAST OF THE AREA OF LOW
PRESSURE SHOULD LIFT NORTH TODAY. MEANWHILE BROAD UVV WILL MOVE
INTO THE PLAINS WITH STEEP MID LEVEL LAPSE RATES OF 7 TO 9 DEG
CELSIUS PER KM. THE LATEST NAM/HRR/ECMWF DO NOT HAVE MUCH IN THE
WAY OF PRECIP TODAY...ALTHOUGH THEY ALL DO DEVELOP SOME PRECIP
THIS EVENING AS THE LOW LEVEL JET STRENGTHENS.
TODAY...TEMPERATURES WILL BE TRICKY AND WILL BE DEPENDENT ON CLOUD
COVER AND HOW FAR NORTH THE WRMFNT MAKES IT. WE HAVE SOME HIGH
CLOUDS NOW...BUT LOOK FOR INCREASING CLOUDS AS AS A RESULT OF WARM AIR
ADVECTION THROUGHOUT THE DAY. HAVE A GRADIENT IN THE TEMPERATURES FROM
NORTH TO SOUTH. THINK THE SOUTHERN COUNTIES WILL SEE THE WARM
FRONT LIFT INTO THE AREA SO HAVE THE WARMEST TEMPS THERE. HIGHS
TODAY SHOULD BE IN THE 50S NORTH TO AROUND 80 SOUTH. SFC DEWPOINTS
IN THE SOUTH INCREASE TO AROUND 60. WILL NOT HIT THE PROBABILITY
OF PRECIPITATION (POP) VERY HARD DURING THE DAY...HOWEVER DO HAVE
SOME LOWER POPS IN. INCREASE THE POPS THIS EVENING WITH THE FRONT
IN THE AREA...HEATING...AND INCREASING LOW LEVEL WINDS. NEGATIVE
LIFTED INDICES AND INSTABILITY OF ABOUT 1000 JOULES/KILOGRAM OF
CAPE TRACK INTO SOUTHERN NEBRASKA. DEEP LAYER SHEAR IS 65-75KTS.
HELICITY ALSO INCREASES WITH 0-1KM HELICITY OF 200 TO 600 M2/S2.
IN ADDITION...THERE ARE SOME STRONGER H7 AND H5 WINDS THAT WILL
MOVE IN ALOFT. A LOOK AT THE 18Z AIR FORCE WEATHER AGENCY (AFWA)
MESOSCALE AND GLOBAL ENSEMBLES (MEPS/GEPS)...ALSO TRIES TO FOCUS
MORE ON THE 00Z TO 06Z TIME PERIOD. AS A RESULT OF THESE
FACTORS...THE STORM PREDICTION CENTER HAS PLACED US IN THE SLIGHT
RISK CATEGORY. HAIL IS EXPECTED TO BE THE PRIMARY HAZARD THEN
WINDS...AND DUE TO THE FRONTAL BOUNDARY AND HIGH HELICITY VALUES
...ENHANCED STRETCHING NEAR THE BOUNDARY AND INGESTING OF SFC
BASED INSTABILITY...A TORNADO CANNOT BE RULED OUT.
THE MID LEVEL TROF ROTATES THRU THE NORTHERN ROCKIES MONDAY
NIGHT AND INTO THE PLAINS TUESDAY...MEANWHILE..THE SFC LOW PRES
SYSTEM TRACKS FARTHER EAST INTO EASTERN NEBRASKA. THERE IS ANOTHER
JET SEGMENT THAT MOVES INTO THE PLAINS AND CAPE INCREASES 800-1600
JOULES/KILOGRAM. DEEP LAYER SHEAR IS A LITTLE HIGHER AT 70 TO 85
KTS. TEMPERATURES SHOULD AGAIN TOP OUT IN THE 60S AND 70S WITH
HIGHER DEWPOINTS AHEAD OF THE COLD FRONT. THUS THE BETTER CHC FOR
THUNDERSTORMS CONTINUES TUESDAY AFTERNOON WITH THE COLD FRONT AND
DECREASES FROM WEST TO EAST AS THE FRONT PUSHES OUT OF THE AREA
TUESDAY NIGHT. AGAIN...SOME OF THESE STORMS MAY BE SEVERE. BEHIND
THE COLD FRONT LATER TUESDAY INTO WEDNESDAY...THE MORE ORGANIZED
PRECIPITATION SHOULD REMAIN TO THE NORTH OF THE FORECAST AREA.
TEMPS ARE COLD ENOUGH FOR A MIX...BUT FOR NOW THINK MOST OF IT
WILL BE TO THE NORTH.
STILL LOOKS UNSETTLED FOR THURSDAY NIGHT AND FRIDAY AND COLDER
INTO THE WEEKEND WITH ANOTHER STORM SYSTEM AND POTENTIAL FOR
RAIN/SNOW. DID NOT MAKE CHANGES IN THE EXTENDED.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
FRONTAL BOUNDARY HAS STALLED IN KANSAS AND NORTHERN MISSOURI EARLY
THIS MORNING. THAT FRONT WILL START TO LIFT BACK TO THE NORTH TODAY.
INITIALLY LIGHT NORTHEAST WINDS WILL BECOME EAST AND INCREASE...
THEN BECOME SOUTHEAST. EXPECT AT LEAST SOME AREAS OF CEILINGS TO
DEVELOP BETWEEN 3000 AND 5000 FEET PRIOR TO 18Z...AND SOME LIGHT
PRECIPITATION IS POSSIBLE. HOWEVER...NOT SURE THAT THESE CEILINGS
WILL OCCUR RIGHT AT THE TAF SITES. WILL MONITOR AND UPDATE AS
NEEDED. IT DOES APPEAR THAT CEILINGS COULD DROP TO BELOW 3000
FEET...BUT MAINLY AFTER 00Z. THUNDERSTORM CHANCES APPEAR TOO LOW
TO MENTION AT THIS TIME...BUT THERE DOES APPEAR TO BE SOME CHANCE
ESPECIALLY AT KLNK AND KOMA AFTER 23Z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY/MILLER