FXUS63 KOAX 291619
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1119 AM CDT SUN MAY 29 2011
.UPDATE...
MADE MINOR TEMPERATURE ADJUSTMENTS THIS AFTERNOON.
&&
.DISCUSSION...
TRICKY TEMPERATURE FORECAST AS LOW CLOUDS AND EASTERLY SURFACE
FLOW NORTH OF NORTHWARD ADVANCING WARM FRONT WILL LIKELY KEEP SOME
READINGS IN 60S THIS AFTERNOON WHILE SERN NEBRASKA CLIMBS WELL INTO
THE 80S. IN UPDATE DID NOT STRAY TOO FAR FROM 12Z NAM IN BRINGING
THE FRONT CLOSE TO PLATTE RIVER IN NEBRASKA AND I80 IN
IOWA...ALTHOUGH KEPT WARMEST TEMPS IN SERN NEBRASKA. SOME DRIZZLE
WAS STILL OCCURRING AND LEFT MENTION IN GRIDS TILL 18Z ALTHOUGH
WORDING WAS DROPPED IN LEGACY ZFP SINCE FORECAST BEGAN WITH AFTERNOON.
THUNDERSTORM CHANCES LATER THIS AFTERNOON ALSO UNCERTAIN AS HOT
ELEVATED MIXED LAYER PER 12Z DDC/TOP SOUNDINGS WILL ATTEMPT TO CAP
OFF MAJORITY OF FORECAST AREA BASED ON 12Z NAM BUFKIT.
HOWEVER...SINCE CAP WAS MINIMAL NEAR 00Z AT OMA/HNR...LEFT POPS
ALONE FOR AFTERNOON. IF CAP IS OVERCOME...HODOGRAPHS SUPPORTED
TORNADO THREAT WITH HELICITY VALUES OVER 500 AT OMA/HNR...A BIG IF HOWEVER.
CHERMOK
&&
.PREV DISCUSSION... /ISSUED 330 AM CDT SUN MAY 29 2011/
DISCUSSION...
PRIMARY FORECAST CONCERNS ARE THUNDERSTORM CHANCES OVER THE NEXT 48
HOURS...WINDS MONDAY AND TEMPERATURES.
UPPER AIR CHARTS FROM LAST EVENING SHOWED THE FOLLOWING. AT 300 MB...
STRONG WINDS WERE NOTED WITH JETSTREAM EXTENDING FROM CENTRAL
CALIFORNIA ACROSS THE ROCKIES INTO SOUTH DAKOTA...SOUTHERN MINNESOTA
AND WISCONSIN. CLOSED LOW AT 500 MB WAS OVER OREGON WITH 12 HOUR
HEIGHT FALLS MAX OF 130 METERS AT KOAK. AT 700 MB...TEMPERATURES OF
15 DEGREES CELSIUS OR WARMER WERE NOTED OVER NEW MEXICO...TEXAS AND
OKLAHOMA. THERE WAS STILL A FAIRLY TIGHT THERMAL GRADIENT OVER THE
CENTRAL PLAINS. AT 850 MB...MOISTURE WAS POOLED FROM NORTH TEXAS
UP INTO PARTS OF OKLAHOMA...KANSAS AND MISSOURI. VERY WARM AIR...
WITH TEMPERATURES OF 30 DEGREES CELSIUS WERE NOTED ACROSS PARTS OF
NEW MEXICO AND WEST TEXAS. WATER VAPOR IMAGERY SHOWED THAT 500 MB
CLOSED LOW CONTINUE TO DIG SOUTHWARD AND WAS OVER NORTHERN
CALIFORNIA EARLY THIS MORNING. AT 08Z...SURFACE ANALYSIS SHOWED A
FRONTAL BOUNDARY STRETCHING FROM SOUTHERN ILLINOIS BACK INTO LOW
PRESSURE IN NORTHEAST NEW MEXICO. ANOTHER LOW WAS NEAR THE BORDER
OF UTAH AND COLORADO.
FRONTAL BOUNDARY SHOULD TRY TO LIFT NORTHWARD TODAY AS A FAIRLY
COMPLEX LOW PRESSURE SYSTEM ORGANIZES OVER COLORADO. THUNDERSTORM
CHANCES WILL CONTINUE OVER MUCH OF THE AREA TODAY...THEN SHIFT UP
INTO THE DAKOTAS AND MINNESOTA BY LATE TONIGHT. AT LEAST SOME
SEVERE STORMS WILL BE POSSIBLE...WITH HAIL THE MAIN THREAT.
MODELS SHOW 700 MB TEMPERATURES WARMING OVER THE LOCAL AREA TODAY
AND AT LEAST OUR SOUTHERN COUNTIES SHOULD BECOME CAPPED THIS
AFTERNOON. EXPECT HIGHS TO RANGE FROM THE UPPER 60S NORTH TO THE
LOWER AND MID 80S SOUTH. THIS WILL ALL BE DEPENDENT ON LOCATION
OF FRONT AND AMOUNT OF CLOUD COVER.
THAT WARM BUBBLE WILL CONTINUE TO BUILD NORTH TONIGHT...PUSHING THE
CHANCE FOR SHOWERS AND THUNDERSTORMS OUT OF OUR AREA BY 12Z MONDAY.
WINDY CONDITIONS ARE EXPECTED MONDAY...AND A WIND ADVISORY MAY BE
NEEDED. TEMPERATURES SHOULD REACH THE MID AND UPPER 80S DURING THE
AFTERNOON. LEFT A SMALL CHANCE FOR THUNDERSTORMS WEST OF HIGHWAY 81
FOR THE LATE AFTERNOON...BUT CHANCES ARE MUCH HIGHER IN THE EVENING.
00Z MODELS SHOWED THE 500 MB CLOSED LOW KICKING OUT NORTHEAST FROM
WYOMING MONDAY AND INTO SOUTHERN MANITOBA BY TUESDAY AFTERNOON. THE
COLD FRONT SHOULD BE A FOCAL POINT FOR THUNDERSTORMS BY 00Z TUESDAY
WITH 500 METER MIXED LAYER CAPE VALUES REACHING 2000-3000 J/KG. SO
SOME SEVERE STORMS APPEAR LIKELY.
AFTER THAT SYSTEM PULLS INTO SOUTHEAST CANADA...PATTERN SHOULD
FEATURE A RIDGE OVER PARTS OF THE CENTRAL AND EASTERN UNITED STATES
AND A TROUGH OVER THE FAR WEST. MADE ONLY MINOR CHANGES TO FORECAST
BEYOND TUESDAY.
MILLER
AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
THE MAIN CHALLENGE WITH THE AVIATION FORECAST WILL BE THE TIMING OF
SHOWERS AND THUNDERSTORMS. A WARM FRONT MOVING NORTH THROUGH
NEBRASKA TODAY WILL TRIGGER ADDITIONAL CONVECTIVE ACTIVITY. THERE
ARE CURRENTLY SEVERAL AREAS OF SHOWERS AND THUNDERSTORMS ON-GOING IN
THE PLAINS EARLY THIS MORNING...INCLUDING A LARGE AREA OF HEAVY RAIN
OVER NORTHEAST NEBRASKA. EXPECT THIS AREA TO GRADUALLY MOVE
NORTHEAST THIS MORNING...BUT WILL IMPACT KOFK AT LEAST THROUGH 12Z.
NEWLY DEVELOPED SHOWERS AND A FEW THUNDERSTORMS OVER NORTHEAST
KANSAS SHOULD DRIFT NORTH AND IMPACT THE KLNK AND KOMA SITES BY MID
MORNING. A FEW OF THESE STORMS COULD BE STRONG.
NIETFELD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$