FXUS63 KOAX 300836
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
336 AM CDT MON MAY 30 2011
.DISCUSSION...
THE CHANCE OF SEVERE STORMS FROM LATE THIS AFTERNOON INTO THE EARLY
MORNING HOURS OF TUESDAY IS THE PRIMARY FORECAST CONCERN. WINDS FOR
TODAY ARE A SECOND CONCERN.
WATER VAPOR IMAGERY EARLY THIS MORNING SHOWED MID LEVEL LOW PRESSURE
SYSTEM OVER IDAHO AND UTAH. 00Z 300 MB CHART SHOWED WINDS 90 KNOTS
OR MORE EXTENDING FROM SOUTHERN CALIFORNIA INTO NORTH DAKOTA. THE
STRONGEST 12 HOUR HEIGHT FALLS AT 500 MB WERE LOCATED IN THE BASE OF
THE TROUGH...WITH VALUES ESTIMATED UP TO 100 METERS. WARM 700 MB
TEMPERATURES HAD SPREAD NORTHWARD FROM THE SOUTHWESTERN UNITED
STATES AND SOUTHERN PLAINS INTO NEBRASKA AND IOWA. 850 MB DEWPOINTS
WERE IN THE TEENS IN A NARROW RIBBON FROM TEXAS UP INTO EASTERN
NEBRASKA AND WESTERN IOWA.
STRONG LOW LEVEL WINDS WILL OCCUR ACROSS THE AREA TODAY AHEAD OF A
COLD FRONT THAT WILL TAKE SHAPE TO OUR WEST THIS AFTERNOON. A WIND
ADVISORY WAS ISSUED YESTERDAY...FOR TODAY...AND THAT IS STILL ON
TRACK. DID ADJUST ADVISORY TO START JUST A LITTLE SOONER IN OUR
SOUTHERN COUNTIES. DID NOT CHANGE THE EXPIRATION TIME...BUT THE DAY
SHIFT MAY NEED TO EXTEND THE TIME FOR THE EASTERN PARTS OF THE
FORECAST AREA INTO EARLY EVENING.
THE CURRENT WARM MID LEVEL TEMPERATURES SHOULD CAP MOST IF NOT ALL
CONVECTIVE ACTIVITY IN OUR AREA UNTIL ABOUT 21Z...THEN SEVERE STORMS
SHOULD FIRE WEST OF HIGHWAY 81. 00Z RUN OF NAM12 SHOWED 500 METER
MIXED LAYER CAPE VALUES UP TO AROUND 4000 J/KG IN PARTS OF CENTRAL
AND NORTHEAST NEBRASKA BY MID AFTERNOON. CONVECTIVE INHIBITION
VALUES DECREASE TO LESS THAN 30 J/KG IN OUR FAR WESTERN COUNTIES BY
00Z. EXPECT A SQUALL LINE TO TAKE SHAPE ALONG/AHEAD OF THE FRONT.
INITIALLY...THERE SHOULD BE SOME DISCRETE SUPERCELLS...BUT TENDENCY
WILL BE FOR A LINE AFTER SEVERAL HOURS WITH BOWING SEGMENTS. APPEARS
THERE IS MODEST RISK OF TORNADOES WITH ZERO TO ONE KILOMETER SHEAR
VALUES OF OVER 35 KNOTS AND FAIRLY LOW LIFTED CONDENSATION LEVEL
HEIGHTS.
HAVE STORM CHANCES DECREASING FROM WEST TO EAST TONIGHT...AS THE
COLD FRONT AND DRIER AIR SPREAD ACROSS THE REGION. LOWS WILL DROP
INTO THE LOWER 50S IN OUR WESTERN ZONES AND RANGE TO LOWER OR MID
60S FOR LOWS IN SOUTHWEST IOWA. TUESDAY SHOULD BE A DRY DAY WITH
HIGHS IN THE UPPER 70S AND LOWER 80S. AS LOW PRESSURE STRENGTHENS
NEAR THE KANSAS/COLORADO BORDER LATE TUESDAY NIGHT AND WEDNESDAY...
MOISTURE WILL BE LIFTED NORTH OVER A WARM FRONT. A WEAK SHORTWAVE
TROUGH IS ALSO EXPECTED TO MOVE UP FROM THE SOUTHWEST. INCREASED
THUNDERSTORM CHANCES FOR WEDNESDAY A LITTLE FROM PREVIOUS FORECAST.
SHOWERS/THUNDERSTORMS MAY LINGER INTO WEDNESDAY NIGHT. MADE FEW
IF ANY CHANGES TO THE FORECAST FARTHER OUT. PATTERN SHOULD BE FOR
A TROUGH IN THE WESTERN UNITED STATES AND A RIDGE IN THE SOUTHEAST.
THIS KEEPS OUR AREA IN SOUTHWEST MID LEVEL FLOW.
MILLER
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
MAIN AVIATION CONCERNS ARE STRONG SURFACE SOUTHERLY WINDS...
LLWS...AND THEN LATE IN THE PERIOD THERE IS A CONCERN FOR STRONG TO
SEVERE THUNDERSTORMS.
SURFACE WARM FRONT HAS MOVED NORTH OF THE TAF SITES RESULTING IN
SOUTH WINDS AT ALL THREE SITES. ABOVE THE SURFACE AT AROUND 2000
FEET THERE IS A LOW LEVEL JET IN PLACE WITH WINDS OF 200 DEGREES AT
55 KNOTS ON THE FAIRBURY PROFILER. DURING THE MORNING HOURS THIS
WILL CREATE SIGNIFICANT LLWS. DURING THE AFTERNOON HOURS THESE
STRONG WINDS WILL MIX DOWN TO THE SURFACE AND RESULT IN WINDS OF
AROUND 26-30 KNOTS SUSTAINED WITH GUSTS OF 35 TO 40 KNOTS IN THE
AFTERNOON.
A STRONG COLD FRONT WILL THEN MOVE THROUGH THE AREA LATE TONIGHT
SWITCHING THE WINDS AROUND TO THE WEST BUT ALSO TRIGGERING STRONG TO
SEVERE THUNDERSTORMS. INCLUDED A PROB30 GROUP IN THE KOFK TAF AFTER
01Z AND IN THE KLNK TAF AFTER 03Z. KOMA IS FAR ENOUGH EAST THAT THE
FRONT MAY NOT MOVE THROUGH DURING THIS TAF PERIOD AND THUNDERSTORMS
MIGHT BE LATER IN THE NIGHT.
NIETFELD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM CDT THIS EVENING
FOR NEZ011-012-015>018-030>034-042>045-050>053.
WIND ADVISORY FROM 9 AM THIS MORNING TO 7 PM CDT THIS EVENING
FOR NEZ065>068-078-088>093.
IA...WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM CDT THIS EVENING
FOR IAZ043-055-056-069-079-080-090-091.
&&
$$