FXUS63 KOAX 280830
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
330 AM CDT SAT MAY 28 2011
.DISCUSSION...
TEMPERATURES AND THE CHANCE FOR THUNDERSTORMS...SOME OF WHICH MAY BE
SEVERE...ARE THE MAIN FORECAST CONCERNS OVER THE NEXT FEW DAYS.
UPPER AIR CHARTS FROM 00Z SHOWED THE FOLLOWING. AT 300 MB...STRONG
JETSTREAM WINDS WERE NOTED FROM THE PACIFIC EASTWARD INTO THE
CENTRAL PLAINS WITH VALUES 100-140 KNOTS. AT 500 MB...MAIN AREA OF
HEIGHT FALLS EXTENDED FROM OUR AREA NORTHWARD INTO THE DAKOTAS AND
MINNESOTA. FAIRLY TIGHT BAROCLINIC ZONE NOTED UNDER THE JET. 700 MB
TEMPERATURES OF 12-16 DEGREES CELSIUS WERE NOTED ACROSS ARIZONA...
NEW MEXICO AND TEXAS. AT 850 MB...MOIST AXIS STRETCHED FROM TEXAS
UP INTO EASTERN KANSAS AND SOUTHWEST MISSOURI. WATER VAPOR LOOP
EARLY THIS MORNING SHOWED THAT A MID TROPOSPHERIC TROUGH WAS
STARTING TO DIG ALONG THE WEST COAST OF THE UNITED STATES...ABOUT
AS EXPECTED. SURFACE CHART AT 08Z SHOWED LOW PRESSURE CENTERS OVER
SOUTHEAST SASKATCHEWAN AND OVER THE TEXAS PANHANDLE. PRESSURE
GRADIENT IN OUR AREA WAS FAIRLY WEAK AND THUS WINDS WERE LIGHT.
RADARS SHOWED ISOLATED TO SCATTERED LIGHT SHOWERS MOVING EAST ACROSS
THE AREA...WHICH APPEARED TO BE MAINLY ASSOCIATED WITH SOME MID
LEVEL FRONTOGENESIS. WILL KEEP SOME MENTION OF SHOWERS FOR MUCH OF
THE AREA TODAY INTO EARLY AFTERNOON. LOOK FOR HIGHS TODAY MOSTLY
FROM AROUND 70 TO 75...GENERALLY CLOSE TO GFS GUIDANCE.
00Z MODELS WERE IN DECENT AGREEMENT THAT A CLOSED LOW AT 500 MB
WILL MOVE INTO NORTHERN CALIFORNIA TONIGHT. LOW PRESSURE OVER
TEXAS SHOULD MOVE INTO SOUTHWEST KANSAS BY 12Z SUNDAY. EXPECT
SHOWERS AND THUNDERSTORMS TO DEVELOP OVER OUR AREA...ESPECIALLY
AFTER MIDNIGHT AS LOW LEVEL JET AND ISENTROPIC LIFT INCREASE.
THERE APPEARS TO BE A SMALL CHANCE FOR SEVERE STORMS WITH HAIL
OVERNIGHT. OUR MID LEVEL FLOW WILL TURN FROM WEST TO SOUTHWEST
AND THE WARM FRONT TO OUR SOUTH SHOULD TRY TO LIFT UP INTO
SOUTHEAST NEBRASKA AND SOUTHWEST IOWA. TEMPERATURES SOUTH OF
THE FRONT WILL LIKELY REACH INTO THE 80S...WITH A SHARP CUTOFF
AND COOLER TEMPERATURES TO THE NORTH. THERE IS POTENTIAL FOR A
BIG BUST IN HIGHS SUNDAY. RIGHT NOW...HAVE HIGHS INTO THE 80S
NEAR THE KANSAS AND MISSOURI BORDERS...BUT ONLY IN THE 60S FOR
OUR ABOUT THE NORTHERN HALF OF THE FORECAST AREA. IT APPEARS
THAT THE FRONT WILL CONTINUE TO LIFT NORTH SUNDAY NIGHT...WITH
ISOLATED SEVERE STORMS POSSIBLE ACROSS NORTHEAST NEBRASKA. TO
THE SOUTH...THE MID LEVELS SHOULD BECOME WARM ENOUGH TO CAP
MOST OR ALL THUNDERSTORM ACTIVITY. DID INCLUDE A SLIGHT CHANCE
SUNDAY EVENING FOR OUR SOUTHERN ZONES. IT APPEARS THAT HAIL
WOULD AGAIN BE THE MAIN THREAT ACROSS NORTHEAST NEBRASKA...
BUT STRONG OUTFLOW WINDS ALSO APPEAR POSSIBLE. RIGHT NOW...
MONDAY LOOKS BREEZY AND WARM WITH HIGHS 85 TO 90. STORMS WILL
PROBABLY HOLD OFF UNTIL EVENING WHEN COLD FRONT MOVES IN FROM
THE WEST...BUT DID USE A BLEND OF 00Z ECMWF AND 00Z GFS MONDAY
AFTERNOON. GFS SUGGESTS STORMS COULD DEVELOP WEST OF HIGHWAY
81 BUT LATE AFTERNOON. SEVERE STORMS SEEM LIKE A GOOD BET FOR
MONDAY EVENING ACROSS MUCH OF THE AREA.
TUESDAY SHOULD BE A DRY DAY...BUT THERE SHOULD BE SOME CHANCES
LATER IN THE WEEK AS A SUMMERTIME RING OF FIRE TYPE PATTERN
DEVELOPS AROUND THE STRONG 500 MB HIGH CENTER ACROSS THE
SOUTHERN PLAINS. HIGHS WEDNESDAY THROUGH FRIDAY SHOULD BE IN
THE MID 80S TO LOWER 90S.
MILLER
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
CHALLENGING AVIATION FORECASTS THIS MORNING WITH HIGH VARIABILITY IN
CLOUD HEIGHTS AS WELL AS VISIBILITIES. THE PERSISTENT SOUTHERLY
FLOW AT THE SURFACE HAS TRANSPORTED ENOUGH MOISTURE INTO THE LOWER
LEVELS TO RESULT IN AREAS OF FOG AND IFR CIGS EARLY THIS MORNING.
MULTIPLE CLOUD LAYERS ARE PRESENT AS THE JET STREAM CONTINUES TO
PUSH MID AND HIGH LEVEL MOISTURE INTO THE REGION FROM THE WEST.
SCATTERED LIGHT SHOWERS HAVE DEVELOPED IN THE MOIST AIRMASS...
ALTHOUGH INSTABILITY APPEARS TO BE TOO WEAK TO SUPPORT STRONG
UPDRAFTS AND/OR THUNDERSTORMS.
THROUGHOUT THE DAY...THE MODEL GUIDANCE SUGGESTS THE CIGS WILL
IMPROVE TO VFR CONDITIONS BUT THE MODEL GUIDANCE HAS NOT REPRESENTED
THE CURRENT CONDITIONS WELL. GIVEN THE HIGH RELATIVE HUMIDITY AND
LACK OF A SIGNIFICANT CHANGE TO THE AIRMASS...THE TAF FORECASTS ARE
MORE PESSIMISTIC WITH IMPROVING CONDITIONS. WITH DAYTIME WARMING OF
THE LOW LEVELS THERE SHOULD INDEED BE AN OVERALL IMPROVEMENT AND WE
EXPECT MOSTLY MVFR TO VFR CONDITIONS...HOWEVER OUR CONFIDENCE IN THE
TIMING OF THIS IMPROVEMENT IS LOW.
NIETFELD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$