FXUS63 KOAX 190838
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
338 AM CDT THU MAY 19 2011
.DISCUSSION...
PRECIPITATION CHANCES THROUGH SATURDAY AND RISK OF SEVERE WEATHER
WILL BE THE PRIMARY CONCERNS FOR THIS FORECAST PACKAGE.
AT 00Z OUR LOCAL SOUNDING WAS DRY BELOW 750MB...HOWEVER SOUNDINGS
TO THE SOUTH IN KANSAS AND OKLAHOMA WERE MOIST...WITH A 15 DEG C
H850 DEWPOINT AT OKLAHOMA CITY AND PRECIPITABLE WATER OF 1.39. AT
00Z THE H50 MID TROPOSPHERIC LOW WAS CLOSED OFF OVR NW ARIZONA
INTO COLORADO. AT 08Z...A BAND OF SHOWERS AND ELEVATED THUNDERSTORMS
WERE LIFTING NORTHEAST PER THE WSR-88D MOSAIC. SOME OF THESE WERE
PRODUCING HAIL WITH A FEW WARNINGS IN KANSAS. THE SURFACE WARM
FRONT WAS WELL TO THE SOUTH IN KANSAS. A STRONG 100KT H30 JET WAS
ROUNDING THE BASE OF THE TROUGH IN ARIZONA AND PROVIDING UPPER
LEVEL DIVERGENCE INTO NEBRASKA. THE STEEP MID LEVEL LAPSE RATES
WERE NOTED OVER CENTRAL KANSAS.
THE SHORT RANGE MODELS LIFT THE MID LEVEL CLOSED LOW INTO SOUTHERN
WYOMING BY 00Z AS SURFACE LOW PRESSURE STRENGTHENS OVER EASTERN
COLORADO. ISENTROPIC LIFT ON THE 300K SURFACE WILL CONTINUE THIS
MORNING AS SHORTWAVE TROF ENERGY MOVES NORTHEAST AROUND THE MID
LEVEL LOW AND THE 30-40KT LOW LEVEL JET TRANSPORTS DEEPER MOISTURE
NORTH. EXPECT SHOWERS AND THUNDERSTORMS TO SPREAD NORTH DURING THE
MORNING HOURS. THE H7 WARM AIR ADVECTION REMAINS PERSISTENT INTO
FRIDAY. THE H85 LOW LEVEL JET WEAKENS TO 20 TO 30 KNOTS LATER THIS
MORNING...BUT INCREASES TO 40KTS AGAIN DURING THE 00-09Z PERIOD
LATER TODAY AND TONIGHT. SURFACE DEWPOINTS WILL INCREASE INTO THE
50S TODAY AND AROUND 60 IN THE SOUTH OVERNIGHT. WILL INCLUDE
HIGHEST CHC OF PRECIPITATION IN THE SOUTH THIS MORNING AND
DECREASE TO A CHANCE FARTHER NORTH. EASTERLY SFC WINDS WILL BECOME
STRONG THIS AFTERNOON AT 20 TO 30 MPH...AND REMAIN BREEZY FROM THE
SOUTHEAST TONIGHT AND FRIDAY.
THE CLOSED MID LEVEL LOW MAKES IT/S WAY NORTH BY SATURDAY MORNING
IS LOCATED OVER EASTERN MONTANA/WESTERN DAKOTAS. SURFACE LOW
PRESSURE WILL MOVE INTO CENTRAL NEBRASKA AND CENTRAL KANSAS BY
THAT TIME. WILL CARRY ON AND OFF SHOWERS AND THUNDERSTORMS
THROUGH SATURDAY MORNING THEN DECREASE TO CHANCE AND SLIGHT CHANCE
SATURDAY NIGHT AND SUNDAY. THE BEST COVERAGE OF SHOWERS APPEARS
DURING THE TONIGHT THROUGH FRIDAY NIGHT TIME PERIOD.
FOR SEVERE THUNDERSTORMS...INSTABILITY STILL APPEARS MARGINAL
TODAY...HOWEVER DEEP LAYER SHEAR IS SUFFICIENT...AND FAIRLY STRONG
TO THE WEST. THE DAY 1 STORM PREDICTION CENTER OUTLOOK HAS THE
ENTIRE AREA IN THE GENERAL THUNDER AND THE SOUTHWEST ZONE IN A
SLIGHT RISK AND THIS SEEMS REASONABLE. WITH CLOUDS...HAVE SFC
TEMPERATURES MOSTLY IN THE 70S. LATER TONIGHT INTO FRIDAY EVENING
THE INSTABILITY INCREASES MORE INTO THE 1000-2000J/KG RANGE AND
THE DEEP LAYER SHEAR IS STRONGER ...>50KTS IN THE WRN AND NRN
ZONES. THIS TIME PERIOD APPEARS TO HAVE A BETTER CHC FOR SVR
STORMS. SPC HAS THE SRN 2/3RD OF THE FORECAST AREA IN THE SLIGHT
RISK...AS THIS IS WHERE THE BETTER INSTABILITY WILL BE...BUT WILL
MENTION THE ENTIRE OUTLOOK AREA IN THE HAZARDOUS WEATHER OUTLOOK DUE
TO THE SHEAR/SUFFICIENT INSTABILITY. LOOK FOR MILDER HIGHS IN THE
70S/80S FRI-SUN.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
CONVECTION THAT WAS OVER KANSAS WEDNESDAY EVENING/EARLY THURSDAY
WILL CONTINUE LIFTING NORTH THROUGH THIS MORNING AS AN UPPER LEVEL
DISTURBANCE PIVOTS INTO SRN NEBRASKA. FOR TAF SITES ACTIVITY HAD
THE HIGHEST PROBABILITY TO REACH KLNK AND A PREVAILING GROUP WAS
FORECAST THERE. CHANCES WERE LESS SO AT KOMA WHERE A TEMPO WAS
CARRIED AND EVEN LESS AT KOFK WHERE NO MENTION WAS MADE WITH 19/06Z
TAFS. SINCE INSTABILITY/LAPSE RATES FORECAST WERE LESS OVER
NEBRASKA THAN LOCATIONS SOUTH...NO TSTM MENTION WAS MADE WITH SHOWERS
IN TAFS BUT TRENDS WILL BE MONITORED TO SEE IF TSRA WILL NEED TO BE
MENTIONED PLUS WHETHER PRECIP CHANCES WILL ALSO BE NEEDED AT KOFK.
IN ADDITION...INCREASED LOW LEVEL MOISTURE SHOULD LOWER CEILINGS
INTO MVFR CATEGORY LATER THIS MORNING/AFTERNOON AND FURTHER LOWERING
IN BOTH CIGS AND VSBYS ARE POSSIBLE THURSDAY NIGHT.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY/CHERMOK