FXUS63 KOAX 131547
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1047 AM CDT FRI MAY 13 2011
.DISCUSSION...
UPDATED THE FORECAST TO MENTION SLIGHTLY COOLER TEMPERATURES TODAY
AS BRISK NORTHWESTERLY WINDS...COMBINED WITH CLOUD COVER THAT WILL
BE HARDPRESSED TO BREAK UP MUCH...KEEPS HIGHS IN THE LOWER TO MID
50S. ALSO ADDED SOME SPRINKLES TO THE AFTERNOON FORECAST IN NORTHEAST
NEBRASKA WHERE STEEPER LAPSE RATES EXIST AS A RESULT OF A COOL
POCKET ALFOT. ALSO ADDED SOME ISOLATED SPRINKLES TO SOUTHWEST IOWA
AND EXTREME SOUTHEAST NEBRASKA AS SYSTEM TO OUR SOUTHEAST SLOWLY
PULLS AWAY.
DEWALD
&&
.PREV DISCUSSION... /ISSUED 341 AM CDT FRI MAY 13 2011/
DISCUSSION...
EARLY MORNING WATER VAPOR IMAGERY INDICATES UPPER LEVEL LOW
PRESSURE NOW SPINNING OVER EASTERN KANSAS. THIS IS EXPECTED TO
CONTINUE TO SLOWLY PUSH OFF TO THE EAST TODAY. THE SURFACE COLD
FRONT IS THROUGH THE ENTIRE FORECAST AREA AS OF 08Z...AND LOW
LEVEL COLD AIR ADVECTION IS EXPECTED THROUGH THE DAY. DEFORMATION
BAND OF -RA ASSOCIATED WITH A PERSISTENT AREA OF MID LEVEL
FRONTOGENESIS OVER THE NORTHERN FORECAST AREA...IS EXPECTED TO
WEAKEN WHILE SHIFTING SOUTHEAST THROUGH THE MORNING. WE WILL
INCLUDE AN ISOLATED SHOWER MENTION THIS MORNING FOR THIS BAND.
OTHERWISE...A FAIRLY EXPANSIVE CLOUD DECK REMAINS UPSTREAM ACROSS
THE DAKOTAS. MODELS...ESPECIALLY THE NAM...WOULD LIKE TO SCATTER
THIS DECK OUT THIS AFTERNOON. THIS MAY BE OVER OPTIMISTIC WITH THE
COLD AIR ADVECTION EXPECTED. IF WE DO GET ANY SCATTERING WE MAY
JUST SEE THE CLOUDS FILL BACK IN WITH SC WITH COLD TEMPS ALOFT AND
STEEP LOW LEVEL LAPSE RATES WITH MIXING TO 850 MB EXPECTED. THIS
APPEARS A LITTLE LESS LIKELY IN THE NORTHWEST WHERE SOME DRIER
AIR SHOULD WORK IN.
AS WE GET INTO TONIGHT...THE UPPER LEVEL LOW OVER SOUTHERN SASK
WILL TRACK SOUTH INTO THE NORTHERN PLAINS...AND EVENTUALLY THE
CENTRAL PLAINS BY THE WEEKEND. THIS WILL BRING ADDITIONAL CLOUDS
FOR SAT/SUN AND A SLIGHT CHANCE OF SHOWERS. THIS APPEARS MOST
LIKELY FROM LATE SATURDAY INTO SATURDAY NIGHT ESPECIALLY ACROSS
THE EASTERN CWA ASSOCIATED WITH THE STRONGEST PV ADVECTION AND
COLDEST MID LEVEL TEMPERATURES. HAVE LOWERED HIGHS ON BOTH SAT AND
SUN MOST AREAS WITH A GOOD DEAL OF CLOUDS AND SOME ISOLATED
SHOWERS AROUND. THIS NEXT UPPER LEVEL LOW WILL START TO EXIT THE
AREA ON SUNDAY WITH HIGH PRESSURE BUILDING IN FOR SUNDAY NIGHT.
THIS WILL LIKELY LEAD TO A COOL NIGHT WITH TEMPERATURES POSSIBLY
DIPPING INTO THE MIDDLE 30S IN THE NORTHWEST FA. TEMPERATURES WILL
START TO RETURN TOWARD NORMAL INTO NEXT WEEK AS AN UPPER LEVEL
RIDGE BUILDS INTO AT LEAST THE HIGH PLAINS WITH DRY WEATHER
EXPECTED THRU AT LEAST WED.
BOUSTEAD
AVIATION...
TAF SITES KOFK/KOMA/KLNK
12Z TAFS
CLOSED MID TROPOSPHERIC LOW PRESSURE OVER KANSAS WILL MOVE INTO
MISSOURI TODAY AND TOWARD SOUTHERN ILLINOIS BY 12Z SATURDAY.
MEANWHILE...A SECOND MID LEVEL AREA OF LOW PRESSURE WILL ROTATE
SOUTH FROM CANADA INTO SOUTH DAKOTA DURING THE PERIOD. WITH THE
FIRST STORM SYSTEM...SOME PATCHY LIGHT RAIN WILL END THIS MORNING
WITH MVFR (LOCAL IFR) CIGS THROUGH THE MORNING. CIGS SHOULD IMPROVE
THIS AFTERNOON...HOWEVER INSTABILITY CU/SHOWERS MAY DEVELOP WITH
RESIDUAL MOISTURE...STEEP LOW LEVEL LAPSE RATES...AND TRIGGER TEMPS
IN THE UPPER 40S. THUS MVFR CIGS COULD FILL BACK IN. THESE CLOUDS
SHOULD DIMINISH THIS EVENING WITH THE LOSS OF HEATING. LOW LEVEL
MOISTURE RETURNS FRIDAY NIGHT WITH THE APPROACH OF THE NEXT STORM
SYSTEM AND SHOULD SEE MVFR CIGS AFTER 06Z TONIGHT. NORTH TO
NORTHWEST WINDS 15 TO 25KTS SUSTAINED WITH GUSTS AROUND 30KTS FOR
TODAY. THE WINDS SHOULD DECREASE TO 8-12KTS AFTER 01Z TONIGHT.
ZAPOTOCNY
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$