FXUS63 KOAX 151803
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
103 PM CDT FRI JUL 15 2011
.UPDATE...
UPDATED THE FORECAST EARLIER THIS MORNING TO DELAY THE EXCESSIVE
HEAT WARNING FOR PARTS OF THE FORECAST AREA. ADJUSTED SHRA/TSRA
CHANCES INTO THE AFTERNOON AND OVERNIGHT HOURS ALONG WITH CLOUDS
AND TEMPERATURES FORECASTS.
&&
.DISCUSSION...
SHOWERS AND THUNDERSTORMS...ALTHOUGH DIMINISHED CONTINUE ACROSS
PARTS OF THE CENTRAL AND NORTHERN FORECAST AREA. CLOUDS WILL
CONTINUE TO AFFECT THE AREA BY HOLDING DOWN TEMPERATURES. ADJUSTED
THE START OF THE EXCESSIVE HEAT WARNING...WAS NOT SURE HOW FAR
SOUTH THE THICKER CLOUDS WOULD BE...SO HELD ON TO IT NEAR THE
PLATTE RIVER. THE SHORTWAVE MOVING THRU MN/IA/SE NEB WILL TRY TO
RE-IGNITE TSRA THIS AFTERNOON AND TONIGHT. THE WARMING MID LEVELS
IN THE SOUTHWEST SHOULD HINDER STORM DEVELOPMENT...WITH INCREASING
CHANCE FOR STORMS IN NORTHEAST NEBRASKA AND WESTERN IOWA. ALSO
WILL HAVE TO WATCH THE EDGE OF THE CLOUD AREA WHERE INCREASED
DIFFERENTIAL HEATING WILL TAKE PLACE. H925 LLJ INCREASES
TONIGHT...SO THE CHC FOR TSRA WILL CONTINUE OVERNIGHT. SPC DOES
HAVE PARTS OF THE AREA IN A SLIGHT RISK. WITH STORMS THAT
DEVELOP...LOCALLY HEAVY RAIN WILL BE POSSIBLE.
&&
.PREV DISCUSSION... /ISSUED 325 AM CDT FRI JUL 15 2011/
DISCUSSION...
PERSISTENT HEAT AND HUMIDITY THROUGH THE MIDDLE OF NEXT WEEK ALONG
WITH SPORADIC THUNDERSTORM CHANCES INTO SATURDAY ARE THE MAIN
FORECAST CONCERNS.
UPPER RIDGE EXTENDING FROM WEST TEXAS INTO SOUTHEAST NEBRASKA THIS
MORNING WILL CONTINUE BUILDING NORTH AND NORTHWEST THROUGH SATURDAY
AND WILL REMAIN ENTRENCHED OVER OUR AREA THROUGH AT LEAST EARLY NEXT
WEEK. CURRENT STORM TRACK AROUND THE RIDGE WILL REMAIN MOSTLY WEST
AND NORTH OF EASTERN NEBRASKA...BUT WE CAN NOT RULE OUT A STRAY
STORM FROM ENTERING PARTS OF THE CWA THROUGH SATURDAY.
MID LEVEL WAVE ROTATING AROUND PERIPHERY OF RIDGE THIS MORNING WAS
SPARKING SCATTERED CONVECTION ACROSS WESTERN AND PARTS OF CENTRAL
NEBRASKA. MORE ISOLATED SHOWERS WERE NOTED IN NORTHWEST KANSAS. ALL
THIS ACTIVITY WAS DRIFTING MAINLY NORTH NORTHEAST SUGGESTING IT WILL
STAY WEST OF OUR AREA. HOWEVER AXIS OF MOST UNSTABLE CAPE EXTENDED
FROM EASTERN SOUTH DAKOTA INTO OUR NORTHWEST CWA AS PER SPC
MESOANALYSIS PAGE. STORMS HAVE INTENSIFIED A BIT OVER THE LAST
HOUR...AND WILL BE MOVING INTO MORE UNSTABLE AIR. SO EXPECT ACTIVITY
TO CONTINUE THROUGH MID MORNING. SOME STORMS MAY WORK EAST INTO
NORTHEAST NEBRASKA...SO HAVE INCLUDED MORNING POPS THERE.
A SIMILAR SCENARIO IS POSSIBLE TONIGHT WITH STORMS SKIRTING OUR FAR
NORTHWEST COUNTIES. HOWEVER BOTH NAM AND GFS DEVELOP AN AREA OF
CONVECTION IN CENTRAL OR SOUTH CENTRAL NEBRASKA AFTER MIDNIGHT AND
MOVE IT THROUGH THE CWA SATURDAY MORNING. AM GOING TO IGNORE THIS
FOR NOW AS DEVELOPMENT IN RIDGE AXIS IS UNLIKELY...BUT IT IS
SOMETHING TO WATCH AND BE AWARE OF AS IT WILL HAVE AN AFFECT ON
TEMPERATURES SATURDAY.
SPEAKING OF TEMPERATURES...IT SEEMS PRETTY CERTAIN WE WILL HAVE
SEVERAL DAYS OF HIGHS EASILY INTO THE MID AND UPPER 90S ALONG WITH
HIGH HUMIDITY. UPPER RIDGE WILL SUPPRESS AFTERNOON CLOUDS/STORMS
THIS AFTERNOON THROUGH AT LEAST MONDAY...AND MOST LIKELY TUESDAY AND
WEDNESDAY BEFORE A BREAKDOWN IN THE RIDGE OCCURS AS A WAVE MOVES
THROUGH THE NORTHERN PLAINS. DEW POINTS WERE ALREADY IN THE LOW TO
MID 70S IN THE CWA THIS MORNING...AND MODELS ONLY INCREASE THOSE
THIS WEEKEND. EVAPOTRANSPIRATION FROM AREA CROPS WILL ALSO HELP
BOOST DEW POINTS LOCALLY. AFTERNOON MIXING MAY DRIVE DEW POINTS DOWN
FROM TIME TO TIME...ESPECIALLY MONDAY THROUGH WEDNESDAY...BUT
TEMPERATURES WILL RESPOND UPWARD AS A RESULT. SO RUNNING HEAT INDEX
COMPUTATIONS YIELDS 105 TO 112 VALUES FROM THIS AFTERNOON THROUGH
EARLY NEXT WEEK. OVERNIGHT LOWS IN THE MID TO UPPER 70S WITH HIGH
HUMIDITY WILL NOT PROVIDE RELIEF FROM THE HEAT. SO OUR CURRENT
EXCESSIVE HEAT WARNING THROUGH MONDAY WILL REMAIN INTACT...WITH A
WATCH STILL IN EFFECT TUESDAY AND WEDNESDAY.
REALLY NO MAJOR CHANGES FROM GOING FORECAST.
DERGAN
AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
VFR CIGS ASSOCIATED WITH CONVECTION OVER CENTRAL NEBRASKA EXPECTED
TO CONTINUE TO GRADUALLY SPREAD EAST THROUGH 12Z. PATCHY IFR OR MVFR
CIGS AND VSBYS POSSIBLE PRIOR TO 12Z AS CLEAR SKIES AND LIGHT WINDS
ALLOW SURFACE LAYER TO APPROACH SATURATION. MODELS SUGGEST SOME
POTENTIAL FOR CONVECTION LATE AFTERNOON BUT WILL LEAVE OUT AT THIS
TIME DUE TO UNCERTAINTY IN TIMING AND STRENGTH OF MID LEVEL WAVE
INDICATED BY MODELS.
FOBERT
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...EXCESSIVE HEAT WARNING UNTIL 7 AM CDT TUESDAY FOR NEZ034-044-045-
050>053-065>068-078-088>093.
EXCESSIVE HEAT WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY
EVENING FOR NEZ011-012-015>018-030>034-042>045-050>053-
065>068-078-088>093.
EXCESSIVE HEAT WARNING FROM 1 PM SATURDAY TO 7 AM CDT TUESDAY
FOR NEZ011-012-015>018-030>033-042-043.
IA...EXCESSIVE HEAT WARNING UNTIL 7 AM CDT TUESDAY FOR IAZ043-055-056-
069-079-080-090-091.
EXCESSIVE HEAT WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY
EVENING FOR IAZ043-055-056-069-079-080-090-091.
&&
$$
ZAPOTOCNY