FXUS63 KOAX 142041
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
ISSUED BY NATIONAL WEATHER SERVICE HASTINGS NE
340 PM CDT THU JUL 14 2011
.DISCUSSION...FOCUS CENTERS ON THE UPCOMING EXTREME HEAT. THAT BEING
SAID...CHANCES FOR THUNDERSTORMS REMAIN IN THE FORECAST
TONIGHT...AND AGAIN FRIDAY/FRIDAY NIGHT. PATTERN ALOFT REVEALED THE
UPPER LEVEL RIDGE OF HIGH PRESSURE HAD EXPANDED NORTH FROM THE
SOUTHERN PLAINS INTO THE CENTRAL PLAINS TODAY...WHILE UPSTREAM...A
TROUGH WAS EVIDENT IN THE PACIFIC NORTHWEST AND ALONG THE WEST
COAST.
SUBTLE SHORTWAVES TRANSLATING AROUND THE RIDGE BY INITIATE
CONVECTION TONIGHT AND AGAIN THE SPC WRF IS THE MOST ROBUST WITH ITS
DEPICTION. LATEST SPC MESO DATA INDICATES HIGH INSTABILITY WITH
CAPES IN EXCESS OF 4000 J/KG AND CAP WEAKENING. SHEAR VALUES ARE
HIGHEST IN THE NORTH...AROUND 30KTS...AND MOISTURE IS NOT AN ISSUE
WITH SFC DPS WELL INTO THE 70S. THE NAM SUGGESTED TIMING MAY HAVE
BEEN AS EARLY AS THIS AFTN BUT WRF SUGGESTS MAINLY A NOCTURNAL
EVENT. GIVEN TRENDS SO FAR...THE LATER TIME FRAME SEEMS TO BE MORE
IN LINE CLOSER TO WRF. IF STORMS CAN GO...SEVERE STORMS ARE
POSSIBLE WITH LARGE HAIL...DAMAGING WINDS AND HEAVY RAINFALL THE
MAIN HAZARDS. HAVE CARRIED LOW POPS FOR THE CWA TONIGHT...WITH SOME
LINGERING CHCS IN THE EAST FRIDAY MORNING.
THE UPPER RIDGE AXIS CONTINUES TO BUILD ON FRIDAY AND TEMPERATURES
CONTINUE TO CLIMB. HAVE SOME CONCERNS THAT CLOUD COVER MAY HAVE
HAVE AN IMPACT ON TEMPS AND DEGREE OF HEAT ON FRIDAY. FORECAST
TEMPS ARE IN THE MID 90S OVERALL AND WITH DPS IN THE MIDDLE
70S...HEAT INDEX VALUES ARE STILL EXPECTED TO BE AROUND 105F. THE
HEAT WILL CONTINUE TO BUILD OVER THE WEEKEND AND CONTINUE INTO NEXT
WEEK AS THE CENTER OF THE RIDGE BECOMES ENTRENCHED ACROSS THE
CENTRAL PLAINS. THIS WILL LEAD TO A PROLONGED PERIOD OF HOT DAYTIME
TEMPERATURES...WITH LITTLE RELIEF AT NIGHT. HAVE WENT AHEAD WITH AN
EXCESSIVE HEAT WARNING HEADLINE BEGINNING FRIDAY AND LASTING THROUGH
MONDAY...WITH EXCESSIVE HEAT WATCH IN EFFECT FOR TUESDAY/WEDNESDAY.
THE RIDGE BEGINS TO SHIFT FARTHER SOUTH INTO THE SOUTHERN PLAINS
REGION MID TO LATE WEEK OF NEXT WEEK AND TEMPS SHLD DECREASE SOME.
FOR FRIDAY AFTN...SHORTWAVE TRANSLATING ON EDGE OF RIDGE WILL BRING
ANOTHER CHC FOR CONVECTION MAINLY FOR NORTHERN PORTIONS OF THE
CWA...WHILE WARM MID LEVEL TEMPS/STRENGTHENING CAP BEGINS TO BUILD
IN THE SW/INHIBITING CONVECTION. EXTREME INSTABILITY WILL BE
PRESENT...SHEAR MAY NEAR 30KTS IN THE FAR NORTH...BUT AGAIN IF
STORMS GO...SEVERE WEATHER POTENTIAL REMAINS IN THE EXTREME
INSTABILITY. CONVECTIVE CHCS MAY PERSIST FOR A FEW HOURS SATURDAY
MORNING IN THE NORTHEAST...THEN THE FORECAST DRIES THEREAFTER AS
RIDGE SETTLES IN.
&&
.AVIATION...MVFR CEILINGS WILL LINGER EARLY THIS AFTERNOON BUT
GRADUALLY LIFT BY MID/LATE AFTERNOON. EXPECT VISIBILITIES IN THE
OMAHA AREA TO ALSO IMPROVE ABOVE 6SM. LEFT A VICINITY THUNDERSTORM
IN THE OMAHA WITH TAIL END OF SHORT WAVE LINGER DOWN TOWARD THE
MISSOURI VALLEY ON WATER VAPOR...AND THE RUC HINTING AT SOME
LINGERING DEVELOPMENT FOR A TIME. OTHERWISE...LOOKING FOR A
PERSISTENT...MOIST SOUTHEAST FLOW TO ONCE AGAIN RESULT IN SOME LATE
NIGHT FOG/HAZE AND REDUCED VISIBILITIES THROUGHOUT EASTERN NEBRASKA
BEFORE STRONG SOUTH WINDS DEVELOP BY MIDDAY FRIDAY.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...EXCESSIVE HEAT WARNING FROM NOON FRIDAY TO 7 AM CDT TUESDAY FOR
NEZ011-012-015>018-030>034-042>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.
IA...EXCESSIVE HEAT WARNING FROM NOON FRIDAY TO 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.
&&
$$
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