FXUS63 KOAX 272054
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
353 PM CDT FRI MAY 27 2011
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT.
STOUT UPPER JET WAS REACHING ACROSS THE INTER-MOUNTAIN WEST WAS
KEEPING FLOW ZONAL OVER THE WRN/CNTRL STATES WITH AN ELONGATED
VORTICITY CHANNEL STRADDLING THE U.S./CANADIAN BORDER. AT THE SFC...
LOW PRESSURE REFLECTION WAS SITUATED OVER ND/CANADIAN BORDER WITH A
TROF EXTENDING DOWN THRU THE DAKOTAS INTO CNTRL NEB. MODELS
INDICATING NEAR ZONAL FLOW WILL TRANSITION TONIGHT TO MORE MERIDIONAL
PATTERN OVER THE PLAINS EARLY NEXT WEAK IN RESPONSE TO STRONG UPPER
LEVEL CLOSED LOW DIGGING DOWN THE WRN CONUS AND BOTTOMING OUT NEAR
THE 4 CORNERS REGION. MAIN CONCERN AT THIS POINT IS POTENTIAL SEVERE
WEATHER LATE AFTN SUNDAY AS WELL AS MONDAY. DECENT MODEL AGREEMENT
WITH SFC CYCLOGENESIS TAKING PLACE IN ERN CO SUNDAY AFTN WITH STOUT
SFC BNDRY EXTENDING EWD TO NRN IL. IMPRESSIVE DESTABILIZATION TAKES
PLACE WITH INFLUX OF LLVL MOIST AND DAYTIME HEATING THAT PUSH MUCAPES
AROUND 4000 J/KG...LI -6 TO -8. HOWEVER...CONVECTION MAY BE LIMITED
AS BOTH THE NAM/GFS SHOW 700MB TEMPS 13C-14C...MLCINH 200-400 J/KG
RANGE...AS WELL AS NIL IMPULSES MOVING THRU TO HELP ERODE CAP. WITH
THIS IN MIND WILL GO WITH LOW END POPS...BUT THINK ITS REASONABLE TO
MENTION POSSIBLE SEVERE. ON MONDAY BUILDING HGTS OVER THE PLAINS WILL
HELP SHOVE THE BNDRY INTO THE DAKOTAS/MN...HOWEVER COLD FRONT ALONG
THE HIGH PLAINS WILL QUICKLY SWEEP EAST THRU THE CNTRL PLAINS AND
BRING ANOTHER CHANCE FOR SEVERE STORMS. AGAIN THOUGH...ENVIRONMENT IS
QUITE UNSTABLE BUT CAPPING IS STRONG AS WELL LEADING UP TO FROPA.
POSSIBLE THOUGH THAT IMPULSE ROTATING AROUND CLOSE UPPER LIFTING
ACROSS THE NRN ROCKIES WILL THIS TIME HELP GET SEVERE STORMS GOING.
.LONG TERM...TUESDAY THROUGH FRIDAY.
MODELS CONSISTENT LAST SEVERAL RUNS ADVERTISING A COLD FRONT PUSHING
INTO THE CNTRL PLAINS LATE MONDAY...THEN STALLING JUST SOUTH OF THE
CWA BY TUESDAY EVENING DUE TO RETROGRADING UPPER LEVEL DOME OF HIGH
PRESSURE. SFC HIGH SITUATED OVER THE SERN STATES WILL MAINTAIN MOIST
RETURN FLOW OVER THE PLAINS WITH PLENTY OF GULF MOISTURE POOLING ON
SOUTH SIDE OF STALLED BNDRY. WILL MAINTAIN CHANCE POPS WITH FROPA
THRU CWA MONDAY NIGHT...BUT GO DRY TUESDAY THRU WED AS BNDRY
REMAINS STALLED SOUTH OF THE CWA OVER KS/MO. GFS/ECM DIFFERING ON
EVENTUAL POSITION OF STALLED FRONT. ECM SHOVES IT INTO THE DAKOTAS
TUESDAY NIGHT THEN BACK SOUTH ACROSS NEB/IA WED AFTN. GFS ON THE
OTHER HAND LIFTS THE FRONT INTO SD WED EVENING. TO COVER THE
DIFFERENCE...WILL RELUCTANTLY ADD TOKEN 20 POPS TO WED NIGHT PD. HIGH
PRESSURE DOME REACHES THE SRN PLAINS DAY 6/7...THUS SEE LITTLE TO
INDICATE ANY PCPN DEVELOPMENT OVER THE CNTRL PLAINS.
DEE
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
AN UPPER LEVEL DISTURBANCE TRACKING ACROSS THE EASTERN DAKOTAS INTO
NCNTRL NEBRASKA AT 27/18Z WILL PUSH A SURFACE TROUGH ACROSS EASTERN
NEBRASKA THROUGH THIS EVENING...ALTHOUGH IT WILL LIKELY WEAKEN AS IT
DOES. ALTHOUGH FIRST BATCH OF SHOWERS MAINLY ASSOCIATED WITH WARM
ADVECTION AHEAD OF THE SYSTEM HAD PUSHED OUT OF NEBRASKA...
ADDITIONAL SHOWERS WILL LIKELY CONTINUE DEVELOPING OVER THE REGION
INTO EARLY EVENING AS SYSTEM TRACKS EAST. OTHER THAN INCLUDING A
FEW HOUR PD OF SHOWERS AT KOFK THROUGH 27/20Z...WITH 18Z ISSUANCE IT
APPEARED BETTER CHANCES WERE NORTH OR NORTHEAST OF TAF SITES SO NO
OTHER MENTION WAS MADE. HOWEVER...CONDITIONS WILL HAVE TO BE
WATCHED CLOSELY FOR DEVELOPMENT FARTHER SW. CONVERGENCE ALONG THE
TROUGH...SOME INCREASE IN LOW LEVEL MOISTURE...AND HEATING HAS
DRIVEN LOW CLOUD DEVELOPMENT AND CIGS HAD EVEN DROPPED INTO IFR
CATEGORY AT KOFK. WOULD SUSPECT CIGS SHOULD GENERALLY BE IN MVFR
CATEGORY THROUGH 28/00Z UNTIL WEAKENING TROUGH AND WANING HEATING
ALLOWS LOWER CLOUDS TO PUSH E OF TAF SITES.
CHERMOK
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$