Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 102321
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
621 PM CDT THU JUL 10 2014

.SHORT TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 255 PM CDT THU JUL 10 2014

SIMILAR TO YESTERDAYS RUN...MODEL AGREE LARGE SCALE FLOW OVER THE
CONUS WILL BE NEAR ZONAL HEADING INTO THIS WEEKEND WHILE A
SHORTWAVE TROF MIGRATES ACROSS WRN CANADA. OVER THE WEEKEND
THOUGH...BLOCKING PATTERN SETS UP WITH SHORTWAVE EVOLVING INTO AN
ANOMALOUS CLOSED LOW BECOMING STUCK OVER CNTRL CANADA. UPPER
PATTERN TURNS HIGHLY AMPLIFIED WITH THE CNTRL/ERN CONUS FALLING
UNDER THE INFLUENCE OF THE UPPER LOW WHILE UPSTREAM RIDGE
DEVELOPS OVER THE WRN CONUS/WRN CANADA.

MESOSCALE ANALYSIS THIS AFTN SHOWING MOISTURE AXIS EXTENDING FROM
ERN OK INTO THE WRN DAKOTAS WITH PWS ROUGHLY 1.5"-2" INCHES.
MEANWHILE OUT GULF MOISTURE ADVECTION WILL BEGIN IN EARNEST LATER
TONIGHT AS SFC HIGH PRESSURE SLIDES EAST AND ALLOWS MOISTURE TO
SLIDE UP ALONG THE WRN HIGH PLAINS. APPEARS THAT MOISTURE RICH
ENVIRONMENT WILL BE IN PLACE THEN THRU THE FCST PD.

MAIN ISSUE TO CONTEND WITH IS LOCATION OF POSSIBLE SVR STORM
DEVELOPMENT ALONG WITH POTENTIAL FOR EXCESSIVE RAINFALL SATURDAY
NIGHT.

LEADING UP STORM DEVELOPMENT...NAM/GFS/ECM ALL AGREE STOUT 310K-315K
ISENTROPIC UPGLIDE WILL COINCIDE WITH MAX OMEGA/PWS AROUND 2"
GENERALLY OVER N-CNTRL AND CNTRL NEB. EXPECT TSTM ACTIVITY TO
DEVELOP INVOF BOUNDARY LYR THETA-E CONVG. ENVIRONMENT WILL BE QUITE
UNSTABLE WITH MUCAPES AROUND 2500 J/KG ALONG WITH EFFECTIVE SHEAR
VALUES APPROACHING 60KT. IN ADDITION...MODERATE 850-250MB
DIFFERENTIAL DIVERGENCE PROGGED OVER THE REGION WILL ENHANCE
LARGE SCALE FORCING OVERNIGHT. AT THIS POINT...CANNOT TOTALLY
DISCOUNT A FEW SEVERE STORMS PENETRATING THE CWA. THUS WILL
MENTION IN UPCOMING ISSUANCE OF HWO.

FRIDAY NIGHT/SATURDAY...HEAVY RAINFALL APPEARS TO BE VERY PROBABLE
MAINLY OVER THE NRN CWA IN ASSOCIATION WITH STALLED FRONTAL BNDRY
EXTENDING ALONG THE SD/NEB BORDER. PRECIP EFFICIENCY WILL BE
FAVORABLE WITH DEEP WARM CLOUD DEPTH IN PLACE ALONG WITH PWS JUST
ABOVE 2" AND KI VALUES 40-45 COINCIDENT TO MAX OMEGA.

FRONTAL BNDRY BEGINS PUSHING SOUTH SAT EVENING WITH DRY AND
RELATIVELY COOL AIRMASS FILTERING IN ON SUNDAY.


.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 255 PM CDT THU JUL 10 2014

TOPIC OF INTEREST IN THE EXTENDED PDS IS TEMPERATURES.
DETERMINISTIC ECM/GFS AS WELL AS ECMENS/CMCENS CONTINUE TO
ADVERTISE STAGNANT LARGE SCALE FLOW WITH A HIGHLY ANOMALOUS CLOSED
UPPER LOW OVER THE ERN CONUS WITH UPSTREAM RIDGE SITUATED OVER THE
WRN CONUS. PATTERN WILL BE QUITE FAVORABLE FOR DRY/COOL AIRMASS
ENVELOPING THE CNTRL PLAINS WITH MEAN TEMPS BELOW NORMAL
PREVAILING INTO EARLY NEXT WEEK. AS A MATTER OF FACT...MORNING
LOWS MONDAY AND TUESDAY WILL BE SHOULD BE APPROACHING NEAR RECORD
VALUES.

&&

.AVIATION...(00Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 619 PM CDT THU JUL 10 2014

GENERALLY VFR CONDITIONS ARE FORECAST THROUGH FRIDAY AFTERNOON.
SHOWERS AND THUNDERSTORMS ARE POSSIBLE BETWEEN 09Z AND 16Z AT ALL
TAF SITES...HOWEVER THEY SHOULD BE RELATIVELY ISOLATED. SOME MVFR
CIGS COULD DEVELOP IN NORTHEAST NEBRASKA NEAR KOFK FOR A TIME
FRIDAY MORNING...OTHERWISE EXPECT SCATTERED TO BROKEN CLOUDS NEAR
FL050 AND SOUTH TO SOUTHEAST WINDS NEAR 12KT THROUGH THE TAF
PERIOD.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

$$

SHORT TERM...DEE
LONG TERM...DEE
AVIATION...DERGAN



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