STORM2K

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 640
NWS STORM PREDICTION CENTER NORMAN OK
300 PM CDT THU JUL 15 2004


THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF


EASTERN NEBRASKA
SOUTHEAST SOUTH DAKOTA


EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 300 PM UNTIL
900 PM CDT.


TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.


THE TORNADO WATCH AREA IS ALONG AND 65 STATUTE MILES EAST AND WEST
OF A LINE FROM 50 MILES NORTH NORTHWEST OF YANKTON SOUTH DAKOTA TO
25 MILES SOUTH SOUTHEAST OF GRAND ISLAND NEBRASKA.


REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA.
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.


OTHER WATCH INFORMATION...CONTINUE...WW 639...


DISCUSSION...SEVERE THUNDERSTORMS WILL RAPIDLY DEVELOP NEAR
INTERSECTION OF SURFACE TROUGH AND CONVECTIVE OUTFLOW BOUNDARY NEAR
SD/NEB BORDER IN NWRN PORTION OF WATCH. WITH EXTREMELY UNSTABLE
AIRMASS AND 40-50 KT OF SHEAR...CONDITIONS FAVORABLE FOR TORNADIC
SUPERCELLS AND VERY LARGE HAIL. STORMS SHOULD DEVELOP SE/S ACROSS
ERN NEB.


AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600.
MEAN STORM MOTION VECTOR 34030.

Notive the towers going up west of sioux city and east of scottsbluff or North of North Platte

Yep, very explosive atmosphere.

Extremely amazed about how quick the skies cleared in my area this afternoon after that first small batch of showers and storms came through. Cleared up at 2pm, MD out, and a watch an hour later.

It's a great Set-up. Stay safe Brian.

The Low level flow is backing around from South at the SFC to westerly around 850H as evidenced on the VWP out of Neligh NB with SB CAPE of nearly 5000 J/kg over the region, below lowest 6km vertical shear of 30-45 KT.

All of those paramaters in combination with one another support tornado-producing supercells.

the LBF 88-D has already deteced a mesocyclone (rotation) and VIL of 90 Kg/m^2 with one of those cells which have just fired up.

Looks like Minnesota wants in on some this action too!!
WW may be issued in next hour

MESOSCALE DISCUSSION 1695
NWS STORM PREDICTION CENTER NORMAN OK
0541 PM CDT THU JUL 15 2004

AREAS AFFECTED...ERN SD INTO CNTRL/SRN MN

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 152241Z - 160015Z

POTENTIAL FOR ORGANIZED SEVERE TSTMS APPEARS TO BE INCREASING ACROSS
THE AREA AND A WW MAY BE REQUIRED.

STORMS HAVE INCREASED IN COVERAGE AND INTENSITY OVER THE PAST HOUR
OR SO FROM PORTIONS OF ERN ND INTO CNTRL MN /NE OF AXN/ AHEAD OF
SHORTWAVE TROUGH DIVING SEWD THROUGH NRN MN. THOUGH DOWNSTREAM
AIRMASS ACROSS MUCH OF CNTRL/SRN MN IS ONLY WEAKLY TO MODERATELY
UNSTABLE WITH MLCAPES OF 500-1000 J/KG...CURRENT WOOD LAKE PROFILER
SUGGESTS THAT AS STORMS CONTINUE TO MOVE S...INFLOW SOURCE REGION
WILL LIKELY BE MORE STRONGLY UNSTABLE AIRMASS IN PLACE ACROSS ERN SD
WHERE MLCAPES HAVE INCREASED TO AROUND 2500 J/KG. ADDITIONALLY...
THIS PROFILER INDICATES RELATIVELY LONG HODOGRAPH WITH 0-6KM SHEAR
OF 50-55KTS. IF STORMS CAN TAP AFOREMENTIONED STRONGER AIRMASS OVER
ERN SD...DEGREE OF SHEAR WILL SUPPORT SUPERCELLS WITH LARGE HAIL AND
DAMAGING WINDS.

STORMS MAY ATTEMPT TO CONGEAL INTO FORWARD-PROPAGATING MCS THIS
EVENING AND TONIGHT WITH WWD DEVELOPMENT POSSIBLE INTO STRONGER CAP
OVER ERN SD. CONVECTIVE TRENDS WILL BE MONITORED AND A WW MAY BE
REQUIRED WITHIN THE HOUR.

..MEAD.. 07/15/2004


ATTN...WFO...DLH...ARX...MPX...FGF...FSD...ABR...

46219789 46109300 43529303 43589783

B-U-S-T in Minnesota well it looks to be that way once they issued the severe thunderstorm watch no storms developed and the 1's that were developed weakened!!! NWS screws it up again

At least in the Greater Omaha metro area, no severe wewather either. However, just off to the northwest, things were quite active.

I would not rule out a renegade severe storm later tonight, but nothing widespread enough to require a watch.

On the Tornado Watch that was issued for Nebraska/southeast South Dakota, it looks like they were smart NOT to replace it. They were talking that it was likely to be replaced earlier, but the storms have pretty much poopered out.