Probably IOP starting 5 PM CDT for SC/SE Nebraska into SW Iowa.  Highest probability of interesting weather expected during max heating time, just south of nearly stationary frontal boundary.  SBCAPE 2000-3000 J/kg and around 30-35 kts of shear should make for some severe storms. Not expecting discrete supercells; bowing segments and possibly some embedded supercells.  Primarily a hail and wind threat.

Schedule:

Now-2:30 PM:  WDSS-II Training—Bill, Pete, Veronica
2:45-3:30 PM:  PAR Training—Bill, Pete, Veronica
3:30-4:00 PM:  Multiradar/Multisensor—Bill, Pete Veronica
4:15-5:00 PM:  CASA Training—Bill, Pete, Veronica
5:00-9:00 PM:  IOP–Bill, Pete, Veronica

Liz Quoetone and Paul Schlatter (EWP Weekly Coordinators, 1-5 June 2009)

After yesterday’s successful real-time IOP, Issues with data latency and dependency became a problem once again today.  The CASA archive event proceeded as planned, while the Florida IOP team of Rob and Mike moved onto a shorter CASA data survey (not a simulated warning operation).  Now, at 4:30 pm CDT, we have moved all 4 forecasters to a brand new LMA archive event.  This is the first time that this case will have been presented to forecasters.  We will break for dinner following this event, and then return at 6:30 pm CDT for PAR and CASA archive events to round out the evening.

Patrick Burke (EWP Weekly Coordinator, 18-22 May 2009)

Mike and Rob have stepped into warning operations in the Tampa Bay CWA.  A line of training cells is oriented SSE to NNW across the CWA.  Individual cells have maintained some identity.  CAPE is relatively large, so the environment is not tropical throughout the column, but tropical moisture is in place at low levels.  The 0-1km shear is modeled at 10 to 15 knots throughout the central and southern peninsula, increasing to the north of a quasi-stationary front that is north of Tampa Bay.

Patrick Burke (EWP Weekly Coordinator, 18-22 May 2009)

Mike and Matthew passed their severe storm off to Rob and Les when it crossed our arbitrary sector boundary at the longitude of KLNX.  Rob and Les have continued warnings, and there was some debate as to what hail size should be mentioned in the new warning.  The radar presentation had become quite impressive around 8 pm CDT.  MESH indicated 2.88 inch diameter hail.  Les argued for baseball size hail in the warning.  Arthur and Patrick argued for something closer to 2 inch, based on reports (phone calls from the HWT and Local Storm Reports from CYS and LBF) throughout the evening that have been consistently lower than the MESH values.  The reports have also indicated very heavy rain.  The storm does not have a very impressive mid level mesocyclone, and Les agreed that was a good reason to undercut MESH in the warning.  Rob issued the warning, mentioning golf balls.  The largest hail reported today has been 1 inch.

Patrick Burke (EWP Weekly Coordinator, 18-22 May 2009)

The storm of greatest interest continues to be this north-south elongated cell that is straddling the frontal zone as it moves east toward the KLNX radar.  The updrafts have remained near but just behind the leading edge of outflow.  The outflow boundary is overtaking the cold front, and a more notable fine line that represents outflow from other cells farther northeast.  The forecasters have seen one or two small circulations form and dissipate at the boundary intersections.  There is some debate as to whether the high LCLs would allow for non-supercell tornadoes in this situation.  Mike and Matthew have continue to issue severe thunderstorm warnings for this cell.  Other cells to the east have remained non-severe in Les and Rob’s opinions, though they would continue Special Weather Statements.

Patrick Burke (EWP Weekly Coordinator, 18-22 May 2009)

Rob has been looking at the Legacy Hail Algorithm on AWIPS to compare with the experimental products.  He discovered that the locally run Legacy Algorithm is not synced to updated environmental data.  The update time is labeled as several years ago.  So that will need to be corrected in the future.

Patrick Burke (EWP Weekly Coordinator, 18-22 May 2009)

Matthew and Mike note that for MESH the associated color tables are slightly different between Google Earth and AWIPS.  These need to be the same to avoid confusion about product times, and help the forecasters to “trust” the data on both platforms.

Patrick Burke (EWP Weekly Coordinator, 18-22 May 2009)

Our teams are working in the North Platte CWA.  They have sectorized, with Matthew and Mike taking storms west of the longitude of the radar, and Rob and Les taking those to the east.  Matthew/Mike have issued one warning, using base data in conjunction with MESH, POSH, and max height of 50 dbZ.  Their cell is elongated and straddling the east to west oriented fontal zone.  Rob and Les have observed numerous microbursts near the radar.  They feel the storms are not severe, but if they had the option – they would issue a Special Weather Statement.

Patrick Burke (EWP Weekly Coordinator, 18-22 May 2009)

Mike and Matthew would very much like to see a MRMS product depicting the max height of the 60 dbZ echo to use in concert with or in place of the 50 dbZ echo product.

Patrick Burke (EWP Weekly Coordinator, 18-22 May 2009)

The cells in far NW Nebraska have weakened.  Other multicell storms were located west of North Platte, and satellite showed some vertical development to the congestus located all along the stalled front in north central Nebraska.  We have relocalized the workstations, and will begin to simulate warning operations in the North Platte, NE, County Warning Area.

Patrick Burke (EWP Weekly Coordinator, 18-22 May 2009)