NCEP HPC Winter Weather Desk 2005 - 2006

1. NCEP HPC Winter Weather Desk 2005 - 2006 Peter C. Manousos NCEP HPC Science & Operations Officer (peter.manousos@noaa.gov)

2. Provide quick overview of products and services Provide deadlines of activities Highlight changes from last season Take any questions Goals of Presentation

3. WWD STRATEGY Based on WFO/HPC feedback and findings during previous WWD and WWEs • Provide prelim (internal) guidance for use at WFOs • Based on GFS, Eta, and SREF • Collaborate as necessary • Routinely by 12 Planet, by phone only when requested by WFO • Finalize public (external) product suite based on prelim products and input from collaboration The collaboration process results in a deterministic forecasts from WFOs complimented with probabilistic forecasts from NCEP. The NWS provides a user what’s most likely to occur and a sense of the possibilities for a winter weather event.

4. Internal (Prelim) Set • For WFO use only • Intentionally not accessible by the public • Model Diagnostic Page • Contains model diagnostic fields used at HPC • Allows WFO and HPC to view same output during collaboration if needed • http://www.hpc.ncep.noaa.gov/mdd/mddoutput • Deterministic Graphics • 24h accumulations of snow/sleet and freezing rain to f72 • Per agreement with WR and CR, available east of 105W • http://www.hpc.ncep.noaa.gov/wwd/internal (username wwd password !!wwd!!) • Availability (notification message sent on 12 Planet) • Day 1 - 0500/1700Z • Day 2 - 0545/1745Z • Day 3 - 0615/01815Z • NOTE – RC had been submitted (July) to get these into GFE, BUT it will not occur this season due to normal RC process and TOC moratorium (no new products over SBN until after Feb 2006).

7. WWD COLLABORATION • Collaboration occurs early in forecast process • Approach is to have HPC provide big picture • HPC is used a resource on pattern evolution • WFOs use expertise to impart local details • HPC contribution during collaborating calls centers on pattern evolution – not watches/warnings • HPC also used as a vehicle to convey information not readily available in AWIPS to the forecaster (model output)

8. WWD Collaboration • WFO/HPC Collaboration windows • 0500/1700Z – 0815/2015Z (3+ hours) • Can occur outside of collaboration window as needed • Routinely via 12 Planet • HPC WWD id is hpc_wwd • Audio alarm triggers at HPC “HPC, hpc, NCEP, ncep, WWD, wwd” • Collaboration calls if needed

9. WWD Collaboration Calls • Collaboration Call Criteria (Guidelines) • Two or more adjacent WFOs impacted by same event • Pattern evolution in question (sufficient uncertainty) • 12 Planet collaboration on pattern evolution becomes inefficient • Who Initiates and Facilitates a Call • Either WFO or HPC • WFO initiated calls • Presupposes the requesting WFO coordinates with adjacent WFOs to have call • Requesting WFO suggest a start time - mutually agreeable to HPC • HPC facilitated calls (we will provide dial in and pass code info on 12 Planet) • Limited to 15 minutes • In rare instances, HPC can initiate a call during rapidly changing situations outside of collaboration windows (reference Jan 2000 event) • What to expect from HPC during a call • Focus will be on pattern evolution and how that pertains to forcing mechanisms expected to produce snow • Additional focus will be on model preference and justification • HPC will not comment on watches/warnings ! • HPC participation in WFO initiated call will end when content naturally progresses towards highlight collaboration (watch/warning)

10. WWD Collaboration • Two way street • If HPC hears nothing from WFO, it assumes the WFOs agree on graphics • If WFOs have a question about HPC graphics, send a chat message or give us a call ! • 301 763 8201

11. !!!!!!! WARNING !!!!!!! • THE INTERNAL SET OF GRAPHICS ARE NOT UPDATED AFTER COLLABORATION !!! • The effects of collaboration are imparted on the EXTERNAL (Final) set of HPC products

12. External Set • Available 0930/2130Z • AWIPS and the web at http://www.hpc.ncep.noaa.gov/wwd/winter_wx.shtml • Intended for Public consumption • Probabilistic Accumulation Graphics • Exceedance of 4”, 8”, 12” combined snow/sleet and .25” ZR accums • 24h increments out to f72 over the CONUS • Low, Moderate and High contours for each threshold • Corresponding Discussion • Low Tracks Graphic • Track of significant lows over the CONUS in 12h increments out to f72 • HPC low accompanied by suite of models low position (as a proxy to spread or uncertainty) • Experimental “pretty” version available too

14. IMPORTANT

17. Deadline Summary • 0400/1600Z • 00/12Z NAM, GFS in through f84 • 09/21SREF in through f84 • 0500/1700Z • WW Model diagnostic web page fully populated • Day 1 Prelim products available, notification sent out on 12 Planet • Collaboration Window opens • 0545/1745Z • Day 2 prelim products available, notification sent out on 12 Planet • 0615/1815Z • Day 3 prelim products available, notification sent out on 12 Planet • 0815/2015Z • Collaboration Window closed • 0930/2130Z • Public Products issued, notification sent out on 12 Planet • September 15th – May 15th (normal season)

18. Significant Changes from last season • Staggered Deadlines for preliminary graphics • Experimental “pretty” version of the low tracks graphic available to public • All references to “wwe” eliminated • Larger Model Diag images on web

19. Other WWD Activities • Internal Training (HPC) • Review of case studies from last season • Experimentation with 2 snow liquid ratio (SLR) algorithms (Cobb, Roebber) in addition to Baxter’s Climo SLR • Graphics depicting hi res grids of snow accumulation for the intermountain region • Derived from HPC QPF run through Mountain Mapper and converted to snow via Snow Liquid Ratio algorithm • 40km HPC Snow grid downscaled to 5km using PRISM data • SREF derived Winter Weather Impact Graphics • 15 member system run at 34km res 2x daily (09/21Z) to f87 • 10 Eta Members, 5 RSM (GFS run on a Eta domain) members

20. Societal Impact of Winter Events defined by more than just accumulation Duration, Timing, Intensity Conveyance of impact could be achieved through SREF derived probability graphics highlighting these attributes Distributed internally for evaluation by WFOs and NCEP Intent is to go public next season BUT NEED YOUR FEEDBACK !!!!! Prelim graphics already produced with consultation and prelim approval to proceed “internally” from BGM, BYZ, and SLC We also need to compile verification 4 Examples…. New Experimental WW Impact Graphics

21. Probability Duration of Winter Event will be at least 24 hours

26. Probability Winter Precip Rate will be at least 1”/hour

35. Probability Sfc Vis will be reduced to at least ¼ mile in Winter Precip

42. Probability of Snow Accumulation on Different Surfaces Probability of 1” or more Snow accumulation on asphalt Probability of 1” or more Snow accumulation on grass

43. QUESTIONS ? peter.manousos@noaa.gov 301 763 8000 x 7307