Presentation on theme: "Challenges Related to Ground Blizzards and Potential Solutions through an IWT Process Jeff Makowski, Thomas Grafenauer, Dave Kellenbenz, Greg Gust National."— Presentation transcript:
Challenges Related to Ground Blizzards and Potential Solutions through an IWT Process Jeff Makowski, Thomas Grafenauer, Dave Kellenbenz, Greg Gust National Weather Service – Grand Forks Northern Plains Winter Storm Conference October 14, 2014
Brief review of local blizzard climatology and blizzards. Forecast challenges associated with last winter’s blizzards. Development of informal integrated warning team (IWT) with area stakeholders. Preliminary results from IWT meetings.
Sustained winds or frequent gusts of 35 mph occurring in combination with considerable falling and/or blowing snow and visibilities reduced to less than one- quarter mile for a period of at least three hours. Pembina, ND Jan 26, 2014 Many of this past winter’s blizzards occurred in the absence of much falling snow
Average 2-3 blizzards/yr
Topography Open, elevated terrain Open, flat terrain More sheltered and tree- covered Red River Valley
Dec 28, 2013 Jan 3, 2014 Jan 16, 2014 Jan 22, 2014 Jan 26, 2014 Feb 13, 2014 Feb 26, 2014 Mar 5, 2014 Mar 21, 2014 Mar 31, 2014 Colorado Low Arctic Front Alberta Clipper South Wind Event
Visible satellite – 1932 Z Mar 31 Snowfall totals
Little falling snow, but snow pack that can be blown. Often occur with Arctic fronts/Clipper systems. Local climatology suggests mixed layer winds of at least kts, on average, for blizzard conditions. Strong low-level cold advection, surface pressure rise maximum, along valley unidirectional (northerly boundary layer winds) flow aid in realizing stronger winds at the surface. Presence of low-level instability (steep lapse rates) can promote snow shower development and aid in momentum transfer of stronger winds to the surface.
925 mb winds, wind speeds (fills) and MSLP at 00z Dec 29 New snow: 0-2”
925 mb winds, 925 mb temperature advection (fills), and MSLP at 00z Dec 29
KMVX – 0749Z 16 Jan 2014 MSAS surface temp. advection (fills), MSLP, 3-hr pressure changes and METARS at 08Z Jan ” snow the prior day
Obtaining ground blizzard conditions dependent upon: Wind speed (can directly forecast Temperature wind/temperature) State of the snow pack (more difficult to assess) Given the lack of significant falling snow, these parameters affect how low visibility gets and whether blizzard conditions develop. Very difficult in some cases to predict with much lead time whether visibility will fall to < ¼ mile.
Wind speed – several mph can make a large difference on how much snow is able to be blown. Temperature – affects the state of the snow pack and nature of any falling snow. How fast does existing snow pack respond to rapidly falling temperatures behind a strong front or to warming temperatures? Snow age – how thick of a crust is on the snow pack and will wind speeds be great enough to break the crust? Falling snow – convective snow showers often can exacerbate conditions.
Terrain: Widely varying conditions between open/rural areas and forested/urban/sheltered areas. Duration: In absence of much falling snow, how long will blizzard conditions persist? Coverage: Isolated to scattered areas of poor visibility vs. widespread blizzard conditions. Time of day: Can affect degree of impact to people and commerce.
Only a portion of warned area affected by blizzard conditions
-Dec 28, 2013: Strength of winds; warm temperatures beforehand and whether existing snow would blow, with little falling snow. -Jan 22, 2014: Strength and placement of strongest winds with little falling snow. -Feb 13, 2014: Strength and placement of strongest winds; expected short duration; scattered coverage; variable snow amounts beforehand; during AM commute. -Feb 26, 2014: Scattered coverage and expected short duration; open-country vs sheltered areas; little falling snow. -Mar 5, 2014: Strength of winds, warming temperatures; amount of snow to blow; open-country vs. sheltered areas; how much new snow? -Mar 21, 2014: Low coverage and expected short duration; warm temperatures beforehand.
Some inconsistencies in handling events from shift to shift (Winter Weather Advisory vs. Blizzard Warning). While impacts often were often less severe and more variable (sheltered vs. open) for the ground blizzards, impacts were significant for those areas affected, with sometimes rapid onset. More sheltered areas/cities often were less affected, and communicating this scenario often proved challenging. Decided to meet with key stakeholders to get a better sense of blizzard impacts and how to serve customers better, leading to initial development of an integrated warning team (IWT).
NOW: Meeting with key stakeholders at venues of opportunity. Emergency managers Department of transportation Education officials Engineers/public works Law enforcement Goal: Forge relationships to gain a better understanding of how blizzards impact operations and what information is needed so we can better serve our partner agencies and the public.
Not meant as outreach, but rather information gathering. Typically we present at planned meetings for various groups. We give a very brief presentation (10-15 minutes). Describe the challenges of the winter season. Tell them a little bit about the NWS. Initiate discussion: How does a blizzard affect your operations? What lead times for blizzards are critical?
LATER: Find volunteers from the participating groups to engage in a more directed IWT process. The plan is as follows: FGF Blizzard IWT concept... Summer/Fall/Winter canvas key stakeholders and solicit volunteers. -- this is being done at venues of opportunity; short discussion at their meetings. Winter form Blizzard Team representatives from above; discuss electronically and explore details. Spring plan for one day IWT meeting with expanded representative pool and public input. Summer continue Blizzard IWT Team process. Fall/Winter enact experimental solutions. We hope to get some more distinct partnership and buy-in through this process.
For marginal type events (i.e. isolated to scattered areas of persistent blizzard conditions, or blizzard conditions for a brief duration), an in between product would be good. Blizzard Warnings have significant impacts – should not be overused. In the product text, specificity with details is important. Most important information is timing (beginning, ending), severity, and duration. Partners value other extra information, such as webinars.
A winter weather (or blizzard) severity index? For the Public? – NO We do not want people in adverse conditions (i.e. a “low end” blizzard may be treated like an advisory). A blizzard is a blizzard, no matter the severity of the expected impacts. For the Decision Makers? – Yes IBW tags and/or preparedness/action statements based on the expected severity would help awareness for planning purposes. Our partners (decision makers) appreciate the extra information that we can provide. Forecast information is collected from a variety of sources (NWS, media, private, internet), and confidence increases for partner agencies as these sources come into agreement.
Near Term IBW-type tags for blizzard severity alone, or all winter weather headlines? Develop preparedness and impact statements based on the expected storm severity. Arrange the text bullets with the most important information (timing, severity, duration), and train staff on how to write these bullets. Develop an in between product for marginal blizzard (blowing snow) events. The best solution may be to develop a local winter storm warning special (i.e. a winter storm warning for blowing snow).
Longer Term Outreach for new warning statements (so that the decision makers know what to look for, and how to utilize the imbedded information). Polygon warnings for blizzards? Develop an application that displays current conditions for external customers (i.e. bulletin board display). Similarly, develop quick links that we can tweet that will arm the public with better information. Develop an internal blizzard (or winter storm) severity index. This severity index would serve two purposes: 1) determine which preparedness/action statements and IBW tags to place in the product text, and 2) provide guidance to the operational forecaster for shift to shift consistency.