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Winter Weather Operations Seminar

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Title: Winter Weather Operations Seminar


1
Winter Weather Operations Seminar 2003-04
2
Winter Weather Operations Seminar
2003-04 Overview
3
Criteria for Winter Storms Warnings
Criteria for Winter Storm Warnings
SNOW 2 - 4 in 12 hour period (3 or more
verifies) 3 - 5 in 24 hour period (4 or
more verifies) SLEET 1/2 covers ground
Ice Accumulation 1/4" or more storm total
on trees or power lines or roads
Advisory Highlights SNOW now 1 entire
CWA BLACK ICE cover with an advisory
.
4
Minimum Probabilities for Winter Weather Issuances
MINIMUM Probabilities for Winter Weather
Issuances Probabilities are for hazardous
winter weather conditions developing not
precipitation probabilities
Warnings and advisories gt 60 (likelihood)
of conditions developing
Watches and "advisories may be needed" gt
50 (good chance) of conditions developing
Outlooks gt 30 (chance) of conditions
developing
5
Users Needs
What NWS RAH's Users Need
- Emergency Managers 12-18 hours lead time
(for essential winter storm preparations)
- School Officials Issuances on time
(initial decision on school closures are made
by 5 AM)
- TV media graphics Timely WSWs and AFDs
(for producing TV graphics, displaying
watches/warnings) (for communicating the
meteorology supporting winter storm issuance)
- Other forecasters Early Preliminary AFD
(for floating tentative solutions,
setting the stage)
6
Fundamental Principles Guiding RAHs Winter Storm
Issuances
Fundamental Principals Guiding RAH's Winter
Storm Issuances
  • Strive for ACCURACY
  • Provide SUFFICIENT LEAD TIME for users to
    make essential preparations
  • Resist the desire to be the "first with the
    worst
  • Do not succumb to pressure to issue excessive
    lead times when confidence is low.
  • BE ON TIME with issuances

7
Impact of False Alarms and Excessive Lead Times
Impact of False Alarms and Excessive Lead Times
False alarms diminish credibility resulting in
"second guessing" by users making decisions
Longer lead times are subject to more forecast
errors
Watch Warning Critical Success Index Lead
Time (hours) CSI 60 0.00 48
0.15 36 Source - Eastern Region 94 -01
0.30 24 watch warning verification
data 0.45 18 from the 12 original
WSFOs 0.55 12 0.60
Biggest contributor to CSI error's were from FARs
87 of the total CSI variance was explained by
FARs.
Conclusion - Improve CSI by reducing FARs -
Decrease FARs by targeting lead times adequate
for essential preparations and avoiding
excessive lead times for low confidence events.
8
Warnings and Advisories
Warnings (Advisories) Lead Time (hrs - from
onset of pcpn) Users need 12-18 High
confidence 24 GENERALLY NOT RECOMMENDED gt
24 (i.e., 36 hours)
Best Practices for Warnings and
Advisories STRIVE for 12-18, not beyond 24
Exceptions Long holiday weekends may need
longer lead times Other circumstances such as
donut hole in warning coverage
9
Watches
Users in RAH's CWA React to a Watch as a Signal
to Prepare.
Watches Lead Time (hours) RECOMMENDED 24
High confidence 36 GENERALLY NOT
RECOMMENDED gt 36 (i.e., 48 hours)
Best Practices for Watches STRIVE for 24, not
beyond 36
Exceptions Long holiday weekends may need
longer lead times Other circumstances such as
donut hole in watch coverage
10
Outlooks
Outlooks Lead Time (hours) RECOMMENDED 48
- 60 High confidence 72 GENERALLY NOT
RECOMMENDED gt 72 (i.e., days
4-7)
Best Practices for Outlooks STRIVE for 48-60,
not beyond 72
Exceptions Long holiday weekends may need
longer lead times. Other circumstances such as
donut hole in outlook coverage
11
Warnings and Advisories
  • Winter Storm Targeted If High Generally
    Not
  • Issuance Lead Time Confidence
    Recommended
  • Warnings Strive for 12-18 hours
    24 hours gt 24 hours
  • Watches Strive for 24
    36 hours gt 36 hours
  • Outlooks Strive for 48-60 hours
    72 hours gt 72 hours
  • Exceptions to the "generally not recommended time
    frame" (upper limit) include
  • Extended holiday weekends requiring longer lead
    times
  • exceptionally high confidence storms
  • (e.g., super storm of '93)
  • A "doughnut hole" pattern (i.e., RAH is
    surrounded by issuances from other offices)

12
Accuracy/Adequate Lead Time for Essential
Preparation
A good outlook affords more time for issuing a
better watch A good watch affords more time
for issuing a better warning


13
How Definitive Our Issuances Should Be
How Definitive Our Issuances Should Be
WARNINGS Definitive/quantitative ACCUMULATION
as.... range common vs
maximum widespread vs local predominant
p-type emphasized
WATCHES Qualifier POTENTIAL
for... possibly may develop depends
upon track timing uncertainty location
uncertainty p-type uncertainty
OUTLOOKS Well qualified CHANCE for... no
numbers significant snow significant
icing
14
Other Principals Guiding RAHs Winter Storm
Issuances
Other Principals Guiding RAHs Winter Storm
Issuances
Degree of forecaster confidence determines how
far in advance and how definitive our issuances
can be.
When confidence in the forecast process is low
(high) - forecast wording should be less (more)
specific - lead times can be more (less)
conservative - climatology should be more
(less) weighted
It is preferable to expand the threat area,
rather than to retract storm locations previously
included.
Conservative fields (e.g., thickness, height) are
more reliable (i.e., less run to run errors) than
fields based upon parameterization schemes (e.g.,
qpf, omega)
Thickness fields are more reliable than details
displayed in the forecast soundings
15
Other Principals Guiding RAHs Winter Storm
Issuances
Additional Principals Guiding RAHs Winter Storm
Issuances Do not downgrade winter storm warnings
while an event is unfolding or ongoing unless
there is conclusive and overwhelming evidence to
do so. There is little value in doing so since
essential preparations have already been made
Ice accumulation from freezing rain is a self
limiting process unless there is sustained low
level cold air advection to offset warming due to
latent heat release. Significant ice accumulation
will not occur without a source (typically a cold
air high to the north) of low level cold
air. For winter storm issuances and
forecasts....words are important. Predominant
p-types and their impact are not easily
communicated through the GRID displays.
Quantitative descriptions combined with
qualitative impacts such as extremely damaging
ice accumulations of up to 3/4 of an inch will
occur on trees and power lines are most
effective, but should be limited to warnings.
16
Forecast Confidence
Forecast Confidence Confidence determines how
far in advance and how definitive NWS issuances
should be.
Gauging Confidence Confidence increases with
positive answers to these factors
- NWP models consistent model to model - Models
consistent run to run (dprog/dt) - Model
initializations fits observed data well - Model
diagnostics reveal model solutions are handling
key physical processes well - Key
meteorological features are well behaved -
Model solutions and conceptual models based on
past cases are consistent - Consensus of
agreement between NCEP and other offices - Key
ingredients for the event are already in place -
Key model parameters (e.g., qpf, thickness) are
verifying well
17
Decision Maker
The decision maker
- determines forecast for the critical period
(s) - decides issuances - must stay focus on
meteorology - puts out the early AFD -
encouraged to float tentative solutions with
others on staff - usually leads coordination call
Shelter the decision maker
- have enough staff on hand to do so -
stratify forecast periods (critical vs
non-critical) - others answer the majority of
calls - others type issuances - others do
input for WWA...GFE
18
Criteria for Winter Storms Warnings
Criteria for Wind Chill Products
WIND CHILL THRESHOLDS Wind Chill Advisory
Zero to -10 degrees F triggers Wind Chill
Warning -15 to -25 degrees F
triggers Issuances are now via WSWs instead of
NPWs
19
Criteria for Winter Storms Warnings
Snowfall in Products
Days 4 to 7 CHANCE wording only e.g., chance
of snow, chance of rain or snow, chance of
ice, etc Outlook (Days 2-3) Significant winter
storm possible No specifics, just uncertainties
Watch (Late 2nd - 3rd periods) No specific
amounts in text products Text should not lock
into specific details in time and space P-types
may still be an uncertainty Amounts are given in
Grids, RDF, AFM, PFM Warning (1st to 2nd
period) Predominant p-type emphasized Specifics
now in text products Allow your ranges to
expand with the degree of uncertainty Emphasize
common widespread amounts, not just local maximum
amounts
20
WSW
  • Our most critical winter weather issuance
  • Used by the Media to create the map
  • Must be out on time, before the ZFP

21
WSW - Technical Details
  • Primary vehicle to describe the event
  • Issue, update, cancel
  • Re-issue with each forecast package
  • Expiration time is time of next issuance

22
PNS
  • Use PNSRAH (SpotLES or county listing format) to
    issue frequent, timely, and informative updates
    during winter weather events
  • snow, sleet, or ice accumulations
  • p-type changes
  • road conditions / power outages
  • changes to precipitation rates
  • development of snow bands
  • changes to the location of principal boundaries
    between precipitation types
  • (e.g, rain/snow, freezing rain/sleet)
  • Activate Skywarn spotters and include NCSU
    student volunteers (SKYWARN will go into STANDBY
    taking 1-3 hourly reports of temp, p-type and
    accumulation)
  • Keeping the public informed of real - time winter
    weather conditions as an event is in progress is
    vital to the protection of life and property and
    cited as one of our most valuable services by the
    TV media.

23
SPS
  • Winter Storm Outlook
  • Emphasize big impact changes during winter storm
    event (eg. rain changing to snow and accumulating
    rapidly, ice accumulating on most roads with
    travel becoming hazardous)
  • Can also be used to augment ZFP and NOW
    emphasizing the onset of the event or other
    special information in dangerous situations.
  • In lieu of an outlook can be used to address
    event uncertainty

24
  • Other Details of Interest
  • Update warnings every 8 hours
  • Update watches outlooks every 12 hours
  • Prioritize SPSs and PNSs
  • Additional NOWs only if time and resources
  • Do not cancel outlooks use SPS to indicate risk
    has
  • diminished.

25
Coordination Guidelines
  • Review WWE graphics as soon as they are posted
  • Early AFD get out front and paste critical
    portions into 12Planet
  • Use ISC in GFE
  • Proposed in WWA
  • Conference Call
  • Every reasonable effort to reach consensus

26
Suggested Timing
  • - Preliminary AFD 130
  • - Conference call 200
  • - Update AFD 230
  • - WSW 300

27
Winter Weather Operations Seminar
2003-04 IFPS/GFE
28
GFE Winter Weather OpsMethodology
29
GFE Winter Weather Ops Methodology
  • Start with most complicated portion first get
    it out of the way
  • Suggested wx/pop first, then work your way up
  • Consider creative division of duties among staff
  • A does all storm grids, B does pre-storm
    grids, C does post-storm grids
  • A does all wx/pop/QPF/sky grids, B and
    possibly C do all temp/wind/fire wx grids
  • Other duty-allocation methods?
  • Definitive early intra-office coordination a
    must!

30
GFE Winter Weather Ops Methodology
  • Stress accuracy for predicting predominant ptype
    by using 6-hour long grid boxes (wx, pop, qpf)
  • Shorter intervals (3-hour long grids or even
    hourly) can be used in 1st period if there is
    high confidence in
  • the forecast
  • a significant sociological impact associated with
    ptype change
  • Make sure all times of PoP boxes line up with wx
    and qpf grids otherwise youll have
    inconsistencies!

31
GFE Winter Weather Ops Methodology
  • There are a few different options for
    constructing Wx grids
  • Determine p-type corridors ahead of time,
    sketching it out on a map as weve always done,
    then manually construct PoP grids, use edit
    areas and Common Values dropdown menu or Pickup
    Value GUI to assign Wx to corridors.
  • Plus More control of Wx, with specificity
    regarding type(s) and coverage/probability.
  • Minus A lot of clicking can be confusing if
    its a long duration event with a lot of mixes
    and probabilities have to ensure a match between
    PoP and Wx.

32
GFE Winter Weather Ops Methodology
  • There are a few different options for
    constructing Wx grids
  • BostonWinterWxTool (with Wx being edited,
    right-click to bring up smart tool menu
    select). This uses several other grids,
    including thickness grids, to construct Wx based
    on the TRENDS partial thickness technique.
  • Plus Convenient in that it uses grids done
    already ensures correlation with PoP so there
    are no inconsistencies.
  • Minus Can create a huge mess of Wx (tests with
    very simple setups still yielded 10 or more areas
    with differing Wx/probability), making zone
    groupings very difficult leads to very long ZFP
    text the need for extensive postprocessing
    have to complete QPF, QPF-6hr, PoP, T, and two
    thickness grids before running busy GUI.

33
GFE Winter Weather Ops Methodology
  • There are a few different options for
    constructing Wx grids
  • All_Wx_Tool still being tested, but shows
    promise.
  • Plus Ensures correlation with PoP so there are
    no inconsistencies works by allowing you to
    choose a mix, then puts in probability of that
    mix using PoP grids.
  • Minus Still may not yield the kind of wording
    you want not very sophisticated as it doesnt
    improve much on Pickup method.

34
GFE Winter Weather Ops Methodology
  • There are a few different options for
    constructing Wx grids
  • All_Wx_Tool still being tested, but shows
    promise.
  • Plus Ensures correlation with PoP so there are
    no inconsistencies works by allowing you to
    choose a mix, then puts in probability of that
    mix using PoP grids.
  • Minus Still may not yield the kind of wording
    you want not very sophisticated as it doesnt
    improve much on Pickup method.

35
GFE Winter Weather Ops Methodology
  • Promoted approach Start with PoP

filling in using edit areas and Assign Value
(right-click on map to select)
36
GFE Winter Weather Ops Methodology
  • Make use of Select Homogeneous Area
    (right-click menu) to make edit areas

37
GFE Winter Weather Ops Methodology
  • Once you have your PoP, click on corresponding Wx
    grid, do Pickup Value, and Assign Value.

38
GFE Winter Weather Ops Methodology
  • Select Homogeneous Area on your next PoP area

39
GFE Winter Weather Ops Methodology
  • and click on Wx and Assign Value of the next
    weather selection.

40
GFE Winter Weather Ops Methodology
  • Finally, Select Homogeneous Area to make the last
    edit area

41
GFE Winter Weather Ops Methodology
  • and assign the weather mix.

42
GFE Winter Weather Ops Methodology
  • Using the pickup window may seem cumbersome with
    all of the clicking, but this will enable you to
    select a PREDOMINANT P-TYPE, with lesser chances
    of other p-types.

Make use of the Mix or Or buttons to further
refine p-type descriptions.
43
GFE Winter Weather Ops Methodology
  • You can also use the Common Values menu. With
    desired edit area selected, put the cursor on the
    color scale (top of map), right-click, and choose
    Select Common Values. Follow the dropdown menus
    until you reach your desired weather type.

44
GFE Winter Weather Ops Methodology
  • Then, to start layering p-types, you must change
    the Weather Edit Mode to Combine rather than
    Replace. Do a right-click on the map (not the
    color scale) to get to this option.

45
GFE Winter Weather Ops Methodology
  • With edit area selected (done using Select
    Homogeneous Area on the already-defined area of
    Wx) and Combine on, you can then layer, say, a
    Chc IP- atop your Def ZR-.

46
GFE Winter Weather Ops Methodology
  • With edit area selected (done using Select
    Homogeneous Area on the already-defined area of
    Wx) and Combine on, you can then layer, say, a
    Chc IP- atop your Def ZR- giving you these
    results.

47
End of GFE Winter Weather OpsMethodology
48
BostonWinterWxTool Example
  • PoP

49
BostonWinterWxTool
  • QPF

50
BostonWinterWxTool
  • 1000-850 mb
  • thickness

51
BostonWinterWxTool
  • 850-500 mb
  • thickness

52
BostonWinterWxTool
  • The GUI

53
BostonWinterWxTool
  • The resulting
  • Wx

54
BostonWinterWxTool
  • The resulting
  • Wx

55
Winter Weather Operations Seminar 2003-04 WWA
56
WWA
  • New and Improved ???

57
Changing duration will not change
product expiration
Must edit ProdExp using arrows
58
Important Edit text in AWIPS Text window
firstspell check and then copy into WWA
Descriptive or Synopsis window.
59
Important Edit text in AWIPS Text window
firstspell check and then copy into WWA
Descriptive or Synopsis window.
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WWA upgrade allows you to edit text in transmit
window
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Winter Weather Operations Seminar 2003-04 WWE
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Winter Weather Operations Seminar
2003-04 Aviation
79
Aviation Forecasting
  • Winter Weather Concerns

80
  • Reduced Visibility, Low Ceilings, and Icing are
    major factors in 70 percent of fatal accidents.

81
Icing
  • Clear FZRA, FZDZ adds significant weight,
    reduced aerodynamic performance

82
  • Rime Fog/Cloud droplets reduced aerodynamic
    performance
  • Mixed

83
Couple of Points to Keep in Mind
Most Important Portion of the TAF is the 2-6 hour
Forecast
Amendments to update for current conditions are
not forecasts. We must be alert for Amendments in
this period!
CAD does not follow diurnal cycles be sure that
the meteorological reasoning concurs with your
improving trend.
Keep it simple beyond 12 hours. Remember, the
users are required to use the lowest value in the
time period. You are not helping them out by
adding Prob/Tempo/Becmg groups, especially in the
later periods.
84
Good Bye
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