Transcript Pulse Thunderstorm Operating Strategies

Pulse Thunderstorm
Operating Strategies
Mike Cammarata
NOAA/NWS Columbia, SC
Overview
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Introduction
What we look at
What we look for
An example
Climatology
 Thunderstorm days at CAE (per LCD)
– May
– June
– July
– August
6.1
9.3
12.3
9.4
 That’s at a point…we have radar ops for
predominately pulse storms on the order of
twice those numbers
 Prime time … noon through 8 pm
Pulse Storm Severe Weather Threat
 Microbursts
– Less than 4 km in outflow diameter
– Peak winds last 2-5 min at most
– Potential for F0 – F1 wind damage
– Wind shear may reduce aircraft performance
 Large Hail
– Usually 0.75 to 1.00 in
Convective Potential Analysis
 Analysis of stability and shear paramteters
 During the convective season we do this
every day at least twice per day
 Important to anticipate convective mode and
type of threat
 Factors into warning decision e.g., if
downburst threat is high, more likely to issue
warning for marginal criteria
Mesoscale Desk
 Ongoing meso analysis helps us to
anticipate convective initiation and monitor
Near Storm Environment for ongoing event
 Satellite and lightning data very important
 Look for trends
 Satellite sounder data
 ACARS data
Mesoscale Desk
http://www.orbit.nesdis.noaa.gov/smcd/opdb/aviation/mb.html
Mesoscale Desk
 http://www.orbit.nesdis.noaa.gov/smcd/opdb/aviation/mb.html
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LI
TPW
CAPE
CIN
WINDEX
Theta-e deficit SFC – 300 mb
Wet Microburst Severity Index (WMSI)
GOES Soundings
Mesoscale Desk
http://www.orbit.nesdis.noaa.gov/smcd/opdb/aviation/mb.html
Mesoscale Desk
 The Local Analysis and Prediction System
(LAPS) integrates data from virtually every
meteorological observation system into a very
high-resolution gridded framework centered on a
forecast office's domain of responsibility. Thus, the
data from local mesonetworks of surface
observing systems, Doppler radars, satellites,
wind and temperature (RASS) profilers (404 and
boundary-layer 915 MHz), radiometric profilers, as
well as aircraft are incorporated every hour into a
three-dimensional grid covering a 1040km by
1240km area.
Mesoscale Desk
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LAPS Sounding
for CAE
Mesoscale Desk
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LAPS CAPE
LAPS SFC Wind
Radar mosaic
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LAPS analyses
are available for a
variety of surface
and upper air
fields
Mesoscale Desk
SPC Web site – Composite Maps and Hourly Mesoscale Analyses
http://www.spc.noaa.gov/exper/mesoanalysis/s1/index2.html
Staffing
 Minimum requirements
– Radar operator/Warning Met
– Meso (TAF’s, NOW, SPS, ongoing convective and meso
analysis)
– Synoptic (grids, updates to public products)
– HMT (2) (NWR, NOW, SPS, LSR, Hydro)
– Coordinator
– Ham Radio Net Controller(s)
– Additional staff if widespread convection
– Sectorize if you can
– Polygon beta test site
 Verification … real time and subsequent day
What we look at
 CR/VIL Combo
– Lower values filtered (<30 dBz, <30 g/kg)
– Highlights stronger cells, cuts down on clutter
– Looping reveals trends
– Filtering can highlight outflows
 Overlay
– Lightning (look for trends)
– MSAS wind barbs (convergence)
– LAPS/MSAS LI or Cape (instability)
What we look at
 CR
 Laps wind
barbs
 Lightning
What we look at
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Good example of color
scheme highlighting
outflow boundaries
What we look at
 LRM2 (24-34kft), LRM3 (>34kft), ULR, VIL, ET
– Lower values filtered
– Look for values surpassing thresholds
– ULR can be set based on expected height of
storm or temp level e.g., -20C
What we look at
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4 Panel
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VIL
CR
LRM2
LRM3
63 dBZ > 24k ft
56 dBZ > 33k ft
What we look at
 All tilts Z/V 8 bit – monitor data as it arrives
– Elevated high reflectivity cores
– MARC signatures
– Storm top divergence
– Strong low level winds
 4-panel Displays can be used as well
What we look at
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4 Panel display shows
high reflectivity cores and
TBSS
What we look at
 RCS (used heavily)
– High reflectivity cores
– Tilt
 VCS (used by some)
– Storm Top Divergence
– Mid-level convergence
– Near ground divergence – outflow
Supercell Storm!
What we look at
 CR/VIL, LRM’s, ET’s from adjacent offices
– Different perspective
– Corroboration
– Cone of silence
What we look at
 Base Velocity 0.5
8 bit
– Look for strong low level radial velocities
– use a “compressed” 8 bit color curve to better
highlight velocities near threshold values.
– Only good within 30 nm of radar
– By the time a downburst signature shows up in
the data it may be too late for lead time
What we look at
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Base Velocity image
showing thunderstorm
downburst signature
What we look at
 Scan
– Trend Set – VIL, dBZ, dBZ ht, top, posh
– Good for prioritizing and assessing trends with
individual cells
– Filter based on VIL or dbz
What we look at
What we look at
 Satellite and observed data
– IR and VIS
– Surface obs including mesonet data
– MSAS and LAPS
 LI CAPE
 Pressure change
 Wind barbs
What we look at
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ASOS sites (yellow)
Mesonet sites (blue)
What we look for
 VIL decreases by at least 10 kg/m2 and
 Height of max reflectivity decreases by at
least 8 kft. (Storm collapse)
 POD .88 and FAR .25
– Reference … An Overview of Operational Forecasting for Wet Microbursts. William
P. Roeder 45th Weather Squadron, USAF
– http://www.wdtb.noaa.gov/workshop/psdp/
– WDTB Pulse Storm Downburst Prediction Workshop
 Use VIL … SCAN
 May be too late for lead time by the time the storm
collapses
What we look for
See 02 Aug 2002 WES Sim guide
 Relatively higher height of first echo
appearance (20-30 kft) for severe storms vs.
non-severe (10-20 kft)
 Usually maintain 50-55 dBZ closed
reflectivity contour as core descends
 Centroid of high reflectivity core above 25 kft
and top of core above 30 kft
 Old rule 55 dBZ above 30 kft
 Use RCS and/or All tilts Z/V 8 bit
What we look for
See 02 Aug 2003 WES Sim guide
 MARC signature
– 50 kt convergence in 5-11 kft AGL layer
– Convergence in or near high reflectivity core
– Works up to 90 miles from radar (Falk et al.
1998)
 Use All tilts Z/V 8 bit, VCS
What we look for
MARC signature
http://www.srh.noaa.gov/shv/Downburst_Climo.htm
What we look for
Reference Mackey 1998
http://www.wdtb.noaa.gov/workshop/psdp/index.htm
What we look for
Reference Mackey 1998
http://www.wdtb.noaa.gov/workshop/psdp/index.htm
What we look for
TBSS
What we look for
TBSS
What we look for
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4 Panel display
showing monster
TBSS and high
reflectivity core
This storm produced
baseball size hail
What we look for
CAE VIL of the Day
 Computed as part of Convective potential
analysis
 Logistic Regression equation …predictand is
the probability of large hail
 Predictors include VIL, VIL density, 500mb T,
and Totals Totals index
What we look for
CAE VIL of the Day
What we look for
 VIL Density = VIL (g/kg) / ET (kft)
 Values > 3.5 had a .9 POD at TUL
– Amburn, S. A. and P. L. Wolf, 1997: VIL density as a hail indicator. Wea. and
Forecasting, 12, 473-478.
– Greg Tipton, John DiStefano WFO Wilmington, Ohio
 Use 4 panel
VIL ET LRM2 LRM3
What we look for
From OTB now WDTB
 Storm Top Divergence
– > .75 in
– 1.75 in
– 2.50 in
– 2.75 in
– 4.00+ in
|Vout| + |Vin|
80 – 110 kt
110 – 135 kt
135 – 175 kt
175 – 225 kt
> 225 kt
 Use All tilts Z/V 8 bit, VCS
What we look for
 Height of 65 dBZ
 96% severe if above freezing level
– Gerard, A., 1998: Operational observations of Extreme Reflectivity values in
Convective Cells. Natl. Wea. Digest, 22, 3-8.
– Greg Tipton, John DiStefano WFO Wilmington, Ohio
 Very soon after getting 88D in 1994 we
noticed this to be highly reliable indicator
 Good for severe hail and/or wind
 Use RCS and/or All tilts Z/V 8 bit
Verification
 Sources
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County EM Directors
County EM Dispatch
Local Sheriff, Police, Fire depts.
Spotters
HAM net
Post Offices
Local and regional Utilities
State and local parks and marinas
Media
Churches
Phone book and Street Atlas
An Example – 17 May 2005
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Weakly sheared environment
Weak to moderate instability
Cold pool aloft with upper low over area
WBZ 9400 ft
Freezing level around 12000 ft
VIL of Day 43 g/kg
An Example – 17 May 2005
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Reflectivity
1905 GMT
Core - 17200 ft
43 dBZ
An Example – 17 May 2005
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Reflectivity
1911 GMT
Core 18500 ft
67 dBZ
TBSS
WBZ 9400 ft
An Example – 17 May 2005
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Reflectivity
1915 GMT
Core 19600 ft
68 dBZ
TBSS
An Example – 17 May 2005
 LRM 2 24-33k ft
 1905 GMT
 Nothing
An Example – 17 May 2005
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LRM 2 24-33k ft
1915 GMT
50-57 dBZ
Significant
increase in 10 min
An Example – 17 May 2005
 RCS
 1915 GMT
 65-70 dBZ
elevated core to
around 15k ft
An Example – 17 May 2005
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KCLX VIL
1905 GMT
10-15 g/kg
KCAE VIL never got
above 35 g/kg …
close to radar
An Example – 17 May 2005
 KCLX VIL
 1910 GMT
 5-10 g/kg
An Example – 17 May 2005
 KCLX VIL
 1915 GMT
 25-30 g/kg
An Example – 17 May 2005
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KCLX VIL
1920 GMT
45-50 g/kg
VIL of day was
43 g/kg
 Note that VIL
reached
highest value
about 10 mins
after other
products
An Example – 17 May 2005
 Warning was issued based on TBSS from
1911 GMT scan
 At 1930 received several reports of .88 in
hail