Western California Dan Tomaso Tyler Roys amp Brian Clavier HPC Analysis Monday 26 12z Forecast Concerns Timing Forecast Concerns Timing Forecast Concerns TerrainPType Forecast Concerns Previous Day ID: 574958
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Slide1
February 6, 2012 Verification
Western California
Dan Tomaso, Tyler Roys,
& Brian ClavierSlide2
HPC Analysis, Monday 2/6 12zSlide3
Forecast Concerns- TimingSlide4
Forecast Concerns- TimingSlide5
Forecast Concerns- Terrain/P-TypeSlide6
Forecast Concerns- Previous Day
Warming due to compression with easterly, downsloping winds, Plot valid 2/5 2343zSlide7
FORECAST PERIOD BEGINS!Slide8
Forecast Concerns- High Wind Potential
Will 850 mb winds mix to the surface?850 mb
observations valid at 2/6 12zSlide9
Forecast Concerns- Freeze Possibility?
Plot valid 2/6 1243z
<= 32°F for 3 hours
is need for Freeze/Frost to verifySlide10
Forecast Concerns- 2/6 12z
Easterly winds at the onset?Slide11
HPC Analysis, Monday 2/6 12zSlide12
HPC Analysis, Tuesday 2/7 00zSlide13
HPC Analysis, Tuesday 2/7 12zSlide14
Regional Radar- 2/7 0201zSlide15
Regional Radar- 2/7 0800zSlide16
Regional Radar- 2/7 1159zSlide17
Eliminating Categories
“All-zero categories”All winter precipitation events (Categories 1-11)Used Redding observations and other cold sites to rule these out. Temperatures increased through our period.
Also used NOHRSC database:Slide18
Eliminating Categories
No snow=no blowing & drifting snow (Cat. 15)No blowing dust reports (Cat. 14)No smoke reported in ASOS/AWOS obs. (Cat. 16)Note: We did read through every ASOS/AWOS ob.
Visibilities from reports > 0.5 mile (No to Cat. 17)
Wind chill and extreme chill ruled out from coldest sites and wind chill chart (Cat. 18 & Cat. 19)
Flood categories (Cat. 21-24) ruled out via ASOS/AWOS
obs
and
Mesonet
obs
found at
http://www.wrh.noaa.gov/sgx/gmap/index.phpSlide19
Eliminating Categories
Lightning (Cat. 25) ruled out based on PSU eWall lightning data (next slide)Thunderstorm and severe thunderstorm (Cat. 26 & 27) ruled out based on ASOS/AWOS reports and lack of lightningSlide20Slide21
Verifying High Winds/Severe Winds
Checked each ASOS/AWOS ob in our zonesExample:KSNS 071153Z AUTO 11031G38KT 10SM FEW120 16/01 A2973 RMK AO2
PK WND 11038/1153
SLP077 60000 T01610006 10178 20150 58015 TSNO
Also used max wind reports from NWS
Mesonet
Checked data quality by using surrounding reportsSlide22
High Wind Verification
Zones 1-4, 505, 508, 510, 512, 513, 517, 518, 528Slide23
Severe Wind Verification
Zones 1 and 510Gusts exceeded 50 knotsSlide24
Verifying Temperatures
Again ASOS/AWOS, Mesonet reports were used.Every zone examined in this waySlide25
Freeze Verification
Zones 4 & 15
Highest elevation sites
P-type again was not an issue as warm air pushed temperatures above freezingSlide26
Temperature ≥ 68°F VerificationSlide27
Temperature ≥ 68°F Verification
Zones 1, 3, 508, 510-511, 513-518, and 528
Easterly winds the culprit!Slide28
Verifying Precip
Used ASOS/AWOS and Mesonet reportsDifferent format for Mesonet reports:
http://www.cnrfc.noaa.gov/google_precip.php
Radar imagery (as seen before)
Radar estimated rainfall:
http://water.weather.gov/precip/Slide29
Mesonet ReportsSlide30
Precipitation Ending 2/7 12zSlide31
≥0.25” Precip
Verification
Zones 2, 17, 18, 63, 64, 76, 505-507, 510Slide32
3 hours of Precip Verification
Same zones verified as ≥0.25” precip category
Zones 2, 17, 18, 63, 64, 76, 505-507, 510
Used radar, ASOS/AWOS, and
mesonet
reportsSlide33
Verification Summary
No zones verified for Cat. 1-11, 14-19, & 21-27Zones that verified for high winds: 1-4, 505, 508, 510, 512, 513, 517, 518, 528Zones that verified for severe winds: 1 & 510Zones that verified for freeze/frost: 4 &
15
Zones that verified for T
≥ 68°F:
1, 3, 508, 510-511, 513-518, and 528
Zones that verified for
Precip
. Total
≥0.25” and 3 hours of
precip
:
2, 17, 18, 63, 64, 76, 505-507, 510
Slide34
Lessons Learned
Beware of downsloping winds!Timing of precip- GFS more on target than NAMProgression of storm system faster over water?
Look at observations first while forecasting
Leads to “
gimme
” points
Overlay terrain map on zone map, where is terrain an issue?
For verifying out west:
Mesonet
data!