Events went from 95 to 150, then down and then up to 235 or so over about 20 minutes. Report of 0.50" hail in people sparse area about 20 minutes after first increase...and coinciding with 2nd increase in events.
Monday, June 26, 2017
GLM Flash Increase
Comment early on about GLM event increases picking up on quickly intensifying convection, also the pulse nature.
Events went from 95 to 150, then down and then up to 235 or so over about 20 minutes. Report of 0.50" hail in people sparse area about 20 minutes after first increase...and coinciding with 2nd increase in events.
Events went from 95 to 150, then down and then up to 235 or so over about 20 minutes. Report of 0.50" hail in people sparse area about 20 minutes after first increase...and coinciding with 2nd increase in events.
Warning 2
Due to severe prob heads up and the appearance of a well pronounced TBSS from the Hastings radar issued a warning for severe hail. 2 LSR confirm hail, interesting that the lightning data would not indicate very vigorous updrafts even with high dbz values.
NWP fields in ProbSevere
A conversation with a forecaster working in the Goodland, KS CWA yielded some good points about the NWP fields in ProbSevere. ProbSevere currently uses data derived from the Rapid Refresh (RAP). ProbSevere uses several analysis/forecast hours to do a 'compositing' for most fields, usually taking the maximum over that time, followed by a spatial smoothing. It uses the F-01, F00, F01, F02, and F03 fields (i.e., the previous analysis, 'current' analysis, and the 1, 2, and 3 hour forecast fields). In this way, when new data arrives, it is 'centered' on the 1-hour forecast time. This is because RAP data typically has about a 1-hour latency from the analysis time. This temporal compositing and spatial smoothing help mitigate timing/placement errors of features or gradients in the NWP data.
The forecaster noted that it might be a good idea to put analysis time in the ProbSevere readout, so forecasters know how old the data are. This would also help inform forecasters if there was a jump in the probabilities, they could discern if it was just new NWP data being incorporated, or if the jump was from changes in the observed radar, satellite growth rates, or total lightning fields. We also discussed the advantages of grouping all the NWP fields together in the readout.
The forecaster noted that it might be a good idea to put analysis time in the ProbSevere readout, so forecasters know how old the data are. This would also help inform forecasters if there was a jump in the probabilities, they could discern if it was just new NWP data being incorporated, or if the jump was from changes in the observed radar, satellite growth rates, or total lightning fields. We also discussed the advantages of grouping all the NWP fields together in the readout.
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| A severe storm in western Kansas, with hail reports of at least 1.75" diameter. |
Goodland Kansas Discussion
Morning fog has given way to full sunshine leading to CAPE values now in the 2500 plus range. AT the same time a front is sliding down from the north. The cu field is starting to show development back in eastern Colorado and South Nebraska. As the afternoon progresses storms should fire along the boundary and drift south. Main threats appear to be large hail and damaging straight line winds with stronger updrafts into he evening.
Pendleton Area Forecast Discussion for this afternoon and evening June 26, 2017
Water vapor imagery shows an upper level short wave axis across the Pacific northwest just to the west of northwest California and the southwest part of Oregon state. The upper short wave axis is forecast to move to the northeast this afternoon and evening. Surface observations show a nicely warm up on going early this afternoon with temperatures in the mid 90s. Areas to the northwest and southeast of Pendleton are experiencing convention where a differential airmass resides. With more heating expected within the next few hours in combination with increasing CAPE values based on GFS forecast sounding in addition to an increased of simulated HiRes models ref data, expect strong to severe storms to develop quickly in the next few hours. There is a potential for severe large hail and thunderstorm damaging wind gusts mainly from central to northeast of the state of Oregon.
Wait for it!
Wait for it!
Diff H20V image
Note on the color scheme of image below...kinda like it. Maybe its something new but the the shortwave/vort type energy on west edge of convection in southern OR shows up fairly well.
June 26: PDT PM Forecast Thoughts
Forecast Thoughts for Pendleton CWFA this afternoon/early evening
Combination of elements coming together for active afternoon of thunderstorms across especially the central and eastern part of the forecast area. Small but strongish upper low off the southwest coast set to move into northern CA area by the overnight hours. Already seeing high based convection in the over southeast 1/4 of forecast area with nose of H25 jet. We have seen an increase in lightning activity the last 60-75 minutes. RGB satellite H2O vapor products show nicely the lead wave out from the upper low as it triggers the current high based convection. Satellite derived winds suggest slightly less speed aloft than NAM12 forecast, but not much as the storms encounter favorable upper diffluence with time. Steep mid-lapse rates atop moderate instability (temps in mid 90s/dewpoints mid 50s), especially at lower elevations, will be fuel for expected storm development in the 20-22Z time. Once more development begins, coverage should rapidly increase. Forecast soundings suggest main hazard will be localized severe wind gusts with forecast inverted-V soundings and 40-50 T-TD spreads. Some marginal hail risk possible as well.
Watching closely the northwest forecast the next hour or so as storms in Yakima county continue to slide northeast and hold together with lightning still steady but a bit up and down. The DPI lifted index suggests this may hold together long with lower LIs...which coincides with 90 degree surface temperatures and dewpoints in the middle 50s in eastern Yakima county.
Few images showing LIs lowering near storms in northwest CWFA.
Combination of elements coming together for active afternoon of thunderstorms across especially the central and eastern part of the forecast area. Small but strongish upper low off the southwest coast set to move into northern CA area by the overnight hours. Already seeing high based convection in the over southeast 1/4 of forecast area with nose of H25 jet. We have seen an increase in lightning activity the last 60-75 minutes. RGB satellite H2O vapor products show nicely the lead wave out from the upper low as it triggers the current high based convection. Satellite derived winds suggest slightly less speed aloft than NAM12 forecast, but not much as the storms encounter favorable upper diffluence with time. Steep mid-lapse rates atop moderate instability (temps in mid 90s/dewpoints mid 50s), especially at lower elevations, will be fuel for expected storm development in the 20-22Z time. Once more development begins, coverage should rapidly increase. Forecast soundings suggest main hazard will be localized severe wind gusts with forecast inverted-V soundings and 40-50 T-TD spreads. Some marginal hail risk possible as well.
Watching closely the northwest forecast the next hour or so as storms in Yakima county continue to slide northeast and hold together with lightning still steady but a bit up and down. The DPI lifted index suggests this may hold together long with lower LIs...which coincides with 90 degree surface temperatures and dewpoints in the middle 50s in eastern Yakima county.
Few images showing LIs lowering near storms in northwest CWFA.
Using SPC Meso-analysis reveals favorable environment for storm development. CAPES in the 1500-2000 J/kg range.Over the GLD CWA and surrounding counties expect storms in southern Nebraska to move southeast into the forecast area, most likely along the outflow boundary that was approaching from eastern Kansas and from the isolated thunderstorms just developing in eastern Colorado. Looked at the RGB in which the color curve highlights the lower level clouds in southeast Kansas to southern Missouri(magenta in lower right image). Too much cloud development by this time for 10.33-12.33 to show any moisture convergence not already seen in the visible.
EWP Week 2 Day 1 Operations, Feedback
For the first day of the EWP Spring Experiment Week Two, participants are operating in the Pendleton, OR and Goodland, KS CWAs.
-Holly Obermeier
GOES-16 ABI Imagery and products
- · Imagery/Derived/Channel Differences/RGB Composites
o
Really key during storm initiation, to notice if
some towers were really going to “take off” or not
o
Amazing to see updrafts forming…but have to
remember there are a lot of frames in 12 minutes of data…load more frames for
more temporal length, takes some getting used to
o
Great to see gradients
o
Liked the day convection, it worked well in the
Pacific NW
o
Liked to color scheme of the differential water
vapor…it showed the pieces of energy and could easily see the dry air on the
edge of the forcing
o
Felt CAPE compared the GFS forecast soundings
did pretty well…but sometimes there was too much data missing due to cloud cover
- · GLM
o
All like the interpolated data…pixels look too
big otherwise
o
Would like to draw a box on the map and pull the
lightning numbers from that specific spot
- · NUCAPS
o
Like to be able to see the environmental
profiles from the morning to the afternoon
-Holly Obermeier
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