heavy rain event in tx/ok on 8-10 october 2011
DESCRIPTION
Heavy rain event in TX/OK on 8-10 October 2011. Show part of the event here (runs from 00z/10 October) Summary There is an explosion of reflectivity in the LAPS and STMAS forecasts right away Noticed this in other cases I have saved over the last month - PowerPoint PPT PresentationTRANSCRIPT
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Heavy rain event in TX/OK on 8-10 October 2011
• Show part of the event here (runs from 00z/10 October)• Summary
• There is an explosion of reflectivity in the LAPS and STMAS forecasts right away• Noticed this in other cases I have saved over the last month• This leads to an over-forecast of reflectivity compared to the observed fields• Not seen in the HRRR, which generally under-forecasts the reflectivity until ~2-3 h into the forecast
• 3-h total precipitation forecast comparisons• Pretty large differences seen between LAPS and STMAS, with STMAS total precip quite a bit higher than the
observed.
• Scores (did not find scores for STMAS, so compared LAPS with HRRR for HWT domain)• For 20 dBZ LAPS verifies better (higher ETS) for first 3 h, but at the expense of ~double the bias
• This goes along with the visual appearance of over-prediction of >=20 dBZ echo
• For 30 and 40 dBZ LAPS still has higher bias, but ETS is actually lower
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Runs from 00z/10 Oct 2011 - Analyses0-h Composite Reflectivity
The reflectivity scale is the same for the LAPS/STMAS runs, so there are some small differences in the
initial composite reflectivity fields.
LAPS analysis STMAS 0-h
HRRR 0-h LAPS CONUS 0-h
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Runs from 00z/10 Oct 2011-Analyses0-h Surface Reflectivity
We do see some differences in the initial surface reflectivity fields between STMAS and the LAPS CONUS run (and of course the
HRRR, which at the initial time is more representative of the 13-km
RUC scale). The NOWRAD reflectivity has a similar (but not
identical) scale to LAPS/STMAS, so a conclusion from this would be
that the 0-h model surface reflectivity is weaker than the
observed reflectivity.
STMAS analysis STMAS 0-h
HRRR 0-hLAPS CONUS 0-h
NOWRAD and observations
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Runs from 00z/10 Oct 2011
15-min Composite Reflectivity valid 0015z
The most obvious thing we see in the STMAS and LAPS forecasts is the “explosion” of reflectivity by 15-min into the forecast. In the
LAPS CONUS run it is more over KS, while in STMAS is more elongated across the entire domain. We do
NOT see this change in the observed field (LAPS Analysis), nor in the HRRR (in the HRRR starting to see “scaling” to the 3 km model
scale.
LAPS analysis STMAS
HRRR LAPS CONUS
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Runs from 00z/10 Oct 2011
15-min Surface Reflectivity valid 0015z
Differences in the surface reflectivity fields between STMAS
and the LAPS CONUS run are seen. No verification field is available for 15-min in, but do have a NOWRAD
image for 0030z (next set of slides).
STMAS
HRRR 15-min surface reflectivity not available
LAPS CONUS
NOWRAD and observations not available
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Runs from 00z/10 Oct 2011
30-min Composite Reflectivity valid 0030z
The composite reflectivity forecasts from STMAS and LAPS do not change too much between 15 min and this 30 min forecast, with somewhat more of a change for
LAPS (increase in higher level reflectivity, especially the smaller-scale cells in OK into northern TX). Comparison to the LAPS analysis indicates both would be an over-forecast, which is seen in the bias
verification (shown later).
LAPS analysis STMAS
HRRR LAPS CONUS
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Runs from 00z/10 Oct 201130-min Surface Reflectivity valid
0030z
Differences are seen in the surface reflectivity forecasts with STMAS somewhat smoother
overall. The color table in the NOWRAD is close to the model color table, and there is only a
small amount of reflectivity over 50 dBZ in the observations compared to the forecasts.
STMAS
LAPS CONUS
NOWRAD
HRRR 30-min surface reflectivity not available
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Runs from 00z/10 Oct 2011
1-h Composite Reflectivity valid 0100z
The composite reflectivity forecasts from STMAS and LAPS do not show as much increase as they
did in the first 15 min of the forecast, but compared to
verification both are still over-forecasts, while the HRRR is
somewhat under-forecast (and also still rather smooth).
LAPS analysis STMAS
HRRR LAPS CONUS
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Runs from 00z/10 Oct 2011
1-h Surface Reflectivity valid 0100z.
It is pretty clear that at the surface there is far more reflectivity (both higher-level and 20 dBZ level) than
in the observed field for both STMAS and (to a lesser extent) LAPS. The HRRR is at the other
end of the spectrum with too little forecast reflectivity.STMAS analysis STMAS
HRRR LAPS CONUS
NOWRAD and observations
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Runs from 00z/10 Oct 2011
2-h Composite Reflectivity valid 0200z
STMAS now has quite a bit more of the ~20-30 dBZ mid level echo
compared to LAPS, which is settling down more. HRRR
reflectivity area is growing and is now fairly close to the LAPS
analysis. Interesting that for LAPS and STMAS the situation is
reversed over eastern CO (LAPS more reflectivity, STMAS less).
LAPS analysis STMAS
HRRR LAPS CONUS
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Runs from 00z/10 Oct 2011
2-h Surface Reflectivity valid 0200z
Surface reflectivity comparisons are pretty similar to what we saw
for the 1-h forecasts.
LAPS analysis STMAS
HRRR LAPS CONUS
NOWRAD and observations
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Runs from 00z/10 Oct 2011
3-h Composite Reflectivity valid 0300z
STMAS now has even more of the ~20-30 dBZ mid level echo
compared to LAPS and to the observed (see arrows). LAPS still
has too much 50+ dBZ echo compared to what is seen in the analysis. The HRRR reflectivity
area now looks pretty close to the LAPS analysis.
LAPS analysis STMAS
HRRR LAPS CONUS
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Runs from 00z/10 Oct 2011
3-h Surface Reflectivity valid 0300z
Seems to be a gradual decrease in forecast reflectivity in LAPS (now maybe too little compared to the analysis?), while STMAS isn’t too
far off in area of ~20 dBZ and greater echo. HRRR area of ~20 dBZ echo is still on the low side.
LAPS analysis STMAS
HRRR LAPS CONUS
NOWRAD and observations
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Runs from 00z/10 Oct
2011-3-h Total
precipitation forecasts
ending 0300z
STMAS, which had the greatest coverage of
higher level reflectivity, ends up producing the most rainfall (quite a
bit more then the verification showed). LAPS and the HRRR
forecasts are closer to what was observed. No forecast correctly
predicted the location of the 3”+ observed
maximum near the sw LA/TX border, but LAPS and the HRRR have a
max nearby.
QPE analysisSTMAS
HRRR LAPS CONUS
1.25” max
3.00” max
2-3” max(Several in line)
2-3” max(only one, rest are 1-1.5 and a
couple of 1.5-2”)1-2” maxima(several in line)
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Bias and ETS scores: LAPS and HRRR compared (STMAS apparently not available for verification). LAPS verifies better but with higher bias (excessive coverage).
LAPS - greenHRRR - blue 20 dBZ Bias
30 dBZ Bias
40 dBZ Bias
20 dBZ ETS
Note that for the higher reflectivities the ETS score is only better for < 15 min, but the bias is still quite a bit higher for LAPS.
30 dBZ ETS
40 dBZ ETS