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

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

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

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

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

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

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

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

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

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

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

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

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

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)

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