northeast/awt event from 19 oct 2011

Northeast/AWT Event from 19 Oct 2011

• Complex set up with 2 systems• One more over the Northeast that is more tropical like.• Second area of precipitation in the Ohio Valley associated with a more “standard” surface low.

• Looked at set of runs from 12z/19 October; emphasis on the first 30 minutes.• LAPS_CI, STMAS_CI, STMAS_CI_CYC and HRRR

• Some observations• LAPS_CI initial analysis was quite “hot” (reflectivity very high). • Some questions about what we should be seeing.• Very high bias for LAPS_CI• ETS “cross-over” with the HRRR is after about 30-40 minutes for this case.

Overview – NOWRAD and obs: Location of the cross-sections shown later indicated by the white line.

1200 UTC 1215 UTC

1230 UTC 1245 UTC

Overview – NOWRAD and obs: Location of the cross-sections shown later indicated by the white line.

1300 UTC 1400 UTC

1800 UTC

There are two separate systems, one is a deep surface low in Ohio that is strengthening. Lots of heavy precipitation with this but less convective then the system along the East Coast. This system is more tropical in nature with no strong surface low. Precipitation over New England is likely a result of this warm and moist air overrunning lower level cool air. The cross-section cuts through both of these areas (the cross-section is used for initial times only).

Initial fields of Composite Reflectivity

from 12z runs (compared to the LAPS analysis and NOWRAD)

LAPS and STMAS certainly begin with a better looking

reflectivity field than does the HRRR, but why is the LAPS_CI initial composite reflectivity

so “hot”?

LAPS_CI HRRR

STMAS_CI STMAS_CI_CYC

LAPS Analysis NOWRAD

15-min forecasts of Composite Reflectivity

from 12z runs (valid 1215 UTC) compared to the LAPS analysis and

NOWRAD

The behavior that has been seen is for the composite

reflectivity to rapidly increase after 0-h, and this is seen in STMAS_CI, and, to a lesser

extent, in STMAS_CI_CYC. The opposite is seen in the LAPS_CI

forecast in terms of the maximum reflectivity, but the 0-h field was much stronger

than the STMAS runs and the analysis. Note, however, that

the area of composite reflectivity does grow (too

much compared to the analysis) in both the LAPS and

STMAS runs.

LAPS_CI HRRR




from 12z runs (valid 1230 UTC) compared to the LAPS analysis and

NOWRAD

The behavior that has been seen is for the composite

reflectivity to rapidly increase after 0-h, and this is seen in STMAS_CI, and, to a lesser

extent, in STMAS_CI_CYC. The opposite is seen in the LAPS_CI

forecast in terms of the maximum reflectivity, but the 0-h field was much stronger

than the STMAS runs and the analysis. Note, however, that

the area of composite reflectivity does grow (too

much compared to the analysis) in both the LAPS and

STMAS runs.

LAPS_CI HRRR



Initial cross-section of reflectivity from 12z

runs (compared to the LAPS analysis and

NOWRAD plan view)

LAPS_CI certainly has stronger reflectivity than the STMAS

runs.

LAPS_CI HRRR


LAPS AnalysisNOWRAD


from 12z runs (compared to the LAPS analysis and NOWRAD

plan view)

Clearly the analyses are different (lower reflectivity) than the 15-min forecasts

from LAPS_CI and the STMAS runs.

LAPS_CI HRRR


LAPS AnalysisNOWRAD

Initial (0-h)Wind Divergence

from 12z runs (compared to the LAPS analysis and

NOWRAD plan view)

Comments:

LAPS_CI HRRR

STMAS_CI STMAS_CI balanced

LAPS AnalysisNOWRADLAPS Balanced Wind DIV Analysis

STMAS_CI_CYC

STMAS_CI_CYC balanced divergence

15-min forecast cross-sections of

Wind Divergence from 12z runs valid 1215z

(compared to the LAPS analysis)

Comments: why do the forecasts have so much more detail then the

analyses?

LAPS_CI HRRR


LAPS AnalysisNOWRADLAPS Balanced Wind DIV Analysis

Initial cross-section of

Wind Omega and Balanced wind omega

from 12z runs

Comments:

LAPS_CI HRRR


LAPS AnalysisNOWRADLAPS Balanced Wind Omega Analysis

STMAS_CI balanced omega

STMAS_CI_CYC balanced omega

Initial cross-section of Balanced cloud omega from 12z runs

Should they all be identical (as they are in this case)?

LAPS_CI cloud omega

NOWRAD

STMAS_CI_CYC balanced cloud omega

LAPS_CI balanced cloud omega

STMAS_CI balanced cloud omega

15-min forecast cross-sections of

Wind Omega from 12z runs valid 1215z (compared to

the LAPS analysis)

Comments

LAPS_CI HRRR


LAPS AnalysisNOWRADLAPS Balanced Wind Omega Analysis

Comparison of 1-h accumulated

precipitation forecasts from the 12z runs

I wanted to see if the greater composite reflectivity that occurs

quickly into the runs translates into more precipitation right away. It does seem to for LAPS_CI, which

started with such high reflectivity. But amounts from STMAS runs do not seem out of line compared to

the HRRR. Have not carefully compared to the observed.

LAPS_CI HRRR


QPE Analysis NOWRAD Analysis

1900 UTC

20 dBZ Bias

30 dBZ ETS

Scores for surface reflectivity: ETS and Biasewp1 = laps_ci

40 dBZ ETS

30 dBZ Bias

40 dBZ Bias

Cross-over with the HRRR occurs after only 30-40 min for this case.

20 dBZ ETS

hrrr wsm6 = stmas_ci wrf-cyc = stmas_ci _cyc

The exact match for LAPS_CI and STMAS_CI_CYC seems to indicate that this is for composite reflectivity. The “smearing” of the initial reflectivity in the HRRR from using the 13-km RUC likely gives it the higher bias at the beginning.

The increasing bias for LAPS_CI by 2-h into the forecast is consistent with what we saw in the figures.

As with 30 dBZ, the better ETS scores for LAPS_CI and STMAS_CI_CYC come at the expense of higher bias. STMAS_CI_CYC nicely comes down to little bias (matching the HRRR) before 2-h out, but LAPS_CI actually peaks at 2-h. Question- The bias behavior looks like it must be (?) surface or low-level reflectivity, since the composite really grows quickly (and too much) by 15-min.

1900 UTC

20 dBZ Bias

30 dBZ ETS

Scores for composite reflectivity: ETS and Biasewp1 = laps_ci

40 dBZ ETS

30 dBZ Bias

40 dBZ Bias

20 dBZ ETS


I’m surprised that LAPS_CI does not have a higher bias earlier?

1900 UTC

20 dBZ Bias

30 dBZ ETS

Scores for “composite2” reflectivity: ETS and Biasewp1 = laps_ci

40 dBZ ETS

30 dBZ Bias

40 dBZ Bias

What is “composite2”?

20 dBZ ETS


This looks more like we see, although why is the bias for LAPS_CI so low at 0-h?

northeast/awt event from 19 oct 2011

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