northeast/awt widespread rains from 7 dec 2011 slow-moving surface low eventually accelerated...

Northeast/AWT Widespread rains from 7 Dec 2011

• Slow-moving surface low eventually accelerated through the Northeast • Some heavy rainfall, particularly after 18z and 00z/8 Dec

• Looked at set of runs from 12z/7 Dec and 18z/7 Dec.• And precipitation only from 00z/8 Dec• LAPS_CI, STMAS_CI, STMAS_CI_CYC and HRRR• So far have assembled the 12z/7 Dec comparisons

• Some observations• See notes on the slides• For this case the HRRR seems to catch up quickly.

• LAPS and STMAS configurations• LAPS_CI = ewp1 is the LAPS initialized WRF run• STMAS_CI = wsm6 is STMAS initialized new version of WRF run testing ingest of STMAS vertical omega• STMAS_CI_CYC = a standard STMAS run using an older version of WRF

Initial fields of Composite Reflectivity

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

LAPS and STMAS are pretty much identical and at the initial time have far more

detail then the initial HRRR composite reflectivity.

LAPS_CI HRRR

STMAS_CI STMAS_CI_CYC

LAPS Analysis NOWRAD

Initial fields of Surface Reflectivity

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

LAPS and STMAS are pretty much identical at the surface as well. Interesting structure in the HRRR; not sure what it

means!

LAPS_CI HRRR



Initial fields of 700 mb Wind

Divergence from 12z runs (compared to the

LAPS analyses)

There is a lot of “convective-scale” detail in both STMAS

initial fields. Is this to be expected?

LAPS_CI HRRR


LAPS Analysis - Divergence LAPS Analysis – Balanced Divergence

Initial fields of 700 mb Wind Omega

from 12z runs (compared to the LAPS

analyses)

Nothing really at time 0-h.

LAPS_CI HRRR


LAPS Analysis - Omega LAPS Analysis – Balanced Wind Omega

15-min forecast of Composite Reflectivity

from 12z runs valid 1215z (compared to

the LAPS analysis and NOWRAD)

Not sure this qualifies as a “reflectivity burst”, but

certainly there is an increase over the initial time in the

LAPS and STMAS forecasts.

LAPS_CI HRRR



15-min forecast of Surface Reflectivity from 12z runs valid 1215z (compared to

the LAPS analysis and NOWRAD)

At the surface the LAPS and STMAS forecasts are both quite close and appear to

verify pretty well. There is not much difference between LAPS

and the STMAS forecasts.

LAPS_CI HRRR



15-min forecast of 700 mb Wind


LAPS analyses) valid 1215z

There remains a lot of “convective-scale” detail in both

STMAS initial fields.

LAPS_CI HRRR



15-min forecast of 700 mb Wind Omega

from 12z runs (compared to the LAPS analyses) valid 1215z

More detail in both STMAS initial fields.

LAPS_CI HRRR



60-min forecast of Composite Reflectivity

from 12z runs valid 1300z (compared to the

LAPS analysis and NOWRAD)

The white arrows point to the 2 areas of the strongest observed composite reflectivity; central

PA, extreme southern NJ, south of Cape Cod, and most of WV.

All the models forecast the strongest reflectivity somewhat

displaced from where it is observed at least for some of

the 4 areas of stronger reflectivity. The HRRR has

developed stronger reflectivity on the eastern side of its

reflectivity forecast, and not so much back in WV and PA. The 2

STMAS forecasts may come closest to the PA and WV areas,

and are pretty close to each other. The character of the LAPS

forecast is quite different from STMAS, which has more detail.

LAPS_CI HRRR



60-min forecast of Surface Reflectivity from

12z runs valid 1300z (compared to the LAPS analysis and NOWRAD)

There are some interesting differences in the forecasts. The strongest surface reflectivity in

the LAPS analysis and NOWRAD extends from central PA to

south-central NY, and all the forecasts miss this area,

especially the HRRR. But the HRRR has not trouble forming a strong line of cells from about

DC to south of Cape Cod, which turns out to be an over-

prediction of the echo intensity in these areas.

LAPS_CI HRRR



60-min forecast of 700 mb Wind


LAPS analyses) valid 1300z

There are some differences between STMAS_CI and

STMAS_CI_CYC.

LAPS_CI HRRR



60-min forecast of 700 mb Wind Omega

from 12z runs (compared to the LAPS analyses) valid 1300z

Different detail in the more banded HRRR (off the coast).

LAPS_CI missing

HRRR



Comparison of 1-h accumulated

precipitation forecasts from the 12z runs for

period ending 13z

I was unsure of the amount of precipitation falling from NJ to south of Cape Cod, but the QPE

analysis shows areas of 0.2-0.4”, and the HRRR captures this zone of precip best. There is a broader area of precipitation from LAPS_CI into

NY that is not seen in the other runs, and is spotty in this area in the verification. Another area of locally heavier observed precip is in south-central PA with 0.2-0.4” observed.

The STMAS runs have the most forecast for this area (although still

only 0.05-0.10”). It seems the bottom line from this comparison is

that the HRRR is quickly able to produce heavier rains from a

narrow band of convection just off the coast, while the other runs do not handle this well. This area of

precipitation was in more of a warmer air mass than the other

precip farther inland.

LAPS_CI HRRR


QPE Analysis NOWRAD Analysis at 13z

3-h forecast of Composite Reflectivity

from 12z runs valid 1500z (compared to the

LAPS analysis and NOWRAD)

The white arrows point to some of the areas of higher reflectivity in the LAPS analysis. The yellow arrows show the leading edge

of what looks like a line feature that forms in the STMAS runs.

Do not see though any evidence of this feature in the analyses. LAPS_CI is the only forecast to

shift the higher reflectivities into eastern New England.

LAPS_CI HRRR



3-h forecast of Surface Reflectivity from

12z runs valid 1500z (compared to the LAPS analysis and NOWRAD)

Qualitatively it would be hard to say that the HRRR forecast is

not at least a little better than the others at this point.

LAPS_CI HRRR



Comparison of 3-h accumulated precipitation forecasts from the 12z runs for period ending 15z

Note that the scale is different for the forecasts in order to get the 3-h total precipitation. Some things to note include:1) LAPS has the most precip into New England.2) HRRR still has the most precip, with a max of 1-2” from NJ to south of Cape Cod. Observed in this area is in the 0.2-0.4” range with a few maxima of 0.4-0.6”. While the LAPS and STMAS runs have much less in this area they really miss this max.3) All the runs have a pretty good northern edge to the precip area.4) The STMAS and LAPS forecasts for se PA area are somewhat more than observed.

LAPS_CI HRRR



Comparison of 6-h accumulated precipitation forecasts from the 12z runs for period ending 18z

The scale is the same as in the previous slide. Things to note include:1) Now we see some bigger differences between STMAS_CI and STMAS_CI_CYC. 2) LAPS still has the most precip into New England, and this looks good.3) The max forecast values are in the 1-2” range in each model forecast, with the greatest area in this range in the HRRR and STMAS_CI_CYC forecasts. The observations show max values generally in the 0.4-0.6” range, except a small area up to 1” in WV. So the more area of predictions in the higher range the greater the over-prediction.

LAPS_CI HRRR



20 dBZ Bias 20 dBZ ETS

30 dBZ Bias

40 dBZ Bias

30 dBZ ETS

40 dBZ ETS

northeast/awt widespread rains from 7 dec 2011 slow-moving surface low eventually accelerated...

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