2 pane view

2 pane gif showing rapid cloud top cooler in the southern NE Panhandle over a 20 minute period. Coincided to higher prob severe information at the time.
GLM flashes roughly doubled.


Benjamin

As a previous blog from today showed the success of the experimental NUCAPS retrieval modification in indicating the cap at LBF, this note points out a limitation of the product.  Because the algorithm always creates low levels that are well-mixed in both temperature and moisture, if the low levels are in fact not well mixed, an error will result.  Today a special 2000 UTC radiosonde launched from Rapid City, SD indicated that the low levels were well mixed in temperature, but not in water vapor:

Compare the experimental NUCAPS retrieval from around 1900 UTC:

This issue will be part of the "next steps" in the experimental NUCAPS project.

You may also notice that the surface values of temperature and mixing ratio differ quite a bit between the two profiles.  Remember, the NUCAPS retrieval is from 1900 UTC and the special radiosonde is from 2000 UTC.  Over that hour the temperature at Rapid City increased from 84 to 92 and the dewpoint decreased from 57 to 52.

Jack Dostalek

First Warning

Issued SVR for storm ahead of an outflow boundary. Was based more on storm structure. Trend of cooling tops on IR helped confidence. ProbSvr low at the time of warning.

Value of storm-top information

Forecasters working in the Rapid City, SD CWA noted some storms finally showing signs of strengthening in western Nebraska, with cores developing on radar and evident in 10.35µm channel imagery. The toggling of images below shows development of rapid cooling on the northwest end of a large mass of deep convection (Fig. 1). A forecaster noted that the satellite growth rates were N/A in ProbSevere (Fig. 2). This is because the region was already "attached" to the thick cirrus mass to its southeast. We discussed using cloud-top features, such as rapid storm-top cooling and OT detection/persistence quantitatively in ProbSevere. The forecasters noted that these features are qualitatively good indicators of storm strengthening (or weakening, when there is warming). GOES-16 data enables forecasters and researchers to see storm-top features and evolution much more clearly than before.

Fig. 1: 10.35µm brightness temperature. See the rapid cooling on the northwest end of the large cirrus mass, near the cursor arrow.

Fig. 2: ProbSevere and MRMS composite reflectivity. Note that the satellite growth rates were not discernible for this storm (N/A). 

Environment getting better for storms to develop

The environment is getting better ahead of the cold front and along and east of a low level jet bringing higher dew points into our area in Rapid City . Latest upper level divergence map from SPC indicates the upper wind flow to be favorable for storm initiation. The short wave trough is still out to the west of the area. Once it nears within the next few hours, we are expecting to have an increase on storm development activity.

NUCAPS Experimental vs. Real Sounding

Comparison of NUCAPS experimental (top) 19Z sounding for LBF area and the actual 20Z LBF sounding.

1 min imagery

Starting to see some growth in the IR images along the eastern edge of the Black Hills from 2110-2115Z, however, no reflectivity on radar yet -Lynford

Update- relectivity at 2128Z showed the first showers developing.

SWD_IR is agreat for day and night operations.

One of my go to products in the 1st two days has been the sandwich products of the IR/VIS and The SWD_IR. Really see many advantages to having this looping on me desktop during my entire shift.

NUCAPPS gridded data cut off

Comparison look for NUCAPS H7-5 lapse rate at 19z and the SPC page lapse rate. similar trends slight differences...NUCAPS on the upper picture was cut off. NUCAPS was less steep with lapse rates.

Derived CAPE shot

Look at Prob. Severe image and those storms moving into initial area of increased CAPE within hour or so.  Moisture continues to surge north into that area of the eastern NE panhandle.