So, it can be refreshing to see when NUCAPS data agree with model data, but I’m often more interested in those cases where there are differences, and potentially important differences.  Notice in the images below the comparisons between NUCAPS 850-500 mb lapse rates and various model data.

Notice the relatively large differences that stretch SW to NE from central W VA into New England.  Taking a look at nearby radar imagery, it’s clear why this area had significantly lower lapse rate values in the NUCAPS data than the models; a line of showers and thunderstorms were present along this path of lower values that was displayed in the NUCAPS gridded data (Image 2).

Of course, the NUCAPS retrievals certainly would have been affected by this area of denser clouds and precipitation.  Nevertheless, lapse rates would be affected (lowered) by the convection in those locations, which is depicted in the NUCAPS data only.  So, the lack of this feature in the models would then affect their forecast in this region going forward.  It will be interesting to see the NUCAP-Forecast data in this type of scenario.  In fact, one of the forecasters here is taking a look.  Anyway, let’s imagine a scenario where this convection had dissipated and left behind a boundary or gradient in temperature/moisture.  The detection of these types of boundaries, that often occur in pulse type convective events especially, can be important for predicting where convection will take place subsequently.

Oh…one more thing, it was interesting to notice the quick air mass recovery and advection of steep lapse rates and instability behind the area of convection in the OH Valley.  So, given ample forcing, further convective development is possible even behind this line.  In fact, the NUCAPS indicates lapse rates ~7 C/km across a broad area on the edge of the swath in the OH Valley.

-Kris W

The air mass in the CTP CWA has been modified somewhat based on earlier convection. Here’s a NUCAPS sounding from central PA (note that it was yellow, meaning it IR retrieval failed due to clouds, but the microwave was successful).

Notice the low level CAP, as well as the modest mid level lapse rates of 6.1 C/km. To get an idea of the air mass characteristics, I looked at a couple of NUCAPS soundings further to the west. The first was west of Pittsburgh along the PA/OH border.

The mid level lapse rates were the same as further east, but the warmer temps and higher dew points were supporting non-zero SBCAPE values. There was still some CIN, however, and the MLCAPE was a paltry 23 J/kg.

Moving further west, I examined a NUCAPS soudning in central Ohio, potentially indicative of the air mass that would move into the CWA later in the day due to the mean westerly flow at mid and upper levels.

There was a noticeable difference in the mid level lapse rates, with a more significant value of 7.1 C/km.  Also notice the DCAPE was in excess of 1000 J/kg, compared to values of 500-600 J/kg further east. This would indicate that there will be at least a threat of severe winds with convection that develops later in the day in the CTP CWA despite the early in the day convection that modified the air mass during.

Thorcaster

Just taking a quick look at the first NUCAPS swath over the CONUS.  I did want to point out the dropout in the swath, that unfortunately occurred along part of the SPC risk axis that stretched SW-NE from Illinois into the lower Great Lakes.  Although, the swath did obtain some soundings in the Marginal Risk area that encompasses much of Ohio.   Clicking  on the soundings in and around the Marginal Risk area indicated a regional location of higher instability.  Although soundings in the SW part of this risk area showed markedly higher instability values.

Notice the are significant differences across this area with overall larger lapse rates and instability in the SW corner of the Marginal Risk Area.  So, it will be interesting to see what unfolds in this area.  As the NUCAPS data indicate, are some areas within the singular Marginal Risk Area more favored for stronger activity, and thus further partitioning is needed?

So, I just wanted to point out some quick features and soundings with the initial NUCAPS swath, although we’re focused to the west today, over the southern Plains again.  We’ll be watching intently for the next NUCAPS swath.

Hi all,

Ok, just a couple of quick observations and comparison of a NUCAPS (direct broadcast) sounding with a modified sounding over an area of interest this afternoon.  The NUCAPS sounding locations and the particular sounding of interest can be seen in Image 1 below.

The next image below (image 2) shows the Direct Broadcast NUCAPS sounding valid ~2000 UTC 20 May 2019.   The sounding indicates high CAPE values at this sounding location (~2800 J/Kg MUCAPE, and 2400 J/Kg MLCAPE), and steep lapse rates aloft, in excess of 8 C/km.  This type of atmospheric profile would support severe weather in the area today.

The next image is the modified sounding taken at the same location.  Notice the increased CAPE values…

By the way, soundings in this general area, including the yellow soundings indicated high CAPEs with “reasonable” looking values.  However, there was a fairly significant gradient noticed in overall low-level instability noticed in soundings to the east of this location.  This could be a good case for the NUCAPS team to go back and take a further look.

-Kris W

So, hello from my initial post from HWT, here during the week of May 20th.  Yes, this is shaping up to be an active day and perhaps week.  Taking a first look at the NUCAPS soundings for this afternoon…and…the latest ~18 UTC swath is just a bit too far east to be of a lot of use here in the primary action area for severe convection.  Notice in the first image the SPC Outlooks (High Risk area nearly entirely to the west of the soundings).   Nevertheless, I’ll take a look at the next swath to see the coverage over the main area of expected severe weather.

-Kris W