CrIS/ATMS soundings processed through the NOAA Unique Combine Processing System (NUCAPS) are available in AWIPS. SPoRT is working with the Joint Polar Satellite System (JPSS) Proving Ground to testbed the utility of NUCAPS soundings to anticipate hurricane tropical to extratropical transition. Although satellite derived soundings are “smoother” than radiosondes they can provide valuable information about the depth of moist or dry layers in data sparse regions. Forecasters can anticipate extratropical transition by identifying the dry slot and upstream potential vorticity anomalies on satellite imagery that may interact with a storm while also considering many other factors that lead to extratropical transition. Although Hurricane Matthew is not expected to undergo extratropical transition for quite a few days, the NUCAPS Soundings can be used to diagnose the temperature and moisture characteristics surrounding the hurricane as highlighted below.
GOES-13 water vapor imagery shows dry upper levels west of Hurricane Matthew and abundant moisture surrounding the system (Fig. 1). Since water vapor imagery can only detect moisture characteristics in the mid-to upper- levels of the atmosphere, the NUCAPS soundings (green dots on Fig. 1) can be analyzed to provide more information about the vertical extent of the dry air and whether it is in close proximity to the hurricane in the mid- to lower- levels.
Scroll down through the example Soundings to compare the changes in moisture conditions west of Hurricane Matthew. Soundings 1 and 2 (Fig. 2 and 3), taken in a region of dry air as identified by the orange color enhancement on the water vapor imagery, confirm a dry column throughout the depth of the atmosphere. Sounding 3 (Fig. 4) shows the drying is not as intense in the upper-levels and mid-level drying extends down to about 600 mb. Sounding 4 and 5 (Fig. 5 and 6) show upper level conditions are more moist closer to the hurricane, as expected from the water vapor imagery. While Sounding 4 (Fig. 5) shows moist conditions throughout the atmospheric column, Sounding 5 (Fig. 6) does show mid-level dry air is present. Previous analysis of Sandy 2012 and Arthur 2014 showed the same signature (e. g., similar to Sounding 5) became more abundant surrounding the systems as upper-level dry air intruded. Currently, there are very few soundings with this signature surrounding Hurricane Matthew. The NUCAPS soundings confirm dry atmospheric conditions are well west of the system and there is very little mid- to low- level dry air in the proximity of the system. This preliminary example is presented but as Hurricane Matthew continues to evolve NUCAPS Soundings and SPoRT Ozone Products will be analyzed to discern the utility for anticipating dry air intrusion and associated hurricane tropical to extratropical transition.