Good evening and early morning! The NHC downgraded from 70 percent to 40 percent the probability of 97L becoming a tropical depression.

Tonight there is an upper level low between 850 and 500 mbs located almost directly over the disturbance and an upper low at 300 and 200 mbs over the Northern Bahamas. NHC sampled extensively the area this evening and reported wind shear and dry air as the primary causes as to why the wave has not developed.

This upper level low is not vertically stacked as depicted at various levels this evening and the overall system has moved very little over the past 12 hours and appears to have deepened as water vapor imagery clearly shows an elongated north to south upper level low.

This ULL has resulted in wind shear aloft between 30 and 40 knots directly to the west of the system and continues to impact the system tonight.

There is strong thunderstorm activity underneath the upper level low but that is not unusual nor is it uncommon for depressions to develop under an upper level low.

I see nothing on tonight's upper level analysis and 21/18Z model run to suggest this system will develop into something serious though the track is through the oil slick and to LA.

The axis of the wave is right along this axis of dry/moisture axis and as long as this persists; 97L will remain a wave.

Conclusion....I cannot rule out this system may become a depression, but it's going to be slow and it's going to be in a hostile environment. It will have a better opportunity to develop once west of FL and the ULL leaves itself of the area.