Disturbance 90L brings heavy rain to Puerto Rico; major pollution in California
A surface low pressure system (90L) just east of Puerto Rico is moving to the west at 5-10 mph. This low is entangled with an upper-level low pressure system that is bringing about 30 knots of wind shear, so no development is likely today. Long range radar out of Puerto Rico shows bands of heavy rain hitting the islands and surrounding waters, but these bands are not well-organized. Satellite loops show most of the heavy thunderstorm activity is to the northeast of the low's center of circulation, and high wind shear is keeping this thunderstorm activity disorganized. This morning's QuikSCAT pass missed 90L.
Figure 1. Latest satellite image of 90L. Image credit: NOAA.
The surface low is expected to separate from the upper level low tonight and move west-southwest or southwest across Puerto Rico, bringing the threat of heavy rain and flooding to the island. Recent rains have left large areas of interior and western Puerto Rico at or near saturation, and mudslides were reported yesterday in Utuado. Flooding problems and mudslides are likely across Puerto Rico and the Virgin Islands Friday and Saturday, and this is shaping up to be the most significant rain event of the fall wet season thus far for Puerto Rico.
On Friday and Saturday, 90L will move westward along or just south of Hispaniola, bringing heavy rain, flash flooding, and possible mudslides to that island. The ECMWF and NOGAPS models predict that wind shear will drop to 10-20 knots by Friday night, which may allow some slow development of the disturbance if the center remains over water. The GFS model keeps wind shear 20-30 knots through the period, and does not develop 90L. By Saturday, the storm will near Jamaica, and the ECMWF and NOGAPS models predict a tropical depression will form by Sunday. Steering currents grow weak on Monday, and the storm could stall out for many days in the Western Caribbean, in an area of low wind shear and high heat content waters. This may allow the system to intensify into a hurricane. The eventual fate of this system is highly uncertain, since steering currents will be so weak. Those of you planning to travel to the Western Caribbean next week should keep a close watch on this system. NHC has not scheduled any flights into 90L yet.
It is possible that wind shear and passage over the islands will sufficiently disrupt this disturbance so that it does not develop. However, surface pressures have fallen 2-3 mb over most of the Western Caribbean the past two days, and there is a good chance that a new area of disturbed weather will develop. One such disturbance formed yesterday south of Haiti, but has since dissipated. Unsettled rainy weather can be expected to affect much of the Western Caribbean over the coming week.
California's fires
Surface maps show that the high pressure system that brought this week's strong Santa Ana winds to Southern California has now moved east and is over Colorado. The Santa Ana winds have ceased over California, and only light winds with afternoon sea breezes are expected today and for the next seven days. No precipitation is expected for at least the next week. The combination of light winds and lack of rain will make for a serious air pollution hazard in the region, until the fires are extinguished. There is still plenty of smoke over the ocean waters (Figure 2) that will get blown back over land by afternoon sea breezes over the next week.
Figure 2. Visible satellite image at 1:45 pm PDT Wednesday October 24, showing a huge area of smoke over the Pacific Ocean. Some of this smoke is being blown northward (top of image), and is expected to move over northern California and northern Nevada over next two days. This northward-moving smoke is being lifted by the flow around an approaching low pressure system, and is not expected to affect air quality near the surface. However, the smoke just offshore San Diego and Los Angeles will remain near the surface, and some of it will be pushed back over land by afternoon sea breezes. Image credit: NASA.
Jeff Masters
with all the smoke in the air the moon last night was looking like holloween.
Reader Comments
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When u get a chance, I'd be glad to hear your comments on the SW CAR. Just ITCZ interaction, or potentially something more later?
incase u missed it this is what accuweather said before the west cuba blob came into the picture last night
Link
Good morning everyone,
still got some back reading to do but I did open this link by stormybil. Thanks for the info.
I don't like what he is saying here at all.
Any flights scheduled to take a look at 90L -
AND - How about the convection at the end of the stalled front? Looks like the tropics are alive and kicking!
(although I "thought" that Felix and Dean crossed just south of Jamaica and Caiman and some of the models send 90L in that general direction......
OK, see what u r thinking about now. I guess we were thinking more about point of entry into the CAR also. But enough of the models do seem to thread 90L between JA and the other Greater Antillies to make that an equal possibility. As I said earlier, a lot is going to depend on how far S the SW movement takes it during the course of the day. Unfortunately IMO if it DOES go south, the potential for significant development increases due to increased SSTs in the area.
BTW, people on the E coast FL, are u feeling a bit cooler this a.m.? Outside temps here are finally cooling off a bit in the mornings. Afternoons are still pretty warm, though.
Morning StormW I would like to know if this system has the potential to get to the strength of wilma considering it is October already and the water temperature. Thank you in advance for your input
Action: | Ignore User
Well it is always possible but the chances of that happening are slim. Heat content is high is some areas but not as high as when Wilma developed. Although i believe there is enough heat content and warm water to support a Intense hurricane if conditions are right. As we all know however, Tropical activity is very unpredictable so we will just have to see what unfolds.
GOES-12 WV Loop of the Tropical Basin Link
Thunderstorm
Humidity: 92%
Dew Point: 72 °F / 22 °C
Wind: Calm
Wind Gust: 1.0 mph / 1.6 km/h
Pressure: 29.93 in / 1013.4 hPa (Falling)
Heat Index: 73 °F / 23 °C
Yes it is nicer here in SE Fla (Broward) but cool weather I think is because of rain. It is still predicted toget up to 85 today in my area! LOL That "cold" front didn't really affect us.
799. weathermanwannabe 8:28 AM EDT on October 26, 2007
(although I "thought" that Felix and Dean crossed just south of Jamaica and Caiman and some of the models send 90L in that general direction......
OK, see what u r thinking about now. I guess we were thinking more about point of entry into the CAR also.
The Java is starting to kick-in; Yeah, that's what I meant (where it could end up) as opposed to the point of entry...Thank You!
WSW with 90L, almost more W to WSW. ECMWF still likes South Florida for a target. And yes Baha, the weather, although rainy, is great. Struggling to get out of the 70's, much needed break from the heat.
just looking at steering and shear. The system will be fighting shear for 24-36 hours. Then it becomes interesting. If you look at the current steering it looks like a south tip florida problem. But, as the front retrogrates back as a warm front it should allow a more West move. But right now tough to call.
Thanks!
Tampa, can I encourage you to try hitting [enter] once or twice before you put you image info in? That way you last word won't end up stuck to the picture . . . .
Thanks!
My bad. Fixed it. Thank you.
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