Sunday, August 10, 2008

Tricky forecast this week

The biggest thing I have seen from today is the major influence of the weakening high pressure system diminishing the rain as it entered our region this evening. I saw a weakening high pressure system b/c I fully expect this system to be completely gone in about 12 to 24 hours. This being said, precipitation will build into our day tomorrow. (the image at the top is the QPF for Monday through Tuesday: produced by NWS)

Overall, the models do not agree, but the main synopsis is the progression of the low pressure system creating a good chance of rain through Wednesday. WRF actually shows the best shot at rain Tuesday afternoon through early Wednesday morning as a shortwaves pushes through our region. This shortwave will come after Monday's upper-level divergence, which will become a main mechanism to help create lift and produce our rain forecast. This forecast is tricky for me and several other forecasters b/c the timing and location of the rain is hard to find during this upper-level divergence.

The shortwave pushing through on Tuesday is a little easier to pick out the timing and location as it will move through like a typical front. WRF, GFS, and NAM models are similar on the timing and location of this shortwave. WRF is a little more extreme in rain totaling over 2 inches in some locations through Tuesday night.

My thoughts...Monday is the most difficult, but I wouldn't be surprised to see showers influencing our viewing region west of I-59. As the evening moves along, I would expect the precip to roll into our eastern counties. Then, tuesday should start off clear on our radar, but the best chance of rain should roll in by the late-afternoon. This precip looks to last until early Wednesday morning. In the end, a lot can change in this forecast within the next 24 hours. As with any forecast, mother nature can throw us a curve ball and reassign the location and timing of Monday/Tuesday's events.

Remember to catch Rex's forecast tomorrow morning and at mid-day. He will definitely have a good wrap with the updated products.

Last note: Things are looking interesting in our tropical forecast. A couple of global models are showing 3 low pressure systems in the atlantic by the end of the week.

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