Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 110903

Area Forecast Discussion
National Weather Service Tucson AZ
203 AM MST Mon Dec 11 2017

.SYNOPSIS...Plenty of cloud cover today thanks to a low pressure
system sitting over Baja California. This low will sit to our south
into Thursday with clouds and potentially a few sprinkles at times
near the Mexico border. Then mostly clear and dry through next
weekend with above normal temperatures continuing.


.DISCUSSION...An upper low is doing the sit and spin over Baja
California which continues to direct high level moisture over the
area. That high level moisture is expected to deepen downward
through the day as a vort lobe rotates northward around the low. If
it wasn`t for the very dry sub-cloud/near surface layer we might
have been able to get a few measurable rain showers across southern
areas but instead will likely just see virga with a few rogue rain
drops which is already in the forecast near the border.

The low will be a slow drifter and is expected to slowly ease its way
to the east through Wednesday under the large scale ridge then shift
toward the south as the ridge builds west and it begins to feel the
influence of the central U.S. trough. Throughout this time the
impact will be minimal, mainly high clouds. Then clear skies will be
the rule as dry northwest flow redevelops over the region with the
longwave ridge axis well to our west.

Throughout this entire period we will continue the warmer than
average conditions we have become accustomed to this season. Low and
high temperatures will generally be 5-10 degrees warmer than average
through next weekend.


.AVIATION...Valid thru 12/12Z.
BKN-OVC clouds around 20k ft AGL through the period with SCT-BKN
clouds 10k-15k ft AGL into this evening. KTUS will see elevated SELY
winds at 12-15 kts through 11/16Z. Elsewhere, SFC winds will be
ELY/SELY at less than 10 kts. Aviation discussion not updated for TAF


.FIRE WEATHER...A slight chance of light showers is possible across
southern Santa Cruz and Cochise counties this afternoon and evening.
Otherwise, dry conditions will persist through the forecast period.
20-foot winds will generally be easterly-southeasterly into Thursday
at less than 15 mph.





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