Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 201638

Area Forecast Discussion
National Weather Service Tucson AZ
938 AM MST Wed Sep 20 2017

.SYNOPSIS...A low pressure system will bring strong and gusty
winds to the area Thursday into the weekend. A few showers or
thunderstorms may accompany the system, but should remain very
isolated. The system will also usher in cooler temperatures
Friday, with readings remaining below average through at least the
middle of next week.


.DISCUSSION...For today, the morning 12Z KTWC sounding showed
precipitable water down to .82 inches in a zonal westerly flow.
We`ll start to see mid and low levels gain a more southwesterly
inflection over the next 24 hours as a trough develops northwest
of us. Expect another nice CU field this afternon, with very
isolated convection possible. Isolated as in Tristan de Cunha, the
single most remote inhabited place in the world. The nearest land
to the island is South Africa, about 1700 miles away.

No updates this morning. Please see the previous discussion below
for additional details (about the weather, not Tristan de Cunha).


.AVIATION...Valid thru 21/18Z.
VFR with FEW-SCT clouds above 8k ft AGL. SFC wind becoming SWLY
late this morning to 12-16 kts with gusts to 25 kts continuing
through the afternoon hours then diminishing overnight. Aviation
discussion not updated for TAF amendments.


.FIRE WEATHER...A deepening upper trough over the western United
States will result in gusty southwest winds, especially during the
afternoon and evening hours through Saturday. The strongest winds
are expected on Thursday and Friday, with a cooling trend Friday
through Sunday. A few storms will be possible near eastern and
southeastern mountains before drying out this weekend.


.PREV DISCUSSION...Dry conditions with daytime temperatures
running a few degrees above normal can be expected today and
Thursday. Thereafter, models continued to deepen a low pressure
system over the western United States Thursday into the weekend.
Moisture needed to support rainfall appeared to be very limited
compared to previous solutions the past few days. Thus, confidence
remained low for rain chances south and east of Tucson Thursday
and Friday. Otherwise, the system will bring strong and gusty
winds especially Thursday and Friday. Cooler temperatures will
also follow on Friday and remain below normal over the weekend
into at least the middle of next week.






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