Scientific Forecaster Discussion
fxus65 ktwc 180910
Area forecast discussion
National Weather Service Tucson Arizona
210 am MST Wed Oct 18 2017
Synopsis...continued above normal temperatures. A fast moving
disturbance will bring isolated showers and thunderstorms Wednesday
night into Thursday, mainly near eastern mountains. Expect some
minor cooling Friday and Saturday, then near record high
temperatures are possible early next week as high pressure aloft
builds over the area.
Discussion...cloud cover associated with an upper level disturbance
moving across northern Sonora mx will be diminishing from west to
east today. A weak upper level trof, currently located between
Frisco and la, will deepen a bit later today into tonight as it
moves into the state. This system will bring a slight chance of
sprinkles or very light showers to parts of the forecast area later
tonight into Thursday. Well above normal high temperatures will
continue today and Thursday. Breeziness kicks up a bit on Friday as
an upper level trof passes by to our north. This system will bring
much welcomed cooler temperatures by Saturday with highs, Dare I say
it, near or slightly above normal. Enjoy it for it will be short
lived as strong high pressure aloft will be building over the desert
SW early next week, resulting in record or near record high
Aviation...valid thru 19/12z.
Few-scattered clouds at 8-12k ft above ground level and scattered-broken clouds above 20k ft above ground level
thru 18/18z, then clearing from west to east with scattered clouds above
20k ft above ground level til 19/04z. Aft 19/04z, scattered-broken clouds at 8-12k ft above ground level.
Slight chance of -shra aft 19/06z. Surface wind terrain driven and less
than 12 kts through the forecast period. Aviation discussion not
updated for taf amendments.
Fire weather...a weak disturbance will result in a slight chance of
showers and thunderstorms tonight and Thursday. Dry conditions are
then expected across the area into at least the middle of next week.
Normal diurnal wind trends will continue through Thursday, becoming
breezy from the southwest on Friday into Saturday. An easterly wind
regime then sets up for Sunday into early next week.
Climate...record or near record high temperatures are likely early
next week as a strong ridge of high pressure aloft for October
builds over the area. Current forecast high of 97 for Tucson Intl
next Tuesday, if correct, would be the 2nd latest occurrence of 97
in the calendar on record. The record latest date is Oct 27 2016.
There is a small chance next Tuesday that the high at Tucson Intl
could it 98 which, if that happens, would be the latest occurrence
of 98 in the calendar on record, besting the current latest date of
Oct 19 in 1921 & 1991.