Severe Thunderstorm Warning 20, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
203 PM MST Thu Jun 27 2024

.SYNOPSIS...Southeast Arizona will continue to see enough
moisture for a daily chance of thunderstorms. Storm chances
increase over the weekend and early next week. Some storms will
generate strong winds and locally heavy rainfall.

&&

.DISCUSSION...Latest (2030Z) radar scans show thunderstorms
developing south of Coronado National Monument with another storm
struggling to form near Green Valley. CAPE values are up in the
1500-2000j/kg across the region. The higher values are along the
international border to the southeastern Cochise County, along
with better environment for thunderstorms. 12Z HREF paintball
plots highlights the international border this afternoon and into
the early evening. The biggest threats is gusty erratic winds and
locally intense rainfall. The PWATs are 1.56 inches from this
morning and will stay elevated through the rest of the weekend.
Tomorrow, HREF 3 hour probability matched mean shows a signal for
more substantial rainfall south of Nogales which could result in a
rise in the Santa Cruz River and Nogales Wash. Something to keep
an eye on tomorrow afternoon.

This weekend, the high pressure center will push off to the east
and be a better position to bring in southerly moisture flow.
Thunderstorm chances increases along with coverage starting
Saturday. Sunday appears to be the one of the more active days due
to weak disturbance moving around the high pressure center.

Next week, the high pressure will sit more to our east and thus opening
the moisture flow gate a little more. PWATs will be increasing
close to the 1.7-2 inch mark across most of Southeast Arizona.
The ensemble models show a signal for above normal rain amounts by
starting as early as Tuesday through at least Thursday. One way
to look at it, 33% of the 100 member ensemble show a wetter
solution with 24 hour rain totals 0.75 inches to some locally
areas close to 1.50 inches. The other two thirds show rainfall
amounts a little less than that but is worth to keep an eye out
over the next several days. At the moment, there is low confidence
since it is close to a week out but there is increase risk for
flooding impacts especially with the 4th of July events coming up.

&&

.AVIATION...Valid through 29/00Z.
FEW-SCT 5-10 kft and SCT-BKN 20-25 kft AGL thru the forecast
period. Isolated -TSRA thru 28/03Z with brief MFR conditions
possible near storms, mainly along the international border and in
the White Mountains. SFC winds generally 10 kts with the
occasional gust up to 20 kts in the afternoons, except for gusty
outflow winds from storms. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Relatively deep moisture will stick around through
the forecast period. This will give isolated thunderstorms and
showers today and tomorrow, mainly south and east of Tucson.
Moisture will increase more through the weekend and into the new
week to bring higher chances and coverage for thunderstorms and
showers each day. Strong erratic gusty winds of 40 mph or higher
can be expected with any storm development, along with locally
brief heavy rainfall. Outside of thunderstorm winds, 20-foot
winds will generally be 15 mph or less each afternoon with the
occasional gust of 20 mph. Min RHs will generally be around 20% in
the valleys and 30s in the mountains with good overnight
recoveries.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&

KJS

Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson