Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 06/27/16

Area Forecast Discussion
National Weather Service Flagstaff AZ
857 PM MST SUN JUN 26 2016

.SYNOPSIS...On Monday, expect scattered showers and thunderstorms,
primarily along and south of the Mogollon Rim. Strong, gusty
winds are possible near any storms. Beginning Tuesday, monsoonal
moisture is forecast to spread across all of northern Arizona
leading to daily chances for showers and thunderstorms through the
week.

&&

.DISCUSSION...
Only isolated and generally light showers are expected to continue
this evening and overnight. Additional storm development is likely
by late Monday morning.

&&

.PREV DISCUSSION /406 PM MST/...So far today, shower and
thunderstorm activity has generally occurred along and south of
a line from Window Rock to Heber-Overgaard. This area will likely
continue to be the focus for shower activity today, although some
showers may expand westward a bit to include Payson and Clints
Well this afternoon and evening.

On Monday, increasing moisture is forecast along and south of the
Mogollon Rim. This will lead to better chances for showers and
thunderstorms there. These storms will once again be high based,
so strong outflow winds will be the primary hazard.

Beginning Tuesday, high pressure in place near the Four Corners is
forecast to lead to an active monsoon pattern. A moist easterly
flow will transition to a moist southerly wind around the middle
of the week. This will draw deeper moisture into the region
leading to increasing chances for showers and thunderstorms across
all of northern Arizona. This moisture is expected to remain in
place over the following days causing daily chances for showers
and thunderstorms through the remainder of the week.

&&

.AVIATION...For the 06Z Package...Isolated to scattered showers
and thunderstorms expect to develop mainly southeast of a KFLG-
KRQE line after 18Z Monday. Otherwise, expect VFR conditions.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Expect deeper moisture with increasing coverage in
showers and thunderstorms Monday and Tuesday. Storm motion
Monday will generally be from southeast to northwest and south to
north on Tuesday. Expect erratic and gusty winds near any showers
and storms.

Wednesday through Friday...An active wet Monsoon weather pattern
is expected with numerous showers and thunderstorms each day
across northern Arizona.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

PUBLIC...KD/RR
AVIATION...KD
FIRE WEATHER...MAS

For Northern Arizona weather information visit
weather.gov/flagstaff



  [top] Area Forecast Discussion National Weather Service Phoenix AZ 730 PM MST SUN JUN 26 2016 .SYNOPSIS... High pressure will move somewhat north and east of Arizona this week allowing warm temperatures to prevail, but also bring a couple of weather disturbances through the state. An increase in monsoon moisture will accompany these weather systems providing a threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... A well defined circulation center was quite evident in WV imagery across far northern Sonora this evening with stronger ascent and upper divergent signatures analyzed throughout SE AZ. 00Z KTWC sampled rather modest Sfc-H7 8 g/kg mixing ratios, however deep layer moisture flux has advected more favorable 10-11 g/kg profiles northward per objective analysis. Given the general UVV and weakly capped MLCapes around 500 J/kg, more robust convection has developed along the I-19 corridor. Closer towards central AZ, reduced daytime insolation and lower moisture values (closer to 7 g/kg mixing ratios) have yielded negligible instability despite relatively steep midlevel lapse rates. Thus, while virga/sprinkles/very light showers may be possible around the Phoenix metro, convection moving north may meet a fate of dissipation. Will continue to monitor trends through the evening, and would be most concerned about stronger outflows and dust production versus actual storms. One area of somewhat more concern may be through SW AZ where some more palpable instability has been analyzed, and vorticity/divergence fields will translate during the overnight. Several deterministic models and ensemble means suggest midlevel moisture lifted towards a steeper lapse rate environment while low level T/Td spreads narrow. There was enough evidence presented in models and analysis to increase pops and mention showers through the SW parts of the CWA later tonight. Otherwise, made some substantial changes to hourly temperatures based on current trends which were much cooler than previously advertised. && .PREVIOUS DISCUSSION... /240 PM MST SUN JUN 26 2016/ Monday through Saturday... The forecast becomes very complicated this week with respect to shower/thunderstorm potential, coverage, and intensity - mainly across portions of southwest and south central AZ. In other words, can we call it quasi-unsettled this week? We know the monsoon moisture boundary arrived in southeast AZ the past couple of days, and is forecast to spread west and north across the remainder of southern and central AZ this week. And normally this time of year once the moistures in place it should be like clockwork, i.e., first afternoon mountain thunderstorms, then by evening drifting toward the desert edge including developing on convective outflows and/or outflow collisions. Not this week, there is too much going on in the mid and upper atmosphere. For example, the last vestiges of the northwest Mexico inverted trof will move into the region Monday afternoon. More cyclonic flow over southern CA will aid in a threat of thunderstorms over the Joshua Tree National Park mountains, while difluent flow aloft in southwest and south central AZ generates convective potential as well. But a caveat, extensive mid/high clouds associated with the inverted trof axis may cut down on afternoon heating and the convective potential in the south central AZ Monday. And for Tuesday and Tuesday night, while 300/250 mb flows become southwesterly, a developing 500 mb easterly flow advects a weak mid level disturbance from New Mexico into southeast and south Central AZ late Tuesday afternoon and night. 500 mb disturbances usually spark overnight convection under very moist conditions. Therefore there is much uncertainty, and we can go on and on for Wednesday through Saturday. Therefore, the best approach is to call is quasi-unsettled, or a broad brush approach to shower/thunderstorm potential since 1) the monsoon moisture will be in place, and 2) models will no doubt have trouble forecasting any minor perturbations in this developing convoluted flow aloft. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Low confidence forecast through Monday afternoon as wind direction/shifts will be dictated by outflow boundaries traveling from storms more removed from terminal sites. Southwest winds this evening will shift to an easterly direction earlier than typical due to outflow propagating from eastern AZ, but timing is very uncertain. Cigs 12K-15K ft and occasional virga will be common through Monday morning. Much better chances for stronger east/northeast outflow winds will arrive later Monday afternoon. Actual storms may not survive to lower elevations, though mountain obscuration, blowing dust, and frequent lightning for arrivals/departures to the east may be problematic. Southeast California/Southwest Arizona including KIPL and KBLH: Cigs in a 10K-15K ft will increase through Monday with occasional virga, and possibly a few showers reaching the ground at KIPL. While a south to southeast sfc wind will be preferred, periods of variability will be common Monday morning (especially around showers). A few stronger gusts may also be possible for brief periods. Forecast confidence is only moderate. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool" with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...MO/Vasquez AVIATION...MO FIRE WEATHER...Hernandez
Area Forecast Discussion National Weather Service Phoenix AZ 730 PM MST SUN JUN 26 2016 .SYNOPSIS... High pressure will move somewhat north and east of Arizona this week allowing warm temperatures to prevail, but also bring a couple of weather disturbances through the state. An increase in monsoon moisture will accompany these weather systems providing a threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... A well defined circulation center was quite evident in WV imagery across far northern Sonora this evening with stronger ascent and upper divergent signatures analyzed throughout SE AZ. 00Z KTWC sampled rather modest Sfc-H7 8 g/kg mixing ratios, however deep layer moisture flux has advected more favorable 10-11 g/kg profiles northward per objective analysis. Given the general UVV and weakly capped MLCapes around 500 J/kg, more robust convection has developed along the I-19 corridor. Closer towards central AZ, reduced daytime insolation and lower moisture values (closer to 7 g/kg mixing ratios) have yielded negligible instability despite relatively steep midlevel lapse rates. Thus, while virga/sprinkles/very light showers may be possible around the Phoenix metro, convection moving north may meet a fate of dissipation. Will continue to monitor trends through the evening, and would be most concerned about stronger outflows and dust production versus actual storms. One area of somewhat more concern may be through SW AZ where some more palpable instability has been analyzed, and vorticity/divergence fields will translate during the overnight. Several deterministic models and ensemble means suggest midlevel moisture lifted towards a steeper lapse rate environment while low level T/Td spreads narrow. There was enough evidence presented in models and analysis to increase pops and mention showers through the SW parts of the CWA later tonight. Otherwise, made some substantial changes to hourly temperatures based on current trends which were much cooler than previously advertised. && .PREVIOUS DISCUSSION... /240 PM MST SUN JUN 26 2016/ Monday through Saturday... The forecast becomes very complicated this week with respect to shower/thunderstorm potential, coverage, and intensity - mainly across portions of southwest and south central AZ. In other words, can we call it quasi-unsettled this week? We know the monsoon moisture boundary arrived in southeast AZ the past couple of days, and is forecast to spread west and north across the remainder of southern and central AZ this week. And normally this time of year once the moistures in place it should be like clockwork, i.e., first afternoon mountain thunderstorms, then by evening drifting toward the desert edge including developing on convective outflows and/or outflow collisions. Not this week, there is too much going on in the mid and upper atmosphere. For example, the last vestiges of the northwest Mexico inverted trof will move into the region Monday afternoon. More cyclonic flow over southern CA will aid in a threat of thunderstorms over the Joshua Tree National Park mountains, while difluent flow aloft in southwest and south central AZ generates convective potential as well. But a caveat, extensive mid/high clouds associated with the inverted trof axis may cut down on afternoon heating and the convective potential in the south central AZ Monday. And for Tuesday and Tuesday night, while 300/250 mb flows become southwesterly, a developing 500 mb easterly flow advects a weak mid level disturbance from New Mexico into southeast and south Central AZ late Tuesday afternoon and night. 500 mb disturbances usually spark overnight convection under very moist conditions. Therefore there is much uncertainty, and we can go on and on for Wednesday through Saturday. Therefore, the best approach is to call is quasi-unsettled, or a broad brush approach to shower/thunderstorm potential since 1) the monsoon moisture will be in place, and 2) models will no doubt have trouble forecasting any minor perturbations in this developing convoluted flow aloft. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Low confidence forecast through Monday afternoon as wind direction/shifts will be dictated by outflow boundaries traveling from storms more removed from terminal sites. Southwest winds this evening will shift to an easterly direction earlier than typical due to outflow propagating from eastern AZ, but timing is very uncertain. Cigs 12K-15K ft and occasional virga will be common through Monday morning. Much better chances for stronger east/northeast outflow winds will arrive later Monday afternoon. Actual storms may not survive to lower elevations, though mountain obscuration, blowing dust, and frequent lightning for arrivals/departures to the east may be problematic. Southeast California/Southwest Arizona including KIPL and KBLH: Cigs in a 10K-15K ft will increase through Monday with occasional virga, and possibly a few showers reaching the ground at KIPL. While a south to southeast sfc wind will be preferred, periods of variability will be common Monday morning (especially around showers). A few stronger gusts may also be possible for brief periods. Forecast confidence is only moderate. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool" with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...MO/Vasquez AVIATION...MO FIRE WEATHER...Hernandez
Area Forecast Discussion National Weather Service Flagstaff AZ 406 PM MST SUN JUN 26 2016 .SYNOPSIS...On Monday, there will be enough moisture in place over central and eastern Arizona to cause scattered showers and thunderstorms, primarily along and south of the Mogollon Rim. Strong, gusty winds are possible near any storms. Beginning Tuesday, monsoonal moisture is forecast to spread across all of northern Arizona leading to daily chances for showers and thunderstorms through the week. && .DISCUSSION...So far today, shower and thunderstorm activity has generally occurred along and south of a line from Window Rock to Heber-Overgaard. This area will likely continue to be the focus for shower activity today, although some showers may expand westward a bit to include Payson and Clints Well this afternoon and evening. On Monday, increasing moisture is forecast along and south of the Mogollon Rim. This will lead to better chances for showers and thunderstorms there. These storms will once again be high based, so strong outflow winds will be the primary hazard. Beginning Tuesday, high pressure in place near the Four Corners is forecast to lead to an active monsoon pattern. A moist easterly flow will transition to a moist southerly wind around the middle of the week. This will draw deeper moisture into the region leading to increasing chances for showers and thunderstorms across all of northern Arizona. This moisture is expected to remain in place over the following days causing daily chances for showers and thunderstorms through the remainder of the week. && .AVIATION...For the 00Z Package...Isolated to scattered showers and thunderstorms with possible wind gusts to 40kts from KFLG-KRQE southeast until around 02z. Storms will be possible after 17Z over all of northern Arizona. Otherwise, expect VFR conditions. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect deeper moisture with increasing coverage in showers and thunderstorms Monday and Tuesday. Storm motion Monday will generally be from southeast to northwest and south to north on Tuesday. Expect erratic and gusty winds near any showers and storms. Wednesday through Friday...An active, wet Monsoon weather pattern is expected with numerous showers and thunderstorms each day across northern Arizona. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...RR AVIATION...MAS FIRE WEATHER...MAS For Northern Arizona weather information visit weather.gov/flagstaff
  [top] Area Forecast Discussion National Weather Service Tucson AZ 336 PM MST SUN JUN 26 2016 .SYNOPSIS...Plenty of moisture around this week with an increasing chance of mainly afternoon and evening showers and thunders across Southeast Arizona. && DISCUSSION...Convection is finally firing over expected areas, including areas southeast through southwest of Tucson as well as the east central mountains (northern Graham and Greenlee counties). We had a delays in initiation due to morning cloud cover as well as a bit more convective inhibition to overcome as per the KTWC morning sounding. So the strong outflow from the southern Mogollon Rim is just now pushing southwest into valley locations of Graham county, and it doesn`t really look as strong as the increasing mid level easterly flow suggested earlier. Development across southern areas is increasing, but not anything to write home about either. We may still have some mid level CAPE for an outflow to tap into later this evening, so more debris to contend with early Monday morning. Weak subsidence behind a minor mid level feature shifting north of the area will probably limit thunderstorms to mainly mountain areas Monday. A deeper and stronger fetch around high pressure reconsolidating to our east should push our thunderstorm coverage up as we reinforce available moisture and draw in weak inflections around the high. && AVIATION...VALID THRU 28/00Z. Isolated to scattered -TSRA/-SHRA. The best timing for TSRA is mostly from 20Z this afternoon until 27/08Z this evening. Brief wind gusts to near 40 kts and MVFR conditions due to reduced visibilities will be possible with the stronger TSRA. Isolated -SHRA/-TSRA will be possible area-wide late tonight into early Monday afternoon. Otherwise, cloud decks generally ranging from 10k- 15k ft MSL, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && FIRE WEATHER...Expect isolated to scattered showers and thunderstorms this afternoon and evening. Greater coverage of showers and thunderstorms should then occur Monday through next Saturday. Otherwise, daytime minimum relative humidity values will generally range from the mid teens to around 30 percent with fair to good nighttime recovery. 20-foot winds into Monday as well as Thursday through Saturday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east at 5-15 mph with gusts of 15-20 mph. The strongest speeds Tuesday and Wednesday should prevail from shortly after sunrise into the early afternoon hours. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Meyer/Rasmussen Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Tucson AZ 336 PM MST SUN JUN 26 2016 .SYNOPSIS...Plenty of moisture around this week with an increasing chance of mainly afternoon and evening showers and thunders across Southeast Arizona. && DISCUSSION...Convection is finally firing over expected areas, including areas southeast through southwest of Tucson as well as the east central mountains (northern Graham and Greenlee counties). We had a delays in initiation due to morning cloud cover as well as a bit more convective inhibition to overcome as per the KTWC morning sounding. So the strong outflow from the southern Mogollon Rim is just now pushing southwest into valley locations of Graham county, and it doesn`t really look as strong as the increasing mid level easterly flow suggested earlier. Development across southern areas is increasing, but not anything to write home about either. We may still have some mid level CAPE for an outflow to tap into later this evening, so more debris to contend with early Monday morning. Weak subsidence behind a minor mid level feature shifting north of the area will probably limit thunderstorms to mainly mountain areas Monday. A deeper and stronger fetch around high pressure reconsolidating to our east should push our thunderstorm coverage up as we reinforce available moisture and draw in weak inflections around the high. && AVIATION...VALID THRU 28/00Z. Isolated to scattered -TSRA/-SHRA. The best timing for TSRA is mostly from 20Z this afternoon until 27/08Z this evening. Brief wind gusts to near 40 kts and MVFR conditions due to reduced visibilities will be possible with the stronger TSRA. Isolated -SHRA/-TSRA will be possible area-wide late tonight into early Monday afternoon. Otherwise, cloud decks generally ranging from 10k- 15k ft MSL, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && FIRE WEATHER...Expect isolated to scattered showers and thunderstorms this afternoon and evening. Greater coverage of showers and thunderstorms should then occur Monday through next Saturday. Otherwise, daytime minimum relative humidity values will generally range from the mid teens to around 30 percent with fair to good nighttime recovery. 20-foot winds into Monday as well as Thursday through Saturday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east at 5-15 mph with gusts of 15-20 mph. The strongest speeds Tuesday and Wednesday should prevail from shortly after sunrise into the early afternoon hours. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Meyer/Rasmussen Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Phoenix AZ 240 PM SUN JUN 26 2016 .SYNOPSIS... A very warm air mass will keep temperatures above normal through at least the first half of the week. A increase in monsoon moisture is also expected, and will provide a slight threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... Tonight... The inverted trof so noticeable on vapor imagery just south of the AZ border developed an west-east deformation/stretching zone replete with considerable mid/high level cloudiness. Cloudiness was able to retard the heating curve and defer any precip to virga or light showers with the dense clouds. More is expected overnight. However there are a few afternoon thunderstorms in the less cloudy areas of the White Mountains, just west of Nogales along the Mexican border, and in far southeast AZ at 2 pm mst. Monday through Saturday The forecast becomes very complicated this week with respect to shower/thunderstorm potential, coverage, and intensity, mainly across portions of southwest and south central AZ. In other words, can we call it quasi-unsettled this week? We know the monsoon moisture boundary arrived in southeast AZ the past couple of days, and is forecast to spread west and north across the remainder of southern and central AZ this week. And, normally this time of year once the moistures in place it should be like clock-work right, i.e., first afternoon mountain thunderstorms then by evening drifting toward the desert edge, including developing on convective outflows and/or outflow collisions. Not this week, there is too much going on in the mid and upper atmosphere. For example, the last vestiges of the northwest Mexico inverted trof will move into the region Monday afternoon. More cyclonicity over southern CA will develop a threat of thunderstorms over the Joshua Tree National Park mountains, while difluent flow aloft in southwest and south central AZ generates convective potential as well. But a caveat, extensive mid/high clouds associated with the inverted trof axis may cut down on afternoon heating and the convective potential in the south central AZ Monday. And for Tuesday and Tuesday night, while 300/250 mb flows become southwesterly, a developing 500 mb easterly flow advects a weak mid level disturbance from New Mexico into southeast and south Central AZ late Tuesday afternoon and night. 500 mb disturbances usually spark overnight convection under very moist conditions. Therefore there is much uncertainty, and we can go on and on for Wednesday through Saturday. Therefore the best approach is to call is quasi-unsettled, or a broad brush approach to shower/thunderstorm potential since 1) the monsoon moisture will be in place, and 2) models will no doubt have trouble forecasting any minor perturbations in this developing convoluted flow aloft. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Showers moving in from the southeast have caused winds to shift to a southeasterly direction this afternoon over Phoenix terminals. With more activity in southeast AZ still propagating to the northwest, anticipate that these southeasterly winds will stick around for another hour or so before shifting temporarily back to the west around 22Z. Speeds will remain around 10 kts, however cannot rule out gusty erratic winds and blowing dust from distant south and east AZ storms for the remainder of the day at Phoenix terminals. However, low confidence in exact spatial and temporal coverage precludes mention in 18Z TAF. Broken to overcast mid to high clouds aoa 10kft will continue to advect into the region for the remainder of the day before decreasing in coverage early tomorrow morning. Southeast California/Southwest Arizona including KIPL and KBLH: Skies will remain mostly clear with a few passing high clouds around 15-20 kft. Winds will remain out of the south at KBLH and out of the southeast at KIPL, with speeds generally around 10-15 kts accompanied by a few afternoon gusts up to 20 to 25 kts. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool," with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...Vasquez AVIATION...Hernandez FIRE WEATHER...Hernandez
Area Forecast Discussion National Weather Service Flagstaff AZ 940 AM MST SUN JUN 26 2016 .SYNOPSIS...Dry and hot weather will persist across far western Arizona today. Mid level moisture will remain over central and eastern Arizona through Monday, and bring widely scattered showers and thunderstorms. Strong, gusty winds are possible near any storms. Monsoonal moisture to increase and spread across northern Arizona on Tuesday, with increasing daytime shower and thunderstorm activity lasting through the week. && .DISCUSSION...For today, the highest moisture and best chances for showers and thunderstorms will be along and south of the White Mountains and the eastern Mogollon Rim. Elsewhere, drier air and more stable conditions will limit convective activity. Slight chances for showers are forecast along the western Mogollon Rim, including the city of Flagstaff. This seems reasonable as an extensive cumulus field is expected to develop with heating. As highlighted in the previous forecast discussion, today`s storms will once again be high-based leading to the potential for strong outflows from collapsing storms. In terms of forecast updates, the current forecast appears to be on track and no short term updates are anticipated at this time. && .PREV DISCUSSION /303 AM MST/... Northern Arizona will be slowly transitioning to a monsoon thunderstorm pattern over the next two days. Strong and gusty outflow winds should be expected near any storms or virga. The Flagstaff airport did have 2 periods of outflow wind gusts to 48 and 47 mph yesterday, an indication of outflow speeds possible through Monday afternoon. Satellite imagery this morning shows the monsoonal moisture plume running from NW Mexico through Tucson then northeastward through New Mexico. Satellite derived pw values are up to near 1.5 inches around Tuscon this morning. Models remain consistent in showing mid level easterly flow increasing across central and southern AZ today and this will allow moisture to slowly increase across areas along and south of I-40 through Monday. Areas along the Utah border to remain hot and nearly cloud free today as this area is under the high pressure circulation center. Starting Tuesday, models are in good agreement with moist easterly flow through Wednesday morning becoming light southerly through Wednesday. Monsoonal moisture to remain overhead through the week and daytime precip chances were nudged upward a few points along the Mogollon Rim. Max temps to cool to near normal for dates starting Wednesday. && .AVIATION...For the 18Z Package...Isolated to scattered showers and thunderstorms with possible gusts to 40kts will redevelop from KFLG- KRQE southeast this afternoon and evening until around 02z. Otherwise, expect VFR conditions. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Monsoon moisture will slowly increase northward each day. Expect deeper moisture with increasing coverage in showers and thunderstorms starting on Monday. Storm motion today and Monday will generally be from northeast to southwest. Expect erratic and gusty winds near any showers and storms. Tuesday through Thursday...An active wet Monsoon weather pattern is forecast with good shower and thunderstorm coverage each day across northern Arizona. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...RR/DL AVIATION...MAS FIRE WEATHER...MCS For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 940 AM MST SUN JUN 26 2016 .SYNOPSIS...We now have enough moisture for isolated to scattered showers and thunderstorms this weekend. A more favorable flow regime will then provide increased coverage of showers and thunderstorms Monday through next Saturday. && .DISCUSSION...Still plenty of debris cloud this morning with embedded light showers. This is going to slow the heating a bit with initial clearing underway in portions of Cochise and Santa Cruz counties. The 12Z KTWC sounding still has plenty of moisture at 1.4 inches precipitable water. The mid level easterly flow has already increased substantially accompanied by an increase in shear that should help to organize outflow activity this afternoon. The direction favors strong outflow off the Mogollon Rim through Graham county. Latest HRRR trends push 2 strong outflows westward, including the Rim shot and a second outflow from activity in Cochise county pushing west and northwestward. The 12z UofA WRF-NAM paints a similar scenario with the outflow from the Cochise county activity pushing through the Tucson Metro area around mid to late afternoon. Minor adjustments to increase activity in the east central mountains and subsequent outflow westward, otherwise we have solid forecast trends. Please see the previous discussion below for additional details. && .AVIATION...VALID THRU 27/18Z. Isolated to scattered -TSRA/-SHRA. The best timing for TSRA at the KTUS/KOLS/KDUG terminals is mostly from 20Z this afternoon until 27/02Z this evening. Brief wind gusts to near 40 kts and MVFR conditions due to reduced visibilities will be possible with the stronger TSRA. Isolated -SHRA/-TSRA will be possible area-wide late tonight into early Monday morning. Otherwise, cloud decks generally ranging from 10k- 15k ft MSL, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect isolated to scattered showers and thunderstorms this afternoon and evening. Greater coverage of showers and thunderstorms should then occur Monday through next Saturday. Otherwise, daytime minimum relative humidity values will generally range from the mid teens to around 30 percent with fair to good nighttime recovery. 20-foot winds into Monday as well as Thursday through Saturday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east at 5-15 mph with gusts of 15-20 mph. The strongest speeds Tuesday and Wednesday should prevail from shortly after sunrise into the early afternoon hours. && .PREV DISCUSSION...The hi-res models suggest a scenario late tonight similar to that presently occurring across the area. In other words, a fairly widespread convective debris cloud cover with patches of sprinkles or light rain. 26/00Z GFS/ECMWF/CMC remained fairly similar regarding the synoptic scale pattern regime over the southwestern states starting Monday and continuing into early next weekend. Strong high pressure aloft Monday is progged to become centered over southern Utah. The GFS/ ECMWF depict an inverted trough to move into southwestern AZ from the northern Gulf of California Monday. Quick glance at the U/A WRF-NAM suggests that showers/tstms Monday afternoon would only be confined to the White Mountains and near the international border adjacent Santa Cruz/southern Pima County. Thus, there is the potential that Monday may be a "down day" perhaps due to subsidence on the eastern periphery of the aforementioned inverted trough. Forecast confidence in this particular detail is somewhat low, however. Thus, for this forecast package, have continued with scattered showers/tstms mainly from Tucson eastward/southward. Thereafter, not much daily variation in shower/tstm coverage is anticipated Tuesday into next Saturday. The deterministic GFS/ECMWF/ CMC were similar with maintaining fairly ample moisture across this forecast area. These solutions were similar with the continuation of a light ely/sely mid-level flow regime thru about Wednesday. The mid- level flow regime is then progged to become more wly/swly especially from Tucson westward starting Thursday and continuing into next Saturday. This subtle change may be sufficient for at least a slight downward trend in shower/tstm coverage, especially across western sections. Again, forecast confidence is fairly low at this time in stating that a definitive downward precip trend anywhere in the area is in the offing late this week. High temps for the Tucson metro area and locales west-to-northwest of Tucson will be near normal during much of this forecast period. However, daytime temps for locales east-to-south of Tucson, such as Safford, Douglas and Nogales will average a few degs below normal this week. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Meyer/Francis Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson Area Forecast Discussion National Weather Service Tucson AZ 915 PM MST SUN JUN 26 2016 .SYNOPSIS...Plenty of moisture around this week with an increasing chance of mainly afternoon and evening showers and thunders across Southeast Arizona. && .DISCUSSION...Earlier this afternoon and evening showers and thunderstorms developed generally from extreme southeastern Pima county and across eastern Santa Cruz county. These showers and storms then moved rapidly northwest across parts of the Tucson metro where they caused damage, with power lines and trees down earlier this evening, mainly in the area from 1st Ave to Campbell Ave and from River to Prince. In addition, moderate to heavy rainfall occurred in this same general area, with amounts ranging from around 0.50 -0.80 inches, with only an isolated report above 1.25 inches. The Tucson Intl Airport reported a total of 0.11 inches so far for the day. Radar mosaic from around the region is detecting a batch of light rain that extends across much of northeast Pima county and further to the southeast into extreme eastern Santa Cruz county and southwest Cochise county. All of this activity will continue to march to the northwest during the remainder of the evening and will diminish in the process. The inherited POP forecast for the rest of tonight is still in good shape, so no changes are planned at this time. However, will continue to monitor satellite and radar trends and will make adjustments if warranted. As of 04Z (9 PM MST), temperatures across the region ranged from the upper 60s to the mid 80s, with the Tucson Intl Airport reporting a temp of 80 degs, after reaching an afternoon high temp of 102 degs, which was exactly normal for this date. The rainfall resulted in cooling temperatures in several locations, especially for the Tucson metro, so will make some adjustments to the short term hourly temperature grids to reflect the most recent trends. For details beyond tonight, please refer to the previous discussion below. && .AVIATION...VALID THRU 28/06Z. Isolated to scattered -TSRA/-SHRA. The best timing for -TSRA/-SHRA is mostly until around 27/08Z. Isolated -SHRA/-TSRA will still be possible area-wide late tonight into early Monday afternoon. Otherwise, cloud decks generally ranging from 10k-15K FT MSL, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated showers and thunderstorms will remain possible through the rest of this evening and overnight. Greater coverage of showers and thunderstorms should then occur Monday through next Saturday. Otherwise, daytime minimum relative humidity values will generally range from the mid teens to around 30 percent with fair to good nighttime recovery. 20-foot winds into Monday as well as Thursday through Saturday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east at 5-15 mph with gusts of 15-20 mph. The strongest speeds Tuesday and Wednesday should prevail from shortly after sunrise into the early afternoon hours. && .PREV DISCUSSION...Weak subsidence behind a minor mid level feature shifting north of the area will probably limit thunderstorms to mainly mountain areas Monday. A deeper and stronger fetch around high pressure reconsolidating to our east should push our thunderstorm coverage up as we reinforce available moisture and draw in weak inflections around the high. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ DISCUSSION...Mollere PREVIOUS DISCUSSION...Meyer/Rasmussen Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
  [top] Area Forecast Discussion National Weather Service Flagstaff AZ 857 PM MST SUN JUN 26 2016 .SYNOPSIS...On Monday, expect scattered showers and thunderstorms, primarily along and south of the Mogollon Rim. Strong, gusty winds are possible near any storms. Beginning Tuesday, monsoonal moisture is forecast to spread across all of northern Arizona leading to daily chances for showers and thunderstorms through the week. && .DISCUSSION... Only isolated and generally light showers are expected to continue this evening and overnight. Additional storm development is likely by late Monday morning. && .PREV DISCUSSION /406 PM MST/...So far today, shower and thunderstorm activity has generally occurred along and south of a line from Window Rock to Heber-Overgaard. This area will likely continue to be the focus for shower activity today, although some showers may expand westward a bit to include Payson and Clints Well this afternoon and evening. On Monday, increasing moisture is forecast along and south of the Mogollon Rim. This will lead to better chances for showers and thunderstorms there. These storms will once again be high based, so strong outflow winds will be the primary hazard. Beginning Tuesday, high pressure in place near the Four Corners is forecast to lead to an active monsoon pattern. A moist easterly flow will transition to a moist southerly wind around the middle of the week. This will draw deeper moisture into the region leading to increasing chances for showers and thunderstorms across all of northern Arizona. This moisture is expected to remain in place over the following days causing daily chances for showers and thunderstorms through the remainder of the week. && .AVIATION...For the 06Z Package...Isolated to scattered showers and thunderstorms expect to develop mainly southeast of a KFLG- KRQE line after 18Z Monday. Otherwise, expect VFR conditions. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect deeper moisture with increasing coverage in showers and thunderstorms Monday and Tuesday. Storm motion Monday will generally be from southeast to northwest and south to north on Tuesday. Expect erratic and gusty winds near any showers and storms. Wednesday through Friday...An active wet Monsoon weather pattern is expected with numerous showers and thunderstorms each day across northern Arizona. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...KD/RR AVIATION...KD FIRE WEATHER...MAS For Northern Arizona weather information visit weather.gov/flagstaff
  [top] Area Forecast Discussion National Weather Service Phoenix AZ 730 PM MST SUN JUN 26 2016 .SYNOPSIS... High pressure will move somewhat north and east of Arizona this week allowing warm temperatures to prevail, but also bring a couple of weather disturbances through the state. An increase in monsoon moisture will accompany these weather systems providing a threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... A well defined circulation center was quite evident in WV imagery across far northern Sonora this evening with stronger ascent and upper divergent signatures analyzed throughout SE AZ. 00Z KTWC sampled rather modest Sfc-H7 8 g/kg mixing ratios, however deep layer moisture flux has advected more favorable 10-11 g/kg profiles northward per objective analysis. Given the general UVV and weakly capped MLCapes around 500 J/kg, more robust convection has developed along the I-19 corridor. Closer towards central AZ, reduced daytime insolation and lower moisture values (closer to 7 g/kg mixing ratios) have yielded negligible instability despite relatively steep midlevel lapse rates. Thus, while virga/sprinkles/very light showers may be possible around the Phoenix metro, convection moving north may meet a fate of dissipation. Will continue to monitor trends through the evening, and would be most concerned about stronger outflows and dust production versus actual storms. One area of somewhat more concern may be through SW AZ where some more palpable instability has been analyzed, and vorticity/divergence fields will translate during the overnight. Several deterministic models and ensemble means suggest midlevel moisture lifted towards a steeper lapse rate environment while low level T/Td spreads narrow. There was enough evidence presented in models and analysis to increase pops and mention showers through the SW parts of the CWA later tonight. Otherwise, made some substantial changes to hourly temperatures based on current trends which were much cooler than previously advertised. && .PREVIOUS DISCUSSION... /240 PM MST SUN JUN 26 2016/ Monday through Saturday... The forecast becomes very complicated this week with respect to shower/thunderstorm potential, coverage, and intensity - mainly across portions of southwest and south central AZ. In other words, can we call it quasi-unsettled this week? We know the monsoon moisture boundary arrived in southeast AZ the past couple of days, and is forecast to spread west and north across the remainder of southern and central AZ this week. And normally this time of year once the moistures in place it should be like clockwork, i.e., first afternoon mountain thunderstorms, then by evening drifting toward the desert edge including developing on convective outflows and/or outflow collisions. Not this week, there is too much going on in the mid and upper atmosphere. For example, the last vestiges of the northwest Mexico inverted trof will move into the region Monday afternoon. More cyclonic flow over southern CA will aid in a threat of thunderstorms over the Joshua Tree National Park mountains, while difluent flow aloft in southwest and south central AZ generates convective potential as well. But a caveat, extensive mid/high clouds associated with the inverted trof axis may cut down on afternoon heating and the convective potential in the south central AZ Monday. And for Tuesday and Tuesday night, while 300/250 mb flows become southwesterly, a developing 500 mb easterly flow advects a weak mid level disturbance from New Mexico into southeast and south Central AZ late Tuesday afternoon and night. 500 mb disturbances usually spark overnight convection under very moist conditions. Therefore there is much uncertainty, and we can go on and on for Wednesday through Saturday. Therefore, the best approach is to call is quasi-unsettled, or a broad brush approach to shower/thunderstorm potential since 1) the monsoon moisture will be in place, and 2) models will no doubt have trouble forecasting any minor perturbations in this developing convoluted flow aloft. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Low confidence forecast through Monday afternoon as wind direction/shifts will be dictated by outflow boundaries traveling from storms more removed from terminal sites. Southwest winds this evening will shift to an easterly direction earlier than typical due to outflow propagating from eastern AZ, but timing is very uncertain. Cigs 12K-15K ft and occasional virga will be common through Monday morning. Much better chances for stronger east/northeast outflow winds will arrive later Monday afternoon. Actual storms may not survive to lower elevations, though mountain obscuration, blowing dust, and frequent lightning for arrivals/departures to the east may be problematic. Southeast California/Southwest Arizona including KIPL and KBLH: Cigs in a 10K-15K ft will increase through Monday with occasional virga, and possibly a few showers reaching the ground at KIPL. While a south to southeast sfc wind will be preferred, periods of variability will be common Monday morning (especially around showers). A few stronger gusts may also be possible for brief periods. Forecast confidence is only moderate. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool" with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...MO/Vasquez AVIATION...MO FIRE WEATHER...Hernandez
Area Forecast Discussion National Weather Service Phoenix AZ 730 PM MST SUN JUN 26 2016 .SYNOPSIS... High pressure will move somewhat north and east of Arizona this week allowing warm temperatures to prevail, but also bring a couple of weather disturbances through the state. An increase in monsoon moisture will accompany these weather systems providing a threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... A well defined circulation center was quite evident in WV imagery across far northern Sonora this evening with stronger ascent and upper divergent signatures analyzed throughout SE AZ. 00Z KTWC sampled rather modest Sfc-H7 8 g/kg mixing ratios, however deep layer moisture flux has advected more favorable 10-11 g/kg profiles northward per objective analysis. Given the general UVV and weakly capped MLCapes around 500 J/kg, more robust convection has developed along the I-19 corridor. Closer towards central AZ, reduced daytime insolation and lower moisture values (closer to 7 g/kg mixing ratios) have yielded negligible instability despite relatively steep midlevel lapse rates. Thus, while virga/sprinkles/very light showers may be possible around the Phoenix metro, convection moving north may meet a fate of dissipation. Will continue to monitor trends through the evening, and would be most concerned about stronger outflows and dust production versus actual storms. One area of somewhat more concern may be through SW AZ where some more palpable instability has been analyzed, and vorticity/divergence fields will translate during the overnight. Several deterministic models and ensemble means suggest midlevel moisture lifted towards a steeper lapse rate environment while low level T/Td spreads narrow. There was enough evidence presented in models and analysis to increase pops and mention showers through the SW parts of the CWA later tonight. Otherwise, made some substantial changes to hourly temperatures based on current trends which were much cooler than previously advertised. && .PREVIOUS DISCUSSION... /240 PM MST SUN JUN 26 2016/ Monday through Saturday... The forecast becomes very complicated this week with respect to shower/thunderstorm potential, coverage, and intensity - mainly across portions of southwest and south central AZ. In other words, can we call it quasi-unsettled this week? We know the monsoon moisture boundary arrived in southeast AZ the past couple of days, and is forecast to spread west and north across the remainder of southern and central AZ this week. And normally this time of year once the moistures in place it should be like clockwork, i.e., first afternoon mountain thunderstorms, then by evening drifting toward the desert edge including developing on convective outflows and/or outflow collisions. Not this week, there is too much going on in the mid and upper atmosphere. For example, the last vestiges of the northwest Mexico inverted trof will move into the region Monday afternoon. More cyclonic flow over southern CA will aid in a threat of thunderstorms over the Joshua Tree National Park mountains, while difluent flow aloft in southwest and south central AZ generates convective potential as well. But a caveat, extensive mid/high clouds associated with the inverted trof axis may cut down on afternoon heating and the convective potential in the south central AZ Monday. And for Tuesday and Tuesday night, while 300/250 mb flows become southwesterly, a developing 500 mb easterly flow advects a weak mid level disturbance from New Mexico into southeast and south Central AZ late Tuesday afternoon and night. 500 mb disturbances usually spark overnight convection under very moist conditions. Therefore there is much uncertainty, and we can go on and on for Wednesday through Saturday. Therefore, the best approach is to call is quasi-unsettled, or a broad brush approach to shower/thunderstorm potential since 1) the monsoon moisture will be in place, and 2) models will no doubt have trouble forecasting any minor perturbations in this developing convoluted flow aloft. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Low confidence forecast through Monday afternoon as wind direction/shifts will be dictated by outflow boundaries traveling from storms more removed from terminal sites. Southwest winds this evening will shift to an easterly direction earlier than typical due to outflow propagating from eastern AZ, but timing is very uncertain. Cigs 12K-15K ft and occasional virga will be common through Monday morning. Much better chances for stronger east/northeast outflow winds will arrive later Monday afternoon. Actual storms may not survive to lower elevations, though mountain obscuration, blowing dust, and frequent lightning for arrivals/departures to the east may be problematic. Southeast California/Southwest Arizona including KIPL and KBLH: Cigs in a 10K-15K ft will increase through Monday with occasional virga, and possibly a few showers reaching the ground at KIPL. While a south to southeast sfc wind will be preferred, periods of variability will be common Monday morning (especially around showers). A few stronger gusts may also be possible for brief periods. Forecast confidence is only moderate. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool" with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...MO/Vasquez AVIATION...MO FIRE WEATHER...Hernandez
Area Forecast Discussion National Weather Service Flagstaff AZ 406 PM MST SUN JUN 26 2016 .SYNOPSIS...On Monday, there will be enough moisture in place over central and eastern Arizona to cause scattered showers and thunderstorms, primarily along and south of the Mogollon Rim. Strong, gusty winds are possible near any storms. Beginning Tuesday, monsoonal moisture is forecast to spread across all of northern Arizona leading to daily chances for showers and thunderstorms through the week. && .DISCUSSION...So far today, shower and thunderstorm activity has generally occurred along and south of a line from Window Rock to Heber-Overgaard. This area will likely continue to be the focus for shower activity today, although some showers may expand westward a bit to include Payson and Clints Well this afternoon and evening. On Monday, increasing moisture is forecast along and south of the Mogollon Rim. This will lead to better chances for showers and thunderstorms there. These storms will once again be high based, so strong outflow winds will be the primary hazard. Beginning Tuesday, high pressure in place near the Four Corners is forecast to lead to an active monsoon pattern. A moist easterly flow will transition to a moist southerly wind around the middle of the week. This will draw deeper moisture into the region leading to increasing chances for showers and thunderstorms across all of northern Arizona. This moisture is expected to remain in place over the following days causing daily chances for showers and thunderstorms through the remainder of the week. && .AVIATION...For the 00Z Package...Isolated to scattered showers and thunderstorms with possible wind gusts to 40kts from KFLG-KRQE southeast until around 02z. Storms will be possible after 17Z over all of northern Arizona. Otherwise, expect VFR conditions. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect deeper moisture with increasing coverage in showers and thunderstorms Monday and Tuesday. Storm motion Monday will generally be from southeast to northwest and south to north on Tuesday. Expect erratic and gusty winds near any showers and storms. Wednesday through Friday...An active, wet Monsoon weather pattern is expected with numerous showers and thunderstorms each day across northern Arizona. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...RR AVIATION...MAS FIRE WEATHER...MAS For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 336 PM MST SUN JUN 26 2016 .SYNOPSIS...Plenty of moisture around this week with an increasing chance of mainly afternoon and evening showers and thunders across Southeast Arizona. && DISCUSSION...Convection is finally firing over expected areas, including areas southeast through southwest of Tucson as well as the east central mountains (northern Graham and Greenlee counties). We had a delays in initiation due to morning cloud cover as well as a bit more convective inhibition to overcome as per the KTWC morning sounding. So the strong outflow from the southern Mogollon Rim is just now pushing southwest into valley locations of Graham county, and it doesn`t really look as strong as the increasing mid level easterly flow suggested earlier. Development across southern areas is increasing, but not anything to write home about either. We may still have some mid level CAPE for an outflow to tap into later this evening, so more debris to contend with early Monday morning. Weak subsidence behind a minor mid level feature shifting north of the area will probably limit thunderstorms to mainly mountain areas Monday. A deeper and stronger fetch around high pressure reconsolidating to our east should push our thunderstorm coverage up as we reinforce available moisture and draw in weak inflections around the high. && AVIATION...VALID THRU 28/00Z. Isolated to scattered -TSRA/-SHRA. The best timing for TSRA is mostly from 20Z this afternoon until 27/08Z this evening. Brief wind gusts to near 40 kts and MVFR conditions due to reduced visibilities will be possible with the stronger TSRA. Isolated -SHRA/-TSRA will be possible area-wide late tonight into early Monday afternoon. Otherwise, cloud decks generally ranging from 10k- 15k ft MSL, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && FIRE WEATHER...Expect isolated to scattered showers and thunderstorms this afternoon and evening. Greater coverage of showers and thunderstorms should then occur Monday through next Saturday. Otherwise, daytime minimum relative humidity values will generally range from the mid teens to around 30 percent with fair to good nighttime recovery. 20-foot winds into Monday as well as Thursday through Saturday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east at 5-15 mph with gusts of 15-20 mph. The strongest speeds Tuesday and Wednesday should prevail from shortly after sunrise into the early afternoon hours. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Meyer/Rasmussen Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Tucson AZ 336 PM MST SUN JUN 26 2016 .SYNOPSIS...Plenty of moisture around this week with an increasing chance of mainly afternoon and evening showers and thunders across Southeast Arizona. && DISCUSSION...Convection is finally firing over expected areas, including areas southeast through southwest of Tucson as well as the east central mountains (northern Graham and Greenlee counties). We had a delays in initiation due to morning cloud cover as well as a bit more convective inhibition to overcome as per the KTWC morning sounding. So the strong outflow from the southern Mogollon Rim is just now pushing southwest into valley locations of Graham county, and it doesn`t really look as strong as the increasing mid level easterly flow suggested earlier. Development across southern areas is increasing, but not anything to write home about either. We may still have some mid level CAPE for an outflow to tap into later this evening, so more debris to contend with early Monday morning. Weak subsidence behind a minor mid level feature shifting north of the area will probably limit thunderstorms to mainly mountain areas Monday. A deeper and stronger fetch around high pressure reconsolidating to our east should push our thunderstorm coverage up as we reinforce available moisture and draw in weak inflections around the high. && AVIATION...VALID THRU 28/00Z. Isolated to scattered -TSRA/-SHRA. The best timing for TSRA is mostly from 20Z this afternoon until 27/08Z this evening. Brief wind gusts to near 40 kts and MVFR conditions due to reduced visibilities will be possible with the stronger TSRA. Isolated -SHRA/-TSRA will be possible area-wide late tonight into early Monday afternoon. Otherwise, cloud decks generally ranging from 10k- 15k ft MSL, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && FIRE WEATHER...Expect isolated to scattered showers and thunderstorms this afternoon and evening. Greater coverage of showers and thunderstorms should then occur Monday through next Saturday. Otherwise, daytime minimum relative humidity values will generally range from the mid teens to around 30 percent with fair to good nighttime recovery. 20-foot winds into Monday as well as Thursday through Saturday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east at 5-15 mph with gusts of 15-20 mph. The strongest speeds Tuesday and Wednesday should prevail from shortly after sunrise into the early afternoon hours. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Meyer/Rasmussen Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Phoenix AZ 240 PM SUN JUN 26 2016 .SYNOPSIS... A very warm air mass will keep temperatures above normal through at least the first half of the week. A increase in monsoon moisture is also expected, and will provide a slight threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... Tonight... The inverted trof so noticeable on vapor imagery just south of the AZ border developed an west-east deformation/stretching zone replete with considerable mid/high level cloudiness. Cloudiness was able to retard the heating curve and defer any precip to virga or light showers with the dense clouds. More is expected overnight. However there are a few afternoon thunderstorms in the less cloudy areas of the White Mountains, just west of Nogales along the Mexican border, and in far southeast AZ at 2 pm mst. Monday through Saturday The forecast becomes very complicated this week with respect to shower/thunderstorm potential, coverage, and intensity, mainly across portions of southwest and south central AZ. In other words, can we call it quasi-unsettled this week? We know the monsoon moisture boundary arrived in southeast AZ the past couple of days, and is forecast to spread west and north across the remainder of southern and central AZ this week. And, normally this time of year once the moistures in place it should be like clock-work right, i.e., first afternoon mountain thunderstorms then by evening drifting toward the desert edge, including developing on convective outflows and/or outflow collisions. Not this week, there is too much going on in the mid and upper atmosphere. For example, the last vestiges of the northwest Mexico inverted trof will move into the region Monday afternoon. More cyclonicity over southern CA will develop a threat of thunderstorms over the Joshua Tree National Park mountains, while difluent flow aloft in southwest and south central AZ generates convective potential as well. But a caveat, extensive mid/high clouds associated with the inverted trof axis may cut down on afternoon heating and the convective potential in the south central AZ Monday. And for Tuesday and Tuesday night, while 300/250 mb flows become southwesterly, a developing 500 mb easterly flow advects a weak mid level disturbance from New Mexico into southeast and south Central AZ late Tuesday afternoon and night. 500 mb disturbances usually spark overnight convection under very moist conditions. Therefore there is much uncertainty, and we can go on and on for Wednesday through Saturday. Therefore the best approach is to call is quasi-unsettled, or a broad brush approach to shower/thunderstorm potential since 1) the monsoon moisture will be in place, and 2) models will no doubt have trouble forecasting any minor perturbations in this developing convoluted flow aloft. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Showers moving in from the southeast have caused winds to shift to a southeasterly direction this afternoon over Phoenix terminals. With more activity in southeast AZ still propagating to the northwest, anticipate that these southeasterly winds will stick around for another hour or so before shifting temporarily back to the west around 22Z. Speeds will remain around 10 kts, however cannot rule out gusty erratic winds and blowing dust from distant south and east AZ storms for the remainder of the day at Phoenix terminals. However, low confidence in exact spatial and temporal coverage precludes mention in 18Z TAF. Broken to overcast mid to high clouds aoa 10kft will continue to advect into the region for the remainder of the day before decreasing in coverage early tomorrow morning. Southeast California/Southwest Arizona including KIPL and KBLH: Skies will remain mostly clear with a few passing high clouds around 15-20 kft. Winds will remain out of the south at KBLH and out of the southeast at KIPL, with speeds generally around 10-15 kts accompanied by a few afternoon gusts up to 20 to 25 kts. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool," with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...Vasquez AVIATION...Hernandez FIRE WEATHER...Hernandez
Area Forecast Discussion National Weather Service Flagstaff AZ 940 AM MST SUN JUN 26 2016 .SYNOPSIS...Dry and hot weather will persist across far western Arizona today. Mid level moisture will remain over central and eastern Arizona through Monday, and bring widely scattered showers and thunderstorms. Strong, gusty winds are possible near any storms. Monsoonal moisture to increase and spread across northern Arizona on Tuesday, with increasing daytime shower and thunderstorm activity lasting through the week. && .DISCUSSION...For today, the highest moisture and best chances for showers and thunderstorms will be along and south of the White Mountains and the eastern Mogollon Rim. Elsewhere, drier air and more stable conditions will limit convective activity. Slight chances for showers are forecast along the western Mogollon Rim, including the city of Flagstaff. This seems reasonable as an extensive cumulus field is expected to develop with heating. As highlighted in the previous forecast discussion, today`s storms will once again be high-based leading to the potential for strong outflows from collapsing storms. In terms of forecast updates, the current forecast appears to be on track and no short term updates are anticipated at this time. && .PREV DISCUSSION /303 AM MST/... Northern Arizona will be slowly transitioning to a monsoon thunderstorm pattern over the next two days. Strong and gusty outflow winds should be expected near any storms or virga. The Flagstaff airport did have 2 periods of outflow wind gusts to 48 and 47 mph yesterday, an indication of outflow speeds possible through Monday afternoon. Satellite imagery this morning shows the monsoonal moisture plume running from NW Mexico through Tucson then northeastward through New Mexico. Satellite derived pw values are up to near 1.5 inches around Tuscon this morning. Models remain consistent in showing mid level easterly flow increasing across central and southern AZ today and this will allow moisture to slowly increase across areas along and south of I-40 through Monday. Areas along the Utah border to remain hot and nearly cloud free today as this area is under the high pressure circulation center. Starting Tuesday, models are in good agreement with moist easterly flow through Wednesday morning becoming light southerly through Wednesday. Monsoonal moisture to remain overhead through the week and daytime precip chances were nudged upward a few points along the Mogollon Rim. Max temps to cool to near normal for dates starting Wednesday. && .AVIATION...For the 18Z Package...Isolated to scattered showers and thunderstorms with possible gusts to 40kts will redevelop from KFLG- KRQE southeast this afternoon and evening until around 02z. Otherwise, expect VFR conditions. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Monsoon moisture will slowly increase northward each day. Expect deeper moisture with increasing coverage in showers and thunderstorms starting on Monday. Storm motion today and Monday will generally be from northeast to southwest. Expect erratic and gusty winds near any showers and storms. Tuesday through Thursday...An active wet Monsoon weather pattern is forecast with good shower and thunderstorm coverage each day across northern Arizona. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...RR/DL AVIATION...MAS FIRE WEATHER...MCS For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 940 AM MST SUN JUN 26 2016 .SYNOPSIS...We now have enough moisture for isolated to scattered showers and thunderstorms this weekend. A more favorable flow regime will then provide increased coverage of showers and thunderstorms Monday through next Saturday. && .DISCUSSION...Still plenty of debris cloud this morning with embedded light showers. This is going to slow the heating a bit with initial clearing underway in portions of Cochise and Santa Cruz counties. The 12Z KTWC sounding still has plenty of moisture at 1.4 inches precipitable water. The mid level easterly flow has already increased substantially accompanied by an increase in shear that should help to organize outflow activity this afternoon. The direction favors strong outflow off the Mogollon Rim through Graham county. Latest HRRR trends push 2 strong outflows westward, including the Rim shot and a second outflow from activity in Cochise county pushing west and northwestward. The 12z UofA WRF-NAM paints a similar scenario with the outflow from the Cochise county activity pushing through the Tucson Metro area around mid to late afternoon. Minor adjustments to increase activity in the east central mountains and subsequent outflow westward, otherwise we have solid forecast trends. Please see the previous discussion below for additional details. && .AVIATION...VALID THRU 27/18Z. Isolated to scattered -TSRA/-SHRA. The best timing for TSRA at the KTUS/KOLS/KDUG terminals is mostly from 20Z this afternoon until 27/02Z this evening. Brief wind gusts to near 40 kts and MVFR conditions due to reduced visibilities will be possible with the stronger TSRA. Isolated -SHRA/-TSRA will be possible area-wide late tonight into early Monday morning. Otherwise, cloud decks generally ranging from 10k- 15k ft MSL, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect isolated to scattered showers and thunderstorms this afternoon and evening. Greater coverage of showers and thunderstorms should then occur Monday through next Saturday. Otherwise, daytime minimum relative humidity values will generally range from the mid teens to around 30 percent with fair to good nighttime recovery. 20-foot winds into Monday as well as Thursday through Saturday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east at 5-15 mph with gusts of 15-20 mph. The strongest speeds Tuesday and Wednesday should prevail from shortly after sunrise into the early afternoon hours. && .PREV DISCUSSION...The hi-res models suggest a scenario late tonight similar to that presently occurring across the area. In other words, a fairly widespread convective debris cloud cover with patches of sprinkles or light rain. 26/00Z GFS/ECMWF/CMC remained fairly similar regarding the synoptic scale pattern regime over the southwestern states starting Monday and continuing into early next weekend. Strong high pressure aloft Monday is progged to become centered over southern Utah. The GFS/ ECMWF depict an inverted trough to move into southwestern AZ from the northern Gulf of California Monday. Quick glance at the U/A WRF-NAM suggests that showers/tstms Monday afternoon would only be confined to the White Mountains and near the international border adjacent Santa Cruz/southern Pima County. Thus, there is the potential that Monday may be a "down day" perhaps due to subsidence on the eastern periphery of the aforementioned inverted trough. Forecast confidence in this particular detail is somewhat low, however. Thus, for this forecast package, have continued with scattered showers/tstms mainly from Tucson eastward/southward. Thereafter, not much daily variation in shower/tstm coverage is anticipated Tuesday into next Saturday. The deterministic GFS/ECMWF/ CMC were similar with maintaining fairly ample moisture across this forecast area. These solutions were similar with the continuation of a light ely/sely mid-level flow regime thru about Wednesday. The mid- level flow regime is then progged to become more wly/swly especially from Tucson westward starting Thursday and continuing into next Saturday. This subtle change may be sufficient for at least a slight downward trend in shower/tstm coverage, especially across western sections. Again, forecast confidence is fairly low at this time in stating that a definitive downward precip trend anywhere in the area is in the offing late this week. High temps for the Tucson metro area and locales west-to-northwest of Tucson will be near normal during much of this forecast period. However, daytime temps for locales east-to-south of Tucson, such as Safford, Douglas and Nogales will average a few degs below normal this week. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Meyer/Francis Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson Area Forecast Discussion National Weather Service Phoenix AZ 441 AM MST MON JUN 27 2016 .UPDATE...Updated Aviation Discussion... && .SYNOPSIS... High pressure will move somewhat north and east of Arizona this week allowing warm temperatures to prevail, but also bring a couple of weather disturbances through the state. An increase in monsoon moisture will accompany these weather systems providing a threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... Early this morning a well defined inverted trof could be seen moving westward across far southern/southwestern Arizona, and this feature was clearly evident in vapor imagery as well as recent plot data. Circulation around this feature was spreading increasing moisture westward and into the desert west of Phoenix; latest blended total precipitable water imagery indicated pwat values over 1.2 inches over portions of the southwest deserts. The inverted trof created good upper difluence across the central and western deserts and coupled with a good uvv field, a field of mostly light showers could be seen spreading into the western deserts at 2 am. As this inverted trof slowly pushes west today we can expect a continued slight chance of showers or thunderstorms across much of the lower deserts to the west of Phoenix including portions of SE California. Later this afternoon and evening across south central Arizona, the forcing becomes weaker behind the exiting inverted trof but there is weak southeast steering flow and sufficient deeper moisture and instability to allow for a 15-20 percent chance of mainly evening thunderstorms over the central deserts and a chance of storms over higher terrain east of Phoenix. This is supported by various mesoscale models such as the NMM6km. Clouds and moisture working across the lower deserts will keep high temps today mostly below the 110 degree mark, even over the far western deserts. Model guidance, including operational runs of the GFS and ECMWF, as well as ensemble guidance such as the GEFS and NAEFS, continue to call for a very monsoonal pattern to develop across the desert southwest starting Tuesday and continuing through the end of the work week. Initially the main upper high center forms near the four corners, setting up a deeper southeast steering flow over most of the area which will steadily transport increasing and deeper moisture westward over the lower deserts. PWAT values steadily climb and are forecast to exceed 1.5 inches across the main monsoon moisture corridor which sets up just east of the lower Colorado River Valley and extends into far eastern Arizona. The steering flow is favorable to bring mountain storms into the lower deserts, and from time to time there will be disturbances rotating around the main upper high which will serve to enhance thunderstorm coverage and intensity. Model guidance typically has a hard time with the exact timing and track of these features and we generally cannot place a lot of faith in them more than a day or two down the road. Overall we are looking at a rather broad brushed forecast with 10-20 percent chances of mainly afternoon and evening storms over the deserts mainly east of the lower CO river valley, and 30-40 percent chances across the higher terrain east of Phoenix. Later in the week the upper high starts to shift towards the southeast and steering flow becomes more southerly. Still, moisture remains high and in fact the GFS calls for PWAT value in the central deserts to approach 2 inches later Thursday into Friday. This would suggest a much better chance for heavy rains to accompany any storms that develop. Of course, as moisture increases the temperatures will fall off and by midweek high temps across south central Arizona will approach and then fall below seasonal normals. It will stay a bit hotter further west where the atmosphere is a bit drier, with highs over 110 expected for much of the week. During the upcoming weekend, as low pressure sets up along the Pacific northwest coast, and as the high shifts further to the southeast, the upper streamline fields and steering flow turn towards the southwest over most of the area. This starts to bring in drier air from the southwest and we can expect rain chances to diminish from west to east with time. By Sunday afternoon, thunderstorm chances look to be confined mostly to higher terrain areas east and southeast of central Phoenix as skies become mostly sunny over the central and western deserts. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Much better chances for stronger east/northeast outflow winds are likely late this afternoon, but confidence in timing is still somewhat low. Actual storms may not survive to lower elevations, though mountain obscuration, blowing dust, and frequent lightning for arrivals/departures to the east may be problematic. Persistent easterly winds this evening should occur earlier this normal. Sct to bkn mid and high clouds should persist through Tuesday morning. Southeast California/Southwest Arizona including KIPL and KBLH: Cigs in a 10K-15K ft range will persist through this afternoon with some gradual thinning of cloud cover tonight. Virga showers this morning over the terminals are likely and should dissipate by around noon. While a south to southeast sfc wind will be preferred through this afternoon, winds will eventually become more southwesterly this evening. A few stronger gusts may also be possible for brief periods, especially this evening. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool" with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...CB AVIATION...Kuhlman FIRE WEATHER...Hernandez
  [top] Area Forecast Discussion National Weather Service Flagstaff AZ 400 AM MST MON JUN 27 2016 .SYNOPSIS...Expect scattered showers and thunderstorms today along and south of the Mogollon Rim, and isolated storms elsewhere. Strong, gusty winds are possible near any storms. Beginning Tuesday, monsoonal moisture is forecast to increase across all of northern Arizona leading to daily chances for showers and thunderstorms through the week. && .DISCUSSION... Moisture is increasing across central and eastern AZ this morning per satellite pw estimates and sfc dew point data. The highest pw values should remain along and south of I-40 today, while shallow sfc moisture has made it as far north as Page this morning. Thus scattered showers and thunderstorms are expected this afternoon and evening along the Mogollon Rim from Happy jack eastward with isolated storm coverage elsewhere. Most of the storms will be high based, with strong outflow winds probable from them. Storm motion today from east to west. On Tuesday, high pressure aloft will become centered near the Four Corners. We will see a moist easterly flow Tuesday that transitions to a moist southerly wind around the middle of the week. This will draw deeper moisture into the region leading to increasing chances for showers and thunderstorms across all of northern Arizona. Expect better chances for measurable rainfall starting Wednesday. This moisture is expected to remain in place through at least Saturday bringing daily chances for showers and thunderstorms. && .AVIATION...For the 12Z Package...Scattered TSRA will develop from KFLG - KRQE south this afternoon and evening with isolated TSRA possible elsewhere. Gusty winds near 40 kts and moderate rain possible in storms. Otherwise, expect VFR conditions. Activity decreasing aft 06Z though a few showers may continue overnight. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...An increase in moisture will lead to scattered thunderstorms from the Mogollon Rim to the Chuska Mountains south this afternoon and evening. Isolated storms are possible elsewhere. Storm motion will be from east to west today. Moisture increases into Tuesday with scattered storms expected. Storm motion becomes more south to north on Tuesday. Expect erratic and gusty winds near any showers and storms. Wednesday through Friday...An active wet Monsoon weather pattern is expected with scattered showers and thunderstorms each day across northern Arizona. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...DL AVIATION...MCS FIRE WEATHER...MCS For Northern Arizona weather information visit weather.gov/flagstaff
  [top] Area Forecast Discussion National Weather Service Tucson AZ 345 AM MST MON JUN 27 2016 .SYNOPSIS...Expect scattered showers and thunderstorms into next weekend. Daytime temperatures will be near normal or a few degrees below normal, depending upon location. && .DISCUSSION...An expansive area of high pressure aloft will prevail over the southwest states during the next several days, with the upper high to generally be centered near the Four Corners region. The flow around this high pressure in combination with adequate moisture will translate into isolated to scattered showers and thunderstorms through Tuesday. 27/00Z GFS/ECMWF/CMC, the 27/03Z SREF and the 27/00Z Univ. of AZ WRF- NAM/GFS suggest the potential for increased coverage of showers and thunderstorms starting Wednesday and continuing through at least Friday. These solutions particularly point toward Wednesday as being quite active, as a low-level convergence axis becomes established over central portions of this forecast area. The models also depict a light mid-level northeasterly steering flow should be present. Thus, chance-category PoPs exists Wednesday across much of southeast AZ. Showers and thunderstorms initiating northeast of Tucson Wednesday would have an increased potential to produce strong and gusty outflows as they move southwestward. Ample moisture in combination with a fairly deep sely/sly flow regime will likely maintain scattered coverage of showers and thunderstorms Thursday and Friday, with the best chance of precip to occur during the afternoon/ evening hours. The deterministic GFS/ECMWF were then similar with depicting a drying trend across western sections next weekend. This drier wly/nwly flow aloft regime west of Tucson is in response to a broad upper ridge extending from Texas to Florida, and a weak upper trough near the west coast. Enough moisture will remain from Tucson eastward/ southward to the New Mexico/international borders to justify isolated to scattered showers and thunderstorms Saturday and Sunday. Per coord with WFO PSR, did opt for precip-free conditions next Sunday across western Pima County. High temps into next weekend will be quite close to seasonal normals or a few degrees below normal, depending upon location. && .AVIATION...VALID THRU 28/12Z. Isolated -SHRA will prevail thru 15Z-17Z this morning, then isolated to scattered -TSRA/-SHRA this afternoon and evening. Brief wind gusts to near 40 kts and MVFR conditions due to reduced visibilities will be possible with the stronger TSRA. Isolated -SHRA/-TSRA will then occur late tonight into early Tuesday morning. Otherwise, cloud decks generally ranging from 10k-15k ft msl, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Scattered showers and thunderstorms will prevail into next weekend. 20-foot winds today as well as Thursday through Sunday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east to southeast at 5-15 mph with gusts of 15-20 mph. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson Francis
Area Forecast Discussion National Weather Service Phoenix AZ 310 AM MST MON JUN 27 2016 .SYNOPSIS... High pressure will move somewhat north and east of Arizona this week allowing warm temperatures to prevail, but also bring a couple of weather disturbances through the state. An increase in monsoon moisture will accompany these weather systems providing a threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... Early this morning a well defined inverted trof could be seen moving westward across far southern/southwestern Arizona, and this feature was clearly evident in vapor imagery as well as recent plot data. Circulation around this feature was spreading increasing moisture westward and into the desert west of Phoenix; latest blended total precipitable water imagery indicated pwat values over 1.2 inches over portions of the southwest deserts. The inverted trof created good upper difluence across the central and western deserts and coupled with a good uvv field, a field of mostly light showers could be seen spreading into the western deserts at 2 am. As this inverted trof slowly pushes west today we can expect a continued slight chance of showers or thunderstorms across much of the lower deserts to the west of Phoenix including portions of SE California. Later this afternoon and evening across south central Arizona, the forcing becomes weaker behind the exiting inverted trof but there is weak southeast steering flow and sufficient deeper moisture and instability to allow for a 15-20 percent chance of mainly evening thunderstorms over the central deserts and a chance of storms over higher terrain east of Phoenix. This is supported by various mesoscale models such as the NMM6km. Clouds and moisture working across the lower deserts will keep high temps today mostly below the 110 degree mark, even over the far western deserts. Model guidance, including operational runs of the GFS and ECMWF, as well as ensemble guidance such as the GEFS and NAEFS, continue to call for a very monsoonal pattern to develop across the desert southwest starting Tuesday and continuing through the end of the work week. Initially the main upper high center forms near the four corners, setting up a deeper southeast steering flow over most of the area which will steadily transport increasing and deeper moisture westward over the lower deserts. PWAT values steadily climb and are forecast to exceed 1.5 inches across the main monsoon moisture corridor which sets up just east of the lower Colorado River Valley and extends into far eastern Arizona. The steering flow is favorable to bring mountain storms into the lower deserts, and from time to time there will be disturbances rotating around the main upper high which will serve to enhance thunderstorm coverage and intensity. Model guidance typically has a hard time with the exact timing and track of these features and we generally cannot place a lot of faith in them more than a day or two down the road. Overall we are looking at a rather broad brushed forecast with 10-20 percent chances of mainly afternoon and evening storms over the deserts mainly east of the lower CO river valley, and 30-40 percent chances across the higher terrain east of Phoenix. Later in the week the upper high starts to shift towards the southeast and steering flow becomes more southerly. Still, moisture remains high and in fact the GFS calls for PWAT value in the central deserts to approach 2 inches later Thursday into Friday. This would suggest a much better chance for heavy rains to accompany any storms that develop. Of course, as moisture increases the temperatures will fall off and by midweek high temps across south central Arizona will approach and then fall below seasonal normals. It will stay a bit hotter further west where the atmosphere is a bit drier, with highs over 110 expected for much of the week. During the upcoming weekend, as low pressure sets up along the Pacific northwest coast, and as the high shifts further to the southeast, the upper streamline fields and steering flow turn towards the southwest over most of the area. This starts to bring in drier air from the southwest and we can expect rain chances to diminish from west to east with time. By Sunday afternoon, thunderstorm chances look to be confined mostly to higher terrain areas east and southeast of central Phoenix as skies become mostly sunny over the central and western deserts. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Low confidence forecast through Monday afternoon as wind direction/shifts will be dictated by outflow boundaries traveling from storms more removed from terminal sites. Southwest winds this evening will shift to an easterly direction earlier than typical due to outflow propagating from eastern AZ, but timing is very uncertain. Cigs 12K-15K ft and occasional virga will be common through Monday morning. Much better chances for stronger east/northeast outflow winds will arrive later Monday afternoon. Actual storms may not survive to lower elevations, though mountain obscuration, blowing dust, and frequent lightning for arrivals/departures to the east may be problematic. Southeast California/Southwest Arizona including KIPL and KBLH: Cigs in a 10K-15K ft will increase through Monday with occasional virga, and possibly a few showers reaching the ground at KIPL. While a south to southeast sfc wind will be preferred, periods of variability will be common Monday morning (especially around showers). A few stronger gusts may also be possible for brief periods. Forecast confidence is only moderate. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool" with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...CB AVIATION...MO FIRE WEATHER...Hernandez
Area Forecast Discussion National Weather Service Tucson AZ 915 PM MST SUN JUN 26 2016 .SYNOPSIS...Plenty of moisture around this week with an increasing chance of mainly afternoon and evening showers and thunders across Southeast Arizona. && .DISCUSSION...Earlier this afternoon and evening showers and thunderstorms developed generally from extreme southeastern Pima county and across eastern Santa Cruz county. These showers and storms then moved rapidly northwest across parts of the Tucson metro where they caused damage, with power lines and trees down earlier this evening, mainly in the area from 1st Ave to Campbell Ave and from River to Prince. In addition, moderate to heavy rainfall occurred in this same general area, with amounts ranging from around 0.50 -0.80 inches, with only an isolated report above 1.25 inches. The Tucson Intl Airport reported a total of 0.11 inches so far for the day. Radar mosaic from around the region is detecting a batch of light rain that extends across much of northeast Pima county and further to the southeast into extreme eastern Santa Cruz county and southwest Cochise county. All of this activity will continue to march to the northwest during the remainder of the evening and will diminish in the process. The inherited POP forecast for the rest of tonight is still in good shape, so no changes are planned at this time. However, will continue to monitor satellite and radar trends and will make adjustments if warranted. As of 04Z (9 PM MST), temperatures across the region ranged from the upper 60s to the mid 80s, with the Tucson Intl Airport reporting a temp of 80 degs, after reaching an afternoon high temp of 102 degs, which was exactly normal for this date. The rainfall resulted in cooling temperatures in several locations, especially for the Tucson metro, so will make some adjustments to the short term hourly temperature grids to reflect the most recent trends. For details beyond tonight, please refer to the previous discussion below. && .AVIATION...VALID THRU 28/06Z. Isolated to scattered -TSRA/-SHRA. The best timing for -TSRA/-SHRA is mostly until around 27/08Z. Isolated -SHRA/-TSRA will still be possible area-wide late tonight into early Monday afternoon. Otherwise, cloud decks generally ranging from 10k-15K FT MSL, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated showers and thunderstorms will remain possible through the rest of this evening and overnight. Greater coverage of showers and thunderstorms should then occur Monday through next Saturday. Otherwise, daytime minimum relative humidity values will generally range from the mid teens to around 30 percent with fair to good nighttime recovery. 20-foot winds into Monday as well as Thursday through Saturday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east at 5-15 mph with gusts of 15-20 mph. The strongest speeds Tuesday and Wednesday should prevail from shortly after sunrise into the early afternoon hours. && .PREV DISCUSSION...Weak subsidence behind a minor mid level feature shifting north of the area will probably limit thunderstorms to mainly mountain areas Monday. A deeper and stronger fetch around high pressure reconsolidating to our east should push our thunderstorm coverage up as we reinforce available moisture and draw in weak inflections around the high. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ DISCUSSION...Mollere PREVIOUS DISCUSSION...Meyer/Rasmussen Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Flagstaff AZ 857 PM MST SUN JUN 26 2016 .SYNOPSIS...On Monday, expect scattered showers and thunderstorms, primarily along and south of the Mogollon Rim. Strong, gusty winds are possible near any storms. Beginning Tuesday, monsoonal moisture is forecast to spread across all of northern Arizona leading to daily chances for showers and thunderstorms through the week. && .DISCUSSION... Only isolated and generally light showers are expected to continue this evening and overnight. Additional storm development is likely by late Monday morning. && .PREV DISCUSSION /406 PM MST/...So far today, shower and thunderstorm activity has generally occurred along and south of a line from Window Rock to Heber-Overgaard. This area will likely continue to be the focus for shower activity today, although some showers may expand westward a bit to include Payson and Clints Well this afternoon and evening. On Monday, increasing moisture is forecast along and south of the Mogollon Rim. This will lead to better chances for showers and thunderstorms there. These storms will once again be high based, so strong outflow winds will be the primary hazard. Beginning Tuesday, high pressure in place near the Four Corners is forecast to lead to an active monsoon pattern. A moist easterly flow will transition to a moist southerly wind around the middle of the week. This will draw deeper moisture into the region leading to increasing chances for showers and thunderstorms across all of northern Arizona. This moisture is expected to remain in place over the following days causing daily chances for showers and thunderstorms through the remainder of the week. && .AVIATION...For the 06Z Package...Isolated to scattered showers and thunderstorms expect to develop mainly southeast of a KFLG- KRQE line after 18Z Monday. Otherwise, expect VFR conditions. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect deeper moisture with increasing coverage in showers and thunderstorms Monday and Tuesday. Storm motion Monday will generally be from southeast to northwest and south to north on Tuesday. Expect erratic and gusty winds near any showers and storms. Wednesday through Friday...An active wet Monsoon weather pattern is expected with numerous showers and thunderstorms each day across northern Arizona. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...KD/RR AVIATION...KD FIRE WEATHER...MAS For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Phoenix AZ 730 PM MST SUN JUN 26 2016 .SYNOPSIS... High pressure will move somewhat north and east of Arizona this week allowing warm temperatures to prevail, but also bring a couple of weather disturbances through the state. An increase in monsoon moisture will accompany these weather systems providing a threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... A well defined circulation center was quite evident in WV imagery across far northern Sonora this evening with stronger ascent and upper divergent signatures analyzed throughout SE AZ. 00Z KTWC sampled rather modest Sfc-H7 8 g/kg mixing ratios, however deep layer moisture flux has advected more favorable 10-11 g/kg profiles northward per objective analysis. Given the general UVV and weakly capped MLCapes around 500 J/kg, more robust convection has developed along the I-19 corridor. Closer towards central AZ, reduced daytime insolation and lower moisture values (closer to 7 g/kg mixing ratios) have yielded negligible instability despite relatively steep midlevel lapse rates. Thus, while virga/sprinkles/very light showers may be possible around the Phoenix metro, convection moving north may meet a fate of dissipation. Will continue to monitor trends through the evening, and would be most concerned about stronger outflows and dust production versus actual storms. One area of somewhat more concern may be through SW AZ where some more palpable instability has been analyzed, and vorticity/divergence fields will translate during the overnight. Several deterministic models and ensemble means suggest midlevel moisture lifted towards a steeper lapse rate environment while low level T/Td spreads narrow. There was enough evidence presented in models and analysis to increase pops and mention showers through the SW parts of the CWA later tonight. Otherwise, made some substantial changes to hourly temperatures based on current trends which were much cooler than previously advertised. && .PREVIOUS DISCUSSION... /240 PM MST SUN JUN 26 2016/ Monday through Saturday... The forecast becomes very complicated this week with respect to shower/thunderstorm potential, coverage, and intensity - mainly across portions of southwest and south central AZ. In other words, can we call it quasi-unsettled this week? We know the monsoon moisture boundary arrived in southeast AZ the past couple of days, and is forecast to spread west and north across the remainder of southern and central AZ this week. And normally this time of year once the moistures in place it should be like clockwork, i.e., first afternoon mountain thunderstorms, then by evening drifting toward the desert edge including developing on convective outflows and/or outflow collisions. Not this week, there is too much going on in the mid and upper atmosphere. For example, the last vestiges of the northwest Mexico inverted trof will move into the region Monday afternoon. More cyclonic flow over southern CA will aid in a threat of thunderstorms over the Joshua Tree National Park mountains, while difluent flow aloft in southwest and south central AZ generates convective potential as well. But a caveat, extensive mid/high clouds associated with the inverted trof axis may cut down on afternoon heating and the convective potential in the south central AZ Monday. And for Tuesday and Tuesday night, while 300/250 mb flows become southwesterly, a developing 500 mb easterly flow advects a weak mid level disturbance from New Mexico into southeast and south Central AZ late Tuesday afternoon and night. 500 mb disturbances usually spark overnight convection under very moist conditions. Therefore there is much uncertainty, and we can go on and on for Wednesday through Saturday. Therefore, the best approach is to call is quasi-unsettled, or a broad brush approach to shower/thunderstorm potential since 1) the monsoon moisture will be in place, and 2) models will no doubt have trouble forecasting any minor perturbations in this developing convoluted flow aloft. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Low confidence forecast through Monday afternoon as wind direction/shifts will be dictated by outflow boundaries traveling from storms more removed from terminal sites. Southwest winds this evening will shift to an easterly direction earlier than typical due to outflow propagating from eastern AZ, but timing is very uncertain. Cigs 12K-15K ft and occasional virga will be common through Monday morning. Much better chances for stronger east/northeast outflow winds will arrive later Monday afternoon. Actual storms may not survive to lower elevations, though mountain obscuration, blowing dust, and frequent lightning for arrivals/departures to the east may be problematic. Southeast California/Southwest Arizona including KIPL and KBLH: Cigs in a 10K-15K ft will increase through Monday with occasional virga, and possibly a few showers reaching the ground at KIPL. While a south to southeast sfc wind will be preferred, periods of variability will be common Monday morning (especially around showers). A few stronger gusts may also be possible for brief periods. Forecast confidence is only moderate. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool" with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...MO/Vasquez AVIATION...MO FIRE WEATHER...Hernandez
Area Forecast Discussion National Weather Service Phoenix AZ 730 PM MST SUN JUN 26 2016 .SYNOPSIS... High pressure will move somewhat north and east of Arizona this week allowing warm temperatures to prevail, but also bring a couple of weather disturbances through the state. An increase in monsoon moisture will accompany these weather systems providing a threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... A well defined circulation center was quite evident in WV imagery across far northern Sonora this evening with stronger ascent and upper divergent signatures analyzed throughout SE AZ. 00Z KTWC sampled rather modest Sfc-H7 8 g/kg mixing ratios, however deep layer moisture flux has advected more favorable 10-11 g/kg profiles northward per objective analysis. Given the general UVV and weakly capped MLCapes around 500 J/kg, more robust convection has developed along the I-19 corridor. Closer towards central AZ, reduced daytime insolation and lower moisture values (closer to 7 g/kg mixing ratios) have yielded negligible instability despite relatively steep midlevel lapse rates. Thus, while virga/sprinkles/very light showers may be possible around the Phoenix metro, convection moving north may meet a fate of dissipation. Will continue to monitor trends through the evening, and would be most concerned about stronger outflows and dust production versus actual storms. One area of somewhat more concern may be through SW AZ where some more palpable instability has been analyzed, and vorticity/divergence fields will translate during the overnight. Several deterministic models and ensemble means suggest midlevel moisture lifted towards a steeper lapse rate environment while low level T/Td spreads narrow. There was enough evidence presented in models and analysis to increase pops and mention showers through the SW parts of the CWA later tonight. Otherwise, made some substantial changes to hourly temperatures based on current trends which were much cooler than previously advertised. && .PREVIOUS DISCUSSION... /240 PM MST SUN JUN 26 2016/ Monday through Saturday... The forecast becomes very complicated this week with respect to shower/thunderstorm potential, coverage, and intensity - mainly across portions of southwest and south central AZ. In other words, can we call it quasi-unsettled this week? We know the monsoon moisture boundary arrived in southeast AZ the past couple of days, and is forecast to spread west and north across the remainder of southern and central AZ this week. And normally this time of year once the moistures in place it should be like clockwork, i.e., first afternoon mountain thunderstorms, then by evening drifting toward the desert edge including developing on convective outflows and/or outflow collisions. Not this week, there is too much going on in the mid and upper atmosphere. For example, the last vestiges of the northwest Mexico inverted trof will move into the region Monday afternoon. More cyclonic flow over southern CA will aid in a threat of thunderstorms over the Joshua Tree National Park mountains, while difluent flow aloft in southwest and south central AZ generates convective potential as well. But a caveat, extensive mid/high clouds associated with the inverted trof axis may cut down on afternoon heating and the convective potential in the south central AZ Monday. And for Tuesday and Tuesday night, while 300/250 mb flows become southwesterly, a developing 500 mb easterly flow advects a weak mid level disturbance from New Mexico into southeast and south Central AZ late Tuesday afternoon and night. 500 mb disturbances usually spark overnight convection under very moist conditions. Therefore there is much uncertainty, and we can go on and on for Wednesday through Saturday. Therefore, the best approach is to call is quasi-unsettled, or a broad brush approach to shower/thunderstorm potential since 1) the monsoon moisture will be in place, and 2) models will no doubt have trouble forecasting any minor perturbations in this developing convoluted flow aloft. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Low confidence forecast through Monday afternoon as wind direction/shifts will be dictated by outflow boundaries traveling from storms more removed from terminal sites. Southwest winds this evening will shift to an easterly direction earlier than typical due to outflow propagating from eastern AZ, but timing is very uncertain. Cigs 12K-15K ft and occasional virga will be common through Monday morning. Much better chances for stronger east/northeast outflow winds will arrive later Monday afternoon. Actual storms may not survive to lower elevations, though mountain obscuration, blowing dust, and frequent lightning for arrivals/departures to the east may be problematic. Southeast California/Southwest Arizona including KIPL and KBLH: Cigs in a 10K-15K ft will increase through Monday with occasional virga, and possibly a few showers reaching the ground at KIPL. While a south to southeast sfc wind will be preferred, periods of variability will be common Monday morning (especially around showers). A few stronger gusts may also be possible for brief periods. Forecast confidence is only moderate. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool" with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...MO/Vasquez AVIATION...MO FIRE WEATHER...Hernandez
Area Forecast Discussion National Weather Service Flagstaff AZ 406 PM MST SUN JUN 26 2016 .SYNOPSIS...On Monday, there will be enough moisture in place over central and eastern Arizona to cause scattered showers and thunderstorms, primarily along and south of the Mogollon Rim. Strong, gusty winds are possible near any storms. Beginning Tuesday, monsoonal moisture is forecast to spread across all of northern Arizona leading to daily chances for showers and thunderstorms through the week. && .DISCUSSION...So far today, shower and thunderstorm activity has generally occurred along and south of a line from Window Rock to Heber-Overgaard. This area will likely continue to be the focus for shower activity today, although some showers may expand westward a bit to include Payson and Clints Well this afternoon and evening. On Monday, increasing moisture is forecast along and south of the Mogollon Rim. This will lead to better chances for showers and thunderstorms there. These storms will once again be high based, so strong outflow winds will be the primary hazard. Beginning Tuesday, high pressure in place near the Four Corners is forecast to lead to an active monsoon pattern. A moist easterly flow will transition to a moist southerly wind around the middle of the week. This will draw deeper moisture into the region leading to increasing chances for showers and thunderstorms across all of northern Arizona. This moisture is expected to remain in place over the following days causing daily chances for showers and thunderstorms through the remainder of the week. && .AVIATION...For the 00Z Package...Isolated to scattered showers and thunderstorms with possible wind gusts to 40kts from KFLG-KRQE southeast until around 02z. Storms will be possible after 17Z over all of northern Arizona. Otherwise, expect VFR conditions. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect deeper moisture with increasing coverage in showers and thunderstorms Monday and Tuesday. Storm motion Monday will generally be from southeast to northwest and south to north on Tuesday. Expect erratic and gusty winds near any showers and storms. Wednesday through Friday...An active, wet Monsoon weather pattern is expected with numerous showers and thunderstorms each day across northern Arizona. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...RR AVIATION...MAS FIRE WEATHER...MAS For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 336 PM MST SUN JUN 26 2016 .SYNOPSIS...Plenty of moisture around this week with an increasing chance of mainly afternoon and evening showers and thunders across Southeast Arizona. && DISCUSSION...Convection is finally firing over expected areas, including areas southeast through southwest of Tucson as well as the east central mountains (northern Graham and Greenlee counties). We had a delays in initiation due to morning cloud cover as well as a bit more convective inhibition to overcome as per the KTWC morning sounding. So the strong outflow from the southern Mogollon Rim is just now pushing southwest into valley locations of Graham county, and it doesn`t really look as strong as the increasing mid level easterly flow suggested earlier. Development across southern areas is increasing, but not anything to write home about either. We may still have some mid level CAPE for an outflow to tap into later this evening, so more debris to contend with early Monday morning. Weak subsidence behind a minor mid level feature shifting north of the area will probably limit thunderstorms to mainly mountain areas Monday. A deeper and stronger fetch around high pressure reconsolidating to our east should push our thunderstorm coverage up as we reinforce available moisture and draw in weak inflections around the high. && AVIATION...VALID THRU 28/00Z. Isolated to scattered -TSRA/-SHRA. The best timing for TSRA is mostly from 20Z this afternoon until 27/08Z this evening. Brief wind gusts to near 40 kts and MVFR conditions due to reduced visibilities will be possible with the stronger TSRA. Isolated -SHRA/-TSRA will be possible area-wide late tonight into early Monday afternoon. Otherwise, cloud decks generally ranging from 10k- 15k ft MSL, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && FIRE WEATHER...Expect isolated to scattered showers and thunderstorms this afternoon and evening. Greater coverage of showers and thunderstorms should then occur Monday through next Saturday. Otherwise, daytime minimum relative humidity values will generally range from the mid teens to around 30 percent with fair to good nighttime recovery. 20-foot winds into Monday as well as Thursday through Saturday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east at 5-15 mph with gusts of 15-20 mph. The strongest speeds Tuesday and Wednesday should prevail from shortly after sunrise into the early afternoon hours. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Meyer/Rasmussen Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Tucson AZ 336 PM MST SUN JUN 26 2016 .SYNOPSIS...Plenty of moisture around this week with an increasing chance of mainly afternoon and evening showers and thunders across Southeast Arizona. && DISCUSSION...Convection is finally firing over expected areas, including areas southeast through southwest of Tucson as well as the east central mountains (northern Graham and Greenlee counties). We had a delays in initiation due to morning cloud cover as well as a bit more convective inhibition to overcome as per the KTWC morning sounding. So the strong outflow from the southern Mogollon Rim is just now pushing southwest into valley locations of Graham county, and it doesn`t really look as strong as the increasing mid level easterly flow suggested earlier. Development across southern areas is increasing, but not anything to write home about either. We may still have some mid level CAPE for an outflow to tap into later this evening, so more debris to contend with early Monday morning. Weak subsidence behind a minor mid level feature shifting north of the area will probably limit thunderstorms to mainly mountain areas Monday. A deeper and stronger fetch around high pressure reconsolidating to our east should push our thunderstorm coverage up as we reinforce available moisture and draw in weak inflections around the high. && AVIATION...VALID THRU 28/00Z. Isolated to scattered -TSRA/-SHRA. The best timing for TSRA is mostly from 20Z this afternoon until 27/08Z this evening. Brief wind gusts to near 40 kts and MVFR conditions due to reduced visibilities will be possible with the stronger TSRA. Isolated -SHRA/-TSRA will be possible area-wide late tonight into early Monday afternoon. Otherwise, cloud decks generally ranging from 10k- 15k ft MSL, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && FIRE WEATHER...Expect isolated to scattered showers and thunderstorms this afternoon and evening. Greater coverage of showers and thunderstorms should then occur Monday through next Saturday. Otherwise, daytime minimum relative humidity values will generally range from the mid teens to around 30 percent with fair to good nighttime recovery. 20-foot winds into Monday as well as Thursday through Saturday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east at 5-15 mph with gusts of 15-20 mph. The strongest speeds Tuesday and Wednesday should prevail from shortly after sunrise into the early afternoon hours. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Meyer/Rasmussen Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Phoenix AZ 240 PM SUN JUN 26 2016 .SYNOPSIS... A very warm air mass will keep temperatures above normal through at least the first half of the week. A increase in monsoon moisture is also expected, and will provide a slight threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... Tonight... The inverted trof so noticeable on vapor imagery just south of the AZ border developed an west-east deformation/stretching zone replete with considerable mid/high level cloudiness. Cloudiness was able to retard the heating curve and defer any precip to virga or light showers with the dense clouds. More is expected overnight. However there are a few afternoon thunderstorms in the less cloudy areas of the White Mountains, just west of Nogales along the Mexican border, and in far southeast AZ at 2 pm mst. Monday through Saturday The forecast becomes very complicated this week with respect to shower/thunderstorm potential, coverage, and intensity, mainly across portions of southwest and south central AZ. In other words, can we call it quasi-unsettled this week? We know the monsoon moisture boundary arrived in southeast AZ the past couple of days, and is forecast to spread west and north across the remainder of southern and central AZ this week. And, normally this time of year once the moistures in place it should be like clock-work right, i.e., first afternoon mountain thunderstorms then by evening drifting toward the desert edge, including developing on convective outflows and/or outflow collisions. Not this week, there is too much going on in the mid and upper atmosphere. For example, the last vestiges of the northwest Mexico inverted trof will move into the region Monday afternoon. More cyclonicity over southern CA will develop a threat of thunderstorms over the Joshua Tree National Park mountains, while difluent flow aloft in southwest and south central AZ generates convective potential as well. But a caveat, extensive mid/high clouds associated with the inverted trof axis may cut down on afternoon heating and the convective potential in the south central AZ Monday. And for Tuesday and Tuesday night, while 300/250 mb flows become southwesterly, a developing 500 mb easterly flow advects a weak mid level disturbance from New Mexico into southeast and south Central AZ late Tuesday afternoon and night. 500 mb disturbances usually spark overnight convection under very moist conditions. Therefore there is much uncertainty, and we can go on and on for Wednesday through Saturday. Therefore the best approach is to call is quasi-unsettled, or a broad brush approach to shower/thunderstorm potential since 1) the monsoon moisture will be in place, and 2) models will no doubt have trouble forecasting any minor perturbations in this developing convoluted flow aloft. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Showers moving in from the southeast have caused winds to shift to a southeasterly direction this afternoon over Phoenix terminals. With more activity in southeast AZ still propagating to the northwest, anticipate that these southeasterly winds will stick around for another hour or so before shifting temporarily back to the west around 22Z. Speeds will remain around 10 kts, however cannot rule out gusty erratic winds and blowing dust from distant south and east AZ storms for the remainder of the day at Phoenix terminals. However, low confidence in exact spatial and temporal coverage precludes mention in 18Z TAF. Broken to overcast mid to high clouds aoa 10kft will continue to advect into the region for the remainder of the day before decreasing in coverage early tomorrow morning. Southeast California/Southwest Arizona including KIPL and KBLH: Skies will remain mostly clear with a few passing high clouds around 15-20 kft. Winds will remain out of the south at KBLH and out of the southeast at KIPL, with speeds generally around 10-15 kts accompanied by a few afternoon gusts up to 20 to 25 kts. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool," with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...Vasquez AVIATION...Hernandez FIRE WEATHER...Hernandez
Area Forecast Discussion National Weather Service Flagstaff AZ 940 AM MST SUN JUN 26 2016 .SYNOPSIS...Dry and hot weather will persist across far western Arizona today. Mid level moisture will remain over central and eastern Arizona through Monday, and bring widely scattered showers and thunderstorms. Strong, gusty winds are possible near any storms. Monsoonal moisture to increase and spread across northern Arizona on Tuesday, with increasing daytime shower and thunderstorm activity lasting through the week. && .DISCUSSION...For today, the highest moisture and best chances for showers and thunderstorms will be along and south of the White Mountains and the eastern Mogollon Rim. Elsewhere, drier air and more stable conditions will limit convective activity. Slight chances for showers are forecast along the western Mogollon Rim, including the city of Flagstaff. This seems reasonable as an extensive cumulus field is expected to develop with heating. As highlighted in the previous forecast discussion, today`s storms will once again be high-based leading to the potential for strong outflows from collapsing storms. In terms of forecast updates, the current forecast appears to be on track and no short term updates are anticipated at this time. && .PREV DISCUSSION /303 AM MST/... Northern Arizona will be slowly transitioning to a monsoon thunderstorm pattern over the next two days. Strong and gusty outflow winds should be expected near any storms or virga. The Flagstaff airport did have 2 periods of outflow wind gusts to 48 and 47 mph yesterday, an indication of outflow speeds possible through Monday afternoon. Satellite imagery this morning shows the monsoonal moisture plume running from NW Mexico through Tucson then northeastward through New Mexico. Satellite derived pw values are up to near 1.5 inches around Tuscon this morning. Models remain consistent in showing mid level easterly flow increasing across central and southern AZ today and this will allow moisture to slowly increase across areas along and south of I-40 through Monday. Areas along the Utah border to remain hot and nearly cloud free today as this area is under the high pressure circulation center. Starting Tuesday, models are in good agreement with moist easterly flow through Wednesday morning becoming light southerly through Wednesday. Monsoonal moisture to remain overhead through the week and daytime precip chances were nudged upward a few points along the Mogollon Rim. Max temps to cool to near normal for dates starting Wednesday. && .AVIATION...For the 18Z Package...Isolated to scattered showers and thunderstorms with possible gusts to 40kts will redevelop from KFLG- KRQE southeast this afternoon and evening until around 02z. Otherwise, expect VFR conditions. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Monsoon moisture will slowly increase northward each day. Expect deeper moisture with increasing coverage in showers and thunderstorms starting on Monday. Storm motion today and Monday will generally be from northeast to southwest. Expect erratic and gusty winds near any showers and storms. Tuesday through Thursday...An active wet Monsoon weather pattern is forecast with good shower and thunderstorm coverage each day across northern Arizona. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...RR/DL AVIATION...MAS FIRE WEATHER...MCS For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 940 AM MST SUN JUN 26 2016 .SYNOPSIS...We now have enough moisture for isolated to scattered showers and thunderstorms this weekend. A more favorable flow regime will then provide increased coverage of showers and thunderstorms Monday through next Saturday. && .DISCUSSION...Still plenty of debris cloud this morning with embedded light showers. This is going to slow the heating a bit with initial clearing underway in portions of Cochise and Santa Cruz counties. The 12Z KTWC sounding still has plenty of moisture at 1.4 inches precipitable water. The mid level easterly flow has already increased substantially accompanied by an increase in shear that should help to organize outflow activity this afternoon. The direction favors strong outflow off the Mogollon Rim through Graham county. Latest HRRR trends push 2 strong outflows westward, including the Rim shot and a second outflow from activity in Cochise county pushing west and northwestward. The 12z UofA WRF-NAM paints a similar scenario with the outflow from the Cochise county activity pushing through the Tucson Metro area around mid to late afternoon. Minor adjustments to increase activity in the east central mountains and subsequent outflow westward, otherwise we have solid forecast trends. Please see the previous discussion below for additional details. && .AVIATION...VALID THRU 27/18Z. Isolated to scattered -TSRA/-SHRA. The best timing for TSRA at the KTUS/KOLS/KDUG terminals is mostly from 20Z this afternoon until 27/02Z this evening. Brief wind gusts to near 40 kts and MVFR conditions due to reduced visibilities will be possible with the stronger TSRA. Isolated -SHRA/-TSRA will be possible area-wide late tonight into early Monday morning. Otherwise, cloud decks generally ranging from 10k- 15k ft MSL, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect isolated to scattered showers and thunderstorms this afternoon and evening. Greater coverage of showers and thunderstorms should then occur Monday through next Saturday. Otherwise, daytime minimum relative humidity values will generally range from the mid teens to around 30 percent with fair to good nighttime recovery. 20-foot winds into Monday as well as Thursday through Saturday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east at 5-15 mph with gusts of 15-20 mph. The strongest speeds Tuesday and Wednesday should prevail from shortly after sunrise into the early afternoon hours. && .PREV DISCUSSION...The hi-res models suggest a scenario late tonight similar to that presently occurring across the area. In other words, a fairly widespread convective debris cloud cover with patches of sprinkles or light rain. 26/00Z GFS/ECMWF/CMC remained fairly similar regarding the synoptic scale pattern regime over the southwestern states starting Monday and continuing into early next weekend. Strong high pressure aloft Monday is progged to become centered over southern Utah. The GFS/ ECMWF depict an inverted trough to move into southwestern AZ from the northern Gulf of California Monday. Quick glance at the U/A WRF-NAM suggests that showers/tstms Monday afternoon would only be confined to the White Mountains and near the international border adjacent Santa Cruz/southern Pima County. Thus, there is the potential that Monday may be a "down day" perhaps due to subsidence on the eastern periphery of the aforementioned inverted trough. Forecast confidence in this particular detail is somewhat low, however. Thus, for this forecast package, have continued with scattered showers/tstms mainly from Tucson eastward/southward. Thereafter, not much daily variation in shower/tstm coverage is anticipated Tuesday into next Saturday. The deterministic GFS/ECMWF/ CMC were similar with maintaining fairly ample moisture across this forecast area. These solutions were similar with the continuation of a light ely/sely mid-level flow regime thru about Wednesday. The mid- level flow regime is then progged to become more wly/swly especially from Tucson westward starting Thursday and continuing into next Saturday. This subtle change may be sufficient for at least a slight downward trend in shower/tstm coverage, especially across western sections. Again, forecast confidence is fairly low at this time in stating that a definitive downward precip trend anywhere in the area is in the offing late this week. High temps for the Tucson metro area and locales west-to-northwest of Tucson will be near normal during much of this forecast period. However, daytime temps for locales east-to-south of Tucson, such as Safford, Douglas and Nogales will average a few degs below normal this week. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Meyer/Francis Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
AREA FORECAST DISCUSSION
National Weather Service San Diego CA
852 AM PDT MON JUN 27 2016 .SYNOPSIS... High pressure aloft will continue hot weather for inland areas through Wednesday followed by slow cooling into next weekend as high pressure aloft weakens and a weak trough of low pressure develops over the Pacific Northwest. Mid and high level moisture associated with a disturbance moving through the region will bring a slight chance of afternoon and early evening thunderstorms with gusty winds through Wednesday, mainly near the mountains. The marine layer and onshore flow will keep coastal high temperatures cooler with areas of night and morning low clouds and fog. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Visible and radar imagery is showing an easterly upper level wave moving through the region, bringing mid and high level clouds and some light radar returns which are likely producing only virga or sprinkles. The 12Z Miramar sounding shows precipitable water having increased to 1.48 inches, although the majority of the moisture appears to be above 700 mb, with a dry layer noted below 700 mb until you reach the 10 deg C marine layer inversion near 1000 ft MSL. It is due to the dry layer below 700 mb that most of the precipitation may evaporate before reaching the ground, which is why most of it will appear as virga or maybe some sprinkles. These clouds will continue to move through Southern California through the day, although the moisture field from the NAM12 shows clearing skies intruding in from the south in the afternoon. The amount of cloud cover we have today, and which locations receive more sunlight than others, will play a factor in not only how hot we get today, but also the amount of day-time heating induced instability. Due to the mid and high clouds, temperatures may be reduced slightly compared to yesterday. However, with some higher surface dewpoints in the area (low 60s shown currently over most coast, valley and desert areas), it may feel more muggy and uncomfortable. Despite the increase in moisture and the wave moving overhead, the elevated instability parameters shown by the forecast models for this afternoon are not impressive. Also, the strong easterly flow is not conducive for thunderstorms that develop over the mountains to maintain their structure. Thus, the latest HRRR run doesn`t show much shower or thunderstorm activity this afternoon. Nevertheless, a slight chance for thunderstorms remains in the forecast today for the mountains, with some activity possibly being blown west into the valleys. Meanwhile, marine layer stratus was able to develop over coastal areas today. Stratus should be able to clear out of inland areas by late morning, although the decently strong inversion could keep some low clouds hanging around at the coast. Models show drier air intruding into Southern California Tuesday as flow turns southerly in the wake of the easterly wave, resulting in less of a chance for afternoon mountain thunderstorms. However, the clearer skies and strong ridge over the four corners region should result in hotter conditions, with highs 5-10 degrees above normal. Continued hot for inland areas on Wednesday, with 850 mb temperatures in the deserts reaching 27-29 deg C, and near 26-27 deg C in the valleys. A Heat Advisory continues for the deserts, mountains and valleys through Wednesday. Despite the ridge weakening on Thursday, looks like the 850 mb temperatures do not decrease much, if at all, so hot conditions may continue. Cooler Friday into the weekend as a trough moves into the Pacific Northwest, with a deepening of the marine layer as well, resulting in night and morning stratus into the coast and portions of the valleys. && .AVIATION... 271530Z...Coast/Valleys...Areas of sct-bkn clouds based 800-1200 feet MSL with tops around 1800 ft MSL will burn back to out over the coastal waters. Local vis 2-4 miles along higher coastal terrain/mesas. After 28/06z this evening low clouds bkn-ovc based 800-1200 feet MSL with tops around 1800 ft MSL will push inland about 15 miles with local visibilities 2-4 miles along higher coastal terrain/mesas. There is a moderate risk that the coastal low clouds will again be patchy so the confidence is low on the timing and duration of the bkn low clouds at KSAN tonight. Mountains and Deserts...Sct-bkn clouds based around 10000 feet MSL with unrestricted visibilities. This afternoon between 27/19Z and 28/00Z isolated SHRA/TSRA with cloud bases 9000 ft MSL and tops to 35000 ft MSL will be possible over the mountains. && .MARINE... 830 am...No hazardous marine weather is expected through Friday. && .BEACHES... 830 am...The long period south swell will continue to decrease, but 3-5 foot surf will continue on the southwest facing beaches today. The surf will lower to 2 to 4 feet Tuesday. Another long-period south swell from 200 degrees will bring 4-7 foot surf to southwest facing beaches late Wednesday and Thursday along with dangerous rip currents. && .FIRE WEATHER... Slight chance of dry lightning over the mountains and portions of the valleys this afternoon and evening, as an easterly wave moves through the region. Drying will take place Tuesday through Wednesday, with maybe just enough moisture leftover on Tuesday to produce isolated afternoon thunderstorms over the mountains. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX Watches/Warnings/Advisories... CA...Heat Advisory until 8 PM PDT Wednesday for Apple and Lucerne Valleys-Coachella Valley-Riverside County Mountains-San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Deserts- San Diego County Mountains-San Gorgonio Pass Near Banning. PZ...None. && $$ PUBLIC/FIRE WEATHER...Harrison AVIATION/MARINE/BEACHES...Small Area Forecast Discussion National Weather Service Flagstaff AZ 340 PM MST MON JUN 27 2016 .SYNOPSIS...Daily showers and thunderstorms will increase across norther Arizona this week as a deep moist southerly flow developes across the state. Strong, gusty winds are possible near any storms along with heavy rain and lightning. && .Discussion...Showers and thunderstorms increase across our CWA this afternoon. The least activity is over northwest Coconino County this afternoon. The center of the high pressure will migrate over far northwest New Mexico by Tuesday. This will bring a deep and moist southeast to south flow over Arizona. This lead to increasing chances for showers and thunderstorms each day across all of northern Arizona. Expect better chances for measurable rainfall starting Wednesday. This moisture is expected to remain in place through at least Saturday bringing daily chances for showers and thunderstorms. && .AVIATION...For the 00Z Package...Isolated to scattered TSRA are expect to continue through 06Z Tue. Gusty winds near 40 kts and moderate rain are possible in storms. A few showers may continue overnight, with best chances for this in Coconino and Yavapai Counties. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...An active monsoon pattern in place across northern Arizona will cause daily rounds of scattered showers and thunderstorms. Storm motion will generally be from the south to north. Expect erratic and gusty winds near showers and storms. Thursday through Saturday...An active and wet Monsoon weather pattern will continue with scattered showers and thunderstorms each day across northern Arizona. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC.......MAS AVIATION.....RR FIRE WEATHER...RR For Northern Arizona weather information visit weather.gov/flagstaff
  [top] Area Forecast Discussion National Weather Service Phoenix AZ 156 PM MST MON JUN 27 2016 .Update for Aviation and Fire Weather Discussions. && .SYNOPSIS... High pressure will move somewhat north and east of Arizona this week allowing warm temperatures to prevail, but also bring a couple of weather disturbances through the state. An increase in monsoon moisture will accompany these weather systems providing a threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... Rest of Today and Tonight... A small upper low centered southwest of El Centro early this afternoon continues moving westward. Shower activity associated with it has been weak and isolated. Cloud cover associated with it has been thinning. Stronger convection has begun to develop over the higher terrain of northern and southeastern AZ due to destabilization from surface heating. Storms over the northern half of AZ will also benefit from some upper level diffluence. Hi-res models have been depicting this. They are also in generally good agreement that convection over our area this afternoon and tonight will be spotty. In fact, they are not overly enthusiastic about southeast AZ. But there are indications of outflow moving through the south-central AZ deserts (including Phoenix) from higher terrain late this afternoon/early evening. With surface dew points in the low 50s and being on the back side of the aforementioned upper low, it is not surprising that the models are not depicting an active night for the lower deserts. But still enough factors to keep slight chances going (better chance over Zone 24). Also, with the southeasterly steering flow, debris from Sonora could drift through late tonight. Tuesday through Thursday... There is relatively good model agreement on the evolution of the flow pattern for mid week. In short, anticyclonic flow centered over the Great Basin slowly shifts southeastward becoming centered over Texas by Thursday. Meanwhile, a cutoff low/inverted trough over Texas shifts westward with time with the northern end of it tracking across southern AZ. In the process, deeper moisture spreads over the lower deserts (mainly near and east of the lower Colorado River Valley). With the deeper moisture (most noticeable Wed and Thu), storms that form over the higher terrain will have a better chance of propagating over the lower deserts. However, there is apt to be a fair amount of cloudiness around which can hinder destabilization. Thus, we are not forecasting a big outbreak and PoPs reflect this. Temperatures look to be at their warmest Tuesday (flirting with Excessive Heat criteria near and west of the Lower Colorado River Valley). With more clouds and humidity, temperatures trend down Wed and Thu. Friday through Monday... During the upcoming weekend, as low pressure sets up along the Pacific northwest coast, and as the high shifts further to the southeast, the upper streamline fields and steering flow turn towards the southwest over most of the area. This starts to bring in drier air from the southwest and we can expect rain chances to diminish from west to east with time. By Sunday afternoon, thunderstorm chances look to be confined mostly to higher terrain areas east and southeast of central Phoenix as skies become mostly sunny over the central and western deserts. Little change Monday. Temperatures look to remain reasonable. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: The chance for outflow wind gusts remain a possibility for the late afternoon, but confidence on occurrence is low. The best chance for convection remains in the higher terrain north and east of Phoenix. Sct to bkn mid and high level clouds likely to persist through the period. Otherwise, wind patterns should shift westerly in the afternoon and then easterly in the early morning hours. Southeast California/Southwest Arizona including KIPL and KBLH: Cigs in a 10K-15K ft range will persist through this afternoon with some clearing further to the south into Imperial County. Winds will be more southwesterly in the afternoon through the evening with possibility of a few gusts. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday...Temperatures will continue to cool with highs in the 100-110F range by Sunday. Monsoon moisture levels continue to increase over the region with slight chances for isolated afternoon thunderstorms. The best chances for convective weather remains over the mountains in central and eastern Arizona. Any storms that develop have the ability to produce lightning, gusty winds, and wetting rains. Daytime relative humidities will drop to 15-25 percent but will have nighttime recoveries. Otherwise, winds will be relatively normal in the 5 to 15 mph outside of any storm influenced winds. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...AJ/CB AVIATION...Deemer FIRE WEATHER...Deemer
Area Forecast Discussion National Weather Service Phoenix AZ 156 PM MST MON JUN 27 2016 .SYNOPSIS... High pressure will move somewhat north and east of Arizona this week allowing warm temperatures to prevail, but also bring a couple of weather disturbances through the state. An increase in monsoon moisture will accompany these weather systems providing a threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... Rest of Today and Tonight... A small upper low centered southwest of El Centro early this afternoon continues moving westward. Shower activity associated with it has been weak and isolated. Cloud cover associated with it has been thinning. Stronger convection has begun to develop over the higher terrain of northern and southeastern AZ due to destabilization from surface heating. Storms over the northern half of AZ will also benefit from some upper level diffluence. Hi-res models have been depicting this. They are also in generally good agreement that convection over our area this afternoon and tonight will be spotty. In fact, they are not overly enthusiastic about southeast AZ. But there are indications of outlflow moving through the south-central AZ deserts (including Phoenix) from higher terrain late this afternoon/early evening. With surface dew points in the low 50s and being on the back side of the aforementioned upper low, it is not surprising that the models are not depicting an active night for the lower deserts. But still enough factors to keep slight chances going (better chance over Zone 24). Also, with the southeasterly steering flow, debris from Sonora could drift through late tonight. Tuesday through Thursday... There is relatively good model agreement on the evolution of the flow pattern for mid week. In short, anticyclonic flow centered over the Great Basin slowly shifts southeastward becoming centered over Texas by Thursday. Meanwhile, a cutoff low/inverted trough over Texas shifts westward with time with the northern end of it tracking across southern AZ. In the process, deeper moisture spreads over the lower deserts (mainly near and east of the lower Colorado River Valley). With the deeper moisture (most noticeable Wed and Thu), storms that form over the higher terrain will have a better chance of propagating over the lower deserts. However, there is apt to be a fair amount of cloudiness around which can hinder destabilization. Thus, we are not forecasting a big outbreak and PoPs reflect this. Temperatures look to be at their warmest Tuesday (flirting with Excessive Heat criteria near and west of the Lower Colorado River Valley). With more clouds and humidity, temperatures trend down Wed and Thu. Friday through Monday... During the upcoming weekend, as low pressure sets up along the Pacific northwest coast, and as the high shifts further to the southeast, the upper streamline fields and steering flow turn towards the southwest over most of the area. This starts to bring in drier air from the southwest and we can expect rain chances to diminish from west to east with time. By Sunday afternoon, thunderstorm chances look to be confined mostly to higher terrain areas east and southeast of central Phoenix as skies become mostly sunny over the central and western deserts. Little change Monday. Temperatures look to remain reasonable. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Much better chances for stronger east/northeast outflow winds are likely late this afternoon, but confidence in timing is still somewhat low. Actual storms may not survive to lower elevations, though mountain obscuration, blowing dust, and frequent lightning for arrivals/departures to the east may be problematic. Persistent easterly winds this evening should occur earlier this normal. Sct to bkn mid and high clouds should persist through Tuesday morning. Southeast California/Southwest Arizona including KIPL and KBLH: Cigs in a 10K-15K ft range will persist through this afternoon with some gradual thinning of cloud cover tonight. Virga showers this morning over the terminals are likely and should dissipate by around noon. While a south to southeast sfc wind will be preferred through this afternoon, winds will eventually become more southwesterly this evening. A few stronger gusts may also be possible for brief periods, especially this evening. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool" with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...AJ/CB AVIATION...Kuhlman FIRE WEATHER...Hernandez
  [top] Area Forecast Discussion National Weather Service Tucson AZ 155 PM MST MON JUN 27 2016 .SYNOPSIS...Expect scattered showers and thunderstorms into next weekend. Daytime temperatures will be near normal or a few degrees below normal, depending upon location. && .DISCUSSION...The remnants of this mornings MCV was moving into western Pima county as of 1:30 pm satellite imagery. Radar was showing isolated storms mainly hugging the higher terrain S and E of Tucson. Precipitable water values this afternoon ranged from 1" to 1.50". Isolated to scattered storms for the remainder of this afternoon into this evening with a few showers possible overnight associated with debris cloud cover. Upper high that was over southern Utah this morning will drift to the 4-corners area Tuesday and remain there until Wednesday. This will result in a continued E-SE flow aloft over the area. Tuesday will be a bit more active than today, especially across Sonora where a weakening inverted trof, spun off the bigger one that is east of the Texas Big Bend today, moves thru. Both 12z UofA WRF runs of the NAM and GFS all show thunderstorm outflows Tuesday night pushing into the Gulf thus setting up gulf surge of lower level moisture into the lower deserts on Wednesday. Models indicating another weak inverted trof will be passing through Sonora on Wednesday. We`ve been advertising an uptick in areal coverage of storms on Wednesday and that still looks on track. Will maintain scattered storms for Thursday and Friday. Both GFS and EC are hinting at drier westerly flow aloft late in the weekend into early next week as the upper ridge axis sets up south of the area. Enough residual moisture will be across the eastern half of the forecast area for a chance of afternoon and evening storms. High temperatures will be around normal for most of the area during the next 7 days. && .AVIATION...VALID THRU 28/12Z. Isolated to scattered -TSRA/-SHRA into this evening. Brief wind gusts to near 40 kts and MVFR conditions due to reduced visibilities will be possible with the stronger TSRA. Isolated -SHRA/-TSRA will then occur late tonight into early Tuesday morning. Otherwise, cloud decks generally ranging from 10k-15k ft msl, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Scattered showers and thunderstorms will prevail into next weekend. 20-foot winds today as well as Thursday through Sunday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east to southeast at 5-15 mph with gusts of 15-20 mph. && .CLIMATE...June rainfall at the Tucson airport currently stands at 0.32". This ranks as the 29th wettest June on record. Normal is 0.20" && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Phoenix AZ 940 AM MST MON JUN 27 2016 .SYNOPSIS... High pressure will move somewhat north and east of Arizona this week allowing warm temperatures to prevail, but also bring a couple of weather disturbances through the state. An increase in monsoon moisture will accompany these weather systems providing a threat of afternoon and evening showers and thunderstorms the remainder of week. && .DISCUSSION... A small upper level low is centered just southwest of Yuma this morning. To the north of that is a larger anticyclonic circulation centered over the Great Basin. A smaller anticyclone is centered over north-central Mexico and to the east of that is a cutoff low centered over Texas. The cyclonic feature over and near our forecast area has been keeping weak isolated showers/sprinkles going this morning. Also of note is a zone of strong east-to-west winds in the mid levels due to gradient between the low and the high to the north. This weakens as the day wears on. With 1000-700mb average mixing ratios of 7-8 g/kg, there is just enough moisture for CAPE - though there is still CIN to contend with. But with decent CAPE over southeast AZ and steering flow from the southeast later on, there is a non-zero chance of storms surviving over the lower deserts. Not looking at a big day at this point and hi-res models are not enthusiastic (except for NCAR ensemble). One caveat is that upper level divergence (associated with diffluence from the upper low) could extend further south over our area instead of being focused over FGZ and VEF areas. That could aid storm development (mainly over La Paz and northern Maricopa Counties). No changes to the forecast at this time. && .PREVIOUS DISCUSSION...Issued 310 am MST/PDT... Early this morning a well defined inverted trof could be seen moving westward across far southern/southwestern Arizona, and this feature was clearly evident in vapor imagery as well as recent plot data. Circulation around this feature was spreading increasing moisture westward and into the desert west of Phoenix; latest blended total precipitable water imagery indicated pwat values over 1.2 inches over portions of the southwest deserts. The inverted trof created good upper difluence across the central and western deserts and coupled with a good uvv field, a field of mostly light showers could be seen spreading into the western deserts at 2 am. As this inverted trof slowly pushes west today we can expect a continued slight chance of showers or thunderstorms across much of the lower deserts to the west of Phoenix including portions of SE California. Later this afternoon and evening across south central Arizona, the forcing becomes weaker behind the exiting inverted trof but there is weak southeast steering flow and sufficient deeper moisture and instability to allow for a 15-20 percent chance of mainly evening thunderstorms over the central deserts and a chance of storms over higher terrain east of Phoenix. This is supported by various mesoscale models such as the NMM6km. Clouds and moisture working across the lower deserts will keep high temps today mostly below the 110 degree mark, even over the far western deserts. Model guidance, including operational runs of the GFS and ECMWF, as well as ensemble guidance such as the GEFS and NAEFS, continue to call for a very monsoonal pattern to develop across the desert southwest starting Tuesday and continuing through the end of the work week. Initially the main upper high center forms near the four corners, setting up a deeper southeast steering flow over most of the area which will steadily transport increasing and deeper moisture westward over the lower deserts. PWAT values steadily climb and are forecast to exceed 1.5 inches across the main monsoon moisture corridor which sets up just east of the lower Colorado River Valley and extends into far eastern Arizona. The steering flow is favorable to bring mountain storms into the lower deserts, and from time to time there will be disturbances rotating around the main upper high which will serve to enhance thunderstorm coverage and intensity. Model guidance typically has a hard time with the exact timing and track of these features and we generally cannot place a lot of faith in them more than a day or two down the road. Overall we are looking at a rather broad brushed forecast with 10-20 percent chances of mainly afternoon and evening storms over the deserts mainly east of the lower CO river valley, and 30-40 percent chances across the higher terrain east of Phoenix. Later in the week the upper high starts to shift towards the southeast and steering flow becomes more southerly. Still, moisture remains high and in fact the GFS calls for PWAT value in the central deserts to approach 2 inches later Thursday into Friday. This would suggest a much better chance for heavy rains to accompany any storms that develop. Of course, as moisture increases the temperatures will fall off and by midweek high temps across south central Arizona will approach and then fall below seasonal normals. It will stay a bit hotter further west where the atmosphere is a bit drier, with highs over 110 expected for much of the week. During the upcoming weekend, as low pressure sets up along the Pacific northwest coast, and as the high shifts further to the southeast, the upper streamline fields and steering flow turn towards the southwest over most of the area. This starts to bring in drier air from the southwest and we can expect rain chances to diminish from west to east with time. By Sunday afternoon, thunderstorm chances look to be confined mostly to higher terrain areas east and southeast of central Phoenix as skies become mostly sunny over the central and western deserts. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Much better chances for stronger east/northeast outflow winds are likely late this afternoon, but confidence in timing is still somewhat low. Actual storms may not survive to lower elevations, though mountain obscuration, blowing dust, and frequent lightning for arrivals/departures to the east may be problematic. Persistent easterly winds this evening should occur earlier this normal. Sct to bkn mid and high clouds should persist through Tuesday morning. Southeast California/Southwest Arizona including KIPL and KBLH: Cigs in a 10K-15K ft range will persist through this afternoon with some gradual thinning of cloud cover tonight. Virga showers this morning over the terminals are likely and should dissipate by around noon. While a south to southeast sfc wind will be preferred through this afternoon, winds will eventually become more southwesterly this evening. A few stronger gusts may also be possible for brief periods, especially this evening. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Temperatures will continue to "cool" with highs on Wednesday around 105-112F dropping into the 100-110F range by Sunday. As monsoon moisture levels continue to increase over the region, isolated thunderstorms are possible each afternoon/evening over much of the desert southwest, with the highest chances over the higher terrain of central and eastern Arizona. Accompanying any storm that develops will be wetting rains, gusty erratic winds, and lightning. This increase in moisture will support a rise in minimum humidities, with values ranging in the 15-25 percent range each day with good overnight recoveries. Outside of gusty storm winds, speeds will range between 5 to 15 mph with a few afternoon upslope gusts up to 20 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...AJ PREVIOUS DISCUSSION...CB AVIATION...Kuhlman FIRE WEATHER...Hernandez
Area Forecast Discussion National Weather Service Flagstaff AZ 938 AM MST MON JUN 27 2016 .SYNOPSIS...Expect scattered showers and thunderstorms today along and south of the Mogollon Rim, and isolated storms elsewhere. Strong, gusty winds are possible near any storms. Beginning Tuesday, monsoonal moisture is forecast to increase across all of northern Arizona leading to daily chances for showers and thunderstorms through the week. && .Discussion...The 12Z sounding showed a steady increase in PW from yesterday morning (0.59 vs 0.44) with an easterly steering flow of around 15 MPH today. There is also a slight cap at just above 500 mb (around 20kft msl). Surface dew points in the 40s have pushed all the way to Page this morning. Some cloud cover today will slow surface heating. These two factors will slow convection by an hour or two. In any case, expect convection to start over much of the area by early afternoon. && .PREV DISCUSSION /400 AM MST... Moisture is increasing across central and eastern AZ this morning per satellite PW estimates and sfc dew point data. The highest PW values should remain along and south of I-40 today, while shallow sfc moisture has made it as far north as Page this morning. Thus scattered showers and thunderstorms are expected this afternoon and evening along the Mogollon Rim from Happy jack eastward with isolated storm coverage elsewhere. Most of the storms will be high based, with strong outflow winds probable from them. Storm motion today from east to west. On Tuesday, high pressure aloft will become centered near the Four Corners. We will see a moist easterly flow Tuesday that transitions to a moist southerly wind around the middle of the week. This will draw deeper moisture into the region leading to increasing chances for showers and thunderstorms across all of northern Arizona. Expect better chances for measurable rainfall starting Wednesday. This moisture is expected to remain in place through at least Saturday bringing daily chances for showers and thunderstorms. && .AVIATION...For the 18Z Package...Scattered TSRA will develop from KFLG - KRQE south this afternoon and evening with isolated TSRA possible elsewhere. Gusty winds near 40 kts and moderate rain possible in storms. Otherwise, expect VFR conditions. Activity decreasing aft 06Z though a few showers may continue overnight. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...An increase in moisture will lead to scattered thunderstorms from the Mogollon Rim to the Chuska Mountains south this afternoon and evening. Isolated storms are possible elsewhere. Storm motion will be from east to west today. Moisture increases into Tuesday with scattered storms expected. Storm motion becomes more south to north on Tuesday. Expect erratic and gusty winds near any showers and storms. Wednesday through Friday...An active wet Monsoon weather pattern is expected with scattered showers and thunderstorms each day across northern Arizona. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...MAS/DL AVIATION...MCS FIRE WEATHER...MCS For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Flagstaff AZ 938 AM MST MON JUN 27 2016 .SYNOPSIS...Expect scattered showers and thunderstorms today along and south of the Mogollon Rim, and isolated storms elsewhere. Strong, gusty winds are possible near any storms. Beginning Tuesday, monsoonal moisture is forecast to increase across all of northern Arizona leading to daily chances for showers and thunderstorms through the week. && .Discussion...The 12Z sounding showed a steady increase in PW from yesterday morning (0.59 vs 0.44) with an easterly steering flow of around 15 MPH today. There is also a slight cap at just above 500 mb (around 20kft msl). Surface dew points in the 40s have pushed all the way to Page this morning. Some cloud cover today will slow surface heating. These two factors will slow convection by an hour or two. In any case, expect convection to start over much of the area by early afternoon. && .PREV DISCUSSION /400 AM MST... Moisture is increasing across central and eastern AZ this morning per satellite PW estimates and sfc dew point data. The highest PW values should remain along and south of I-40 today, while shallow sfc moisture has made it as far north as Page this morning. Thus scattered showers and thunderstorms are expected this afternoon and evening along the Mogollon Rim from Happy jack eastward with isolated storm coverage elsewhere. Most of the storms will be high based, with strong outflow winds probable from them. Storm motion today from east to west. On Tuesday, high pressure aloft will become centered near the Four Corners. We will see a moist easterly flow Tuesday that transitions to a moist southerly wind around the middle of the week. This will draw deeper moisture into the region leading to increasing chances for showers and thunderstorms across all of northern Arizona. Expect better chances for measurable rainfall starting Wednesday. This moisture is expected to remain in place through at least Saturday bringing daily chances for showers and thunderstorms. && .AVIATION...For the 18Z Package...Scattered TSRA will develop from KFLG - KRQE south this afternoon and evening with isolated TSRA possible elsewhere. Gusty winds near 40 kts and moderate rain possible in storms. Otherwise, expect VFR conditions. Activity decreasing aft 06Z though a few showers may continue overnight. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...An increase in moisture will lead to scattered thunderstorms from the Mogollon Rim to the Chuska Mountains south this afternoon and evening. Isolated storms are possible elsewhere. Storm motion will be from east to west today. Moisture increases into Tuesday with scattered storms expected. Storm motion becomes more south to north on Tuesday. Expect erratic and gusty winds near any showers and storms. Wednesday through Friday...An active wet Monsoon weather pattern is expected with scattered showers and thunderstorms each day across northern Arizona. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...MAS/DL AVIATION...MCS FIRE WEATHER...MCS For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 930 AM MST MON JUN 27 2016 .SYNOPSIS...Expect scattered showers and thunderstorms into next weekend. Daytime temperatures will be near normal or a few degrees below normal, depending upon location. && .DISCUSSION...Debris cloud cover over the area as of 9 am with embedded light showers/sprinkles. Visible imagery showed a weak MCV over NE Pima county, moving slowly to the west. Upper air maps this morning placed upper high over southern Utah with easterly flow over the area. The Tucson morning sounding still holding with 1.40" PW with values across the area, based on various sources, ranged from 1" to 1.50". 12z UofA WRF NAM focusing isolated to scattered convection this afternoon mostly S and E of Tucson. HRRR still playing catch-up as the 14z run didn`t have any of the shower activity across southern Tucson between 8-9 am. All signs point to a ramp up in areal coverage of storms from Wednesday on. && .AVIATION...VALID THRU 28/12Z. Isolated -SHRA will prevail thru 18Z this morning, then isolated to scattered -TSRA/-SHRA this afternoon and evening. Brief wind gusts to near 40 kts and MVFR conditions due to reduced visibilities will be possible with the stronger TSRA. Isolated -SHRA/-TSRA will then occur late tonight into early Tuesday morning. Otherwise, cloud decks generally ranging from 10k-15k ft msl, and surface wind terrain driven mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Scattered showers and thunderstorms will prevail into next weekend. 20-foot winds today as well as Thursday through Sunday will be terrain driven at less than 15 mph. 20-foot winds Tuesday and Wednesday will generally be from the east to southeast at 5-15 mph with gusts of 15-20 mph. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
AREA FORECAST DISCUSSION
National Weather Service San Diego CA
138 PM PDT MON JUN 27 2016 .SYNOPSIS... High pressure aloft will continue hot weather for inland areas through Wednesday followed by slow cooling into next weekend as high pressure aloft weakens and a weak trough of low pressure develops over the Pacific Northwest. Mid and high level moisture associated with a disturbance moving through the region will bring a slight chance of afternoon and early evening thunderstorms with gusty winds through Wednesday, mainly near the mountains. The marine layer and onshore flow will keep coastal high temperatures cooler with areas of night and morning low clouds and fog. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Visible and radar imagery continues to show mid and high level clouds and some light radar returns associated with an easterly wave which is moving through the region. Most of the fast moving light radar returns are resulting in virga or sprinkles. However, a band of stationary showers has developed and persisted on the desert slopes near Lake Arrowhead over the past hour. The 12Z Miramar sounding shows precipitable water having increased to 1.48 inches, although the majority of the moisture appears to be above 700 mb, with a dry layer noted below 700 mb until you reach the 10 deg C marine layer inversion near 1000 ft MSL. It is due to the dry layer below 700 mb that most of the precipitation may evaporate before reaching the ground, which is why most of it will appear as virga or maybe some sprinkles. The amount of cloud cover we have today, and which locations receive more sunlight than others, is playing a factor in how hot we get today. Due to the mid and high clouds, temperatures have been slightly reduced at 1 pm today compared to 1 pm yesterday in the Inland Empire, all mountain areas, the High Deserts and Coachella Valley. However, with some higher surface dewpoints in the area (low 60s shown currently over most coast, valley and desert areas), it will feel more muggy and uncomfortable. Despite the increase in moisture and the wave moving overhead, the elevated instability parameters shown by the forecast models for this afternoon and evening are still not impressive. Also, the strong easterly flow is not conducive for thunderstorms that develop over the mountains to maintain their structure. Thus, the latest HRRR run shows some light shower activity but not much in the way of thunderstorm activity this afternoon. Nevertheless, slight chance for thunderstorms remains in the forecast today for the mountains, with some activity possibly being blown west into the valleys. Meanwhile, marine layer stratus along the coast this morning was able to clear pretty quickly, but has since re-developed along the immediate coast, likely due to the decently strong marine layer inversion. Models show drier air intruding into Southern California Tuesday and Wednesday as flow turns southerly in the wake of the easterly wave, resulting in less of a chance for afternoon and early evening mountain thunderstorms on those days. However, the clearer skies and strong ridge over the four corners region should result in hotter conditions, with highs 5-10 degrees above normal. Continued hot for inland areas on Wednesday, with 850 mb temperatures in the deserts reaching 27-29 deg C, and near 26-27 deg C in the valleys. A Heat Advisory continues for the deserts, mountains and valleys through Wednesday. Despite the ridge weakening on Thursday, looks like the 850 mb temperatures do not decrease too much, so hot conditions may continue. Cooler Friday into the weekend as a trough moves into the Pacific Northwest, with a deepening of the marine layer as well, resulting in night and morning stratus into the coast and portions of the valleys. && .AVIATION... 271950Z...Coast/Valleys...Areas of sct-bkn clouds based 800-1200 feet MSL with tops around 1500 ft MSL over the coastal waters otherwise mostly clear. After 28/0z this evening low clouds bkn- ovc based 800-1200 feet MSL with tops around 1500 ft MSL will push inland about 15 miles with local visibilities 2-4 miles along higher coastal terrain/mesas. There is a moderate risk that the coastal low clouds will again be patchy so the confidence is low on the timing and duration of the bkn low clouds at KSAN tonight. Some low clouds may temporarily move in on the sea breeze but will leave out of the KSAN TAF. Isolated SHRA/TSRA near the mountains through 28/00z this afternoon with CB bases near 9000 ft MSL and tops to near 35000 ft MSL. Mountains and Deserts...Sct-bkn clouds based around 9000 feet MSL with unrestricted visibilities. This afternoon through 28/00Z isolated SHRA/TSRA with cloud bases 9000 ft MSL and tops to 35000 ft MSL will be possible over the mountains. && .MARINE... 100 pm...No hazardous marine weather is expected through Friday. && .BEACHES... 100 pm...The long period south swell will continue to decrease, but 3-5 foot surf will continue on the southwest facing beaches through tonight. The surf will lower to 2 to 4 feet Tuesday. Another long- period south swell from 200 degrees will bring 4-7 foot surf to southwest facing beaches late Wednesday and Thursday along with dangerous rip currents. && .FIRE WEATHER... Slight chance of dry lightning over the mountains and portions of the valleys this afternoon and evening, as an easterly wave moves through the region. Drying will start to take place Tuesday, with maybe just enough moisture leftover on Tuesday and Wednesday to produce isolated afternoon thunderstorms over the mountains. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX Watches/Warnings/Advisories... CA...Heat Advisory until 8 PM PDT Wednesday for Apple and Lucerne Valleys-Coachella Valley-Riverside County Mountains-San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Deserts- San Diego County Mountains-San Gorgonio Pass Near Banning. PZ...None. && $$ PUBLIC/FIRE WEATHER...Harrison AVIATION/MARINE...Small
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
309 PM CDT MON JUN 27 2016 .SHORT TERM...(This Evening through Tuesday) Issued at 309 PM CDT MON JUN 27 2016 A broad upper level trough was located across the upper Great Lakes and will amplify as it digs southeast across lower MI. The upper flow will become more northwesterly and a short-wave trough across eastern WY and will translate southeast across western NE into central KS by the mid morning hours of Tuesday. A weak front extend from central IA, southwest into south central NE, then recurved northwest into the NE PNHDL. There may be enough surface convergence ahead of the surface front across southeast NE for isolated to scattered thunderstorms to develop late this afternoon or early evening. The HRRR model seems to have a handle on the thunderstorms developing across southwest IA, and shows thunderstorms developing southwest ahead of the weak surface boundary, and then moving southeast across much of northeast KS. If thunderstorms manage to develop across southern NE, they will then move southeast into the northern counties of the CWA. MLCAPE will be around 3,000 J/kg and the 0-6 KM effective shear will be 30 KTS. Therefore, any isolated thunderstorms late this afternoon and early evening across the northern counties of the CWA may be strong to severe with the primary hazard being large hail and damaging wind gusts. If thunderstorms do develop along the weak front late this afternoon and early evening they should weaken and dissipate through the mid evening hours. Tonight, The mesoscale models are showing two thunderstorm complexes developing across the high plains of eastern CO and western NE. Most numerical models show these thunderstorm complexes moving south- southeast across western and central KS, remaining just west of the CWA. However, the NMM and GFS show the northern thunderstorm complex that develops across the western NE panhandle, moving southeast across northwest KS into the western counties of the CWA between 12Z and 15Z TUE. If an MCS manages to develop it may be able to maintain itself due the sufficient MUCAPE and vertical windshear. An MCS may bring the threat for damaging wind gusts to north central KS near sunrise through the mid morning hours of Tuesday. Tuesday, after the potential for morning thunderstorms across north central KS, skies will become partly cloudy. It looks dry for the remainder of the day. Upslope flow across the higher terrain of northeast CO, eastern WY and the western NE panhandle will cause scattered thunderstorms to develop and these storms will organize into an MCS late Tuesday afternoon across the central high plains. Highs Tuesday afternoon will reach the mid to upper 80s. .LONG TERM...(Tuesday Night through Monday) Issued at 309 PM CDT MON JUN 27 2016 In general, chances for precip remain in the forecast through the extended period as models continue to show a conditionally unstable airmass with possible pertibations within the flow. Although confidence in storms occurring at any give time are below normal as the forecast should be driven primarily by mesoscale features, and thunderstorms in one period could affect the next couple periods. For Tuesday night through Thursday, the better chances for thunderstorms looks to be Wednesday or Wednesday night as there continues to be signs for a vort max to move through northwest flow aloft. However there are timing differences with vort max as well as with the location of a possible convective system among the various solutions. Because of this, POPs where kept in the 30 to 50 percent range. Models continue to support temps a little closer to or below normal temps with highs in the lower and mid 80s and lows in the mid 60s. For Thursday night through the weekend, the ECMWF and GFS are showing a little better defined cold front moving into the area and stalling out across east central or southern KS as the synoptic pattern becomes a little less amplified and flow aloft becomes a little more westerly. Since there is not a big change in airmass with the front pushing through well south of the forecast area, potential instability remains possible with disturbances coming off the Rockies. Therefore it is difficult to rule out precip chances through this period as well. The reenforcement of surface ridging should keep highs in the lower and mid 80s and lows in the mid 60s through the weekend. By next Monday, there are indications for shortwave ridging to develop over the central plains and the thermal ridge to build back in from the southwest. With no obvious forcing seen in the models, have trended POPs into the slight chance and temps should be warming up again with some lower 90s possible. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon) Issued at 1238 PM CDT MON JUN 27 2016 Scattered CU will develop at the terminals with bases of 4,000 to 6,000 feet. There may be an thunderstorm around the terminals late this afternoon or this evening. High clouds from a thunderstorm complex moving southeast across central KS will probably prevent ground fog from forming by sunrise. However, if skies remain clear there could be some patchy dense ground fog around the terminals near sunrise Tuesday morning. && .TOP Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Gargan LONG TERM...Wolters AVIATION...Gargan