Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 07/19/16

Area Forecast Discussion
National Weather Service Flagstaff AZ
902 PM MST MON JUL 18 2016

.SYNOPSIS...Monsoon moisture will continue to bring a chance of
showers and thundertorms through Thursday. Strong high pressure
and drier air could result in a downturn in activity toward the
end of the week.

&&

.DISCUSSION...
Thunderstorm activity appears to be trending downward this
evening, with just a few isolated thunderstorms remaining. Will
continue to monitor storms overnight, but the short-term forecast
through morning currently looks in good shape.

&&

.PREV DISCUSSION /250 PM MST/...
The monsoon circulation has brought plentiful atmospheric moisture
back into to the area...with precipitable water values now up to
around 1.0" at KFLG. Instability has been somewhat limited...but
scattered thunderstorms have formed with a few locally heavy
showers, mainly over the higher terrain. Little change in the
overall pattern is anticipated through Thursday with the strong
ridge of high pressure in place over the Southern Plains and moist
southerly flow over Arizona, providing the environment for daily
thunderstorm activity across the forecast area. Storms will move a
bit slower Tuesday through Thursday, leading to a somewhat greater
chance for heavy rainfall accumulations.

Friday through Sunday...forecast models continue to show the
flattening of the ridge over the southern Rockies, and a
decrease in thunderstorm activity Friday through Sunday as drier
air filters in from the west.

&&

.AVIATION...For the 00Z package...Only isolated showers and
thunderstorms are expected for the remainder of tonight. Storms
are likely to become more numerous again after 17Z Tuesday. Expect
visibility reductions and gusty winds near stronger storms
Tuesday. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Monsoon moisture is increasing across the area.
Expect increasing showers and thunderstorm coverage. Gusty
outflow winds are probable from any storms or showers, especially
today. Storm motion today from south to north about 10 mph.

Tuesday through Friday...Monsoon moisture to remain over northern
Arizona, with shower and thunderstorm chances each day. Winds may
become erratic and gusty near thunderstorms.

&&

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

&&

$$

PUBLIC...KD/Bohlin
AVIATION...KD
FIRE WEATHER...BAK

For Northern Arizona weather information visit
weather.gov/flagstaff



  [top] Area Forecast Discussion National Weather Service Phoenix AZ 835 PM MST MON JUL 18 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... A very activity late afternoon/evening for a few selected spots across south-central AZ. The combination of increased moisture levels through the column (KPSR balloon sounding PWAT 1.64 inches) and a weak disturbance that moved northward into southern AZ from northern Mexico triggered scattered showers and thunderstorms late this afternoon over Pima County. Outflow from these storms generated locally dense blowing dust over Pinal County, which contributed to a multi-vehicle accident that shut down I-10 at MP 214 late this afternoon. Outflows from these storms also triggered a few new storms over the greater Phoenix area early this evening. The strongest storm produced 63 mph winds and 0.34 inch of rain at Sky Harbor and localized damaging winds/flooding across central Phoenix. A second storm produced gusty winds and heavy winds over Queen Creek/San Tan Valley. At this hour, all remaining storms are either over Gila County or moved northward into Yavapai County. As far as the forecast for the rest of the night is concerned, although there is still a slight chance of an isolated shower or thunderstorm later tonight as debris cloudiness move northward from the remains of storms south of the international border, it should be quiet over the vast majority of our cwa. with inherited forecasts still looking good. && .PREVIOUS DISCUSSION... Tonight...Elevated amounts of monsoon moisture have now securely covered most of AZ. Athough thermodynamics are there for a few afternoon and evening showers and thunderstorms over our forecast area in south central AZ, this region seems to be in between upper level forcing mechanisms in currently working in northern and southern AZ. With the advent of a fairly strong and unseasonably cold Pacific trof moving into the Pacific northwest, a rather strong southwesterly Jetstream maximum has developed over portions of eastern Nevada and Utah. Accelerating winds aloft, from lighter winds in northern AZ into the Utah flow, has developed an area of upper level speed divergence and resulting convection. To our south near the Mexican border, the approaching massive inverted trof, clearly seen in water vapor imagery over the Mexican state of Chihuahua, is spreading leading edge upper level difluence. Our portions of south central AZ, including areas near Phoenix, are under a relatively stable upper level anti-cyclonic flow regime. Therefore a low grade monsoon forecast is expected for the remainder of this afternoon and evening, i.e. a slight chance of showers and thunderstorms. This forecast is excluding the possibility of copious amounts of convective debris clouds from southern AZ moving north toward Phoenix tonight, and causing the possibility of showers and thunderstorms similar to late Sunday night. So far model forecasts are minimizing this possibility. Tuesday...our office staff eyes are now transfixed on the massive inverted trof seen in water vapor imagery over north central Mexico. Models the past two days have resolved this feature very well at the 300/250 mb level, and latest model forecasts continue the trend of moving the feature bodily into southern AZ, although in a weakened form later Tuesday and Tuesday night. Current model forecast are minimizing the effect of this system in south central AZ, including nearby Phoenix and surrounding areas. From a fundamental stand point this is questionable. Strong differential heating and with weakness aloft normally results in an enhanced threat for storms that can last well into the evening hours. For now we will go with our instincts and raise precip probability a bit in south central AZ for late Tuesday and Tuesday night, with even a slight chance going into Wednesday morning. Wednesday...Monsoon moisture will be still be entrenched over the region. With mid/upper level disturbances should depart the area, resulting in another low grade monsoon forecast for Wednesday afternoon and evening. Thursday through Monday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Outside of a slight chance for a shower/weak thunderstorm later tonight as debris clouds from storms over northern Mexico move over the region, the rest of tonight and Tuesday morning should be quiet, with winds mainly out of a southeasterly direction. There is a slight risk of more convective activity on Tue afternoon, but confidence is too low to include it in the tafs at this time. Winds on Tue afternoon to once again become westerly, with speeds mainly in the 8-10 knot range. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east over central AZ. Under mostly clear skies, sfc winds will favor a southerly direction at KIPL and from a southeasterly direction at KBLH. A few higher gusts will be possible at KBLH, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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...Percha/Vasquez AVIATION...Percha/MO FIRE WEATHER...MO
  [top] Area Forecast Discussion National Weather Service Tucson AZ 325 PM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Scattered to numerous showers and thunderstorms were occurring generally from the Tohono O`odham Nation southeastward into far southeast Pima County, Santa Cruz County, and extreme southwest Cochise County at this time. This area is within a northwest-to-southeast oriented axis of greatest instability as per SPC hourly mesoscale analysis of MUCAPE. Other isolated showers and thunderstorms were also occurring from southcentral Pinal County eastward into western Graham County. Storm motions were mainly northwest around 5-10 kts. IR satellite imagery depicted rapidly cooling cloud tops during the past hour with the showers/tstms across central Pima County. Have favored the Univ of AZ WRF-NAM for precip chances tonight. Thus, expect scattered to perhaps numerous showers/tstms across much of the area this evening. The main concern given relatively slow storm motions and precip water values of 1.25"-1.50" will be locally heavy rainfall. Have maintained a slight chance of showers/tstms late tonight for much of this forecast area. Have noted that the WRF- NAM depicts precip-free conditions late tonight into mid-morning Tuesday. Will defer to the evening shift to adjust PoPs perhaps downward as necessary. Similar coverage of showers/tstms is expected Tuesday afternoon/evening as deep (albeit still light) sely flow aloft continues across the area. Scattered mainly afternoon/evening showers/tstms will also occur Wednesday. Thereafter, the 18/12Z GFS/ECMWF/CMC were similar versus their respective solutions in depicting a gradual daily decrease in showers/tstms to begin Thursday and continue into this weekend. Given the continued ely mid-level flow, precip-free conditions area- wide should not occur as earlier this month. However, moisture should remain sufficient for isolated to scattered afternoon and evening showers and thunderstorms Thursday through next Monday. High temps Tuesday will remain quite close to seasonal normals. A warming trend is forecast to begin Wednesday, and based on various 18/12Z guidance, high temps were increased several degs Thur-Sat versus the previous forecast. At this time, appears that Friday will be the hottest day although Saturday should be quite similar. A moderation in daytime temps should then occur Sunday and Monday. && .AVIATION...VALID THRU 20/00Z. Isolated to scattered SHRA/TSRA will occur through the period, with the best chances during the afternoon and evening hours. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Tuesday afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ DISCUSSION...Francis AVIATION/FIRE WEATHER...French Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Flagstaff AZ 250 PM MST MON JUL 18 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION... The monsoon circulation has brought plentiful atmospheric moisture back into to the area...with precipitable water values now up to around 1.0" at KFLG. Instability has been somewhat limited...but scattered thunderstorms have formed with a few locally heavy showers, mainly over the higher terrain. Little change in the overall pattern is anticipated through Thursday with the strong ridge of high pressure in place over the Southern Plains and moist southerly flow over Arizona, providing the environment for daily thunderstorm activity across the forecast area. Storms will move a bit slower Tuesday through Thursday, leading to a somewhat greater chance for heavy rainfall accumulations. Friday through Sunday...forecast models continue to show the flattening of the ridge over the southern Rockies, and a decrease in thunderstorm activity Friday through Sunday as drier air filters in from the west. && .AVIATION...For the 00Z package...Sct shra/tsra expected to continue through 03z...with isold -shra/-tsra continuing overnight. Sct shra/tsra will redevelop after 18Z Tuesday...with storms most numerous over the higher terrain. Expect visibility reductions and gusty winds near storms. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect another round of thunderstorms over the forecast area Tuesday and Wednesday. Storm motion will generally be from the south to north 5-10 mph. Thursday through Saturday...Scattered thunderstorms will persist across the area on Thursday. Drier air filtering into Arizona from the west will bring a decrease in thunderstorm activity on Friday and Saturday...with minimum RH`s dropping back into the teens to the north and west of Flagstaff. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...Bohlin/BAK AVIATION...BAK FIRE WEATHER...BAK For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Phoenix AZ 200 PM MST MON JUL 18 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... Tonight...Elevated amounts of monsoon moisture have now securely covered most of AZ. Athough thermodynamics are there for a few afternoon and evening showers and thunderstorms over our forecast area in south central AZ, this region seems to be inbetween upper level forcing mechanisms in currently working in northern and southern AZ. With the advent of a fairly strong and unseasonably cold Pacific trof moving into the Pacific northwest, a rather strong southwesterly Jetstream maximum has developed over portions of eastern Nevada and Utah. Accelerating winds aloft, from lighter winds in northern AZ into the Utah flow, has developed an area of upper level speed divergence and resulting convection. To our south near the Mexican border, the approaching massive inverted trof, clearly seen in water vapor imagery over the Mexican state of Chihuahua, is spreading leading edge upper level difluence. Our portions of south central AZ, including areas near Phoenix, are under a relatively stable upper level anti-cyclonic flow regime. Therefore a low grade monsoon forecast is expected for the remainder of this afternoon and evening, i.e. a slight chance of showers and thunderstorms. This forecast is excluding the possibility of copious amounts of convective debris clouds from southern AZ moving north toward Phoenix tonight, and causing the possibility of showers and thunderstorms similar to late Sunday night. So far model forecasts are minimizing this possibility. Tuesday...our office staff eyes are now transfixed on the massive inverted trof seen in water vapor imagery over north central Mexico. Models the past two days have resolved this feature very well at the 300/250 mb level, and latest model forecasts continue the trend of moving the feature bodily into southern AZ, although in a weakened form later Tuesday and Tuesday night. Current model forecast are minimizing the effect of this system in south central AZ, including nearby Phoenix and surrounding areas. From a fundamental stand point this is questionable. Strong differential heating and with weakness aloft normally results in an enhanced threat for storms that can last well into the evening hours. For now we will go with our instincts and raise precip probability a bit in south central AZ for late Tuesday and Tuesday night, with even a slight chance going into Wednesday morning. Wednesday...Monsoon moisture will be still be entrenched over the region. With mid/upper level disturbances should depart the area, resulting in another low grade monsoon forecast for Wednesday afternoon and evening. Thursday through Monday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Timing wind shifts and the potential for gusty outflow winds and localized blowing dust will be the primary aviation concerns through Tuesday morning. Some variability about a southerly wind direction is likely again this afternoon, though eventually should favor southwest by the evening. Thunderstorms forming over SE AZ should move north towards the Phoenix area late in the afternoon with gusty outflow winds preceding them. While the threat of a storm directly affecting an airport is better than Sunday, probabilities are still quite low with better chances of localized blowing dust and more widespread lofted dust and haze affecting slantwise visibilities. Only modest confidence exists timing outflow wind shifts into terminal sites between 02Z- 04Z. Otherwise, developing cigs in a 10K-15K ft range look likely from decaying storms to the south. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east into central AZ. Under mostly clear skies, sfc winds will favor a southerly direction, though will be more variable at KIPL after sunset. A few higher gusts will be possible, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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 FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Phoenix AZ 1230 PM MST MON JUL 18 2016 ...Updated Aviation and Fire Weather... .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle and temperatures will increase to above normal levels. && .DISCUSSION... Woohoo, the monsoon moisture boundary raced north past Phoenix over night and this morning was seen pushing up against the higher elevations of the Mogollon Rim. In other words the southern half of AZ was in the monsoon moisture soup, and noted by the relatively low afternoon convective trigger temperatures at a few locations. For example, based on this mornings weather balloon soundings, the convective trigger temp at Phoenix is 99 deg F, 97 at Tucson, and 92 deg at Globe/Miami (elevation 3-4 thsd ft msl). Even though the afternoon thermodynamics are there, the flow aloft has, and will remain anti-cyclonic and relatively stable today and tonight. In other words, the situation for today favors low topped afternoon convection, mostly in the mountains with possible outflows toward the deserts sparking an isolated desert storm, with convection dissipating quickly after dark, unless. Unless like last night, a surge of convective debris clouds from southeast AZ spread north, creating a well saturated mid level airmass that a gravity wave sparked a few showers and thunderstorms in the Phoenix area after midnight. The gravity wave conclusion was derived from high speed satellite imagery loops. Beyond today, our office staff eyes are now on the massive inverted trof seen in water vapor imagery over the north central Mexican state of Chihuahua. Models the past two days have resolved this feature very well at the 300/250 mb level, and is forecast to move into southeast AZ on Tuesday. For now the low grade monsoon forecast, meaning slight chance of showers and thunderstorms over the south central AZ deserts and mountains look ok for now. We will see how the new models handle Tuesdays inverted trof since model guidance will have incorporated the Chihuahua weather balloon sounding that is launched once per day at 12z. .Previous discussion...503 AM MST... The weather pattern has finally allowed the typical monsoonal circulation to return to the area as the combination of troffing along the Pacific northwest coast and upper ridging over the central CONUS has allowed southerly to southeasterly flow aloft to set up across Arizona. This favorable flow has advected considerable amounts of monsoon moisture into the lower deserts; the latest Phoenix raob had PWAT up to 1.44 inches and Tucson had 1.5 inches. Despite the ample moisture, much of it was at mid and upper levels through, limiting CAPE values. According to the 2 am SPC mesoanalysis graphic, MLCAPE of consequence (over 500 j/kg) was still over far SE Arizona with very low amounts in the central deserts. 2 am radar continued to show showers spreading into south central Arizona from the southeast and isolated thunderstorms are possible but any convection that develops should stay on the weak side into the morning hours. The convection is likely being aided by weak vort maxes rotating into Arizona around the large scale upper high. Should significant clouds and showers persist well into the morning or the early afternoon, instability will again be limited and storm activity tonight will suffer. For the next few days, operational models such as the GFS and ECMWF as well as GEFS data, call for the monsoonal circulation to remain in place with little change from day to day. Moisture will remain relatively plentiful, at least from a PWAT perspective as values upwards of 1.5 inches will stay over much of the lower deserts to the east of the lower Colorado river valley. Most of the CAPE of consequence however is advertised to stay pretty much from Maricopa county eastward each day, suggesting convective potential over the southwest deserts will be limited, and minimal as you move into the deserts of southeast California. Steering flow each day will stay south to southeast but not overly strong, with 700-300mb layer winds mostly between 10 and 15 knots each day. There will be occasional vort maxes/weak inverted trofs rotating around the main upper high and moving north across the central deserts but due to the small scale of these features, they will not be handled very well by the models and as such there will be low confidence in any particular one of these small scale features. As such we will keep a rather low grade monsoon forecast in place today through Wednesday with slight chances for mainly afternoon and evening showers and thunderstorms over the central lower deserts, with better chances over the higher terrain east of Phoenix. Skies will be partly to mostly cloudy much of the time, with the greatest amounts of sunshine likely during later morning through mid afternoon each day. High temperatures will stay near seasonal normals over south central Arizona today, then gradually creep up each day with Phoenix approaching 110 by Wednesday. It will be hotter over the far western deserts and over SE California as the airmass will be drier there. Thursday through Sunday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures be much higher. The driest areas Thursday through Sunday will be southeast California where afternoon temperatures at Imperial, El Centro, and Blythe will at the 114 degree mark. Ouch! Current forecasts will keep Phoenix at or above the 110 degree mark each day. At the moment it appears high temperature will stay below excessive heat warning thresholds but that could change depending upon just how dry we actually get, and how high the heights become over the lower deserts. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Timing wind shifts and the potential for gusty outflow winds and localized blowing dust will be the primary aviation concerns through Tuesday morning. Some variability about a southerly wind direction is likely again this afternoon, though eventually should favor southwest by the evening. Thunderstorms forming over SE AZ should move north towards the Phoenix area late in the afternoon with gusty outflow winds preceding them. While the threat of a storm directly affecting an airport is better than Sunday, probabilities are still quite low with better chances of localized blowing dust and more widespread lofted dust and haze affecting slantwise visibilities. Only modest confidence exists timing outflow wind shifts into terminal sites between 02Z- 04Z. Otherwise, developing cigs in a 10K-15K ft range look likely from decaying storms to the south. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east into central AZ. Under mostly clear skies, sfc winds will favor a southerly direction, though will be more variable at KIPL after sunset. A few higher gusts will be possible, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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/CB/Vasquez AVIATION...MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Phoenix AZ 1230 PM MST MON JUL 18 2016 ...Updated Aviation and Fire Weather... .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle and temperatures will increase to above normal levels. && .DISCUSSION... Woohoo, the monsoon moisture boundary raced north past Phoenix over night and this morning was seen pushing up against the higher elevations of the Mogollon Rim. In other words the southern half of AZ was in the monsoon moisture soup, and noted by the relatively low afternoon convective trigger temperatures at a few locations. For example, based on this mornings weather balloon soundings, the convective trigger temp at Phoenix is 99 deg F, 97 at Tucson, and 92 deg at Globe/Miami (elevation 3-4 thsd ft msl). Even though the afternoon thermodynamics are there, the flow aloft has, and will remain anti-cyclonic and relatively stable today and tonight. In other words, the situation for today favors low topped afternoon convection, mostly in the mountains with possible outflows toward the deserts sparking an isolated desert storm, with convection dissipating quickly after dark, unless. Unless like last night, a surge of convective debris clouds from southeast AZ spread north, creating a well saturated mid level airmass that a gravity wave sparked a few showers and thunderstorms in the Phoenix area after midnight. The gravity wave conclusion was derived from high speed satellite imagery loops. Beyond today, our office staff eyes are now on the massive inverted trof seen in water vapor imagery over the north central Mexican state of Chihuahua. Models the past two days have resolved this feature very well at the 300/250 mb level, and is forecast to move into southeast AZ on Tuesday. For now the low grade monsoon forecast, meaning slight chance of showers and thunderstorms over the south central AZ deserts and mountains look ok for now. We will see how the new models handle Tuesdays inverted trof since model guidance will have incorporated the Chihuahua weather balloon sounding that is launched once per day at 12z. .Previous discussion...503 AM MST... The weather pattern has finally allowed the typical monsoonal circulation to return to the area as the combination of troffing along the Pacific northwest coast and upper ridging over the central CONUS has allowed southerly to southeasterly flow aloft to set up across Arizona. This favorable flow has advected considerable amounts of monsoon moisture into the lower deserts; the latest Phoenix raob had PWAT up to 1.44 inches and Tucson had 1.5 inches. Despite the ample moisture, much of it was at mid and upper levels through, limiting CAPE values. According to the 2 am SPC mesoanalysis graphic, MLCAPE of consequence (over 500 j/kg) was still over far SE Arizona with very low amounts in the central deserts. 2 am radar continued to show showers spreading into south central Arizona from the southeast and isolated thunderstorms are possible but any convection that develops should stay on the weak side into the morning hours. The convection is likely being aided by weak vort maxes rotating into Arizona around the large scale upper high. Should significant clouds and showers persist well into the morning or the early afternoon, instability will again be limited and storm activity tonight will suffer. For the next few days, operational models such as the GFS and ECMWF as well as GEFS data, call for the monsoonal circulation to remain in place with little change from day to day. Moisture will remain relatively plentiful, at least from a PWAT perspective as values upwards of 1.5 inches will stay over much of the lower deserts to the east of the lower Colorado river valley. Most of the CAPE of consequence however is advertised to stay pretty much from Maricopa county eastward each day, suggesting convective potential over the southwest deserts will be limited, and minimal as you move into the deserts of southeast California. Steering flow each day will stay south to southeast but not overly strong, with 700-300mb layer winds mostly between 10 and 15 knots each day. There will be occasional vort maxes/weak inverted trofs rotating around the main upper high and moving north across the central deserts but due to the small scale of these features, they will not be handled very well by the models and as such there will be low confidence in any particular one of these small scale features. As such we will keep a rather low grade monsoon forecast in place today through Wednesday with slight chances for mainly afternoon and evening showers and thunderstorms over the central lower deserts, with better chances over the higher terrain east of Phoenix. Skies will be partly to mostly cloudy much of the time, with the greatest amounts of sunshine likely during later morning through mid afternoon each day. High temperatures will stay near seasonal normals over south central Arizona today, then gradually creep up each day with Phoenix approaching 110 by Wednesday. It will be hotter over the far western deserts and over SE California as the airmass will be drier there. Thursday through Sunday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures be much higher. The driest areas Thursday through Sunday will be southeast California where afternoon temperatures at Imperial, El Centro, and Blythe will at the 114 degree mark. Ouch! Current forecasts will keep Phoenix at or above the 110 degree mark each day. At the moment it appears high temperature will stay below excessive heat warning thresholds but that could change depending upon just how dry we actually get, and how high the heights become over the lower deserts. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Timing wind shifts and the potential for gusty outflow winds and localized blowing dust will be the primary aviation concerns through Tuesday morning. Some variability about a southerly wind direction is likely again this afternoon, though eventually should favor southwest by the evening. Thunderstorms forming over SE AZ should move north towards the Phoenix area late in the afternoon with gusty outflow winds preceding them. While the threat of a storm directly affecting an airport is better than Sunday, probabilities are still quite low with better chances of localized blowing dust and more widespread lofted dust and haze affecting slantwise visibilities. Only modest confidence exists timing outflow wind shifts into terminal sites between 02Z- 04Z. Otherwise, developing cigs in a 10K-15K ft range look likely from decaying storms to the south. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east into central AZ. Under mostly clear skies, sfc winds will favor a southerly direction, though will be more variable at KIPL after sunset. A few higher gusts will be possible, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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/CB/Vasquez AVIATION...MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Flagstaff AZ 1004 AM MST MON JUL 18 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION...The subtropical ridge remains in a favorable position for moisture advection into Arizona through Friday. This translates into a moderate grade Monsoon with good chances for showers and thunderstorms each day. A few storms will develop in the overnight periods as a few upper level 200-300mb disturbances roll across the state. We sent out a quick update to increase shower chances this evening. Otherwise the forecast grids look good. && .PREV DISCUSSION /430 AM MST/... For today through Thursday...Due to the position of the high southerly flow and monsoon moisture will remain over northern Arizona. There should be some increase in moisture values over Sunday so shower and thunderstorm activity is expected to be more widespread. Instability and strength of any storms will be inhibited by general mid to high level cloud cover and the fact that the pattern doesn`t favor a decent push of low level moisture. In other words, precipitation amounts will mostly remain on the low to modest side. From Friday onward...Models show strong high pressure aloft building across Arizona into California. As a result, a drier air mass will filter in from the west. Low to no grade monsoon activity will be the result should this pattern materialize. && .AVIATION...For the 18Z package...sct-nmrs shra/tsra expected to develop this afternoon...continuing through 03z. Brief visibility reductions and gusty winds possible near storms. isold-sct -shra will continue aft 05Z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Monsoon moisture is increasing across the area. Expect increasing showers and thunderstorm coverage. Gusty outflow winds are probable from any storms or showers, especially today. Storm motion today from south to north about 10 mph. Tuesday through Friday...Monsoon moisture to remain over northern Arizona, with shower and thunderstorm chances each day. Winds may become erratic and gusty near thunderstorms. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...Bohlin/McCollum AVIATION...BAK FIRE WEATHER...DL For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 915 AM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into the upcoming weekend. && .DISCUSSION...Isolated showers were occurring in western Pima County east of Ajo at this time. Otherwise, visible satellite imagery depicted mostly clear skies to partly cloudy skies from Tucson westward into western Pima County, and mostly clear skies across eastern sections. Ample moisture exists with dewpoints at lower elevations valid 16Z ranging from the mid 50s-lower 60s. 18/12Z KTWC sounding total precip water value of 1.50" was about 0.15" higher versus 24 hours ago. 18/12Z upper air plots depicted a broad ridge over the southern CONUS, with a 597 DM high centered over northern Mississippi. Meanwhile, a deep upper trough was over the Pacific NW, and deep easterly/southeasterly flow prevailed across southeast AZ. Given the greater extent of clearing skies especially across eastern sections versus Sunday morning, am inclined to expect that shower/ tstm development later this morning will occur across favored ranges such as the Chiricahua Mountains. The 18/14Z HRRR supports this notion, the showers/tstms should migrate wwd/nwwd this afternoon. Quick glance at the 18/12Z Univ. of AZ WRF-NAM suggests shower/tstm development may also occur further westward by 19Z, and favor locales from Nogales to Kitt Peak. Water vapor imagery depicts a cyclonic twist approaching this area from the southeast over central Sonora Mexico. A much larger cyclonic circulation was south of the Texas Big Bend, or far eastern Chihuahua Mexico. This system may have more influence for this forecast area Tuesday. At any rate and without a further recitation of various NWP models, expect scattered to perhaps numerous showers and thunderstorms this afternoon and evening. The lowest coverage should occur across western Pima County where only isolated showers/tstms are expected. The main concern this afternoon/evening will be the potential for locally heavy rainfall and brief strong wind gusts that may approach severe thresholds. A slight chance of showers/tstms continues for much of the area late tonight. High temps this afternoon will be quite similar to temps achieved Sunday, or perhaps generally a couple of degs lower depending upon location. May make some minor PoP adjustments for this afternoon/evening, but this will not affect the overall scenario. Please refer to the additional sections for further detail. && .AVIATION...VALID THRU 19/18Z. Isolated -SHRA mainly west of KTUS this morning, then scattered to numerous -TSRA/-SHRA this afternoon and evening. The favored locales will be from KTUS vicinity east and south to the New Mexico/ International borders. Forecast confidence is sufficiently high to include VCTS in the KDUG/KOLS TAFs this afternoon and evening. VCTS may be delayed at KTUS until after 20/00Z. Isolated -SHRA and possible -TSRA to continue late tonight/early Tuesday morning. Outside of thunderstorm outflows, surface wind will generally be variable in direction less than 12 kts thru the period. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture and a favorable flow regime will maintain the daily cycle of scattered to perhaps numerous showers and thunderstorms through Wednesday. The bulk of this activity will occur during the afternoon and evening hours, and a slight chance of showers and thunderstorms will continue during the overnight hours. Thereafter, a gradual decrease in thunderstorm coverage is expected Thursday into the upcoming weekend. Outside of gusty thunderstorm outflows, 20-foot winds will be terrain driven and mostly less than 15 mph. && .PREV DISCUSSION /340 AM MST/...The 330 am radar imagery showed a distinctive circulation just west of Willcox, moving to the WNW. This MCV is associated with decaying MCS that formed over eastern Cochise county last night and produced areas of locally heavy rain. Douglas airport recorded 1.75" last night which set a daily record and also ranks as the 9th wettest July day on record. The MCV will be one of several features that will have an impact on todays forecast. Last nights MCS likely associated with a weak disturbance aloft that moved across northern Chihuahua MX. Water vapor was also showing an inverted trof approaching the Texas Big Bend this morning. A challenging forecast indeed for the next 12-18 hours. One would go with the idea that after the morning activity ends, that there will be lesser activity this afternoon due to debris cloud cover slowly diminishing which cuts down on heating thus being a few degrees cooler than Sunday. However both HRRR and 00z WRF NAM/GFS fire scattered storms this afternoon. Confidence is low will this forecast. Tomorrow likely will be another forecast challenge based on what will transpire today. Again confidence is low. Wednesday through next weekend will see a gradual decrease in moisture and thus areal coverage of storms as the sub-tropical high expands west into the eastern Pacific. Temperature warming up but likely not as hot as the GFS would suggest if going by low-level thickness numbers, which are higher than EC. Something to keep watch. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
332 PM PDT SUN JUL 17 2016 .SYNOPSIS...An upper level trough offshore will maintain slightly below normal temperatures across the interior through early this week. A deepening marine layer will result in continued cloud cover and drizzle overnight tonight and Monday morning along the Redwood Coast. && .DISCUSSION...Very few changes were made to the weekly forecast today as things appear to be unfolding largely as predicted. The "big" weather story in the near term continues to be the gradual approach of an upper level trough from the northwest, which is already resulting in milder temperatures than we`ve seen over the past few days. High temperatures across interior valleys this afternoon are running approximately 5 to 12 degrees below where they were at this time yesterday, which is indicative of both a deepening marine layer moving farther inland and lowering 1000-500 mb thicknesses as the trough moves closer. The deepening marine layer also allowed stratus to move much farther into the interior coastal valleys and lower elevation coastal hills this morning, and these clouds have struggled to clear out through the day. This is expected to repeat itself tonight, and clouds may travel even farther inland as a shortwave moves onshore. Drizzle and maybe even some light rain showers are expected overnight in coastal areas as well, mostly in Humboldt and Del Norte counties. As for the potential for convection/lightning this evening farther inland, the higher mountains of the Trinity Horn region have provided just enough of an elevated heat source to generate some agitated cumulus this afternoon, but thus for no precipitation has been observed south of approximately Crater Lake in Oregon. However, satellite imagery reveals a subtle shortwave rounding the base of its parent trough just offshore, and additional forcing from this impulse may be enough to trigger more vigorous convection and showers this evening. Given that these showers are initiating right along the border of Siskiyou and Trinity counties currently, and that the steering flow will likely carry these storms northwest as they develop, it continues to appear that lightning chances are very low for Trinity county, and much more likely across central Siskiyou county. Even there, lightning will likely be somewhat sporadic. The situation for tomorrow and Tuesday appears to be somewhat similar as the parent trough is expected to stall just off the coast, while additional subtle shortwaves move through the area during the afternoon and evening each day. Expect temperatures to be another 5 or so degrees cooler, again with slight chances for showers across the mountains of northeast Trinity county. By Wednesday, the upper level trough will very slowly drift northward, and temperatures will incrementally climb through the end of the week as well. This will also reduce the already low chances for showers across our mountains, although one final shortwave passing through the area on Thursday may be enough to trigger a shower or two. && .AVIATION...MVFR to LIFR conditions can be found along the coast this afternoon which will continue into the evening and overnight hours. The question for this forecast period is whether or not the marine layer and associated stratus will penetrate far enough inland to reach Ukiah. Current model data suggests VFR conditions, but satellite imagery from this morning depicted that the stratus was just out of reach for the area. I think that there is a decent shot of this happening so the KUKI TAF set has been amended to hint at some of these lower cloud levels. If it does indeed make it to KUKI, the terminal will likely see IFR or LIFR conditions similar to the coast. KAR && .MARINE...Northerly winds will continue to decrease into the upcoming week as strong high pressure offshore shifts westward and allows the pressure gradient to weaken across the coastal waters. The ASCAT pass this afternoon showed the winds north of Cape Mendocino had fallen below small craft criteria so those advisories were expired with the 3 PM update today. The southern waters, however, are still gusting around 20 to 25 kt this afternoon. The advisories south of the cape should be set to expire tonight as winds decrease further. The gradient will remain relatively weak through the early half of the upcoming week bringing mostly light to moderate north winds. Models suggest that winds will increase again by next weekend. Steep seas will gradually subside through the evening with relatively low sea state around 4 to 6 ft expected for the early half of the week. Small southerly swells will continue to propagate the waters this week. /KML && .EKA Watches/Warnings/Advisories... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 3 PM PDT this afternoon for PZZ470. Small Craft Advisory until 9 PM PDT this evening for PZZ455-475. && $$ Visit us at http://WWW.WEATHER.GOV/EUREKA Follow us on facebook and twitter at: http://www.facebook.com/NWSEureka http://www.twitter.com/nwseureka FOR FORECAST ZONE INFORMATION SEE FORECAST ZONE MAP ONLINE: http://www.weather.gov/eureka/zonemap.png
Area Forecast Discussion National Weather Service San Francisco Bay Area 252 PM PDT SUN JUL 17 2016 .SYNOPSIS...Cooler than normal temperatures along with overnight clouds and patch fog are expected to persist through Tuesday. A gradual warming trend is then forecast to begin around the middle of the week. && .DISCUSSION...As of 3:00 PM PDT Sunday...Little surprise in the weather today as temperatures are running a bit cooler than this time yesterday due to lower 500 mb heights plus a stronger onshore push at the surface. Similar to the last few days, clouds quickly burned off this morning for inland locations and retreated to the coast. Satellite shows a hodgepodge of sun and clouds at the coast at this time. Look for clouds to advance back to many inland spots overnight with patchy fog also likely. Models continue to show the potential for coastal drizzle as well. Lows will be in the 50s for most locations. A few degrees of additional cooling looks likely for Monday as the longwave trof off the slightly deepens while 925 MB temps drop 3 to 5C from today. This will translate into 70s for most inland spots while 60s will continue to be common at the coast. Only southern Monterey and San Benito counties will likely see highs in the 80s to lower 90s. Tuesday should be a near repeat of Monday. Starting on Wednesday temperatures will be on the increase as a ridge of high pressure to our south slowly rebuilds back into our region. 925 MB values will increase by about 10C by Friday while 500 MB heights advance up to 10 DM. By the weekend inland highs will be back into the upper 80s to lower 100s with 60s and 70s still at the coast. Longer range forecasts to the end of the month favor dry conditions with warmer than normal temperatures. && .AVIATION...As of 11:00 AM PDT Sunday...Stratus is rapidly retreating to the coast with most area terminals anticipated to scatter out within the next hour or so. Monterey Bay terminals will take longer to scatter out. The marine layer remains around 2000 feet and anticipated to deepen more as a trough of low pressure deepens off the west coast. This will allow for further inland intrusion over the region tonight into Monday as well as possibly earlier onset time this evening. Moderate west winds will persist through the day with gusty winds expected this afternoon once the seabreeze sets up. Vicinity of KSFO...VFR conditions expected to prevail today. The seabreeze will reach 15 to 20 kt this afternoon with gusts to 25 kt possible. Stratus will make and early return this evening potentially impacting the terminals by 03z. Confidence is moderate. SFO Bridge Approach...Same as KSFO with low cloud expected to fill back into the bay after 07z tonight. Monterey Bay Terminals...Stratus will scatter out temporarily over KMRY today approx. 19z with a return as early as 00z this afternoon. Winds are expected to 15 kt this afternoon with gusts to 20 kt possible. Confidence is moderate. && .MARINE...as of 3:00 PM PDT Sunday...A low pressure system developing to the north over the Pacific Northwest will maintain moderate northwesterly flow across the northern coastal waters through late tonight. Winds will be locally strong off coastal points where typical coastal jets form...otherwise light winds expected over the southern half of the forecast area. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tday...SCA...Pigeon Pt to Pt Pinos 0-10 nm from 3 PM SCA...Pt Arena to Pt Reyes 0-10 nm SCA...Pt Reyes to Pigeon Pt 0-10 nm SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm from 3 PM SCA...SF Bay from 2 PM && $$ PUBLIC FORECAST: Bell AVIATION: CW MARINE: CW Visit us at www.weather.gov/sanfrancisco Follow us on Facebook and twitter at: www.Facebook.com/nwsbayarea www.twitter.com/nwsbayarea
Area Forecast Discussion National Weather Service Phoenix AZ 215 PM MST SUN JUL 17 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle and temperatures will increase to above normal levels. && .DISCUSSION... Tonight... A fairly complicated pattern with regards to precipitation in south central AZ will develop later this afternoon and evening. It seems that mid level disturbances are flying off the shelf so to speak, and into southern AZ. One feature was noted this morning in weather balloon data and later with sunlight, visible satellite imagery. This feature was responsible for increased thunderstorm activity between Gila Bend and the Mexican border at noon. Then there is another large mid level circulation feature in northwest Mexico (an MCV from last nights Sonora Mex convection) that is forecast by the models to move into AZ just west of Tucson by 5 pm MST. The GFS model is forecasting a couple of Omega field 500-300 mb bullseye areas from Pinal County just north to Tucson, to portions of south Central AZ just north of the Mexican Border this evening. Therefore with increased moisture, and a couple of nearby dynamical features, it would be best to increase chances for showers and thunderstorms over our south central AZ zones, with the best chances southwest and south of Phoenix. Diminishing showers are expected after midnight partial clearing skies. Monday...Much higher monsoon moisture will have spread over the region by Monday afternoon. With the lack of any notable mid/upper level disturbances, we will go with a standard low grade monsoon forecast, i.e. slight chance of afternoon and evening thunderstorms especially mountains east of Phoenix. Tuesday...The easterly wave moving out of west Texas this evening (Sunday) and into Chihuahua and Sonora Mexico is progged by the GFS model to bodily move into southern Arizona by late Tuesday afternoon and night. We have elevated the threat of precip slightly in south central AZ Tuesday evening because of this feature. Wednesday...Monsoon moisture will be still be entrenched over the region. Again without any mid/upper level disturbances expected, only a slight chance of showers and thunderstorms are forecast for south central AZ. Thursday through Sunday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures be much higher. The driest areas Thursday through Sunday will be southeast California where afternoon temperatures at Imperial, El Centro, and Blythe will flatline at the 114 degree mark. Ouch! && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Only low to moderate confidence with respect to wind shifts and shower potential through Monday morning under fairly persistent 12K- 15K ft cigs. Virga/sprinkles/isold light showers will pass through the Phoenix area this afternoon as sfc winds will generally favor a SSW direction. Some variability in wind direction is likely with these showers and a 160V240 direction would not be unexpected through the afternoon/early evening. Still unsure whether enough instability can be realized in SE AZ to allow thunderstorms to form yielding northward moving outflow boundaries. Enough evidence exists in models to keep some semblance of an outflow boundary and SE sfc winds entering Phoenix terminals this evening. Timing is very uncertain. Regardless of outflow, an earlier onset of an easterly wind direction looks more likely. Could also see residual leftover showers passing through Phoenix later this evening and tonight, though intensity would most likely be light and impacts minimal. Southeast California/Southwest Arizona including KIPL and KBLH: Only moderate confidence in terminal forecasts through Monday morning as thicker 15K-20K cigs spread into SE CA. While virga/sprinkles may occur briefly, any thunderstorm activity should remain well east of the area. Sfc winds will favor a southerly direction (occasionally gusty at KBLH), though a brief period of evening SW winds at KIPL will be likely; and a remote chance of a more easterly outflow component (or allowing variable directions) arriving late tonight. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Moisture and relative humidity values will decrease very slightly through the latter half of the week as high pressure tends to strengthen and air temperatures climb back to into an above normal range. Thunderstorm and wetting rain potential will generally be limited to higher terrain locations north and east of Phoenix, with better potential for outflow winds heading downhill into lower elevations of central Arizona. Minimum relative humidity values in a 15 to 25 percent range during the middle of the week will fall to a 10 to 20 percent range by the end of the week. Overnight recovery will be fair to good. Outside of winds near thunderstorms, directions will favor an upslope component in the afternoon with typical gustiness and light overnight drainage. $$ .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...Vasquez AVIATION...MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Phoenix AZ 215 PM MST SUN JUL 17 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle and temperatures will increase to above normal levels. && .DISCUSSION... Tonight... A fairly complicated pattern with regards to precipitation in south central AZ will develop later this afternoon and evening. It seems that mid level disturbances are flying off the shelf so to speak, and into southern AZ. One feature was noted this morning in weather balloon data and later with sunlight, visible satellite imagery. This feature was responsible for increased thunderstorm activity between Gila Bend and the Mexican border at noon. Then there is another large mid level circulation feature in northwest Mexico (an MCV from last nights Sonora Mex convection) that is forecast by the models to move into AZ just west of Tucson by 5 pm MST. The GFS model is forecasting a couple of Omega field 500-300 mb bullseye areas from Pinal County just north to Tucson, to portions of south Central AZ just north of the Mexican Border this evening. Therefore with increased moisture, and a couple of nearby dynamical features, it would be best to increase chances for showers and thunderstorms over our south central AZ zones, with the best chances southwest and south of Phoenix. Diminishing showers are expected after midnight partial clearing skies. Monday...Much higher monsoon moisture will have spread over the region by Monday afternoon. With the lack of any notable mid/upper level disturbances, we will go with a standard low grade monsoon forecast, i.e. slight chance of afternoon and evening thunderstorms especially mountains east of Phoenix. Tuesday...The easterly wave moving out of west Texas this evening (Sunday) and into Chihuahua and Sonora Mexico is progged by the GFS model to bodily move into southern Arizona by late Tuesday afternoon and night. We have elevated the threat of precip slightly in south central AZ Tuesday evening because of this feature. Wednesday...Monsoon moisture will be still be entrenched over the region. Again without any mid/upper level disturbances expected, only a slight chance of showers and thunderstorms are forecast for south central AZ. Thursday through Sunday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures be much higher. The driest areas Thursday through Sunday will be southeast California where afternoon temperatures at Imperial, El Centro, and Blythe will flatline at the 114 degree mark. Ouch! && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Only low to moderate confidence with respect to wind shifts and shower potential through Monday morning under fairly persistent 12K- 15K ft cigs. Virga/sprinkles/isold light showers will pass through the Phoenix area this afternoon as sfc winds will generally favor a SSW direction. Some variability in wind direction is likely with these showers and a 160V240 direction would not be unexpected through the afternoon/early evening. Still unsure whether enough instability can be realized in SE AZ to allow thunderstorms to form yielding northward moving outflow boundaries. Enough evidence exists in models to keep some semblance of an outflow boundary and SE sfc winds entering Phoenix terminals this evening. Timing is very uncertain. Regardless of outflow, an earlier onset of an easterly wind direction looks more likely. Could also see residual leftover showers passing through Phoenix later this evening and tonight, though intensity would most likely be light and impacts minimal. Southeast California/Southwest Arizona including KIPL and KBLH: Only moderate confidence in terminal forecasts through Monday morning as thicker 15K-20K cigs spread into SE CA. While virga/sprinkles may occur briefly, any thunderstorm activity should remain well east of the area. Sfc winds will favor a southerly direction (occasionally gusty at KBLH), though a brief period of evening SW winds at KIPL will be likely; and a remote chance of a more easterly outflow component (or allowing variable directions) arriving late tonight. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday... Moisture and relative humidity values will decrease very slightly through the latter half of the week as high pressure tends to strengthen and air temperatures climb back to into an above normal range. Thunderstorm and wetting rain potential will generally be limited to higher terrain locations north and east of Phoenix, with better potential for outflow winds heading downhill into lower elevations of central Arizona. Minimum relative humidity values in a 15 to 25 percent range during the middle of the week will fall to a 10 to 20 percent range by the end of the week. Overnight recovery will be fair to good. Outside of winds near thunderstorms, directions will favor an upslope component in the afternoon with typical gustiness and light overnight drainage. $$ .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...Vasquez AVIATION...MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Reno NV 208 PM PDT SUN JUL 17 2016 .SYNOPSIS...High fire danger and hazardous boating conditions on area lakes will continue Monday due to gusty winds and persistent dry weather. Winds will diminish a bit for Tuesday, followed by typical summertime weather for the second half of the week. && .SHORT TERM... Winds and the persistent dry weather are the main forecast concerns for the next couple days. Gusts over 30 mph and low humidity have increased the threat for dangerous fire weather conditions, see the Fire Weather discussion below more details. Winds are also negatively impacting those heading out on the lakes, gusty winds and hazardous waves for small boats, kayaks and paddle boards. Low pressure that`s been well forecast the last week remains off the Pacific Northwest coast with the jet stream sitting over northwest Nevada. The strongest winds aloft are forecast from late tonight to Monday evening. This may prevent winds from decoupling tonight in some locations. If the winds do go light tonight, gusty winds will quickly redevelop in the lower elevations Monday morning. Peak gusts Monday will climb up to near 40 mph, and may reach 70-75 mph over mountain tops and ridge lines. For Tuesday, the low and the jet retreat to the north ever so slightly and that may be enough to decrease the magnitude and duration of the peak afternoon winds. However breezy conditions are likely with continued impacts to boating and fire danger. Brong .LONG TERM...Wednesday through Sunday... No significant changes to the ongoing forecast as dry and hot conditions are expected to prevail. Temperatures will climb a little each day, topping out in the mid 80s for Sierra valleys and 90s to around 100 in lower valleys by the end of the week. Winds will be thermally driven with zephyr like winds developing each afternoon along the east slopes of the Sierra and working out into western NV during the evening. At the beginning of period, upper trough will be offshore with jet cutting across northern CA and Pacific Northwest while upper ridge will be centered over the central part of the country. Medium range models want to gradually build or retrograde ridge westward, but this may take some time as shortwave energy works through the Pacific Northwest. So while there could be some slight fluctuation in winds and temperatures as we make our way through the week, they should be minor ones. Hohmann && .AVIATION... Winds will continue to be gusty through Monday with winds strongest Monday afternoon as jet develops over area late tonight and into Monday morning. Gusts this evening will generally be around 25-30 kts before rising into the 30-35 kt range on Monday. Winds will remain moderate immediately above valley floors tonight with weak shallow inversions confined mainly to the lower valley floors. So KTVL/KTRK will likley remain mixed tonight. Confidence in LLWS is still low as model soundings indicated a more southerly component aligning with surface winds. The most likely location would be KTVL/KTRK 06z-20z Monday. Ridge gusts 50-60 kts will result in lee side turbulence. Hohmann && .FIRE WEATHER... Winds are increasing early this afternoon as the first Red Flag Warning takes effect. The Surprise Valley and extreme northwest NV may have more borderline humidity conditions, as values are currently near or above 20%, otherwise the humidity is already 15% or less in the rest of today`s warning area. No changes were made to today`s warning, although some sites in western Fire Zone 453 may also reach critical values of wind and humidity for a portion of the late afternoon. For tonight, winds will remain gusty over the ridges and favored mid slopes for the Tahoe basin and Sierra Front. Overnight humidity recovery will also continue to be poor for the mid slopes and ridges. For Monday, all zones in the watch were upgraded to Red Flag Warnings as most guidance data continues to support a longer period of gusty winds up to 40 mph at times, with ridge level gusts above 50 mph. Just outside the warning areas, fire zone 271 may see a few sites have humidity dip below 15%, but most areas should not be that dry. In fire zones 273 and 459, overall wind speeds are expected to be lower, although gusts may occasionally edge above 30 mph in some sites north of Bridgeport-Walker Lake. By Tuesday, the low begins to lift to the north with the stronger portion of the upper jet over northwest CA. While we can`t completely rule out a short period of wind gusts in the 30-35 mph range, it appears more likely that gusts will generally range from 25-30 mph and resemble a more typical late day zephyr over far western NV and northeast CA. MJD && .REV Watches/Warnings/Advisories... NV...Red Flag Warning until 10 PM PDT this evening NVZ450-458. Red Flag Warning from 10 AM to 9 PM PDT Monday NVZ458. Lake Wind Advisory until 10 PM PDT this evening NVZ002. Lake Wind Advisory from 10 AM to 9 PM PDT Monday NVZ002. Red Flag Warning from 10 AM to 9 PM PDT Monday NVZ450-453. Lake Wind Advisory from 10 AM to 9 PM PDT Monday NVZ004. CA...Red Flag Warning until 10 PM PDT this evening CAZ270-278. Red Flag Warning from 10 AM to 9 PM PDT Monday CAZ270-278. Lake Wind Advisory from 10 AM to 9 PM PDT Monday CAZ071. Lake Wind Advisory until 10 PM PDT this evening CAZ072. Lake Wind Advisory from 10 AM to 9 PM PDT Monday CAZ072. Red Flag Warning from 10 AM to 9 PM PDT Monday CAZ272. && $$ For more information from the National Weather Service visit... http://weather.gov/reno
Area Forecast Discussion National Weather Service Sacramento CA 153 PM PDT SUN JUL 17 2016 .SYNOPSIS... Near to below normal temperatures are expected today through Tuesday as a disturbance moves north of NorCal. Temperatures will gradually warm up starting Wednesday. Dry weather will continue over the next 7 days. .DISCUSSION... (Today through Wednesday Night) A deep marine layer along the coast along with a trough remaining over the west coast will help to keep temperatures below normal through Wednesday. The marine layer continues to be at around 2000 feet deep with moderate flow expected to continue through the delta. Low clouds look like they will not fully clear from the Bay Area this afternoon. This should help to increase the chances for some low clouds to advect into the valley late tonight and Monday morning. Slight cooling is expected over todays highs with Monday looking like it will be the coolest day this week. Highs in the valley will mainly be in the 80s. A trough will remain along the west coast throughout most of the week to help keep cooler than normal temperatures each day through Wednesday. Isolated thunderstorms may occur the next couple of days west and north of Shasta County with all other areas remaining dry. .EXTENDED DISCUSSION (Thursday THROUGH Sunday) High pressure develops over the desert southwest late this week. As a result, a warming trend is expected across interior northern California during the extended period. A trough will linger along the Pacific Northwest, but model guidance continues to forecast building heights aloft. Daytime highs could be 5-10 degrees above normal by Sunday. Many Valley locations might reach the triple digit mark early next week. && .AVIATION... Mainly VFR conditions the next 24 hours. South to west winds 10 to 16 kt with gusts up to 25 kt will continue across Valley TAF sites into Monday, with locally stronger gusts near the Delta and over higher terrain. IFR ceilings may move through the Delta into the Sacramento region early Monday morning. Dang && .STO Watches/Warnings/Advisories... None. && $$
Area Forecast Discussion National Weather Service San Joaquin Valley - Hanford CA 141 PM PDT SUN JUL 17 2016 .SYNOPSIS... Dry weather and near normal temperatures will be present across central California this week. && .DISCUSSION...An upper trough continues to impact the west coast resulting in a subtle cooling trend across central California. Temperatures this afternoon were generally 2 to 4 degrees cooler compared to yesterday, with most San Joaquin Valley locations forecast to remain below the century mark. Breezy winds from the west were present along the west side of the San Joaquin Valley this afternoon with gusts between 20 and 30 mph and gusts between 30 and 40 mph across the desert and the Kern County mountains. The HRRR and high res ARW and NMM indicate winds strengthening into the evening hours. Dry conditions were also present across the desert and Kern County mountains where relative humidity values in the single digits were common. A Red Flag Warning remains in effect for these areas as well as parts of the southern Sierra Nevada through this evening due to enhanced fire danger. Otherwise, little change in the upper level weather pattern through Tuesday, with the upper trough dominating the west coast. An upper ridge centered over Texas and Oklahoma is forecast to nudge west into Arizona and southern California mid week resulting in a subtle warming trend for central California. Monsoonal moisture is forecast to remain well to the east of the region, keeping the area dry for at least the next 7 days. Looking ahead, the Climate Prediction Centers 8 to 14 day outlook (valid from July 25th through the 31st) calls for a high probability of above normal temperatures for all of California, and in fact for all areas west of the Rockies. && .AVIATION... VFR conditions can be expected through central California for at least the next 24 hours. && .AIR QUALITY ISSUES... On Monday July 18 2016... Unhealthy for sensitive groups in Fresno and Tulare Counties and Sequoia National Park and Forest. Further information is available at Valleyair.org && .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is high. Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.php for additional information an/or to provide feedback. && .HNX Watches/Warnings/Advisories... Red Flag Warning until 9 PM PDT this evening CAZ295-297>299. && $$ public...Riley avn/fw...BSO synopsis...Riley weather.gov/hanford
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1045 PM CDT MON JUL 18 2016 ...Updated to near term forecast through tonight... .UPDATE... Issued at 1039 PM CDT MON JUL 18 2016 Large MCS is becoming increasingly organized over western NE and far northeast CO late this evening. While Corfidi vectors do have a bit of a southerly angle to them, the larger scale wave forcing this activity is moving sharply toward the north and the instability axis seems to extend almost due east. Forecasting soundings for north central KS indicate that a cold pool would have to be quite deep in order to lift parcels to the LFC later tonight, and while it appears unlikely, have included a slight chance for thunderstorms in northern KS on the off chance that the outflow makes its way into the area with enough energy to maintain a few thunderstorms. Short range models, specifically the HRRR and experimental HRRR now have some run-to-run consistency in developing weak warm advection showers and perhaps a thunderstorm in parts of eastern KS after 1 AM. This also seems to be a questionable idea but not completely unreasonable given a bit of moisture aloft and weak but persistent isentropic lift so have included a few hours of a slight chance for thunderstorms in eastern KS early this morning as well. && .SHORT TERM...(This Evening through Tuesday) Issued at 329 PM CDT MON JUL 18 2016 At 20Z, water vapor imagery shows a cloud band with moisture streaming into the Central Rockies with another cloud band stretched from the northern Central Plains into the Ohio Valley up through the New England States. Some storms still along the stationary boundary at the surface into northwestern MO and extreme southeastern IA. Storms also beginning to fire over the foothills of the Rockies into the panhandle of Nebraska. In northeastern Kansas, forecasting a mostly dry period in the short term as heights continue to rise steadily overnight into the day on Tuesday. An MCS may develop overnight associated with the storms previously mentioned over the Rockies. These should stay to the north of the outlook area tonight though as the LLJ convergence is focused to our northwest. Only the NAM brings some of this activity close to the area with all the other short term guidance taking the storms on a northerly track into northern Nebraska and northwestern Iowa overnight. Therefore, not expecting much if any influence from a cold outflow to impact our area even though there is a brief period of isentropic lift that advects over the the region on the 315K to 320K surface. Lack of mid level moisture should keep storms to the north. That said, do expect temperatures to increase again tomorrow into the mid to upper 90s with dewpoints into the upper 60s and low 70s. This should continue to put heat index values into the 105F range while lowest heat index values will be at or above 75F. Have kept heat advisory going for the evening and have upgraded to a heat warning starting Tuesday afternoon as many days of at least heat advisory heat index values are expected. The bottom line is the heat will be the main forecast concern through the period. .LONG TERM...(Tuesday Night through Monday) Issued at 329 PM CDT MON JUL 18 2016 Tuesday night through Thursday... With upper high centered over the Southern/Central Plains during this period, and no real low-level convergence features expected to impact eastern KS, expect dry weather to continue. With dewpoints from the upper 60s to mid 70s, and afternoon high temperatures in the 96 to 103 degree range, afternoon heat indices should be in the 103 to 108 degree range. Overnight lows are only expected to fall to the mid to upper 70s. Thursday Night through Monday... A stout upper-level ridge will continue to be center of the central United States through the end of the week. High temperatures will soar into the upper 90s and lower 100s Friday afternoon. These very hot temperatures coupled with high dewpoints, heat indices will range from 105 to 110 degrees (possibly warmer). Saturday becomes a bit tricky as both the EC and GFS bring a weak cold front through portions of the area. Not only would it "cool" temperatures back into the lower to middle 90s, but precip chances also increase. The front appears to stall out in the vicinity of the outlook area for the remainder of the weekend. Guidance suggests weak 500MB waves will traverse the CWA along the surface boundary. Therefore, have at least slight chance PoPs across the area, along with cooler temperatures. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening) Issued at 640 PM CDT MON JUL 18 2016 VFR conditions are likely through the TAF period. Winds at 800 feet AGL will approach 35 kts between 04Z-11Z but should stay just less than LLWS criteria. && .TOP Watches/Warnings/Advisories... Excessive Heat Warning from 1 PM Tuesday to 7 PM CDT Friday for KSZ008>012-020>024-026-034>040-054>056-058-059. Heat Advisory until 1 PM CDT Tuesday for KSZ008>012-020>024-026- 034>040-054>056-058-059. && $$ UPDATE...Barjenbruch SHORT TERM...Drake LONG TERM...Baerg/GDP AVIATION...Barjenbruch
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
643 PM CDT MON JUL 18 2016 ...Update to aviation forecast discussion... .SHORT TERM...(This Evening through Tuesday) Issued at 329 PM CDT MON JUL 18 2016 At 20Z, water vapor imagery shows a cloud band with moisture streaming into the Central Rockies with another cloud band stretched from the northern Central Plains into the Ohio Valley up through the New England States. Some storms still along the stationary boundary at the surface into northwestern MO and extreme southeastern IA. Storms also beginning to fire over the foothills of the Rockies into the panhandle of Nebraska. In northeastern Kansas, forecasting a mostly dry period in the short term as heights continue to rise steadily overnight into the day on Tuesday. An MCS may develop overnight associated with the storms previously mentioned over the Rockies. These should stay to the north of the outlook area tonight though as the LLJ convergence is focused to our northwest. Only the NAM brings some of this activity close to the area with all the other short term guidance taking the storms on a northerly track into northern Nebraska and northwestern Iowa overnight. Therefore, not expecting much if any influence from a cold outflow to impact our area even though there is a brief period of isentropic lift that advects over the the region on the 315K to 320K surface. Lack of mid level moisture should keep storms to the north. That said, do expect temperatures to increase again tomorrow into the mid to upper 90s with dewpoints into the upper 60s and low 70s. This should continue to put heat index values into the 105F range while lowest heat index values will be at or above 75F. Have kept heat advisory going for the evening and have upgraded to a heat warning starting Tuesday afternoon as many days of at least heat advisory heat index values are expected. The bottom line is the heat will be the main forecast concern through the period. .LONG TERM...(Tuesday Night through Monday) Issued at 329 PM CDT MON JUL 18 2016 Tuesday night through Thursday... With upper high centered over the Southern/Central Plains during this period, and no real low-level convergence features expected to impact eastern KS, expect dry weather to continue. With dewpoints from the upper 60s to mid 70s, and afternoon high temperatures in the 96 to 103 degree range, afternoon heat indices should be in the 103 to 108 degree range. Overnight lows are only expected to fall to the mid to upper 70s. Thursday Night through Monday... A stout upper-level ridge will continue to be center of the central United States through the end of the week. High temperatures will soar into the upper 90s and lower 100s Friday afternoon. These very hot temperatures coupled with high dewpoints, heat indices will range from 105 to 110 degrees (possibly warmer). Saturday becomes a bit tricky as both the EC and GFS bring a weak cold front through portions of the area. Not only would it "cool" temperatures back into the lower to middle 90s, but precip chances also increase. The front appears to stall out in the vicinity of the outlook area for the remainder of the weekend. Guidance suggests weak 500MB waves will traverse the CWA along the surface boundary. Therefore, have at least slight chance PoPs across the area, along with cooler temperatures. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening) Issued at 640 PM CDT MON JUL 18 2016 VFR conditions are likely through the TAF period. Winds at 800 feet AGL will approach 35 kts between 04Z-11Z but should stay just less than LLWS criteria. && .TOP Watches/Warnings/Advisories... Excessive Heat Warning from 1 PM Tuesday to 7 PM CDT Friday for KSZ008>012-020>024-026-034>040-054>056-058-059. Heat Advisory until 1 PM CDT Tuesday for KSZ008>012-020>024-026- 034>040-054>056-058-059. && $$ SHORT TERM...Drake LONG TERM...Baerg/GDP AVIATION...Barjenbruch
  [top] Area Forecast Discussion National Weather Service Wichita KS 624 PM CDT MON JUL 18 2016 .SYNOPSIS... Issued at 311 PM CDT Mon Jul 18 2016 In the upper levels, water vapor imagery shows one shortwave tracking across western Quebec with another impulse rotating over the Pacific NW. Meanwhile, ridging is in place over the Rockies into the Plains. At the surface, weak lee troughing is in place with a weak front extending across northern MO into southern Nebraska. && .SHORT TERM...(This evening through Friday) Issued at 311 PM CDT Mon Jul 18 2016 The main theme for the next few days will be for the upper ridge to continue to build and expand over the Plains through Fri. This will allow for plenty of sun and a warming trend. Temps Tue look like the "coolest" through at least Fri before the more serious heat starts Wed and continues through the end of the work week. Should start to see more widespread highs at or above 100 by Wed. The only good news is that we should start to see afternoon dew points mix out for mid-late week which should limit the 110+ heat indices. Due to the prolonged period of 100-105+ heat, will continue with heat headlines along and east of I-135. .LONG TERM...(Saturday through Monday) Issued at 311 PM CDT Mon Jul 18 2016 Upper pattern will slowly start to flatten out starting Sat and continue into the start of the work week. There is also some model agreement in some shortwave energy sliding across the northern Plains and into the western Great Lakes region by Sun which may try and push a front into northern Kansas. In addition, the more zonal flow will allow some of the weak impulses to track over the area which may spark off a few storms. Confidence in storm chances through these periods is extremely low as models will have a hard time resolving these smaller scale features this far out. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 620 PM CDT Mon Jul 18 2016 VFR forecast at all sites throughout the period. Fair weather cumulus should dissipate around sunset. Winds increase in the morning with few cumulus redeveloping mainly at KCNU, with KSLN/KICT likely on western fringe of few-scattered cloud deck. -Howerton && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 74 96 75 100 / 0 0 0 0 Hutchinson 74 97 75 100 / 0 0 0 0 Newton 75 95 75 99 / 0 0 0 0 ElDorado 75 95 75 98 / 0 0 0 0 Winfield-KWLD 75 95 75 99 / 0 0 0 0 Russell 74 98 75 102 / 10 0 0 0 Great Bend 74 98 74 101 / 0 0 0 0 Salina 76 99 76 102 / 10 10 0 0 McPherson 74 97 75 100 / 0 0 0 0 Coffeyville 75 95 75 96 / 0 0 0 0 Chanute 75 94 74 95 / 0 0 0 0 Iola 74 94 74 95 / 10 0 0 0 Parsons-KPPF 74 94 74 95 / 0 0 0 0 && .ICT Watches/Warnings/Advisories... Heat Advisory until 8 PM CDT Friday for KSZ051-068-069-083- 092>096-098>100. Excessive Heat Warning from noon Tuesday to 8 PM CDT Friday for KSZ049-052-053-070>072. Heat Advisory until noon CDT Tuesday for KSZ049-052-053-070>072. && $$ SHORT TERM...RBL LONG TERM...RBL AVIATION...PJH
  [top] Area Forecast Discussion National Weather Service Goodland KS 516 PM MDT MON JUL 18 2016 .SHORT TERM...(This afternoon through Tuesday) Issued at 147 PM MDT Mon Jul 18 2016 Early afternoon satellite and RAP upper level analysis shows large scale ridge entrenched across the central US, with monsoonal flow in across through the central Rockies. A shortwave trough is currently rotating into northern Colorado/southern Wyoming with thunderstorms activity initiating in the higher terrain. A warm front is slowly progressing northward over our CWA and is still roughly south of I-70. Early this afternoon-Tonight: Warm front has been slower to lift north than models had previously indicated, however a strong CAP in place is limiting initiation within frontal zone. Thunderstorm activity may still initiate as the front lifts north and thunderstorms in Colorado may also begin to sneak into our far west before main area of thunderstorms develops this evening. As the shortwave moves out of the Rockies into western Nebraska this should help speed up the movement on the warm front and by 00z this feature should be near the northern part of our CWA. Higher resolution models support thunderstorms merging into a cluster or complex as LLJ increases this evening and then tracking over our far northwest and this is where I placed highest PoPs. There is a deep/moist air mass in place with PWATs exceeding 1.0" and Tds (within frontal zone) in the 60-70 range. Thunderstorm motions are expected to be around 15 kt and east-southeast flow overrunning the frontal zone could lead to training of thunderstorm activity. This raises the possibility for locally heavy rainfall amounts and at least a localized risk for flooding in our northwest. Initially CAPE will be favorable for severe thunderstorms, however deep layer sheer is very marginal and main CAPE axis will trend northward with front. Tuesday: Ridge continues to amplify shifting main flow further west away from our CWA. Some guidance is still hinting at isolated thunderstorms moving into northwest portions of Yuma county, however confidence is not high this will make it this far east. Slight chance PoPs were maintained for now. Temperatures will trend upwards with strengthening of the ridge and increasing southerly flow with high temperatures at least in the upper 90s for most locations and near 100 (to the low 100s) in our north and east. Heat index values appear to remain near 100F due to slightly lower Td values, so will hold off on any highlights. .LONG TERM...(Tuesday night through Monday) Issued at 205 PM MDT Mon Jul 18 2016 Hot temperatures are anticipated during the longterm period, with high pressure impacting the region into the weekend. Midweek appears to be mainly dry while precipitation chances persist throughout the extended. Tuesday night through Thursday night: High pressure remains centered over the CONUS and ridging dominates the pattern through midweek. Could see isolated thunderstorms in the northwestern portion of the area each afternoon/evening Tuesday and Wednesday as monsoonal moisture wraps around the western side of the ridge. The high pressure elongates over the southern half of the country on Thursday. Thunderstorm chances return to the region in the evening as the ridge begins to flatten. Friday through Monday: At the end of the work week, a shortwave pushes from the Pacific Northwest towards the northern Plains. This disturbance sends a cold front south Friday night into Saturday, bringing increased thunderstorm chances on Saturday and slightly cooler temperatures for the weekend/early next week. The ridge retreats to the west on Sunday and Monday, and a more active pattern develops over the High Plains with continued precipitation chances as disturbances move through the flow. Heat: Hot temperatures are expected on Wednesday and Thursday before a cooling trend in the extended. Highs top out in the upper 90s along and west of the Colorado border while temperatures in the 100-104 range are forecast to the east. With heat index values near 105 along and east of Highway 25, am thinking a heat advisory may be needed for at least Wednesday and Thursday. Temperatures look to trend downward from Friday onward with highs in the upper 80s to low 90s by Sunday. Lows will be in the 60s to mid 70s in the long term period. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 513 PM MDT Mon Jul 18 2016 Scattered thunderstorms in northeast Colorado will struggle to make much eastward progress tonight with storm motions taking them northeast into Wyoming and the Nebraska panhandle. As a result...will not mention thunderstorms at either KMCK or KGLD. Otherwise...expecting VFR conditions to prevail with southeast winds diminishing after sunset tonight but increasing again Tuesday morning from the southwest. && .GLD Watches/Warnings/Advisories... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...JBH AVIATION...024
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1241 PM CDT SUN JUL 17 2016 .UPDATE... Issued at 1241 PM CDT SUN JUL 17 2016 Scattered thunderstorms continue across the counties near the Nebraska border early this afternoon in a zone of surface-925 mb convergence along with cold pool interactions and weak isentropic lift. Expect the storms to last for the next few hours before gradually lifting to the northeast. With clouds and precipitation will also adjust high temperatures downward as well. && ...Update to aviation forecast discussion... .SHORT TERM...(Today and Tonight) Issued at 258 AM CDT SUN JUL 17 2016 A cluster of storms has formed along the KS/NE state line in western KS, and is currently moving eastward. Ahead of the cluster mucape is around 1500-2000 j/kg, which spreads into portions of eastern KS. Also, the low level jet is maximized over this region, and is beginning to veer, which may allow the storms to maintain strength the next few hours. The high res model guidance shows these storms possibly forming into a bowing segment across north central KS. If strong enough the convective cores may be capable of transporting higher winds down to the surface. The latest run of the HRRR is advertising a small area of damaging winds within the bowing segment. SPC mesoanalysis shows an area of high downdraft cape over north central KS that would support the possibility of strong winds. If the storm cluster can reach northeast KS it should weaken as the low level jet decreases, and becomes more focused on the backside. The forecast area should clear out later today. Temperatures will heat up ahead of a cold front moving southward through NE. High temperatures should range from mid 90s to the lower 100s. Dew points will range from the mid 60s to the lower 70s. The combination of heat and humidity will cause heat indices to reach 105 for several hours this afternoon across east central KS. The cold front is forecasted to reach far southeast NE in the early morning hours. Models are developing showers and storms along this front across northern KS in the predawn hours. The instability is not forecasted to be that high during this timeframe therefore the severe threat is low. The GFS is hinting at some isentropic lift over eastern KS ahead of the front, and is developing convection around sunrise. Although the moisture in those layers appears rather limited so have kept only slight chances. .LONG TERM...(Monday through Saturday) Issued at 258 AM CDT SUN JUL 17 2016 Kept some slight chances for thunder in the northern counties into early Monday as convection may still linger before 18z, although better chances are north. Could see a repeat of this late Monday into early Tuesday morning as the LLJ once again interacts with a shortwave moving over the ridge and across the front just to our north, generating storms to our north. Beyond these two time periods, have pulled chances for rain as the strong upper high moves over the state into the week. Temperatures Monday and Tuesday are forecast in the 90s, with heat indices just shy of advisory criteria. If dewpoints rise a few degrees however, would likely be enough to bump much of the area into heat advisory numbers. Mid level temps rise about 2C each day Wednesday into Friday, and surface temperatures reflect this increase, with many areas in our western half over the century mark for much of this period. We may end up with several days of heat advisory criteria between Wednesday and into the weekend. && .AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon) Issued at 1241 PM CDT SUN JUL 17 2016 VFR conditions are expected through the period with convection remaining to the north of the terminals. Winds around 10 to 15 kts with gusts to 24 kts are expected through 00Z then decrease to 10 kts or less. Low level wind shear is expected tonight with the increase of the low level jet so included in the forecast from 07Z-14Z Monday. && .TOP Watches/Warnings/Advisories... Heat Advisory until 8 PM CDT this evening for KSZ024-026-039-040- 055-056-059. && $$ UPDATE...53 SHORT TERM...Sanders LONG TERM...67 AVIATION...53
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
619 AM CDT SUN JUL 17 2016 ...Update to aviation forecast discussion... .SHORT TERM...(Today and Tonight) Issued at 258 AM CDT SUN JUL 17 2016 A cluster of storms has formed along the KS/NE state line in western KS, and is currently moving eastward. Ahead of the cluster mucape is around 1500-2000 j/kg, which spreads into portions of eastern KS. Also, the low level jet is maximized over this region, and is beginning to veer, which may allow the storms to maintain strength the next few hours. The high res model guidance shows these storms possibly forming into a bowing segment across north central KS. If strong enough the convective cores may be capable of transporting higher winds down to the surface. The latest run of the HRRR is advertising a small area of damaging winds within the bowing segment. SPC mesoanalysis shows an area of high downdraft cape over north central KS that would support the possibility of strong winds. If the storm cluster can reach northeast KS it should weaken as the low level jet decreases, and becomes more focused on the backside. The forecast area should clear out later today. Temperatures will heat up ahead of a cold front moving southward through NE. High temperatures should range from mid 90s to the lower 100s. Dew points will range from the mid 60s to the lower 70s. The combination of heat and humidity will cause heat indices to reach 105 for several hours this afternoon across east central KS. The cold front is forecasted to reach far southeast NE in the early morning hours. Models are developing showers and storms along this front across northern KS in the predawn hours. The instability is not forecasted to be that high during this timeframe therefore the severe threat is low. The GFS is hinting at some isentropic lift over eastern KS ahead of the front, and is developing convection around sunrise. Although the moisture in those layers appears rather limited so have kept only slight chances. .LONG TERM...(Monday through Saturday) Issued at 258 AM CDT SUN JUL 17 2016 Kept some slight chances for thunder in the northern counties into early Monday as convection may still linger before 18z, although better chances are north. Could see a repeat of this late Monday into early Tuesday morning as the LLJ once again interacts with a shortwave moving over the ridge and across the front just to our north, generating storms to our north. Beyond these two time periods, have pulled chances for rain as the strong upper high moves over the state into the week. Temperatures Monday and Tuesday are forecast in the 90s, with heat indices just shy of advisory criteria. If dewpoints rise a few degrees however, would likely be enough to bump much of the area into heat advisory numbers. Mid level temps rise about 2C each day Wednesday into Friday, and surface temperatures reflect this increase, with many areas in our western half over the century mark for much of this period. We may end up with several days of heat advisory criteria between Wednesday and into the weekend. && .AVIATION...(For the 12Z TAFS through 12Z Monday Morning) Issued at 614 AM CDT SUN JUL 17 2016 A brief shower or storm could come close to MHK in the next few hours, but given the isolated coverage did not include in the taf. Low level wind shear will decrease the next few hours while the surface wind gusts increase. There is a slight chance for scattered storms late tonight, but confidence is low at this point. && .TOP Watches/Warnings/Advisories... Heat Advisory from 1 PM this afternoon to 8 PM CDT this evening for KSZ024-026-039-040-055-056-059. && $$ SHORT TERM...Sanders LONG TERM...67 AVIATION...Sanders
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
326 AM CDT SUN JUL 17 2016 .SHORT TERM...(Today and Tonight) Issued at 258 AM CDT SUN JUL 17 2016 A cluster of storms has formed along the KS/NE state line in western KS, and is currently moving eastward. Ahead of the cluster mucape is around 1500-2000 j/kg, which spreads into portions of eastern KS. Also, the low level jet is maximized over this region, and is beginning to veer, which may allow the storms to maintain strength the next few hours. The high res model guidance shows these storms possibly forming into a bowing segment across north central KS. If strong enough the convective cores may be capable of transporting higher winds down to the surface. The latest run of the HRRR is advertising a small area of damaging winds within the bowing segment. SPC mesoanalysis shows an area of high downdraft cape over north central KS that would support the possibility of strong winds. If the storm cluster can reach northeast KS it should weaken as the low level jet decreases, and becomes more focused on the backside. The forecast area should clear out later today. Temperatures will heat up ahead of a cold front moving southward through NE. High temperatures should range from mid 90s to the lower 100s. Dew points will range from the mid 60s to the lower 70s. The combination of heat and humidity will cause heat indices to reach 105 for several hours this afternoon across east central KS. The cold front is forecasted to reach far southeast NE in the early morning hours. Models are developing showers and storms along this front across northern KS in the predawn hours. The instability is not forecasted to be that high during this timeframe therefore the severe threat is low. The GFS is hinting at some isentropic lift over eastern KS ahead of the front, and is developing convection around sunrise. Although the moisture in those layers appears rather limited so have kept only slight chances. .LONG TERM...(Monday through Saturday) Issued at 258 AM CDT SUN JUL 17 2016 Kept some slight chances for thunder in the northern counties into early Monday as convection may still linger before 18z, although better chances are north. Could see a repeat of this late Monday into early Tuesday morning as the LLJ once again interacts with a shortwave moving over the ridge and across the front just to our north, generating storms to our north. Beyond these two time periods, have pulled chances for rain as the strong upper high moves over the state into the week. Temperatures Monday and Tuesday are forecast in the 90s, with heat indices just shy of advisory criteria. If dewpoints rise a few degrees however, would likely be enough to bump much of the area into heat advisory numbers. Mid level temps rise about 2C each day Wednesday into Friday, and surface temperatures reflect this increase, with many areas in our western half over the century mark for much of this period. We may end up with several days of heat advisory criteria between Wednesday and into the weekend. && .AVIATION...(For the 06Z TAFS through 06Z Sunday Night) Issued at 1159 PM CDT SAT JUL 16 2016 LLWS is expected as the winds in the 1000-2000 ft layer increase through the night, peaking around 43-48 kts at the 1500 ft level. VFR conditions are likely through the TAF with a small chance for showers or TS at MHK 10Z- 14Z and even smaller chance at TOP/FOE 12Z-15Z. && .TOP Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Sanders LONG TERM...67 AVIATION...Barjenbruch
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1201 AM CDT SUN JUL 17 2016 ...Update to aviation forecast discussion... .SHORT TERM...(This Evening through Sunday) Issued at 323 PM CDT SAT JUL 16 2016 At 20Z, WV imagery shows a complex of storms off over the Dakotas moving east/southeast into the Upper MS Valley. Meanwhile a another upper level low pressure system and associated shortwave continues to work into eastern MT. Further south, a plume of mid to upper level moisture can be seen streaming through the Central Rockies into Nebraska. Subtle shortwaves continue to work through this region. At the surface, an area of low pressure is over northeastern CO vicinity with a warm boundary stretched along and near the KS/NE border. Most of the severe activity today should remain north of the outlook area and be associated with the two northern systems. However, there is a small chance that storms develop this afternoon and evening over northeastern CO and southwestern NE before organizing into a small MCS that could potentially propagate into north central and northeastern KS mainly along the KS/NE border late tonight into early Sunday morning. A LLJ is expected to develop late this evening and veer into the area by early morning. This should help provide instability and convergence needed to keep at least some storms going as they move into the area. The likely threat when they arrive would be some strong gusty winds. For the day Sunday, clearing should continue over northern areas of the CWA. As heights continue to rise throughout the day, do expect that some areas could begin to approach heat advisory levels with high temps over northeast Kansas pushing into upper 90s and some 100s over southwestern counties into north central Kansas. Headline may need to be issued by overnight shift but will hold for now. .LONG TERM...(Sunday Night through Saturday) Issued at 323 PM CDT SAT JUL 16 2016 Sunday Night through Tuesday... Frontal boundary is expected to move into north central and northeast Kansas Sunday night. Low level jet increases through the evening then veers to near westerly by monday morning. There is not much in the way of convergence along the front across northeast Kansas and looks to focus to the northeast of the forecast area. Therefore will leave small pops across the northern CWA north of Interstate 70 Sunday night into Monday morning. Have kept small pops going for areas north of Interstate 70 with the northeast return of the frontal boundary Monday night into Tuesday morning. Lows Sunday night will be in the low to mid 70s. Temperatures warm back into the upper 90s near central Kansas on Monday with lower 90s near the Nebraska border. Heat indices on Monday look to be in the 98 to 104 degree range. By Tuesday expect temperatures to warm into the mid and upper 90s once again with afternoon heat indices in the 100 to 103 degree range. Tuesday Night through Saturday... Mid-level ridging will be in place across the Central Plains for the majority of the period. Good agreement amongst the EC and GFS with the stout ridge overhead through Thursday. High temperatures will soar into the middle 90s to perhaps 100 degrees Tuesday through Thursday. Plentiful boundary layer moisture will contribute to upper 60 to lower 70 degree dewpoints. This combination of heat and humidity will result in heat indicies in the 100 to 110 degree range Tuesday through Thursday. These very hot and humid conditions may continue into the weekend, however model agreement diverges for Friday and Saturday. Both models have a trough across the Northern Plains, however it`s effects on the forecast area differ. The GFS shifts the ridge axis across the Rockies and sweeps a weak cold front through the area. While the EC, keeps the frontal boundary well north of the area, allowing the heat wave to continue. && .AVIATION...(For the 06Z TAFS through 06Z Sunday Night) Issued at 1159 PM CDT SAT JUL 16 2016 LLWS is expected as the winds in the 1000-2000 ft layer increase through the night, peaking around 43-48 kts at the 1500 ft level. VFR conditions are likely through the TAF with a small chance for showers or TS at MHK 10Z- 14Z and even smaller chance at TOP/FOE 12Z-15Z. && .TOP Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Drake LONG TERM...Baerg/53 AVIATION...Barjenbruch
Area Forecast Discussion National Weather Service Dodge City KS 1152 PM CDT SAT JUL 16 2016 ...Updated for Aviation... .UPDATE... Issued at 345 PM CDT Sat Jul 16 2016 Had to make some significant changes to the forecast through this evening. Added isolated to scattered thunderstorms in the grids and forecast through about midnight, to account for convection developing in SE Colorado. Latest HRRR loosely develops these storms into another complex this evening. Other models, including the 18z NAM, do not agree with this, keeping most storms north of SW Kansas tonight. Given the HRRR`s performance last night, went ahead and added some pops. Forecast evolution this evening is more uncertain than usual. MLCAPE axis of 2500 J/kg across W/SW Kansas as of 3 pm would suggest the HRRR is on to something. Lifted index across the western zones down to -8. Some storms may be marginally severe with hail to quarters and winds to 60 mph. Widespread severe weather is not expected...however, models do not appear to have a handle on the current trends, and confidence is lower than usual. && .SHORT TERM...(This evening through Sunday) Issued at 1226 PM CDT Sat Jul 16 2016 Much quieter weather pattern unfolding for SW Kansas. A virtually clear sky early this afternoon. S/SE winds will become strong and gusty this afternoon, in response to a 994 mb surface low near Limon, Colorado and about a 10 mb surface pressure gradient between Syracuse and Kiowa. Some gusts of 30-35 mph will be noted. 12z NAM and HRRR model runs, which did an excellent job forecasting last night`s thunderstorms, both keep tonight`s expected MCS activity mainly north of SW Kansas, across NW Kansas into Nebraska. Kept a slight chance of convection for northern Ellis county through tonight, as that zone will be closest to the Nebraska convection, but am not expecting much. A strong pronounced low level jet is progged by all models to develop after sunset, with 850 mb winds as high as 60 kts. As such, south winds will remain quite elevated all night. This, in turn, will keep temperatures quite elevated, with most locales only falling to the lower 70s Sunday morning. Sunday...Mostly sunny and hot. Strong upper high begins to build strongly into the plains, with 500 mb heights rising sharply from 590 dm Saturday, to 594 dm Sunday afternoon. Afternoon temperatures will be hotter in response, but not as hot as some guidance indicates. Lack of downslope, the upper high organizing east of SW KS near the Ozarks, and most importantly, lush vegetation and standing water from recent rainfall...will all slow down the heating trend. GFS/MAV/MEX guidance in the 100s is too hot for Sunday. Forecasted upper 90s for most zones, and wouldn`t be surprised if I am still several degrees too warm. NAM/ECMWF both suggest perhaps an isolated thunderstorm across the far W/NW zones late Sunday afternoon, but with weak shear and warming temperatures aloft, am not expecting much. .LONG TERM...(Sunday night through Saturday) Issued at 215 PM CDT Sat Jul 16 2016 An extended stretch of typical summer weather...hot and dry... will begin on Monday, and persist into next weekend. Little if any day-to-day variation expected. Hot upper anticyclone establishes near the Ozarks on Monday, and wallows around the southern plains, slowly inching westward, ending up as a 598 dm upper high over SW KS by Saturday. Afternoon temperatures will be in the mid to upper 90s for most locales through Wednesday. Starting about Thursday, the topsoil will have dried enough, and the subsidence from the upper ridge will have gotten close enough, to allow for widespread triple digit heat. Morning low temperatures will hold in the low to mid 70s for all locations. Rain/thunderstorm chances in this pattern are remote, but not completely zero. Medium range models suggest an isolated storm may clip the far W/NW zones during the peak heating hours, farthest from the high pressure ridge`s influence. Purposely kept all pop grids at slight chance (<25%) with no significant rainfall expected. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1147 PM CDT Sat Jul 16 2016 VFR conditions are expected as warm upper ridging moves into the Central Plains. An isolated thunderstorm is possible near KHYS this morning, but not enough confidence to put into forecast. A 50 to 55kt low level jet will continue through 12-15Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 71 99 70 97 / 10 10 10 10 GCK 69 97 69 97 / 10 10 10 20 EHA 71 100 71 98 / 10 10 10 10 LBL 69 101 71 99 / 10 10 10 10 HYS 71 97 71 96 / 20 10 20 20 P28 72 100 73 99 / 10 0 10 10 && .DDC Watches/Warnings/Advisories... NONE. && $$ UPDATE...Turner SHORT TERM...Turner LONG TERM...Turner AVIATION...Kruse Area Forecast Discussion National Weather Service Tucson AZ 250 AM MST TUE JUL 19 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Isolated light showers were occurring early this morning east of Tucson. Expect these to continue thru sunrise as they move to the WNW. A weak MCV was over SW Graham county as of 2 am, but shouldn`t be a player today as it continue to move NNW. What could be a player later today is the inverted trof currently over Chihuahua MX. This feature is moving slowly to the NW toward the area. Hi-res models focusing best activity W of Tucson, with potential for blowing dust across Pinal county towards Phoenix, and Cochise county. PW values across the remain above normal for July so locally heavy rain a threat. Can`t rule out a severe storm or two. Highs today will be around normal. Scattered afternoon/evening storms Wednesday with highs slightly warmer than today. Starting Thursday and continuing through the upcoming weekend there will be a gradual decrease in shower and thunderstorm activity as sub-tropical ridge expands over the southern CONUS. Still hanging on to enough moisture to keep isolated to scattered storms in the forecast. Highs temperatures will be above normal through this period, maxing out on Friday. && .AVIATION...VALID THRU 20/12Z. Isolated showers through the early morning hours. Sct-bkn clouds at 6-9k ft agl and bkn-ovc clouds at 10-14k ft agl. Expect isolated to scattered showers and thunderstorms developing during the late morning and afternoon, persisting through the mid evening hours tonight. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Wednesday morning. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .CLIMATE...As the area heats up again, could see a few spots across the western deserts approach record highs later in the week. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
  [top] Area Forecast Discussion National Weather Service Flagstaff AZ 242 AM MST TUE JUL 19 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION...A wide area of high pressure aloft remained centered over the Oklahoma/Kansas border. The models continue to promise little movement in this high pressure feature over the next few days. The position of the high is placing southerly flow over Arizona with not much change in the moisture profile through Thursday. Moving forward the distribution of showers and thunderstorms will remain very similar to Monday. Isolated heavy rain amounts of an inch or more and localized flooding will be possible. More generally, amounts in the trace to quarter inch category scattered about northern Arizona. From Friday onward...Models show the high pressure system centered over Oklahoma essentially splitting. The western portion of the high will migrate across Arizona and eventually become established over the western United States. If this pattern transpires it will open the door to an influx of drier air from the west. Forecast grids reflect a downturn in monsoon activity but moisture looks too entrenched for a complete shutdown in monsoon activity. We`ll keep you updated. && .AVIATION...For the 12Z package....Primarily VFR conditions are expected for the next 24 hours with bkn cigs aoa 14kft msl. til 17z isolated -shra / tsra possible, then btwn 17z-02z sct-nmrs SHRA/TSRA especially mountain areas. Brief visibility reductions and gusty winds possible near storms. Precipitation coverage decreasing after 02z Weds. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect another round of thunderstorms over the forecast area today and Wednesday. Storm motion will generally be from the south to north 5-10 mph. Thursday through Saturday...Scattered thunderstorms will persist across the area on Thursday. Drier air filtering into Arizona from the west will bring a decrease in thunderstorm activity on Friday and Saturday...with minimum RH`s dropping back into the teens to the north and west of Flagstaff. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...McCollum AVIATION...DL For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 934 PM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Showers and thunderstorms across southeast Arizona had diminished significantly in areal coverage late this evening. A few lingering showers and thunderstorms may continue to impact areas near Douglas through midnight, but not much activity expected thereafter. That said, updated the forecast to reflect this decreasing trend. Please refer to the additional sections in this product for more details. && .AVIATION...VALID THRU 20/06Z. A few lingering showers and thunderstorms can be expected tonight near the International Border. Otherwise, scattered to broken clouds at or above 10kft can be expected through Tuesday morning. Expect afternoon cloud build-ups Tuesday afternoon with isolated to scattered showers and thunderstorms developing through Tuesday evening. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA on Tuesday. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Tuesday afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .PREV DISCUSSION...Similar coverage of showers/tstms as today canbe expected Tuesday afternoon/evening as deep (albeit still light)sely flow aloft continues across the area. Scattered mainly afternoon/evening showers/tstms will also occur Wednesday. Thereafter, the 18/12Z GFS/ECMWF/CMC were similar versus their respective solutions in depicting a gradual daily decrease in showers/tstms to begin Thursday and continue into this weekend. Given the continued ely mid-level flow, precip-free conditions area- wide should not occur as earlier this month. However, moisture should remain sufficient for isolated to scattered afternoon and evening showers and thunderstorms Thursday through next Monday. High temps Tuesday will remain quite close to seasonal normals. A warming trend is forecast to begin Wednesday, and based on various 18/12Z guidance, high temps were increased several degs Thur-Sat versus the previous forecast. At this time, appears that Friday will be the hottest day although Saturday should be quite similar. A moderation in daytime temps should then occur Sunday and Monday. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Tucson AZ 934 PM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Showers and thunderstorms across southeast Arizona had diminished significantly in areal coverage late this evening. A few lingering showers and thunderstorms may continue to impact areas near Douglas through midnight, but not much activity expected thereafter. That said, updated the forecast to reflect this decreasing trend. Please refer to the additional sections in this product for more details. && .AVIATION...VALID THRU 20/06Z. A few lingering showers and thunderstorms can be expected tonight near the International Border. Otherwise, scattered to broken clouds at or above 10kft can be expected through Tuesday morning. Expect afternoon cloud build-ups Tuesday afternoon with isolated to scattered showers and thunderstorms developing through Tuesday evening. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA on Tuesday. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Tuesday afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .PREV DISCUSSION...Similar coverage of showers/tstms as today canbe expected Tuesday afternoon/evening as deep (albeit still light)sely flow aloft continues across the area. Scattered mainly afternoon/evening showers/tstms will also occur Wednesday. Thereafter, the 18/12Z GFS/ECMWF/CMC were similar versus their respective solutions in depicting a gradual daily decrease in showers/tstms to begin Thursday and continue into this weekend. Given the continued ely mid-level flow, precip-free conditions area- wide should not occur as earlier this month. However, moisture should remain sufficient for isolated to scattered afternoon and evening showers and thunderstorms Thursday through next Monday. High temps Tuesday will remain quite close to seasonal normals. A warming trend is forecast to begin Wednesday, and based on various 18/12Z guidance, high temps were increased several degs Thur-Sat versus the previous forecast. At this time, appears that Friday will be the hottest day although Saturday should be quite similar. A moderation in daytime temps should then occur Sunday and Monday. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Flagstaff AZ 902 PM MST MON JUL 18 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION... Thunderstorm activity appears to be trending downward this evening, with just a few isolated thunderstorms remaining. Will continue to monitor storms overnight, but the short-term forecast through morning currently looks in good shape. && .PREV DISCUSSION /250 PM MST/... The monsoon circulation has brought plentiful atmospheric moisture back into to the area...with precipitable water values now up to around 1.0" at KFLG. Instability has been somewhat limited...but scattered thunderstorms have formed with a few locally heavy showers, mainly over the higher terrain. Little change in the overall pattern is anticipated through Thursday with the strong ridge of high pressure in place over the Southern Plains and moist southerly flow over Arizona, providing the environment for daily thunderstorm activity across the forecast area. Storms will move a bit slower Tuesday through Thursday, leading to a somewhat greater chance for heavy rainfall accumulations. Friday through Sunday...forecast models continue to show the flattening of the ridge over the southern Rockies, and a decrease in thunderstorm activity Friday through Sunday as drier air filters in from the west. && .AVIATION...For the 00Z package...Only isolated showers and thunderstorms are expected for the remainder of tonight. Storms are likely to become more numerous again after 17Z Tuesday. Expect visibility reductions and gusty winds near stronger storms Tuesday. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Monsoon moisture is increasing across the area. Expect increasing showers and thunderstorm coverage. Gusty outflow winds are probable from any storms or showers, especially today. Storm motion today from south to north about 10 mph. Tuesday through Friday...Monsoon moisture to remain over northern Arizona, with shower and thunderstorm chances each day. Winds may become erratic and gusty near thunderstorms. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...KD/Bohlin AVIATION...KD FIRE WEATHER...BAK For Northern Arizona weather information visit weather.gov/flagstaff
  [top] Area Forecast Discussion National Weather Service Phoenix AZ 835 PM MST MON JUL 18 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... A very activity late afternoon/evening for a few selected spots across south-central AZ. The combination of increased moisture levels through the column (KPSR balloon sounding PWAT 1.64 inches) and a weak disturbance that moved northward into southern AZ from northern Mexico triggered scattered showers and thunderstorms late this afternoon over Pima County. Outflow from these storms generated locally dense blowing dust over Pinal County, which contributed to a multi-vehicle accident that shut down I-10 at MP 214 late this afternoon. Outflows from these storms also triggered a few new storms over the greater Phoenix area early this evening. The strongest storm produced 63 mph winds and 0.34 inch of rain at Sky Harbor and localized damaging winds/flooding across central Phoenix. A second storm produced gusty winds and heavy winds over Queen Creek/San Tan Valley. At this hour, all remaining storms are either over Gila County or moved northward into Yavapai County. As far as the forecast for the rest of the night is concerned, although there is still a slight chance of an isolated shower or thunderstorm later tonight as debris cloudiness move northward from the remains of storms south of the international border, it should be quiet over the vast majority of our cwa. with inherited forecasts still looking good. && .PREVIOUS DISCUSSION... Tonight...Elevated amounts of monsoon moisture have now securely covered most of AZ. Athough thermodynamics are there for a few afternoon and evening showers and thunderstorms over our forecast area in south central AZ, this region seems to be in between upper level forcing mechanisms in currently working in northern and southern AZ. With the advent of a fairly strong and unseasonably cold Pacific trof moving into the Pacific northwest, a rather strong southwesterly Jetstream maximum has developed over portions of eastern Nevada and Utah. Accelerating winds aloft, from lighter winds in northern AZ into the Utah flow, has developed an area of upper level speed divergence and resulting convection. To our south near the Mexican border, the approaching massive inverted trof, clearly seen in water vapor imagery over the Mexican state of Chihuahua, is spreading leading edge upper level difluence. Our portions of south central AZ, including areas near Phoenix, are under a relatively stable upper level anti-cyclonic flow regime. Therefore a low grade monsoon forecast is expected for the remainder of this afternoon and evening, i.e. a slight chance of showers and thunderstorms. This forecast is excluding the possibility of copious amounts of convective debris clouds from southern AZ moving north toward Phoenix tonight, and causing the possibility of showers and thunderstorms similar to late Sunday night. So far model forecasts are minimizing this possibility. Tuesday...our office staff eyes are now transfixed on the massive inverted trof seen in water vapor imagery over north central Mexico. Models the past two days have resolved this feature very well at the 300/250 mb level, and latest model forecasts continue the trend of moving the feature bodily into southern AZ, although in a weakened form later Tuesday and Tuesday night. Current model forecast are minimizing the effect of this system in south central AZ, including nearby Phoenix and surrounding areas. From a fundamental stand point this is questionable. Strong differential heating and with weakness aloft normally results in an enhanced threat for storms that can last well into the evening hours. For now we will go with our instincts and raise precip probability a bit in south central AZ for late Tuesday and Tuesday night, with even a slight chance going into Wednesday morning. Wednesday...Monsoon moisture will be still be entrenched over the region. With mid/upper level disturbances should depart the area, resulting in another low grade monsoon forecast for Wednesday afternoon and evening. Thursday through Monday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Outside of a slight chance for a shower/weak thunderstorm later tonight as debris clouds from storms over northern Mexico move over the region, the rest of tonight and Tuesday morning should be quiet, with winds mainly out of a southeasterly direction. There is a slight risk of more convective activity on Tue afternoon, but confidence is too low to include it in the tafs at this time. Winds on Tue afternoon to once again become westerly, with speeds mainly in the 8-10 knot range. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east over central AZ. Under mostly clear skies, sfc winds will favor a southerly direction at KIPL and from a southeasterly direction at KBLH. A few higher gusts will be possible at KBLH, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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...Percha/Vasquez AVIATION...Percha/MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Tucson AZ 325 PM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Scattered to numerous showers and thunderstorms were occurring generally from the Tohono O`odham Nation southeastward into far southeast Pima County, Santa Cruz County, and extreme southwest Cochise County at this time. This area is within a northwest-to-southeast oriented axis of greatest instability as per SPC hourly mesoscale analysis of MUCAPE. Other isolated showers and thunderstorms were also occurring from southcentral Pinal County eastward into western Graham County. Storm motions were mainly northwest around 5-10 kts. IR satellite imagery depicted rapidly cooling cloud tops during the past hour with the showers/tstms across central Pima County. Have favored the Univ of AZ WRF-NAM for precip chances tonight. Thus, expect scattered to perhaps numerous showers/tstms across much of the area this evening. The main concern given relatively slow storm motions and precip water values of 1.25"-1.50" will be locally heavy rainfall. Have maintained a slight chance of showers/tstms late tonight for much of this forecast area. Have noted that the WRF- NAM depicts precip-free conditions late tonight into mid-morning Tuesday. Will defer to the evening shift to adjust PoPs perhaps downward as necessary. Similar coverage of showers/tstms is expected Tuesday afternoon/evening as deep (albeit still light) sely flow aloft continues across the area. Scattered mainly afternoon/evening showers/tstms will also occur Wednesday. Thereafter, the 18/12Z GFS/ECMWF/CMC were similar versus their respective solutions in depicting a gradual daily decrease in showers/tstms to begin Thursday and continue into this weekend. Given the continued ely mid-level flow, precip-free conditions area- wide should not occur as earlier this month. However, moisture should remain sufficient for isolated to scattered afternoon and evening showers and thunderstorms Thursday through next Monday. High temps Tuesday will remain quite close to seasonal normals. A warming trend is forecast to begin Wednesday, and based on various 18/12Z guidance, high temps were increased several degs Thur-Sat versus the previous forecast. At this time, appears that Friday will be the hottest day although Saturday should be quite similar. A moderation in daytime temps should then occur Sunday and Monday. && .AVIATION...VALID THRU 20/00Z. Isolated to scattered SHRA/TSRA will occur through the period, with the best chances during the afternoon and evening hours. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Tuesday afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ DISCUSSION...Francis AVIATION/FIRE WEATHER...French Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Flagstaff AZ 250 PM MST MON JUL 18 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION... The monsoon circulation has brought plentiful atmospheric moisture back into to the area...with precipitable water values now up to around 1.0" at KFLG. Instability has been somewhat limited...but scattered thunderstorms have formed with a few locally heavy showers, mainly over the higher terrain. Little change in the overall pattern is anticipated through Thursday with the strong ridge of high pressure in place over the Southern Plains and moist southerly flow over Arizona, providing the environment for daily thunderstorm activity across the forecast area. Storms will move a bit slower Tuesday through Thursday, leading to a somewhat greater chance for heavy rainfall accumulations. Friday through Sunday...forecast models continue to show the flattening of the ridge over the southern Rockies, and a decrease in thunderstorm activity Friday through Sunday as drier air filters in from the west. && .AVIATION...For the 00Z package...Sct shra/tsra expected to continue through 03z...with isold -shra/-tsra continuing overnight. Sct shra/tsra will redevelop after 18Z Tuesday...with storms most numerous over the higher terrain. Expect visibility reductions and gusty winds near storms. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect another round of thunderstorms over the forecast area Tuesday and Wednesday. Storm motion will generally be from the south to north 5-10 mph. Thursday through Saturday...Scattered thunderstorms will persist across the area on Thursday. Drier air filtering into Arizona from the west will bring a decrease in thunderstorm activity on Friday and Saturday...with minimum RH`s dropping back into the teens to the north and west of Flagstaff. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...Bohlin/BAK AVIATION...BAK FIRE WEATHER...BAK For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Phoenix AZ 200 PM MST MON JUL 18 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... Tonight...Elevated amounts of monsoon moisture have now securely covered most of AZ. Athough thermodynamics are there for a few afternoon and evening showers and thunderstorms over our forecast area in south central AZ, this region seems to be inbetween upper level forcing mechanisms in currently working in northern and southern AZ. With the advent of a fairly strong and unseasonably cold Pacific trof moving into the Pacific northwest, a rather strong southwesterly Jetstream maximum has developed over portions of eastern Nevada and Utah. Accelerating winds aloft, from lighter winds in northern AZ into the Utah flow, has developed an area of upper level speed divergence and resulting convection. To our south near the Mexican border, the approaching massive inverted trof, clearly seen in water vapor imagery over the Mexican state of Chihuahua, is spreading leading edge upper level difluence. Our portions of south central AZ, including areas near Phoenix, are under a relatively stable upper level anti-cyclonic flow regime. Therefore a low grade monsoon forecast is expected for the remainder of this afternoon and evening, i.e. a slight chance of showers and thunderstorms. This forecast is excluding the possibility of copious amounts of convective debris clouds from southern AZ moving north toward Phoenix tonight, and causing the possibility of showers and thunderstorms similar to late Sunday night. So far model forecasts are minimizing this possibility. Tuesday...our office staff eyes are now transfixed on the massive inverted trof seen in water vapor imagery over north central Mexico. Models the past two days have resolved this feature very well at the 300/250 mb level, and latest model forecasts continue the trend of moving the feature bodily into southern AZ, although in a weakened form later Tuesday and Tuesday night. Current model forecast are minimizing the effect of this system in south central AZ, including nearby Phoenix and surrounding areas. From a fundamental stand point this is questionable. Strong differential heating and with weakness aloft normally results in an enhanced threat for storms that can last well into the evening hours. For now we will go with our instincts and raise precip probability a bit in south central AZ for late Tuesday and Tuesday night, with even a slight chance going into Wednesday morning. Wednesday...Monsoon moisture will be still be entrenched over the region. With mid/upper level disturbances should depart the area, resulting in another low grade monsoon forecast for Wednesday afternoon and evening. Thursday through Monday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Timing wind shifts and the potential for gusty outflow winds and localized blowing dust will be the primary aviation concerns through Tuesday morning. Some variability about a southerly wind direction is likely again this afternoon, though eventually should favor southwest by the evening. Thunderstorms forming over SE AZ should move north towards the Phoenix area late in the afternoon with gusty outflow winds preceding them. While the threat of a storm directly affecting an airport is better than Sunday, probabilities are still quite low with better chances of localized blowing dust and more widespread lofted dust and haze affecting slantwise visibilities. Only modest confidence exists timing outflow wind shifts into terminal sites between 02Z- 04Z. Otherwise, developing cigs in a 10K-15K ft range look likely from decaying storms to the south. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east into central AZ. Under mostly clear skies, sfc winds will favor a southerly direction, though will be more variable at KIPL after sunset. A few higher gusts will be possible, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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 FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Phoenix AZ 1230 PM MST MON JUL 18 2016 ...Updated Aviation and Fire Weather... .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle and temperatures will increase to above normal levels. && .DISCUSSION... Woohoo, the monsoon moisture boundary raced north past Phoenix over night and this morning was seen pushing up against the higher elevations of the Mogollon Rim. In other words the southern half of AZ was in the monsoon moisture soup, and noted by the relatively low afternoon convective trigger temperatures at a few locations. For example, based on this mornings weather balloon soundings, the convective trigger temp at Phoenix is 99 deg F, 97 at Tucson, and 92 deg at Globe/Miami (elevation 3-4 thsd ft msl). Even though the afternoon thermodynamics are there, the flow aloft has, and will remain anti-cyclonic and relatively stable today and tonight. In other words, the situation for today favors low topped afternoon convection, mostly in the mountains with possible outflows toward the deserts sparking an isolated desert storm, with convection dissipating quickly after dark, unless. Unless like last night, a surge of convective debris clouds from southeast AZ spread north, creating a well saturated mid level airmass that a gravity wave sparked a few showers and thunderstorms in the Phoenix area after midnight. The gravity wave conclusion was derived from high speed satellite imagery loops. Beyond today, our office staff eyes are now on the massive inverted trof seen in water vapor imagery over the north central Mexican state of Chihuahua. Models the past two days have resolved this feature very well at the 300/250 mb level, and is forecast to move into southeast AZ on Tuesday. For now the low grade monsoon forecast, meaning slight chance of showers and thunderstorms over the south central AZ deserts and mountains look ok for now. We will see how the new models handle Tuesdays inverted trof since model guidance will have incorporated the Chihuahua weather balloon sounding that is launched once per day at 12z. .Previous discussion...503 AM MST... The weather pattern has finally allowed the typical monsoonal circulation to return to the area as the combination of troffing along the Pacific northwest coast and upper ridging over the central CONUS has allowed southerly to southeasterly flow aloft to set up across Arizona. This favorable flow has advected considerable amounts of monsoon moisture into the lower deserts; the latest Phoenix raob had PWAT up to 1.44 inches and Tucson had 1.5 inches. Despite the ample moisture, much of it was at mid and upper levels through, limiting CAPE values. According to the 2 am SPC mesoanalysis graphic, MLCAPE of consequence (over 500 j/kg) was still over far SE Arizona with very low amounts in the central deserts. 2 am radar continued to show showers spreading into south central Arizona from the southeast and isolated thunderstorms are possible but any convection that develops should stay on the weak side into the morning hours. The convection is likely being aided by weak vort maxes rotating into Arizona around the large scale upper high. Should significant clouds and showers persist well into the morning or the early afternoon, instability will again be limited and storm activity tonight will suffer. For the next few days, operational models such as the GFS and ECMWF as well as GEFS data, call for the monsoonal circulation to remain in place with little change from day to day. Moisture will remain relatively plentiful, at least from a PWAT perspective as values upwards of 1.5 inches will stay over much of the lower deserts to the east of the lower Colorado river valley. Most of the CAPE of consequence however is advertised to stay pretty much from Maricopa county eastward each day, suggesting convective potential over the southwest deserts will be limited, and minimal as you move into the deserts of southeast California. Steering flow each day will stay south to southeast but not overly strong, with 700-300mb layer winds mostly between 10 and 15 knots each day. There will be occasional vort maxes/weak inverted trofs rotating around the main upper high and moving north across the central deserts but due to the small scale of these features, they will not be handled very well by the models and as such there will be low confidence in any particular one of these small scale features. As such we will keep a rather low grade monsoon forecast in place today through Wednesday with slight chances for mainly afternoon and evening showers and thunderstorms over the central lower deserts, with better chances over the higher terrain east of Phoenix. Skies will be partly to mostly cloudy much of the time, with the greatest amounts of sunshine likely during later morning through mid afternoon each day. High temperatures will stay near seasonal normals over south central Arizona today, then gradually creep up each day with Phoenix approaching 110 by Wednesday. It will be hotter over the far western deserts and over SE California as the airmass will be drier there. Thursday through Sunday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures be much higher. The driest areas Thursday through Sunday will be southeast California where afternoon temperatures at Imperial, El Centro, and Blythe will at the 114 degree mark. Ouch! Current forecasts will keep Phoenix at or above the 110 degree mark each day. At the moment it appears high temperature will stay below excessive heat warning thresholds but that could change depending upon just how dry we actually get, and how high the heights become over the lower deserts. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Timing wind shifts and the potential for gusty outflow winds and localized blowing dust will be the primary aviation concerns through Tuesday morning. Some variability about a southerly wind direction is likely again this afternoon, though eventually should favor southwest by the evening. Thunderstorms forming over SE AZ should move north towards the Phoenix area late in the afternoon with gusty outflow winds preceding them. While the threat of a storm directly affecting an airport is better than Sunday, probabilities are still quite low with better chances of localized blowing dust and more widespread lofted dust and haze affecting slantwise visibilities. Only modest confidence exists timing outflow wind shifts into terminal sites between 02Z- 04Z. Otherwise, developing cigs in a 10K-15K ft range look likely from decaying storms to the south. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east into central AZ. Under mostly clear skies, sfc winds will favor a southerly direction, though will be more variable at KIPL after sunset. A few higher gusts will be possible, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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/CB/Vasquez AVIATION...MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Phoenix AZ 1230 PM MST MON JUL 18 2016 ...Updated Aviation and Fire Weather... .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle and temperatures will increase to above normal levels. && .DISCUSSION... Woohoo, the monsoon moisture boundary raced north past Phoenix over night and this morning was seen pushing up against the higher elevations of the Mogollon Rim. In other words the southern half of AZ was in the monsoon moisture soup, and noted by the relatively low afternoon convective trigger temperatures at a few locations. For example, based on this mornings weather balloon soundings, the convective trigger temp at Phoenix is 99 deg F, 97 at Tucson, and 92 deg at Globe/Miami (elevation 3-4 thsd ft msl). Even though the afternoon thermodynamics are there, the flow aloft has, and will remain anti-cyclonic and relatively stable today and tonight. In other words, the situation for today favors low topped afternoon convection, mostly in the mountains with possible outflows toward the deserts sparking an isolated desert storm, with convection dissipating quickly after dark, unless. Unless like last night, a surge of convective debris clouds from southeast AZ spread north, creating a well saturated mid level airmass that a gravity wave sparked a few showers and thunderstorms in the Phoenix area after midnight. The gravity wave conclusion was derived from high speed satellite imagery loops. Beyond today, our office staff eyes are now on the massive inverted trof seen in water vapor imagery over the north central Mexican state of Chihuahua. Models the past two days have resolved this feature very well at the 300/250 mb level, and is forecast to move into southeast AZ on Tuesday. For now the low grade monsoon forecast, meaning slight chance of showers and thunderstorms over the south central AZ deserts and mountains look ok for now. We will see how the new models handle Tuesdays inverted trof since model guidance will have incorporated the Chihuahua weather balloon sounding that is launched once per day at 12z. .Previous discussion...503 AM MST... The weather pattern has finally allowed the typical monsoonal circulation to return to the area as the combination of troffing along the Pacific northwest coast and upper ridging over the central CONUS has allowed southerly to southeasterly flow aloft to set up across Arizona. This favorable flow has advected considerable amounts of monsoon moisture into the lower deserts; the latest Phoenix raob had PWAT up to 1.44 inches and Tucson had 1.5 inches. Despite the ample moisture, much of it was at mid and upper levels through, limiting CAPE values. According to the 2 am SPC mesoanalysis graphic, MLCAPE of consequence (over 500 j/kg) was still over far SE Arizona with very low amounts in the central deserts. 2 am radar continued to show showers spreading into south central Arizona from the southeast and isolated thunderstorms are possible but any convection that develops should stay on the weak side into the morning hours. The convection is likely being aided by weak vort maxes rotating into Arizona around the large scale upper high. Should significant clouds and showers persist well into the morning or the early afternoon, instability will again be limited and storm activity tonight will suffer. For the next few days, operational models such as the GFS and ECMWF as well as GEFS data, call for the monsoonal circulation to remain in place with little change from day to day. Moisture will remain relatively plentiful, at least from a PWAT perspective as values upwards of 1.5 inches will stay over much of the lower deserts to the east of the lower Colorado river valley. Most of the CAPE of consequence however is advertised to stay pretty much from Maricopa county eastward each day, suggesting convective potential over the southwest deserts will be limited, and minimal as you move into the deserts of southeast California. Steering flow each day will stay south to southeast but not overly strong, with 700-300mb layer winds mostly between 10 and 15 knots each day. There will be occasional vort maxes/weak inverted trofs rotating around the main upper high and moving north across the central deserts but due to the small scale of these features, they will not be handled very well by the models and as such there will be low confidence in any particular one of these small scale features. As such we will keep a rather low grade monsoon forecast in place today through Wednesday with slight chances for mainly afternoon and evening showers and thunderstorms over the central lower deserts, with better chances over the higher terrain east of Phoenix. Skies will be partly to mostly cloudy much of the time, with the greatest amounts of sunshine likely during later morning through mid afternoon each day. High temperatures will stay near seasonal normals over south central Arizona today, then gradually creep up each day with Phoenix approaching 110 by Wednesday. It will be hotter over the far western deserts and over SE California as the airmass will be drier there. Thursday through Sunday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures be much higher. The driest areas Thursday through Sunday will be southeast California where afternoon temperatures at Imperial, El Centro, and Blythe will at the 114 degree mark. Ouch! Current forecasts will keep Phoenix at or above the 110 degree mark each day. At the moment it appears high temperature will stay below excessive heat warning thresholds but that could change depending upon just how dry we actually get, and how high the heights become over the lower deserts. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Timing wind shifts and the potential for gusty outflow winds and localized blowing dust will be the primary aviation concerns through Tuesday morning. Some variability about a southerly wind direction is likely again this afternoon, though eventually should favor southwest by the evening. Thunderstorms forming over SE AZ should move north towards the Phoenix area late in the afternoon with gusty outflow winds preceding them. While the threat of a storm directly affecting an airport is better than Sunday, probabilities are still quite low with better chances of localized blowing dust and more widespread lofted dust and haze affecting slantwise visibilities. Only modest confidence exists timing outflow wind shifts into terminal sites between 02Z- 04Z. Otherwise, developing cigs in a 10K-15K ft range look likely from decaying storms to the south. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east into central AZ. Under mostly clear skies, sfc winds will favor a southerly direction, though will be more variable at KIPL after sunset. A few higher gusts will be possible, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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/CB/Vasquez AVIATION...MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Flagstaff AZ 1004 AM MST MON JUL 18 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION...The subtropical ridge remains in a favorable position for moisture advection into Arizona through Friday. This translates into a moderate grade Monsoon with good chances for showers and thunderstorms each day. A few storms will develop in the overnight periods as a few upper level 200-300mb disturbances roll across the state. We sent out a quick update to increase shower chances this evening. Otherwise the forecast grids look good. && .PREV DISCUSSION /430 AM MST/... For today through Thursday...Due to the position of the high southerly flow and monsoon moisture will remain over northern Arizona. There should be some increase in moisture values over Sunday so shower and thunderstorm activity is expected to be more widespread. Instability and strength of any storms will be inhibited by general mid to high level cloud cover and the fact that the pattern doesn`t favor a decent push of low level moisture. In other words, precipitation amounts will mostly remain on the low to modest side. From Friday onward...Models show strong high pressure aloft building across Arizona into California. As a result, a drier air mass will filter in from the west. Low to no grade monsoon activity will be the result should this pattern materialize. && .AVIATION...For the 18Z package...sct-nmrs shra/tsra expected to develop this afternoon...continuing through 03z. Brief visibility reductions and gusty winds possible near storms. isold-sct -shra will continue aft 05Z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Monsoon moisture is increasing across the area. Expect increasing showers and thunderstorm coverage. Gusty outflow winds are probable from any storms or showers, especially today. Storm motion today from south to north about 10 mph. Tuesday through Friday...Monsoon moisture to remain over northern Arizona, with shower and thunderstorm chances each day. Winds may become erratic and gusty near thunderstorms. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...Bohlin/McCollum AVIATION...BAK FIRE WEATHER...DL For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 915 AM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into the upcoming weekend. && .DISCUSSION...Isolated showers were occurring in western Pima County east of Ajo at this time. Otherwise, visible satellite imagery depicted mostly clear skies to partly cloudy skies from Tucson westward into western Pima County, and mostly clear skies across eastern sections. Ample moisture exists with dewpoints at lower elevations valid 16Z ranging from the mid 50s-lower 60s. 18/12Z KTWC sounding total precip water value of 1.50" was about 0.15" higher versus 24 hours ago. 18/12Z upper air plots depicted a broad ridge over the southern CONUS, with a 597 DM high centered over northern Mississippi. Meanwhile, a deep upper trough was over the Pacific NW, and deep easterly/southeasterly flow prevailed across southeast AZ. Given the greater extent of clearing skies especially across eastern sections versus Sunday morning, am inclined to expect that shower/ tstm development later this morning will occur across favored ranges such as the Chiricahua Mountains. The 18/14Z HRRR supports this notion, the showers/tstms should migrate wwd/nwwd this afternoon. Quick glance at the 18/12Z Univ. of AZ WRF-NAM suggests shower/tstm development may also occur further westward by 19Z, and favor locales from Nogales to Kitt Peak. Water vapor imagery depicts a cyclonic twist approaching this area from the southeast over central Sonora Mexico. A much larger cyclonic circulation was south of the Texas Big Bend, or far eastern Chihuahua Mexico. This system may have more influence for this forecast area Tuesday. At any rate and without a further recitation of various NWP models, expect scattered to perhaps numerous showers and thunderstorms this afternoon and evening. The lowest coverage should occur across western Pima County where only isolated showers/tstms are expected. The main concern this afternoon/evening will be the potential for locally heavy rainfall and brief strong wind gusts that may approach severe thresholds. A slight chance of showers/tstms continues for much of the area late tonight. High temps this afternoon will be quite similar to temps achieved Sunday, or perhaps generally a couple of degs lower depending upon location. May make some minor PoP adjustments for this afternoon/evening, but this will not affect the overall scenario. Please refer to the additional sections for further detail. && .AVIATION...VALID THRU 19/18Z. Isolated -SHRA mainly west of KTUS this morning, then scattered to numerous -TSRA/-SHRA this afternoon and evening. The favored locales will be from KTUS vicinity east and south to the New Mexico/ International borders. Forecast confidence is sufficiently high to include VCTS in the KDUG/KOLS TAFs this afternoon and evening. VCTS may be delayed at KTUS until after 20/00Z. Isolated -SHRA and possible -TSRA to continue late tonight/early Tuesday morning. Outside of thunderstorm outflows, surface wind will generally be variable in direction less than 12 kts thru the period. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture and a favorable flow regime will maintain the daily cycle of scattered to perhaps numerous showers and thunderstorms through Wednesday. The bulk of this activity will occur during the afternoon and evening hours, and a slight chance of showers and thunderstorms will continue during the overnight hours. Thereafter, a gradual decrease in thunderstorm coverage is expected Thursday into the upcoming weekend. Outside of gusty thunderstorm outflows, 20-foot winds will be terrain driven and mostly less than 15 mph. && .PREV DISCUSSION /340 AM MST/...The 330 am radar imagery showed a distinctive circulation just west of Willcox, moving to the WNW. This MCV is associated with decaying MCS that formed over eastern Cochise county last night and produced areas of locally heavy rain. Douglas airport recorded 1.75" last night which set a daily record and also ranks as the 9th wettest July day on record. The MCV will be one of several features that will have an impact on todays forecast. Last nights MCS likely associated with a weak disturbance aloft that moved across northern Chihuahua MX. Water vapor was also showing an inverted trof approaching the Texas Big Bend this morning. A challenging forecast indeed for the next 12-18 hours. One would go with the idea that after the morning activity ends, that there will be lesser activity this afternoon due to debris cloud cover slowly diminishing which cuts down on heating thus being a few degrees cooler than Sunday. However both HRRR and 00z WRF NAM/GFS fire scattered storms this afternoon. Confidence is low will this forecast. Tomorrow likely will be another forecast challenge based on what will transpire today. Again confidence is low. Wednesday through next weekend will see a gradual decrease in moisture and thus areal coverage of storms as the sub-tropical high expands west into the eastern Pacific. Temperature warming up but likely not as hot as the GFS would suggest if going by low-level thickness numbers, which are higher than EC. Something to keep watch. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
319 AM CDT TUE JUL 19 2016 .SHORT TERM...(Today and Tonight) Issued at 319 AM CDT TUE JUL 19 2016 Overnight convection continues over western and central Nebraska at this hour, with increasing clouds and an outflow boundary making its way towards north central Kansas. While a few models generated small area of precip along the 850mb front, seeing little in the way of evidence of this in reality, with only a few mid level clouds forming, then dissipating, over the past hour or so. Will leave precip chances out at this time. Clouds also expected to dissipate later this morning, with temperatures rising into the middle/upper 90s area wide. Dewpoints do drop a few degrees in afternoon mixing, but not enough to bring much impact on heat indicies. Another day of 100-105 heat indicies expected, and will keep the advisory going through the morning. With day 4 of these numbers, and additional days expected, will keep the changeover from advisory to an excessive heat warning this afternoon. .LONG TERM...(Wednesday through Monday) Issued at 319 AM CDT TUE JUL 19 2016 Models in good agreement into the end of the week. Upper high remains over the south central states through these periods with general subsidence resulting. In addition, low-mid level winds increase from the southwest Wednesday into Thursday resulting in even warmer conditions and decreasing moisture in the column. Wednesday afternoon soundings showing little capping but also not seeing any discernible forcing for convection. Hard to rule out something isolated forming but any coverage should be below worthy of a mention. A more substantial cap should build in for Thursday and Friday with 850mb temps rather similar Thursday through Saturday in the 25-30C range for highs around 100F likely. Dewpoint values also well agreed upon to bring peak heat index values to 104-110 through at least Friday. Confidence in the extreme heat wanes by Saturday as the upper high breaks down enough to allow a shortwave moving over it to push a weak boundary into the area. Have kept some small nocturnal pops going in the northwest Friday night as convection could push in from the southwestward extent of the boundary then, with chances across the area Saturday night into Monday as the front lingers. Chances continue to remain small with the weak forcing, but highs should finally cool back to the low to mid 90s for Sunday and Monday. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday Night) Issued at 1155 PM CDT MON JUL 18 2016 VFR conditions are expected throughout the period. Very slight chance for an isolated thunderstorm overnight, as WAA increase. However, confidence is very low with development. Winds will increase from the south at 10-15 knots by 14Z this Tuesday. && .TOP Watches/Warnings/Advisories... Excessive Heat Warning from 1 PM this afternoon to 7 PM CDT Friday for KSZ008>012-020>024-026-034>040-054>056-058-059. Heat Advisory until 1 PM CDT this afternoon for KSZ008>012- 020>024-026-034>040-054>056-058-059. && $$ SHORT TERM...67 LONG TERM...65 AVIATION...Baerg
Area Forecast Discussion National Weather Service Goodland KS 212 AM MDT TUE JUL 19 2016 .SHORT TERM...(This afternoon through Tuesday) Issued at 147 PM MDT Mon Jul 18 2016 Early afternoon satellite and RAP upper level analysis shows large scale ridge entrenched across the central US, with monsoonal flow in across through the central Rockies. A shortwave trough is currently rotating into northern Colorado/southern Wyoming with thunderstorms activity initiating in the higher terrain. A warm front is slowly progressing northward over our CWA and is still roughly south of I-70. Early this afternoon-Tonight: Warm front has been slower to lift north than models had previously indicated, however a strong CAP in place is limiting initiation within frontal zone. Thunderstorm activity may still initiate as the front lifts north and thunderstorms in Colorado may also begin to sneak into our far west before main area of thunderstorms develops this evening. As the shortwave moves out of the Rockies into western Nebraska this should help speed up the movement on the warm front and by 00z this feature should be near the northern part of our CWA. Higher resolution models support thunderstorms merging into a cluster or complex as LLJ increases this evening and then tracking over our far northwest and this is where I placed highest PoPs. There is a deep/moist air mass in place with PWATs exceeding 1.0" and Tds (within frontal zone) in the 60-70 range. Thunderstorm motions are expected to be around 15 kt and east-southeast flow overrunning the frontal zone could lead to training of thunderstorm activity. This raises the possibility for locally heavy rainfall amounts and at least a localized risk for flooding in our northwest. Initially CAPE will be favorable for severe thunderstorms, however deep layer sheer is very marginal and main CAPE axis will trend northward with front. Tuesday: Ridge continues to amplify shifting main flow further west away from our CWA. Some guidance is still hinting at isolated thunderstorms moving into northwest portions of Yuma county, however confidence is not high this will make it this far east. Slight chance PoPs were maintained for now. Temperatures will trend upwards with strengthening of the ridge and increasing southerly flow with high temperatures at least in the upper 90s for most locations and near 100 (to the low 100s) in our north and east. Heat index values appear to remain near 100F due to slightly lower Td values, so will hold off on any highlights. .LONG TERM...(Wednesday through Monday) Issued at 211 AM MDT Tue Jul 19 2016 A large, H5 ridge will encompass the central Plains on Friday with hot temperatures being the prevalent feature. There will be enough available moisture to fire scattered afternoon thunderstorms across the region as a surface low moves slowly eastward. Thunderstorm activity will focus mainly along a theta-e boundary that will set up from southwest to northeast across the CWA. CAPE along the eastern edge of this boundary will exceed 1500 J/Kg late Friday afternoon. Surface low pressure stalls on Saturday with a bit stronger boundary setting up for the weekend. Another round of thunderstorms will be possible Saturday and Sunday afternoon/evening in the presence of this feature. The H5 ridge will flatten at this time however; there is a substantial disagreement between the GFS and the ECMWF with regards to which direction the ridge drifts. The GFS pushes the ridge east where the ECMWF pulls it westward as we head into Monday. Yesterday`s guidance pointed toward general troughing in the east; however today`s model runs are split with the ECMWF still indicating troughing to the east with the GFS trending exactly opposite. I favor the ECMWF slightly due to persistence but will need to watch future iterations. We should see a more unsettled pattern take shape with either solution as the EC brings a series of shortwaves through the region and the GFS brings in monsoonal moisture. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1110 PM MDT Mon Jul 18 2016 At KMCK...A small cluster of showers/thunderstorms will impact the terminal for the first couple of hours of the TAF period. Expect gusty northwest winds and ceilings approaching MVFR as the storms pass. Otherwise...VFR expected through Tuesday with gusty south surface winds. At KGLD...an isolated shower or thunderstorm cant be ruled out overnight but given sparse coverage on radar will not include a mention in the TAF. VFR conditions expected to prevail otherwise with gusty south surface winds. && .GLD Watches/Warnings/Advisories... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...TL AVIATION...024
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1158 PM CDT MON JUL 18 2016 .UPDATE... Issued at 1039 PM CDT MON JUL 18 2016 Large MCS is becoming increasingly organized over western NE and far northeast CO late this evening. While Corfidi vectors do have a bit of a southerly angle to them, the larger scale wave forcing this activity is moving sharply toward the north and the instability axis seems to extend almost due east. Forecasting soundings for north central KS indicate that a cold pool would have to be quite deep in order to lift parcels to the LFC later tonight, and while it appears unlikely, have included a slight chance for thunderstorms in northern KS on the off chance that the outflow makes its way into the area with enough energy to maintain a few thunderstorms. Short range models, specifically the HRRR and experimental HRRR now have some run-to-run consistency in developing weak warm advection showers and perhaps a thunderstorm in parts of eastern KS after 1 AM. This also seems to be a questionable idea but not completely unreasonable given a bit of moisture aloft and weak but persistent isentropic lift so have included a few hours of a slight chance for thunderstorms in eastern KS early this morning as well. && ...Update to aviation forecast discussion... .SHORT TERM...(This Evening through Tuesday) Issued at 329 PM CDT MON JUL 18 2016 At 20Z, water vapor imagery shows a cloud band with moisture streaming into the Central Rockies with another cloud band stretched from the northern Central Plains into the Ohio Valley up through the New England States. Some storms still along the stationary boundary at the surface into northwestern MO and extreme southeastern IA. Storms also beginning to fire over the foothills of the Rockies into the panhandle of Nebraska. In northeastern Kansas, forecasting a mostly dry period in the short term as heights continue to rise steadily overnight into the day on Tuesday. An MCS may develop overnight associated with the storms previously mentioned over the Rockies. These should stay to the north of the outlook area tonight though as the LLJ convergence is focused to our northwest. Only the NAM brings some of this activity close to the area with all the other short term guidance taking the storms on a northerly track into northern Nebraska and northwestern Iowa overnight. Therefore, not expecting much if any influence from a cold outflow to impact our area even though there is a brief period of isentropic lift that advects over the the region on the 315K to 320K surface. Lack of mid level moisture should keep storms to the north. That said, do expect temperatures to increase again tomorrow into the mid to upper 90s with dewpoints into the upper 60s and low 70s. This should continue to put heat index values into the 105F range while lowest heat index values will be at or above 75F. Have kept heat advisory going for the evening and have upgraded to a heat warning starting Tuesday afternoon as many days of at least heat advisory heat index values are expected. The bottom line is the heat will be the main forecast concern through the period. .LONG TERM...(Tuesday Night through Monday) Issued at 329 PM CDT MON JUL 18 2016 Tuesday night through Thursday... With upper high centered over the Southern/Central Plains during this period, and no real low-level convergence features expected to impact eastern KS, expect dry weather to continue. With dewpoints from the upper 60s to mid 70s, and afternoon high temperatures in the 96 to 103 degree range, afternoon heat indices should be in the 103 to 108 degree range. Overnight lows are only expected to fall to the mid to upper 70s. Thursday Night through Monday... A stout upper-level ridge will continue to be center of the central United States through the end of the week. High temperatures will soar into the upper 90s and lower 100s Friday afternoon. These very hot temperatures coupled with high dewpoints, heat indices will range from 105 to 110 degrees (possibly warmer). Saturday becomes a bit tricky as both the EC and GFS bring a weak cold front through portions of the area. Not only would it "cool" temperatures back into the lower to middle 90s, but precip chances also increase. The front appears to stall out in the vicinity of the outlook area for the remainder of the weekend. Guidance suggests weak 500MB waves will traverse the CWA along the surface boundary. Therefore, have at least slight chance PoPs across the area, along with cooler temperatures. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday Night) Issued at 1155 PM CDT MON JUL 18 2016 VFR conditions are expected throughout the period. Very slight chance for an isolated thunderstorm overnight, as WAA increase. However, confidence is very low with development. Winds will increase from the south at 10-15 knots by 14Z this Tuesday. && .TOP Watches/Warnings/Advisories... Excessive Heat Warning from 1 PM Tuesday to 7 PM CDT Friday for KSZ008>012-020>024-026-034>040-054>056-058-059. Heat Advisory until 1 PM CDT Tuesday for KSZ008>012-020>024-026- 034>040-054>056-058-059. && $$ UPDATE...Barjenbruch SHORT TERM...Drake LONG TERM...Baerg/GDP AVIATION...Baerg
AREA FORECAST DISCUSSION
National Weather Service New Orleans LA
345 AM CDT TUE JUL 19 2016 .Discussion... Main focus this week will be impacts from an upper level ridge on the area in terms of temps and convection. This feature, centered near the Texas/Oklahoma border, is currently spreading east today and will expand across the entire southern half of the country throughout the week. The first local change in weather will be a reduction in shower and thunderstorm coverage as subsidence increases. Have lowered rain chances slightly today to mainly 20s with the greatest pops south of a BTR to MSY line along the Atchafalaya Basin. Wednesday will be similar to today albeit possibly slightly warmer. Thursday and Friday looking like they will be the hottest days of the forecast period. Model sounding shows 850mb temps near 21C with dewpoints in the mid to upper 70s in the late mornings and early afternoons. As air temps rise into the mid 90s, the heat indicies could be approaching 110 degrees or higher. So, looking more and more likely that a heat advisory will needed Thursday and Friday. The ridge will begin to weaken through the weekend as a northern stream trough races along the US/Canada border. Temperatures will begin to fall back closer to normal and pops will increase closer to the chance category. MEFFER && .AVIATION... VFR should be present at each terminal with HUM being the site with the best chance at getting a TSRA today. But chances are not high enough to include in taf for any particular site. && .MARINE... Surface ridge extending westward across the northern gulf will keep winds generally east in the 5 to 15 knot range through much of the week. The strong upper/mid level ridge will move out of the West and build over the south-central conus midweek onward. Subsequent local wind regime will be quite light at less than 10 knots and likely variable at times in direction. && .DECISION SUPPORT... DSS code: Green. Deployed: None. Activation: None. Activities: None. Decision Support Services (DSS) Code Legend Green = No weather impacts that require action. Blue = Long-fused watch, warning, or advisory in effect or high visibility event. Yellow = Heightened impacts with short-fused watch, warning or advisory issuances; radar support. Orange = High Impacts; Slight to Moderate risk severe; nearby tropical events; HazMat or other large episodes. Red = Full engagement for Moderate risk of severe and/or direct tropical threats; Events of National Significance. && .PRELIMINARY POINT TEMPS/POPS... MCB 95 73 95 75 / 20 10 30 10 BTR 94 76 94 76 / 20 10 30 10 ASD 93 76 96 77 / 20 10 30 10 MSY 91 79 93 80 / 20 10 30 20 GPT 91 78 93 77 / 20 20 30 20 PQL 94 74 96 73 / 20 20 30 20 && .LIX Watches/Warnings/Advisories... LA...None. GM...None. MS...None. GM...None. && $$
  [top] Area Forecast Discussion National Weather Service Shreveport LA 309 AM CDT TUE JUL 19 2016 .DISCUSSION... An upper level high pressure system continues to be the dominating synoptic feature for the Four-State region as it encompasses the Central Plains and lower Mississippi Valley regions. Along the Southern fringe of the said UL ridge is sea-breeze convection struggling to make it to the LA coast early this morning due to the proximity of the ridge. The HRRR does in fact hint at sea-breeze convection being hard pressed to near central LA later this aftn, however a weakness noted along the Eastern periphery of the upper level ridge that will move Southwest across the region this aftn, coupled with PWATS aoa 2.00 inches and daytime destabilization may lead to diurnally driven isolated showers and thunderstorms just about anywhere across the CWA. Despite slight chances of rainfall and accompanied cloud cover, temps will still manage to warm into the middle to upper 90s this aftn hinted at by a slight uptick in 850 mb temps. With little mixing of the low level moisture, heat indices should have no issue increasing into the 105-109 degree range more so across Southwest AR and portions of East TX and North LA, hence where the Heat Advisory encompasses. Similar wx scenario expected tomorrow so the Heat Advisory valid until 7 pm CDT tomorrow is definitely warranted. Temps are expected to peak near/equate the triple digit mark late week as the 500 mb upper level ridge increases to near 600 dam. With an upslope sfc regime continuing to maintain moist low levels, the Heat Advisory may need to be extended. Furthermore, with the center of the ridge not being directly atop of of the Four-State region, some isolated convection driven by the sea- breeze and/or daytime destabilization may occur. By the weekend through early next week, the ECMWF is consistent in showing the UL ridge migrating to near the Four-corners region resulting in Northwest flow aloft, thus opening the door for disturbances once confined to the Northern CONUS to impinge on the region. The GFS on the other-hand translates the ridge to the North of the region and as such, Easterly disturbances are able to move across the region. In either case, this unsettled pattern may result in the return of showers and thunderstorms, increased cloud cover and temps cool enough to perhaps negate the need for a Heat Advisory. && .PRELIMINARY POINT TEMPS/POPS... SHV 97 78 98 79 / 20 10 20 10 MLU 97 77 98 78 / 20 10 20 10 DEQ 96 75 97 76 / 20 10 20 10 TXK 97 77 98 78 / 20 10 20 10 ELD 96 76 97 78 / 20 10 20 10 TYR 98 77 99 78 / 20 10 10 10 GGG 97 77 98 78 / 20 10 10 10 LFK 96 76 97 76 / 20 10 20 10 && .SHV Watches/Warnings/Advisories... AR...Heat Advisory until 7 PM CDT Wednesday for ARZ050-051-059>061- 070>073. LA...Heat Advisory until 7 PM CDT Wednesday for LAZ001>006-010>014- 017>022. OK...None. TX...Heat Advisory until 7 PM CDT Wednesday for TXZ097-112-126-138- 151-153-166-167. && $$ 29 Area Forecast Discussion National Weather Service Tucson AZ 850 AM MST TUE JUL 19 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...IR/Visible satellite imagery depicted mostly clear skies to partly cloudy skies at this time. Some of the more prominent cyclonic twists were moving northwestward just east of northern Greenlee County, over northwest Sonora, and over east central Sonora. Water vapor imagery also depicted an inverted trough over southern New Mexico southward into northern Chihuahua Mexico. Ample moisture continues across the area with dewpoints at lower elevations valid 15Z ranging from the mid 50s-mid 60s, and 19/12Z KTWC sounding total precip water value was 1.50 inches. There were some differences between the various mesoscale models regarding the development and evolution of showers/tstms later today. Instead of a model rehash, the official forecast of scattered showers/tstms this afternoon/evening appears to be on track. The main concern this afternoon/evening will be the potential for locally heavy rainfall and brief strong wind gusts that may approach severe thresholds. There is also a potential for blowing dust along the Interstate 10 corridor northwest of Tucson to Phoenix. Forecast confidence is not sufficiently high at this time to issue a Blowing Dust Advisory. A slight chance of showers/tstms continues for much of the area late tonight. High temps this afternoon will generally be a few degs warmer versus Monday. Please refer to the additional sections for further detail. && .AVIATION...VALID THRU 20/18Z. Isolated showers through the early morning hours. Sct-bkn clouds at 6-9k ft agl and bkn-ovc clouds at 10-14k ft agl. Expect scattered showers and thunderstorms this afternoon and evening, then tapering in coverage late tonight. Brief wind gusts of 40-45 kts and MVFR conditions will occur with the stronger TSRA. Outside of gusty outflows, surface wind will generally be less than 12 kts through Wednesday morning. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .CLIMATE...As the area heats up again, could see a few spots across the western deserts approach record highs later in the week. && .PREV DISCUSSION /250 AM MST/...Isolated light showers were occurring early this morning east of Tucson. Expect these to continue thru sunrise as they move to the WNW. A weak MCV was over SW Graham county as of 2 am, but shouldn`t be a player today as it continue to move NNW. What could be a player later today is the inverted trof currently over Chihuahua MX. This feature is moving slowly to the NW toward the area. Hi-res models focusing best activity W of Tucson, with potential for blowing dust across Pinal county towards Phoenix, and Cochise county. PW values across the remain above normal for July so locally heavy rain a threat. Can`t rule out a severe storm or two. Highs today will be around normal. Scattered afternoon/evening storms Wednesday with highs slightly warmer than today. Starting Thursday and continuing through the upcoming weekend there will be a gradual decrease in shower and thunderstorm activity as sub-tropical ridge expands over the southern CONUS. Still hanging on to enough moisture to keep isolated to scattered storms in the forecast. Highs temperatures will be above normal through this period, maxing out on Friday. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
  [top] Area Forecast Discussion National Weather Service Phoenix AZ 810 AM MST TUE JUL 19 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next couple of days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures over the central deserts will stay near seasonal normals, with hotter conditions over the western deserts. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... Regional morning weather balloon soundings continued show a rather healthy amount of monsoon moisture strewn across central and southern AZ. Monsoon moisture is not excessive by any means, but not minimal either. And, boundary layer moisture was healthy enough to result in relatively low afternoon convective trigger temperatures like 102 F in Phoenix, 96 in Tucson, and 88 degrees in Globe/Miami (3-4 thsd msl) in the mountains east of Phoenix. Low afternoon convective trigger temperatures make the lower desert airmass in south central AZ susceptible to convection, easily triggered by numerous convective outflow boundaries running across the lower regions later in the day, especially with weakness/support aloft. Upper level weakness and support is what we`ve been focusing on for a few days now with the approaching inverted trof (IT) from Chihuahua Mexico. Models continue to forecast this IT feature, located just southwest of El Paso in morning water vapor imagery, to move into southeast AZ later this afternoon, then across the greater Phoenix area Wednesday afternoon in a much weakened/washed out state. Numerical guidance continues to put PHX and TUS in a chance shwr/tstm category for later today and tonight due to this approaching IT feature. The chance of showers can possibly continue into the night in south central AZ with all the secondary circulations/outflows it can produce. Due to this approaching feature, the moisture rich boundary layer, and relatively low thermodynamic convective trigger temperatures, we will upgrade the probability of precip into the chance category in south central AZ including Phoenix for tonight. Wednesday`s afternoon and evenings low grade monsoon shwr/tstm possibilities look ok for now. Previous discussion still applies. .Previous Discussion...507 AM MST... Monsoon circulation remains entrenched across Arizona with an impressive plume of deep moisture spreading north from northwest Mexico and running north/northeastward across central and eastern Arizona, around the periphery of a very strong upper high centered over the south-central CONUS. This moist plume is easily seen in the current IR and vapor imagery loops. Steering flow across central/eastern AZ is mostly south to southeast, becoming more southwesterly as you move west and into the far southwest AZ deserts and over SE California. Orientation of this flow will keep most of the convection focused over south-central Arizona this week with very little expected into the SE California deserts. PWAT value at Phoenix from the last 00z raob was healthy at 1.64 inches and there was modest CAPE present in the sounding. 2 am surface dewpoints over the central deserts were elevated, ranging mostly from the upper 50s to middle 60s. Little if any shower activity was noted early this morning on radar, just a fair amount of debris cloudiness spreading north across the lower deserts. Overall, for the next couple of days, we are looking at a low to medium grade monsoon in terms of thunderstorm coverage. Most of the convection will be located over south-central Arizona with slight chances of mainly afternoon and evening storms becoming 30 percent or more over the higher terrain east of Phoenix. Steering flow is not especially strong as the 700-300mb mean winds typically run 10- 15 knots, and most of the disturbances that will rotate around the high and serve as "triggers" for convection are not especially dynamical. Latest vapor imagery loop does show a moderately organized inverted trof spinning over NW Mexico, poised to move into southeast Arizona this morning and across portions of south central and east-central AZ during the day, but it is forecast to weaken as it moves through the area so most of the desert POPs will stay below 25 percent this evening. High temperatures over the central deserts today and Wednesday will stay near seasonal normals due to the elevated humidity, with highs reaching or exceeding 110 over the western deserts where the airmass is drier and there will be more solar insolation. Thursday through Saturday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. We still expect high temperatures to generally stay just below excessive heat warning thresholds during the hottest days such as Friday and Saturday; this is supported by HIL data. By Friday, rain chances in the Phoenix area will struggle to exceed around 10 percent due to the drier air in place. Sunday into Monday...The strong upper high continues to build towards the west, with one high center eventually setting up over central CA. Flow around the high becomes more favorable from the east and monsoon moisture starts to return. As such thunderstorm chances start to rise and we will be seeing lower grade conditions with slight chances for afternoon convection over the lower central deserts, along with 20-30 percent chances across the higher terrain of southern Gila County. Temperatures will trend down slightly as humidity levels rise. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: A quiet start to the day with a mix of mid/high clouds moving through and light winds. Thunderstorms are possible again later this afternoon, first developing over the mountains north to east to south of the Phoenix area after 21 UTC. Outflow winds look likely, though hard to discern at this time if they`ll come from the northeast or the southeast (which will impact if any dust comes into play). Seems that some showers will develop later in the evening but low confidence on thunderstorm development/coverage to include in TAFs at this time. Showers could continue into the overnight hours. Southeast California/Southwest Arizona including KIPL and KBLH: Little aviation concerns through into Wednesday morning with few clouds and generally light winds. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Friday through Tuesday... Temperatures will trend back into an above normal range through the weekend as moisture levels thin and humidity values drop. Thunderstorm/wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain of eastern Arizona by Friday/Saturday. Consequently, afternoon humidity levels will drop about ten percent on average, into the 10-25 percent range this weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .SPOTTER INFORMATION STATEMENT... Spotter activation may be required for this evening. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...Vasquez/CB AVIATION...Iniguez FIRE WEATHER...Iniguez/MO
Area Forecast Discussion National Weather Service Phoenix AZ 507 AM MST TUE JUL 19 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next couple of days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures over the central deserts will stay near seasonal normals, with hotter conditions over the western deserts. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... Monsoon circulation remains entrenched across Arizona with an impressive plume of deep moisture spreading north from northwest Mexico and running north/northeastward across central and eastern Arizona, around the periphery of a very strong upper high centered over the south-central CONUS. This moist plume is easily seen in the current IR and vapor imagery loops. Steering flow across central/eastern AZ is mostly south to southeast, becoming more southwesterly as you move west and into the far southwest AZ deserts and over SE California. Orientation of this flow will keep most of the convection focused over south-central Arizona this week with very little expected into the SE California deserts. PWAT value at Phoenix from the last 00z raob was healthy at 1.64 inches and there was modest CAPE present in the sounding. 2 am surface dewpoints over the central deserts were elevated, ranging mostly from the upper 50s to middle 60s. Little if any shower activity was noted early this morning on radar, just a fair amount of debris cloudiness spreading north across the lower deserts. Overall, for the next couple of days, we are looking at a low to medium grade monsoon in terms of thunderstorm coverage. Most of the convection will be located over south-central Arizona with slight chances of mainly afternoon and evening storms becoming 30 percent or more over the higher terrain east of Phoenix. Steering flow is not especially strong as the 700-300mb mean winds typically run 10- 15 knots, and most of the disturbances that will rotate around the high and serve as "triggers" for convection are not especially dynamical. Latest vapor imagery loop does show a moderately organized inverted trof spinning over NW Mexico, poised to move into southeast Arizona this morning and across portions of south central and east-central AZ during the day, but it is forecast to weaken as it moves through the area so most of the desert POPs will stay below 25 percent this evening. High temperatures over the central deserts today and Wednesday will stay near seasonal normals due to the elevated humidity, with highs reaching or exceeding 110 over the western deserts where the airmass is drier and there will be more solar insolation. Thursday through Saturday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. We still expect high temperatures to generally stay just below excessive heat warning thresholds during the hottest days such as Friday and Saturday; this is supported by HIL data. By Friday, rain chances in the Phoenix area will struggle to exceed around 10 percent due to the drier air in place. Sunday into Monday...The strong upper high continues to build towards the west, with one high center eventually setting up over central CA. Flow around the high becomes more favorable from the east and monsoon moisture starts to return. As such thunderstorm chances start to rise and we will be seeing lower grade conditions with slight chances for afternoon convection over the lower central deserts, along with 20-30 percent chances across the higher terrain of southern Gila County. Temperatures will trend down slightly as humidity levels rise. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: A quiet start to the day with a mix of mid/high clouds moving through and light winds. Thunderstorms are possible again later this afternoon, first developing over the mountains north to east to south of the Phoenix area after 21 UTC. Outflow winds look likely, though hard to discern at this time if they`ll come from the northeast or the southeast (which will impact if any dust comes into play). Seems that some showers will develop later in the evening but low confidence on thunderstorm development/coverage to include in TAFs at this time. Showers could continue into the overnight hours. Southeast California/Southwest Arizona including KIPL and KBLH: Little aviation concerns through into Wednesday morning with few clouds and generally light winds. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Friday through Tuesday... Temperatures will trend back into an above normal range through the weekend as moisture levels thin and humidity values drop. Thunderstorm/wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain of eastern Arizona by Friday/Saturday. Consequently, afternoon humidity levels will drop about ten percent on average, into the 10-25 percent range this weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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...Iniguez FIRE WEATHER...Iniguez/MO
Area Forecast Discussion National Weather Service Phoenix AZ 325 AM MST TUE JUL 19 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next couple of days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures over the central deserts will stay neaer seasonal normals, with hotter conditions over the western deserts. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... Monsoon circulation remains entrenched across Arizona with an impressive plume of deep moisture spreading north from northwest Mexico and running north/northeastward across central and eastern Arizona, around the periphery of a very strong upper high centered over the south-central CONUS. This moist plume is easily seen in the current IR and vapor imagery loops. Steering flow across central/eastern AZ is mostly south to southeast, becoming more southwesterly as you move west and into the far southwest AZ deserts and over SE California. Orientation of this flow will keep most of the convection focused over south-central Arizona this week with very little expected into the SE California deserts. PWAT value at Phoenix from the last 00z raob was healthy at 1.64 inches and there was modest CAPE present in the sounding. 2 am surface dewpoints over the central deserts were elevated, ranging mostly from the upper 50s to middle 60s. Little if any shower activity was noted early this morning on radar, just a fair amount of debris cloudiness spreading north across the lower deserts. Overall, for the next couple of days, we are looking at a low to medium grade monsoon in terms of thunderstorm coverage. Most of the convection will be located over south-central Arizona with slight chances of mainly afternoon and evening storms becoming 30 percent or more over the higher terrain east of Phoenix. Steering flow is not especially strong as the 700-300mb mean winds typically run 10- 15 knots, and most of the disturbances that will rotate around the high and serve as "triggers" for convection are not especially dynamical. Latest vapor imagery loop does show a moderately organized inverted trof spinning over NW Mexico, poised to move into southeast Arizona this morning and across portions of south central and east-central AZ during the day, but it is forecast to weaken as it moves through the area so most of the desert POPs will stay below 25 percent this evening. High temperatures over the central deserts today and Wednesday will stay near seasonal normals due to the elevated humidity, with highs reaching or exceeding 110 over the western deserts where the airmass is drier and there will be more solar insolation. Thursday through Saturday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. We still expect high temperatures to generally stay just below excessive heat warning thresholds during the hottest days such as Friday and Saturday; this is supported by HIL data. By Friday, rain chances in the Phoenix area will struggle to exceed around 10 percent due to the drier air in place. Sunday into Monday...The strong upper high continues to build towards the west, with one high center eventually setting up over central CA. Flow around the high becomes more favorable from the east and monsoon moisture starts to return. As such thunderstorm chances start to rise and we will be seeing lower grade conditions with slight chances for afternoon convection over the lower central deserts, along with 20-30 percent chances across the higher terrain of southern Gila County. Temperatures will trend down slightly as humidity levels rise. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Outside of a slight chance for a shower/weak thunderstorm later tonight as debris clouds from storms over northern Mexico move over the region, the rest of tonight and Tuesday morning should be quiet, with winds mainly out of a southeasterly direction. There is a slight risk of more convective activity on Tue afternoon, but confidence is too low to include it in the tafs at this time. Winds on Tue afternoon to once again become westerly, with speeds mainly in the 8-10 knot range. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east over central AZ. Under mostly clear skies, sfc winds will favor a southerly direction at KIPL and from a southeasterly direction at KBLH. A few higher gusts will be possible at KBLH, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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...Percha/MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Tucson AZ 250 AM MST TUE JUL 19 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Isolated light showers were occurring early this morning east of Tucson. Expect these to continue thru sunrise as they move to the WNW. A weak MCV was over SW Graham county as of 2 am, but shouldn`t be a player today as it continue to move NNW. What could be a player later today is the inverted trof currently over Chihuahua MX. This feature is moving slowly to the NW toward the area. Hi-res models focusing best activity W of Tucson, with potential for blowing dust across Pinal county towards Phoenix, and Cochise county. PW values across the remain above normal for July so locally heavy rain a threat. Can`t rule out a severe storm or two. Highs today will be around normal. Scattered afternoon/evening storms Wednesday with highs slightly warmer than today. Starting Thursday and continuing through the upcoming weekend there will be a gradual decrease in shower and thunderstorm activity as sub-tropical ridge expands over the southern CONUS. Still hanging on to enough moisture to keep isolated to scattered storms in the forecast. Highs temperatures will be above normal through this period, maxing out on Friday. && .AVIATION...VALID THRU 20/12Z. Isolated showers through the early morning hours. Sct-bkn clouds at 6-9k ft agl and bkn-ovc clouds at 10-14k ft agl. Expect isolated to scattered showers and thunderstorms developing during the late morning and afternoon, persisting through the mid evening hours tonight. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Wednesday morning. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .CLIMATE...As the area heats up again, could see a few spots across the western deserts approach record highs later in the week. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
  [top] Area Forecast Discussion National Weather Service Flagstaff AZ 242 AM MST TUE JUL 19 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION...A wide area of high pressure aloft remained centered over the Oklahoma/Kansas border. The models continue to promise little movement in this high pressure feature over the next few days. The position of the high is placing southerly flow over Arizona with not much change in the moisture profile through Thursday. Moving forward the distribution of showers and thunderstorms will remain very similar to Monday. Isolated heavy rain amounts of an inch or more and localized flooding will be possible. More generally, amounts in the trace to quarter inch category scattered about northern Arizona. From Friday onward...Models show the high pressure system centered over Oklahoma essentially splitting. The western portion of the high will migrate across Arizona and eventually become established over the western United States. If this pattern transpires it will open the door to an influx of drier air from the west. Forecast grids reflect a downturn in monsoon activity but moisture looks too entrenched for a complete shutdown in monsoon activity. We`ll keep you updated. && .AVIATION...For the 12Z package....Primarily VFR conditions are expected for the next 24 hours with bkn cigs aoa 14kft msl. til 17z isolated -shra / tsra possible, then btwn 17z-02z sct-nmrs SHRA/TSRA especially mountain areas. Brief visibility reductions and gusty winds possible near storms. Precipitation coverage decreasing after 02z Weds. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect another round of thunderstorms over the forecast area today and Wednesday. Storm motion will generally be from the south to north 5-10 mph. Thursday through Saturday...Scattered thunderstorms will persist across the area on Thursday. Drier air filtering into Arizona from the west will bring a decrease in thunderstorm activity on Friday and Saturday...with minimum RH`s dropping back into the teens to the north and west of Flagstaff. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...McCollum AVIATION...DL For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 934 PM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Showers and thunderstorms across southeast Arizona had diminished significantly in areal coverage late this evening. A few lingering showers and thunderstorms may continue to impact areas near Douglas through midnight, but not much activity expected thereafter. That said, updated the forecast to reflect this decreasing trend. Please refer to the additional sections in this product for more details. && .AVIATION...VALID THRU 20/06Z. A few lingering showers and thunderstorms can be expected tonight near the International Border. Otherwise, scattered to broken clouds at or above 10kft can be expected through Tuesday morning. Expect afternoon cloud build-ups Tuesday afternoon with isolated to scattered showers and thunderstorms developing through Tuesday evening. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA on Tuesday. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Tuesday afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .PREV DISCUSSION...Similar coverage of showers/tstms as today canbe expected Tuesday afternoon/evening as deep (albeit still light)sely flow aloft continues across the area. Scattered mainly afternoon/evening showers/tstms will also occur Wednesday. Thereafter, the 18/12Z GFS/ECMWF/CMC were similar versus their respective solutions in depicting a gradual daily decrease in showers/tstms to begin Thursday and continue into this weekend. Given the continued ely mid-level flow, precip-free conditions area- wide should not occur as earlier this month. However, moisture should remain sufficient for isolated to scattered afternoon and evening showers and thunderstorms Thursday through next Monday. High temps Tuesday will remain quite close to seasonal normals. A warming trend is forecast to begin Wednesday, and based on various 18/12Z guidance, high temps were increased several degs Thur-Sat versus the previous forecast. At this time, appears that Friday will be the hottest day although Saturday should be quite similar. A moderation in daytime temps should then occur Sunday and Monday. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Tucson AZ 934 PM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Showers and thunderstorms across southeast Arizona had diminished significantly in areal coverage late this evening. A few lingering showers and thunderstorms may continue to impact areas near Douglas through midnight, but not much activity expected thereafter. That said, updated the forecast to reflect this decreasing trend. Please refer to the additional sections in this product for more details. && .AVIATION...VALID THRU 20/06Z. A few lingering showers and thunderstorms can be expected tonight near the International Border. Otherwise, scattered to broken clouds at or above 10kft can be expected through Tuesday morning. Expect afternoon cloud build-ups Tuesday afternoon with isolated to scattered showers and thunderstorms developing through Tuesday evening. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA on Tuesday. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Tuesday afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .PREV DISCUSSION...Similar coverage of showers/tstms as today canbe expected Tuesday afternoon/evening as deep (albeit still light)sely flow aloft continues across the area. Scattered mainly afternoon/evening showers/tstms will also occur Wednesday. Thereafter, the 18/12Z GFS/ECMWF/CMC were similar versus their respective solutions in depicting a gradual daily decrease in showers/tstms to begin Thursday and continue into this weekend. Given the continued ely mid-level flow, precip-free conditions area- wide should not occur as earlier this month. However, moisture should remain sufficient for isolated to scattered afternoon and evening showers and thunderstorms Thursday through next Monday. High temps Tuesday will remain quite close to seasonal normals. A warming trend is forecast to begin Wednesday, and based on various 18/12Z guidance, high temps were increased several degs Thur-Sat versus the previous forecast. At this time, appears that Friday will be the hottest day although Saturday should be quite similar. A moderation in daytime temps should then occur Sunday and Monday. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Flagstaff AZ 902 PM MST MON JUL 18 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION... Thunderstorm activity appears to be trending downward this evening, with just a few isolated thunderstorms remaining. Will continue to monitor storms overnight, but the short-term forecast through morning currently looks in good shape. && .PREV DISCUSSION /250 PM MST/... The monsoon circulation has brought plentiful atmospheric moisture back into to the area...with precipitable water values now up to around 1.0" at KFLG. Instability has been somewhat limited...but scattered thunderstorms have formed with a few locally heavy showers, mainly over the higher terrain. Little change in the overall pattern is anticipated through Thursday with the strong ridge of high pressure in place over the Southern Plains and moist southerly flow over Arizona, providing the environment for daily thunderstorm activity across the forecast area. Storms will move a bit slower Tuesday through Thursday, leading to a somewhat greater chance for heavy rainfall accumulations. Friday through Sunday...forecast models continue to show the flattening of the ridge over the southern Rockies, and a decrease in thunderstorm activity Friday through Sunday as drier air filters in from the west. && .AVIATION...For the 00Z package...Only isolated showers and thunderstorms are expected for the remainder of tonight. Storms are likely to become more numerous again after 17Z Tuesday. Expect visibility reductions and gusty winds near stronger storms Tuesday. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Monsoon moisture is increasing across the area. Expect increasing showers and thunderstorm coverage. Gusty outflow winds are probable from any storms or showers, especially today. Storm motion today from south to north about 10 mph. Tuesday through Friday...Monsoon moisture to remain over northern Arizona, with shower and thunderstorm chances each day. Winds may become erratic and gusty near thunderstorms. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...KD/Bohlin AVIATION...KD FIRE WEATHER...BAK For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Phoenix AZ 835 PM MST MON JUL 18 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... A very activity late afternoon/evening for a few selected spots across south-central AZ. The combination of increased moisture levels through the column (KPSR balloon sounding PWAT 1.64 inches) and a weak disturbance that moved northward into southern AZ from northern Mexico triggered scattered showers and thunderstorms late this afternoon over Pima County. Outflow from these storms generated locally dense blowing dust over Pinal County, which contributed to a multi-vehicle accident that shut down I-10 at MP 214 late this afternoon. Outflows from these storms also triggered a few new storms over the greater Phoenix area early this evening. The strongest storm produced 63 mph winds and 0.34 inch of rain at Sky Harbor and localized damaging winds/flooding across central Phoenix. A second storm produced gusty winds and heavy winds over Queen Creek/San Tan Valley. At this hour, all remaining storms are either over Gila County or moved northward into Yavapai County. As far as the forecast for the rest of the night is concerned, although there is still a slight chance of an isolated shower or thunderstorm later tonight as debris cloudiness move northward from the remains of storms south of the international border, it should be quiet over the vast majority of our cwa. with inherited forecasts still looking good. && .PREVIOUS DISCUSSION... Tonight...Elevated amounts of monsoon moisture have now securely covered most of AZ. Athough thermodynamics are there for a few afternoon and evening showers and thunderstorms over our forecast area in south central AZ, this region seems to be in between upper level forcing mechanisms in currently working in northern and southern AZ. With the advent of a fairly strong and unseasonably cold Pacific trof moving into the Pacific northwest, a rather strong southwesterly Jetstream maximum has developed over portions of eastern Nevada and Utah. Accelerating winds aloft, from lighter winds in northern AZ into the Utah flow, has developed an area of upper level speed divergence and resulting convection. To our south near the Mexican border, the approaching massive inverted trof, clearly seen in water vapor imagery over the Mexican state of Chihuahua, is spreading leading edge upper level difluence. Our portions of south central AZ, including areas near Phoenix, are under a relatively stable upper level anti-cyclonic flow regime. Therefore a low grade monsoon forecast is expected for the remainder of this afternoon and evening, i.e. a slight chance of showers and thunderstorms. This forecast is excluding the possibility of copious amounts of convective debris clouds from southern AZ moving north toward Phoenix tonight, and causing the possibility of showers and thunderstorms similar to late Sunday night. So far model forecasts are minimizing this possibility. Tuesday...our office staff eyes are now transfixed on the massive inverted trof seen in water vapor imagery over north central Mexico. Models the past two days have resolved this feature very well at the 300/250 mb level, and latest model forecasts continue the trend of moving the feature bodily into southern AZ, although in a weakened form later Tuesday and Tuesday night. Current model forecast are minimizing the effect of this system in south central AZ, including nearby Phoenix and surrounding areas. From a fundamental stand point this is questionable. Strong differential heating and with weakness aloft normally results in an enhanced threat for storms that can last well into the evening hours. For now we will go with our instincts and raise precip probability a bit in south central AZ for late Tuesday and Tuesday night, with even a slight chance going into Wednesday morning. Wednesday...Monsoon moisture will be still be entrenched over the region. With mid/upper level disturbances should depart the area, resulting in another low grade monsoon forecast for Wednesday afternoon and evening. Thursday through Monday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Outside of a slight chance for a shower/weak thunderstorm later tonight as debris clouds from storms over northern Mexico move over the region, the rest of tonight and Tuesday morning should be quiet, with winds mainly out of a southeasterly direction. There is a slight risk of more convective activity on Tue afternoon, but confidence is too low to include it in the tafs at this time. Winds on Tue afternoon to once again become westerly, with speeds mainly in the 8-10 knot range. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east over central AZ. Under mostly clear skies, sfc winds will favor a southerly direction at KIPL and from a southeasterly direction at KBLH. A few higher gusts will be possible at KBLH, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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...Percha/Vasquez AVIATION...Percha/MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Tucson AZ 325 PM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Scattered to numerous showers and thunderstorms were occurring generally from the Tohono O`odham Nation southeastward into far southeast Pima County, Santa Cruz County, and extreme southwest Cochise County at this time. This area is within a northwest-to-southeast oriented axis of greatest instability as per SPC hourly mesoscale analysis of MUCAPE. Other isolated showers and thunderstorms were also occurring from southcentral Pinal County eastward into western Graham County. Storm motions were mainly northwest around 5-10 kts. IR satellite imagery depicted rapidly cooling cloud tops during the past hour with the showers/tstms across central Pima County. Have favored the Univ of AZ WRF-NAM for precip chances tonight. Thus, expect scattered to perhaps numerous showers/tstms across much of the area this evening. The main concern given relatively slow storm motions and precip water values of 1.25"-1.50" will be locally heavy rainfall. Have maintained a slight chance of showers/tstms late tonight for much of this forecast area. Have noted that the WRF- NAM depicts precip-free conditions late tonight into mid-morning Tuesday. Will defer to the evening shift to adjust PoPs perhaps downward as necessary. Similar coverage of showers/tstms is expected Tuesday afternoon/evening as deep (albeit still light) sely flow aloft continues across the area. Scattered mainly afternoon/evening showers/tstms will also occur Wednesday. Thereafter, the 18/12Z GFS/ECMWF/CMC were similar versus their respective solutions in depicting a gradual daily decrease in showers/tstms to begin Thursday and continue into this weekend. Given the continued ely mid-level flow, precip-free conditions area- wide should not occur as earlier this month. However, moisture should remain sufficient for isolated to scattered afternoon and evening showers and thunderstorms Thursday through next Monday. High temps Tuesday will remain quite close to seasonal normals. A warming trend is forecast to begin Wednesday, and based on various 18/12Z guidance, high temps were increased several degs Thur-Sat versus the previous forecast. At this time, appears that Friday will be the hottest day although Saturday should be quite similar. A moderation in daytime temps should then occur Sunday and Monday. && .AVIATION...VALID THRU 20/00Z. Isolated to scattered SHRA/TSRA will occur through the period, with the best chances during the afternoon and evening hours. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Tuesday afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ DISCUSSION...Francis AVIATION/FIRE WEATHER...French Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Flagstaff AZ 250 PM MST MON JUL 18 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION... The monsoon circulation has brought plentiful atmospheric moisture back into to the area...with precipitable water values now up to around 1.0" at KFLG. Instability has been somewhat limited...but scattered thunderstorms have formed with a few locally heavy showers, mainly over the higher terrain. Little change in the overall pattern is anticipated through Thursday with the strong ridge of high pressure in place over the Southern Plains and moist southerly flow over Arizona, providing the environment for daily thunderstorm activity across the forecast area. Storms will move a bit slower Tuesday through Thursday, leading to a somewhat greater chance for heavy rainfall accumulations. Friday through Sunday...forecast models continue to show the flattening of the ridge over the southern Rockies, and a decrease in thunderstorm activity Friday through Sunday as drier air filters in from the west. && .AVIATION...For the 00Z package...Sct shra/tsra expected to continue through 03z...with isold -shra/-tsra continuing overnight. Sct shra/tsra will redevelop after 18Z Tuesday...with storms most numerous over the higher terrain. Expect visibility reductions and gusty winds near storms. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect another round of thunderstorms over the forecast area Tuesday and Wednesday. Storm motion will generally be from the south to north 5-10 mph. Thursday through Saturday...Scattered thunderstorms will persist across the area on Thursday. Drier air filtering into Arizona from the west will bring a decrease in thunderstorm activity on Friday and Saturday...with minimum RH`s dropping back into the teens to the north and west of Flagstaff. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...Bohlin/BAK AVIATION...BAK FIRE WEATHER...BAK For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Phoenix AZ 200 PM MST MON JUL 18 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... Tonight...Elevated amounts of monsoon moisture have now securely covered most of AZ. Athough thermodynamics are there for a few afternoon and evening showers and thunderstorms over our forecast area in south central AZ, this region seems to be inbetween upper level forcing mechanisms in currently working in northern and southern AZ. With the advent of a fairly strong and unseasonably cold Pacific trof moving into the Pacific northwest, a rather strong southwesterly Jetstream maximum has developed over portions of eastern Nevada and Utah. Accelerating winds aloft, from lighter winds in northern AZ into the Utah flow, has developed an area of upper level speed divergence and resulting convection. To our south near the Mexican border, the approaching massive inverted trof, clearly seen in water vapor imagery over the Mexican state of Chihuahua, is spreading leading edge upper level difluence. Our portions of south central AZ, including areas near Phoenix, are under a relatively stable upper level anti-cyclonic flow regime. Therefore a low grade monsoon forecast is expected for the remainder of this afternoon and evening, i.e. a slight chance of showers and thunderstorms. This forecast is excluding the possibility of copious amounts of convective debris clouds from southern AZ moving north toward Phoenix tonight, and causing the possibility of showers and thunderstorms similar to late Sunday night. So far model forecasts are minimizing this possibility. Tuesday...our office staff eyes are now transfixed on the massive inverted trof seen in water vapor imagery over north central Mexico. Models the past two days have resolved this feature very well at the 300/250 mb level, and latest model forecasts continue the trend of moving the feature bodily into southern AZ, although in a weakened form later Tuesday and Tuesday night. Current model forecast are minimizing the effect of this system in south central AZ, including nearby Phoenix and surrounding areas. From a fundamental stand point this is questionable. Strong differential heating and with weakness aloft normally results in an enhanced threat for storms that can last well into the evening hours. For now we will go with our instincts and raise precip probability a bit in south central AZ for late Tuesday and Tuesday night, with even a slight chance going into Wednesday morning. Wednesday...Monsoon moisture will be still be entrenched over the region. With mid/upper level disturbances should depart the area, resulting in another low grade monsoon forecast for Wednesday afternoon and evening. Thursday through Monday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Timing wind shifts and the potential for gusty outflow winds and localized blowing dust will be the primary aviation concerns through Tuesday morning. Some variability about a southerly wind direction is likely again this afternoon, though eventually should favor southwest by the evening. Thunderstorms forming over SE AZ should move north towards the Phoenix area late in the afternoon with gusty outflow winds preceding them. While the threat of a storm directly affecting an airport is better than Sunday, probabilities are still quite low with better chances of localized blowing dust and more widespread lofted dust and haze affecting slantwise visibilities. Only modest confidence exists timing outflow wind shifts into terminal sites between 02Z- 04Z. Otherwise, developing cigs in a 10K-15K ft range look likely from decaying storms to the south. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east into central AZ. Under mostly clear skies, sfc winds will favor a southerly direction, though will be more variable at KIPL after sunset. A few higher gusts will be possible, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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 FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Phoenix AZ 1230 PM MST MON JUL 18 2016 ...Updated Aviation and Fire Weather... .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle and temperatures will increase to above normal levels. && .DISCUSSION... Woohoo, the monsoon moisture boundary raced north past Phoenix over night and this morning was seen pushing up against the higher elevations of the Mogollon Rim. In other words the southern half of AZ was in the monsoon moisture soup, and noted by the relatively low afternoon convective trigger temperatures at a few locations. For example, based on this mornings weather balloon soundings, the convective trigger temp at Phoenix is 99 deg F, 97 at Tucson, and 92 deg at Globe/Miami (elevation 3-4 thsd ft msl). Even though the afternoon thermodynamics are there, the flow aloft has, and will remain anti-cyclonic and relatively stable today and tonight. In other words, the situation for today favors low topped afternoon convection, mostly in the mountains with possible outflows toward the deserts sparking an isolated desert storm, with convection dissipating quickly after dark, unless. Unless like last night, a surge of convective debris clouds from southeast AZ spread north, creating a well saturated mid level airmass that a gravity wave sparked a few showers and thunderstorms in the Phoenix area after midnight. The gravity wave conclusion was derived from high speed satellite imagery loops. Beyond today, our office staff eyes are now on the massive inverted trof seen in water vapor imagery over the north central Mexican state of Chihuahua. Models the past two days have resolved this feature very well at the 300/250 mb level, and is forecast to move into southeast AZ on Tuesday. For now the low grade monsoon forecast, meaning slight chance of showers and thunderstorms over the south central AZ deserts and mountains look ok for now. We will see how the new models handle Tuesdays inverted trof since model guidance will have incorporated the Chihuahua weather balloon sounding that is launched once per day at 12z. .Previous discussion...503 AM MST... The weather pattern has finally allowed the typical monsoonal circulation to return to the area as the combination of troffing along the Pacific northwest coast and upper ridging over the central CONUS has allowed southerly to southeasterly flow aloft to set up across Arizona. This favorable flow has advected considerable amounts of monsoon moisture into the lower deserts; the latest Phoenix raob had PWAT up to 1.44 inches and Tucson had 1.5 inches. Despite the ample moisture, much of it was at mid and upper levels through, limiting CAPE values. According to the 2 am SPC mesoanalysis graphic, MLCAPE of consequence (over 500 j/kg) was still over far SE Arizona with very low amounts in the central deserts. 2 am radar continued to show showers spreading into south central Arizona from the southeast and isolated thunderstorms are possible but any convection that develops should stay on the weak side into the morning hours. The convection is likely being aided by weak vort maxes rotating into Arizona around the large scale upper high. Should significant clouds and showers persist well into the morning or the early afternoon, instability will again be limited and storm activity tonight will suffer. For the next few days, operational models such as the GFS and ECMWF as well as GEFS data, call for the monsoonal circulation to remain in place with little change from day to day. Moisture will remain relatively plentiful, at least from a PWAT perspective as values upwards of 1.5 inches will stay over much of the lower deserts to the east of the lower Colorado river valley. Most of the CAPE of consequence however is advertised to stay pretty much from Maricopa county eastward each day, suggesting convective potential over the southwest deserts will be limited, and minimal as you move into the deserts of southeast California. Steering flow each day will stay south to southeast but not overly strong, with 700-300mb layer winds mostly between 10 and 15 knots each day. There will be occasional vort maxes/weak inverted trofs rotating around the main upper high and moving north across the central deserts but due to the small scale of these features, they will not be handled very well by the models and as such there will be low confidence in any particular one of these small scale features. As such we will keep a rather low grade monsoon forecast in place today through Wednesday with slight chances for mainly afternoon and evening showers and thunderstorms over the central lower deserts, with better chances over the higher terrain east of Phoenix. Skies will be partly to mostly cloudy much of the time, with the greatest amounts of sunshine likely during later morning through mid afternoon each day. High temperatures will stay near seasonal normals over south central Arizona today, then gradually creep up each day with Phoenix approaching 110 by Wednesday. It will be hotter over the far western deserts and over SE California as the airmass will be drier there. Thursday through Sunday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures be much higher. The driest areas Thursday through Sunday will be southeast California where afternoon temperatures at Imperial, El Centro, and Blythe will at the 114 degree mark. Ouch! Current forecasts will keep Phoenix at or above the 110 degree mark each day. At the moment it appears high temperature will stay below excessive heat warning thresholds but that could change depending upon just how dry we actually get, and how high the heights become over the lower deserts. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Timing wind shifts and the potential for gusty outflow winds and localized blowing dust will be the primary aviation concerns through Tuesday morning. Some variability about a southerly wind direction is likely again this afternoon, though eventually should favor southwest by the evening. Thunderstorms forming over SE AZ should move north towards the Phoenix area late in the afternoon with gusty outflow winds preceding them. While the threat of a storm directly affecting an airport is better than Sunday, probabilities are still quite low with better chances of localized blowing dust and more widespread lofted dust and haze affecting slantwise visibilities. Only modest confidence exists timing outflow wind shifts into terminal sites between 02Z- 04Z. Otherwise, developing cigs in a 10K-15K ft range look likely from decaying storms to the south. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east into central AZ. Under mostly clear skies, sfc winds will favor a southerly direction, though will be more variable at KIPL after sunset. A few higher gusts will be possible, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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/CB/Vasquez AVIATION...MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Phoenix AZ 1230 PM MST MON JUL 18 2016 ...Updated Aviation and Fire Weather... .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle and temperatures will increase to above normal levels. && .DISCUSSION... Woohoo, the monsoon moisture boundary raced north past Phoenix over night and this morning was seen pushing up against the higher elevations of the Mogollon Rim. In other words the southern half of AZ was in the monsoon moisture soup, and noted by the relatively low afternoon convective trigger temperatures at a few locations. For example, based on this mornings weather balloon soundings, the convective trigger temp at Phoenix is 99 deg F, 97 at Tucson, and 92 deg at Globe/Miami (elevation 3-4 thsd ft msl). Even though the afternoon thermodynamics are there, the flow aloft has, and will remain anti-cyclonic and relatively stable today and tonight. In other words, the situation for today favors low topped afternoon convection, mostly in the mountains with possible outflows toward the deserts sparking an isolated desert storm, with convection dissipating quickly after dark, unless. Unless like last night, a surge of convective debris clouds from southeast AZ spread north, creating a well saturated mid level airmass that a gravity wave sparked a few showers and thunderstorms in the Phoenix area after midnight. The gravity wave conclusion was derived from high speed satellite imagery loops. Beyond today, our office staff eyes are now on the massive inverted trof seen in water vapor imagery over the north central Mexican state of Chihuahua. Models the past two days have resolved this feature very well at the 300/250 mb level, and is forecast to move into southeast AZ on Tuesday. For now the low grade monsoon forecast, meaning slight chance of showers and thunderstorms over the south central AZ deserts and mountains look ok for now. We will see how the new models handle Tuesdays inverted trof since model guidance will have incorporated the Chihuahua weather balloon sounding that is launched once per day at 12z. .Previous discussion...503 AM MST... The weather pattern has finally allowed the typical monsoonal circulation to return to the area as the combination of troffing along the Pacific northwest coast and upper ridging over the central CONUS has allowed southerly to southeasterly flow aloft to set up across Arizona. This favorable flow has advected considerable amounts of monsoon moisture into the lower deserts; the latest Phoenix raob had PWAT up to 1.44 inches and Tucson had 1.5 inches. Despite the ample moisture, much of it was at mid and upper levels through, limiting CAPE values. According to the 2 am SPC mesoanalysis graphic, MLCAPE of consequence (over 500 j/kg) was still over far SE Arizona with very low amounts in the central deserts. 2 am radar continued to show showers spreading into south central Arizona from the southeast and isolated thunderstorms are possible but any convection that develops should stay on the weak side into the morning hours. The convection is likely being aided by weak vort maxes rotating into Arizona around the large scale upper high. Should significant clouds and showers persist well into the morning or the early afternoon, instability will again be limited and storm activity tonight will suffer. For the next few days, operational models such as the GFS and ECMWF as well as GEFS data, call for the monsoonal circulation to remain in place with little change from day to day. Moisture will remain relatively plentiful, at least from a PWAT perspective as values upwards of 1.5 inches will stay over much of the lower deserts to the east of the lower Colorado river valley. Most of the CAPE of consequence however is advertised to stay pretty much from Maricopa county eastward each day, suggesting convective potential over the southwest deserts will be limited, and minimal as you move into the deserts of southeast California. Steering flow each day will stay south to southeast but not overly strong, with 700-300mb layer winds mostly between 10 and 15 knots each day. There will be occasional vort maxes/weak inverted trofs rotating around the main upper high and moving north across the central deserts but due to the small scale of these features, they will not be handled very well by the models and as such there will be low confidence in any particular one of these small scale features. As such we will keep a rather low grade monsoon forecast in place today through Wednesday with slight chances for mainly afternoon and evening showers and thunderstorms over the central lower deserts, with better chances over the higher terrain east of Phoenix. Skies will be partly to mostly cloudy much of the time, with the greatest amounts of sunshine likely during later morning through mid afternoon each day. High temperatures will stay near seasonal normals over south central Arizona today, then gradually creep up each day with Phoenix approaching 110 by Wednesday. It will be hotter over the far western deserts and over SE California as the airmass will be drier there. Thursday through Sunday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures be much higher. The driest areas Thursday through Sunday will be southeast California where afternoon temperatures at Imperial, El Centro, and Blythe will at the 114 degree mark. Ouch! Current forecasts will keep Phoenix at or above the 110 degree mark each day. At the moment it appears high temperature will stay below excessive heat warning thresholds but that could change depending upon just how dry we actually get, and how high the heights become over the lower deserts. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Timing wind shifts and the potential for gusty outflow winds and localized blowing dust will be the primary aviation concerns through Tuesday morning. Some variability about a southerly wind direction is likely again this afternoon, though eventually should favor southwest by the evening. Thunderstorms forming over SE AZ should move north towards the Phoenix area late in the afternoon with gusty outflow winds preceding them. While the threat of a storm directly affecting an airport is better than Sunday, probabilities are still quite low with better chances of localized blowing dust and more widespread lofted dust and haze affecting slantwise visibilities. Only modest confidence exists timing outflow wind shifts into terminal sites between 02Z- 04Z. Otherwise, developing cigs in a 10K-15K ft range look likely from decaying storms to the south. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east into central AZ. Under mostly clear skies, sfc winds will favor a southerly direction, though will be more variable at KIPL after sunset. A few higher gusts will be possible, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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/CB/Vasquez AVIATION...MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Flagstaff AZ 1004 AM MST MON JUL 18 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION...The subtropical ridge remains in a favorable position for moisture advection into Arizona through Friday. This translates into a moderate grade Monsoon with good chances for showers and thunderstorms each day. A few storms will develop in the overnight periods as a few upper level 200-300mb disturbances roll across the state. We sent out a quick update to increase shower chances this evening. Otherwise the forecast grids look good. && .PREV DISCUSSION /430 AM MST/... For today through Thursday...Due to the position of the high southerly flow and monsoon moisture will remain over northern Arizona. There should be some increase in moisture values over Sunday so shower and thunderstorm activity is expected to be more widespread. Instability and strength of any storms will be inhibited by general mid to high level cloud cover and the fact that the pattern doesn`t favor a decent push of low level moisture. In other words, precipitation amounts will mostly remain on the low to modest side. From Friday onward...Models show strong high pressure aloft building across Arizona into California. As a result, a drier air mass will filter in from the west. Low to no grade monsoon activity will be the result should this pattern materialize. && .AVIATION...For the 18Z package...sct-nmrs shra/tsra expected to develop this afternoon...continuing through 03z. Brief visibility reductions and gusty winds possible near storms. isold-sct -shra will continue aft 05Z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Monsoon moisture is increasing across the area. Expect increasing showers and thunderstorm coverage. Gusty outflow winds are probable from any storms or showers, especially today. Storm motion today from south to north about 10 mph. Tuesday through Friday...Monsoon moisture to remain over northern Arizona, with shower and thunderstorm chances each day. Winds may become erratic and gusty near thunderstorms. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...Bohlin/McCollum AVIATION...BAK FIRE WEATHER...DL For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 915 AM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into the upcoming weekend. && .DISCUSSION...Isolated showers were occurring in western Pima County east of Ajo at this time. Otherwise, visible satellite imagery depicted mostly clear skies to partly cloudy skies from Tucson westward into western Pima County, and mostly clear skies across eastern sections. Ample moisture exists with dewpoints at lower elevations valid 16Z ranging from the mid 50s-lower 60s. 18/12Z KTWC sounding total precip water value of 1.50" was about 0.15" higher versus 24 hours ago. 18/12Z upper air plots depicted a broad ridge over the southern CONUS, with a 597 DM high centered over northern Mississippi. Meanwhile, a deep upper trough was over the Pacific NW, and deep easterly/southeasterly flow prevailed across southeast AZ. Given the greater extent of clearing skies especially across eastern sections versus Sunday morning, am inclined to expect that shower/ tstm development later this morning will occur across favored ranges such as the Chiricahua Mountains. The 18/14Z HRRR supports this notion, the showers/tstms should migrate wwd/nwwd this afternoon. Quick glance at the 18/12Z Univ. of AZ WRF-NAM suggests shower/tstm development may also occur further westward by 19Z, and favor locales from Nogales to Kitt Peak. Water vapor imagery depicts a cyclonic twist approaching this area from the southeast over central Sonora Mexico. A much larger cyclonic circulation was south of the Texas Big Bend, or far eastern Chihuahua Mexico. This system may have more influence for this forecast area Tuesday. At any rate and without a further recitation of various NWP models, expect scattered to perhaps numerous showers and thunderstorms this afternoon and evening. The lowest coverage should occur across western Pima County where only isolated showers/tstms are expected. The main concern this afternoon/evening will be the potential for locally heavy rainfall and brief strong wind gusts that may approach severe thresholds. A slight chance of showers/tstms continues for much of the area late tonight. High temps this afternoon will be quite similar to temps achieved Sunday, or perhaps generally a couple of degs lower depending upon location. May make some minor PoP adjustments for this afternoon/evening, but this will not affect the overall scenario. Please refer to the additional sections for further detail. && .AVIATION...VALID THRU 19/18Z. Isolated -SHRA mainly west of KTUS this morning, then scattered to numerous -TSRA/-SHRA this afternoon and evening. The favored locales will be from KTUS vicinity east and south to the New Mexico/ International borders. Forecast confidence is sufficiently high to include VCTS in the KDUG/KOLS TAFs this afternoon and evening. VCTS may be delayed at KTUS until after 20/00Z. Isolated -SHRA and possible -TSRA to continue late tonight/early Tuesday morning. Outside of thunderstorm outflows, surface wind will generally be variable in direction less than 12 kts thru the period. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture and a favorable flow regime will maintain the daily cycle of scattered to perhaps numerous showers and thunderstorms through Wednesday. The bulk of this activity will occur during the afternoon and evening hours, and a slight chance of showers and thunderstorms will continue during the overnight hours. Thereafter, a gradual decrease in thunderstorm coverage is expected Thursday into the upcoming weekend. Outside of gusty thunderstorm outflows, 20-foot winds will be terrain driven and mostly less than 15 mph. && .PREV DISCUSSION /340 AM MST/...The 330 am radar imagery showed a distinctive circulation just west of Willcox, moving to the WNW. This MCV is associated with decaying MCS that formed over eastern Cochise county last night and produced areas of locally heavy rain. Douglas airport recorded 1.75" last night which set a daily record and also ranks as the 9th wettest July day on record. The MCV will be one of several features that will have an impact on todays forecast. Last nights MCS likely associated with a weak disturbance aloft that moved across northern Chihuahua MX. Water vapor was also showing an inverted trof approaching the Texas Big Bend this morning. A challenging forecast indeed for the next 12-18 hours. One would go with the idea that after the morning activity ends, that there will be lesser activity this afternoon due to debris cloud cover slowly diminishing which cuts down on heating thus being a few degrees cooler than Sunday. However both HRRR and 00z WRF NAM/GFS fire scattered storms this afternoon. Confidence is low will this forecast. Tomorrow likely will be another forecast challenge based on what will transpire today. Again confidence is low. Wednesday through next weekend will see a gradual decrease in moisture and thus areal coverage of storms as the sub-tropical high expands west into the eastern Pacific. Temperature warming up but likely not as hot as the GFS would suggest if going by low-level thickness numbers, which are higher than EC. Something to keep watch. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson Area Forecast Discussion National Weather Service Tucson AZ 245 PM MST TUE JUL 19 2016 .SYNOPSIS...Scattered mainly afternoon and evening showers and thunderstorms will occur again Wednesday. A decrease in coverage of showers and thunderstorms will then prevail Thursday into this weekend. Expect hotter daytime temperatures Thursday through Saturday followed by a minor moderation in temperatures early next week. && .DISCUSSION...Scattered to numerous showers and thunderstorms were occurring generally across central/eastern Pima County, southern Pinal County and Santa Cruz County at this time. Other isolated showers and thunderstorms were also occurring further east across northern Graham County, and the White Mountains. The ongoing showers/tstms will move mainly northwestward during the next few hours, with the main threat being locally heavy rainfall and brief gusty winds. There is still the potential for blowing dust by this evening along the Interstate 10 corridor northwest of Tucson to Phoenix. Various mesoscale models suggest that showers/tstms will this evening mainly across eastern sections as the ongoing showers/tstms decrease markedly in coverage/intensity. Thus, the official forecast continues with scattered showers/ tstms area-wide this evening followed by a slight chance of showers/tstms late tonight into Wednesday morning. Would not be surprised that precip-free conditions occur across much of the area late tonight as has generally been the case the past few nights. However, there will still be enough moisture to support the aforementioned scenario of a slight chance of showers/tstms. Various mesoscale models depict similar coverage of showers/tstms Wednesday. Have continued with scattered mainly afternoon/evening showers/tstms again Wednesday. The 19/12Z GFS/ECMWF/CMC were similar versus their respective solutions in depicting a gradual daily decrease in showers/tstms to begin Thursday and continue into this weekend. Given the progged easterly mid-level flow, precip-free conditions area-wide should not occur as happened earlier this month. However, moisture should remain sufficient for isolated to scattered afternoon and evening showers and thunderstorms Thursday through next Tuesday. A warming trend will occur Wednesday through Friday as heights/ thicknesses increase due to a consolidation of an upper high over southern California. Expect some minor moderation in daytime temps early next week, but daytime temps will remain above normal. && .AVIATION...VALID THRU 21/00Z. Scattered -TSRA/-SHRA this evening followed by isolated -SHRA across the area late tonight into Wednesday morning. Expect scattered -TSRA/-SHRA to return Wednesday afternoon. Brief wind gusts to 45 kts and MVFR conditions will occur with stronger TSRA. Surface wind will generally be variable in direction less than 12 kts thru the period. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Adequate moisture for scattered afternoon and evening thunderstorms again Wednesday. A drying trend will then lead to reduced coverage of showers and thunderstorms Thursday into this weekend. Moisture will remain adequate for isolated to scattered thunderstorms early next week. Outside of gusty thunderstorm outflows, 20-foot winds will be terrain driven and mostly less than 15 mph. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson Francis
  [top] Area Forecast Discussion National Weather Service Phoenix AZ 218 PM MST TUE JUL 19 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next couple of days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures over the central deserts will stay near seasonal normals, with hotter conditions over the western deserts. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... Tonight and Wednesday... Regional morning weather balloon soundings continued show a rather healthy amount of monsoon moisture strewn across central and southern AZ. Monsoon moisture is not excessive by any means, but not minimal either. And, boundary layer moisture was healthy enough to result in relatively low afternoon convective trigger temperatures. This afternoon there seemed to be an early start to convection in southeast AZ and over southern Gila County zone 24. Low afternoon convective trigger temperatures will make the lower desert airmass in south central AZ more susceptible to convection produced by convective outflows moving in from southeast AZ, especially with weakness/support aloft. Upper level weakness and support is what we`ve been focusing on for a few days now with the approaching inverted trof (IT) from Chihuahua Mexico. At 2 pm mst the leading edge of this IT feature had moved into the southeast AZ corner, with convection breaking out ahead of its leading edge, and in a weak difluent zone aloft. Various meso-scale models have widely varying spacial and temporal solutions for convection, but the bottom line is most of it is produced in southeast AZ running along a north south line from near Tucson to our southern Gila County Zone 24. Additionally, some models produce a strong convective outflow that spreads northwest toward Pinal and Maricopa Counties, including Phoenix between 7 pm and 10 pm mst. The magnitude of this outflow boundary will likely initiate secondary convection. Therefore the chance of showers and thunderstorms will continue this evening through late night, with a slight chance of lingering showers continuing through early Wednesday morning. Wednesday...Monsoon moisture will be still be entrenched over the region. With mid/upper level disturbances departing the area, this will result in another low grade monsoon forecast Wednesday afternoon and evening. Thursday through Monday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Thunderstorms are possible this afternoon with development already occurring over the higher terrain to the north and east of Phoenix. These storms, along with any that develop around the metro, could produce outflow winds that could impact any terminal. Current storm development suggests outflows from the north or the east are more likely but the exact timing and direction of wind shifts is difficult pin down at this time Southeast California/Southwest Arizona including KIPL and KBLH: Little aviation concerns through with storm activity well off to the east into central Arizona. Expect mostly clear skies and southerly winds through the evening and into tomorrow. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Friday through Tuesday...Temperatures will trend back into an above normal range through the weekend as moisture levels thin and humidity values drop. Thunderstorm/wetting rain chances dwindle and become mostly limited to the higher terrain of eastern Arizona by Friday and Saturday. Consequently, afternoon humidity levels will drop into the 10-25 percent range this weekend. Outside of any thunderstorms, winds will be typical with some afternoon gustiness. && .SPOTTER INFORMATION STATEMENT... Spotter activation may be required for this evening. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...Vasquez AVIATION...Deemer/Iniguez FIRE WEATHER...Deemer/Iniguez
  [top] Area Forecast Discussion National Weather Service Flagstaff AZ 936 AM MST TUE JUL 19 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION...A wet Monsoon weather pattern continues as the subtropical ridge is in a favorable position for northward advection of moisture into Arizona. Expect good coverage for showers and thunderstorms with subtle changes in the location of the heavy rainfall from day to day. The morning forecast grids look good no updates. && .PREV DISCUSSION /242 AM MST/...A wide area of high pressure aloft remained centered over the Oklahoma/Kansas border. The models continue to promise little movement in this high pressure feature over the next few days. The position of the high is placing southerly flow over Arizona with not much change in the moisture profile through Thursday. Moving forward the distribution of showers and thunderstorms will remain very similar to Monday. Isolated heavy rain amounts of an inch or more and localized flooding will be possible. More generally, amounts in the trace to quarter inch category scattered about northern Arizona. From Friday onward...Models show the high pressure system centered over Oklahoma essentially splitting. The western portion of the high will migrate across Arizona and eventually become established over the western United States. If this pattern transpires it will open the door to an influx of drier air from the west. Forecast grids reflect a downturn in monsoon activity but moisture looks too entrenched for a complete shutdown in monsoon activity. We`ll keep you updated. && .AVIATION...For the 18Z package...Primarily VFR conditions are expected for the next 24 hours with bkn cigs aoa 14kft msl. Look for sct-nmrs SHRA/TSRA between 17z-02z, especially over mountain areas. Brief MVFR/IFR conditions and gusty winds possible with stronger storms. Precipitation coverage decreasing after 02z Wed. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect another round of thunderstorms over the forecast area today and Wednesday. Storm motion will generally be from the south to north 5-10 mph. Thursday through Saturday...Scattered thunderstorms will persist across the area on Thursday. Drier air filtering into Arizona from the west will bring a decrease in thunderstorm activity on Friday and Saturday...with minimum RH`s dropping back into the teens to the north and west of Flagstaff. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...Bohlin/McCollum AVIATION...CLM FIRE WEATHER...DL For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 850 AM MST TUE JUL 19 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...IR/Visible satellite imagery depicted mostly clear skies to partly cloudy skies at this time. Some of the more prominent cyclonic twists were moving northwestward just east of northern Greenlee County, over northwest Sonora, and over east central Sonora. Water vapor imagery also depicted an inverted trough over southern New Mexico southward into northern Chihuahua Mexico. Ample moisture continues across the area with dewpoints at lower elevations valid 15Z ranging from the mid 50s-mid 60s, and 19/12Z KTWC sounding total precip water value was 1.50 inches. There were some differences between the various mesoscale models regarding the development and evolution of showers/tstms later today. Instead of a model rehash, the official forecast of scattered showers/tstms this afternoon/evening appears to be on track. The main concern this afternoon/evening will be the potential for locally heavy rainfall and brief strong wind gusts that may approach severe thresholds. There is also a potential for blowing dust along the Interstate 10 corridor northwest of Tucson to Phoenix. Forecast confidence is not sufficiently high at this time to issue a Blowing Dust Advisory. A slight chance of showers/tstms continues for much of the area late tonight. High temps this afternoon will generally be a few degs warmer versus Monday. Please refer to the additional sections for further detail. && .AVIATION...VALID THRU 20/18Z. Isolated showers through the early morning hours. Sct-bkn clouds at 6-9k ft agl and bkn-ovc clouds at 10-14k ft agl. Expect scattered showers and thunderstorms this afternoon and evening, then tapering in coverage late tonight. Brief wind gusts of 40-45 kts and MVFR conditions will occur with the stronger TSRA. Outside of gusty outflows, surface wind will generally be less than 12 kts through Wednesday morning. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .CLIMATE...As the area heats up again, could see a few spots across the western deserts approach record highs later in the week. && .PREV DISCUSSION /250 AM MST/...Isolated light showers were occurring early this morning east of Tucson. Expect these to continue thru sunrise as they move to the WNW. A weak MCV was over SW Graham county as of 2 am, but shouldn`t be a player today as it continue to move NNW. What could be a player later today is the inverted trof currently over Chihuahua MX. This feature is moving slowly to the NW toward the area. Hi-res models focusing best activity W of Tucson, with potential for blowing dust across Pinal county towards Phoenix, and Cochise county. PW values across the remain above normal for July so locally heavy rain a threat. Can`t rule out a severe storm or two. Highs today will be around normal. Scattered afternoon/evening storms Wednesday with highs slightly warmer than today. Starting Thursday and continuing through the upcoming weekend there will be a gradual decrease in shower and thunderstorm activity as sub-tropical ridge expands over the southern CONUS. Still hanging on to enough moisture to keep isolated to scattered storms in the forecast. Highs temperatures will be above normal through this period, maxing out on Friday. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Phoenix AZ 810 AM MST TUE JUL 19 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next couple of days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures over the central deserts will stay near seasonal normals, with hotter conditions over the western deserts. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... Regional morning weather balloon soundings continued show a rather healthy amount of monsoon moisture strewn across central and southern AZ. Monsoon moisture is not excessive by any means, but not minimal either. And, boundary layer moisture was healthy enough to result in relatively low afternoon convective trigger temperatures like 102 F in Phoenix, 96 in Tucson, and 88 degrees in Globe/Miami (3-4 thsd msl) in the mountains east of Phoenix. Low afternoon convective trigger temperatures make the lower desert airmass in south central AZ susceptible to convection, easily triggered by numerous convective outflow boundaries running across the lower regions later in the day, especially with weakness/support aloft. Upper level weakness and support is what we`ve been focusing on for a few days now with the approaching inverted trof (IT) from Chihuahua Mexico. Models continue to forecast this IT feature, located just southwest of El Paso in morning water vapor imagery, to move into southeast AZ later this afternoon, then across the greater Phoenix area Wednesday afternoon in a much weakened/washed out state. Numerical guidance continues to put PHX and TUS in a chance shwr/tstm category for later today and tonight due to this approaching IT feature. The chance of showers can possibly continue into the night in south central AZ with all the secondary circulations/outflows it can produce. Due to this approaching feature, the moisture rich boundary layer, and relatively low thermodynamic convective trigger temperatures, we will upgrade the probability of precip into the chance category in south central AZ including Phoenix for tonight. Wednesday`s afternoon and evenings low grade monsoon shwr/tstm possibilities look ok for now. Previous discussion still applies. .Previous Discussion...507 AM MST... Monsoon circulation remains entrenched across Arizona with an impressive plume of deep moisture spreading north from northwest Mexico and running north/northeastward across central and eastern Arizona, around the periphery of a very strong upper high centered over the south-central CONUS. This moist plume is easily seen in the current IR and vapor imagery loops. Steering flow across central/eastern AZ is mostly south to southeast, becoming more southwesterly as you move west and into the far southwest AZ deserts and over SE California. Orientation of this flow will keep most of the convection focused over south-central Arizona this week with very little expected into the SE California deserts. PWAT value at Phoenix from the last 00z raob was healthy at 1.64 inches and there was modest CAPE present in the sounding. 2 am surface dewpoints over the central deserts were elevated, ranging mostly from the upper 50s to middle 60s. Little if any shower activity was noted early this morning on radar, just a fair amount of debris cloudiness spreading north across the lower deserts. Overall, for the next couple of days, we are looking at a low to medium grade monsoon in terms of thunderstorm coverage. Most of the convection will be located over south-central Arizona with slight chances of mainly afternoon and evening storms becoming 30 percent or more over the higher terrain east of Phoenix. Steering flow is not especially strong as the 700-300mb mean winds typically run 10- 15 knots, and most of the disturbances that will rotate around the high and serve as "triggers" for convection are not especially dynamical. Latest vapor imagery loop does show a moderately organized inverted trof spinning over NW Mexico, poised to move into southeast Arizona this morning and across portions of south central and east-central AZ during the day, but it is forecast to weaken as it moves through the area so most of the desert POPs will stay below 25 percent this evening. High temperatures over the central deserts today and Wednesday will stay near seasonal normals due to the elevated humidity, with highs reaching or exceeding 110 over the western deserts where the airmass is drier and there will be more solar insolation. Thursday through Saturday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. We still expect high temperatures to generally stay just below excessive heat warning thresholds during the hottest days such as Friday and Saturday; this is supported by HIL data. By Friday, rain chances in the Phoenix area will struggle to exceed around 10 percent due to the drier air in place. Sunday into Monday...The strong upper high continues to build towards the west, with one high center eventually setting up over central CA. Flow around the high becomes more favorable from the east and monsoon moisture starts to return. As such thunderstorm chances start to rise and we will be seeing lower grade conditions with slight chances for afternoon convection over the lower central deserts, along with 20-30 percent chances across the higher terrain of southern Gila County. Temperatures will trend down slightly as humidity levels rise. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: A quiet start to the day with a mix of mid/high clouds moving through and light winds. Thunderstorms are possible again later this afternoon, first developing over the mountains north to east to south of the Phoenix area after 21 UTC. Outflow winds look likely, though hard to discern at this time if they`ll come from the northeast or the southeast (which will impact if any dust comes into play). Seems that some showers will develop later in the evening but low confidence on thunderstorm development/coverage to include in TAFs at this time. Showers could continue into the overnight hours. Southeast California/Southwest Arizona including KIPL and KBLH: Little aviation concerns through into Wednesday morning with few clouds and generally light winds. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Friday through Tuesday... Temperatures will trend back into an above normal range through the weekend as moisture levels thin and humidity values drop. Thunderstorm/wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain of eastern Arizona by Friday/Saturday. Consequently, afternoon humidity levels will drop about ten percent on average, into the 10-25 percent range this weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .SPOTTER INFORMATION STATEMENT... Spotter activation may be required for this evening. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...Vasquez/CB AVIATION...Iniguez FIRE WEATHER...Iniguez/MO
Area Forecast Discussion National Weather Service Phoenix AZ 507 AM MST TUE JUL 19 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next couple of days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures over the central deserts will stay near seasonal normals, with hotter conditions over the western deserts. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... Monsoon circulation remains entrenched across Arizona with an impressive plume of deep moisture spreading north from northwest Mexico and running north/northeastward across central and eastern Arizona, around the periphery of a very strong upper high centered over the south-central CONUS. This moist plume is easily seen in the current IR and vapor imagery loops. Steering flow across central/eastern AZ is mostly south to southeast, becoming more southwesterly as you move west and into the far southwest AZ deserts and over SE California. Orientation of this flow will keep most of the convection focused over south-central Arizona this week with very little expected into the SE California deserts. PWAT value at Phoenix from the last 00z raob was healthy at 1.64 inches and there was modest CAPE present in the sounding. 2 am surface dewpoints over the central deserts were elevated, ranging mostly from the upper 50s to middle 60s. Little if any shower activity was noted early this morning on radar, just a fair amount of debris cloudiness spreading north across the lower deserts. Overall, for the next couple of days, we are looking at a low to medium grade monsoon in terms of thunderstorm coverage. Most of the convection will be located over south-central Arizona with slight chances of mainly afternoon and evening storms becoming 30 percent or more over the higher terrain east of Phoenix. Steering flow is not especially strong as the 700-300mb mean winds typically run 10- 15 knots, and most of the disturbances that will rotate around the high and serve as "triggers" for convection are not especially dynamical. Latest vapor imagery loop does show a moderately organized inverted trof spinning over NW Mexico, poised to move into southeast Arizona this morning and across portions of south central and east-central AZ during the day, but it is forecast to weaken as it moves through the area so most of the desert POPs will stay below 25 percent this evening. High temperatures over the central deserts today and Wednesday will stay near seasonal normals due to the elevated humidity, with highs reaching or exceeding 110 over the western deserts where the airmass is drier and there will be more solar insolation. Thursday through Saturday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. We still expect high temperatures to generally stay just below excessive heat warning thresholds during the hottest days such as Friday and Saturday; this is supported by HIL data. By Friday, rain chances in the Phoenix area will struggle to exceed around 10 percent due to the drier air in place. Sunday into Monday...The strong upper high continues to build towards the west, with one high center eventually setting up over central CA. Flow around the high becomes more favorable from the east and monsoon moisture starts to return. As such thunderstorm chances start to rise and we will be seeing lower grade conditions with slight chances for afternoon convection over the lower central deserts, along with 20-30 percent chances across the higher terrain of southern Gila County. Temperatures will trend down slightly as humidity levels rise. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: A quiet start to the day with a mix of mid/high clouds moving through and light winds. Thunderstorms are possible again later this afternoon, first developing over the mountains north to east to south of the Phoenix area after 21 UTC. Outflow winds look likely, though hard to discern at this time if they`ll come from the northeast or the southeast (which will impact if any dust comes into play). Seems that some showers will develop later in the evening but low confidence on thunderstorm development/coverage to include in TAFs at this time. Showers could continue into the overnight hours. Southeast California/Southwest Arizona including KIPL and KBLH: Little aviation concerns through into Wednesday morning with few clouds and generally light winds. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Friday through Tuesday... Temperatures will trend back into an above normal range through the weekend as moisture levels thin and humidity values drop. Thunderstorm/wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain of eastern Arizona by Friday/Saturday. Consequently, afternoon humidity levels will drop about ten percent on average, into the 10-25 percent range this weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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...Iniguez FIRE WEATHER...Iniguez/MO
Area Forecast Discussion National Weather Service Phoenix AZ 325 AM MST TUE JUL 19 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next couple of days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures over the central deserts will stay neaer seasonal normals, with hotter conditions over the western deserts. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... Monsoon circulation remains entrenched across Arizona with an impressive plume of deep moisture spreading north from northwest Mexico and running north/northeastward across central and eastern Arizona, around the periphery of a very strong upper high centered over the south-central CONUS. This moist plume is easily seen in the current IR and vapor imagery loops. Steering flow across central/eastern AZ is mostly south to southeast, becoming more southwesterly as you move west and into the far southwest AZ deserts and over SE California. Orientation of this flow will keep most of the convection focused over south-central Arizona this week with very little expected into the SE California deserts. PWAT value at Phoenix from the last 00z raob was healthy at 1.64 inches and there was modest CAPE present in the sounding. 2 am surface dewpoints over the central deserts were elevated, ranging mostly from the upper 50s to middle 60s. Little if any shower activity was noted early this morning on radar, just a fair amount of debris cloudiness spreading north across the lower deserts. Overall, for the next couple of days, we are looking at a low to medium grade monsoon in terms of thunderstorm coverage. Most of the convection will be located over south-central Arizona with slight chances of mainly afternoon and evening storms becoming 30 percent or more over the higher terrain east of Phoenix. Steering flow is not especially strong as the 700-300mb mean winds typically run 10- 15 knots, and most of the disturbances that will rotate around the high and serve as "triggers" for convection are not especially dynamical. Latest vapor imagery loop does show a moderately organized inverted trof spinning over NW Mexico, poised to move into southeast Arizona this morning and across portions of south central and east-central AZ during the day, but it is forecast to weaken as it moves through the area so most of the desert POPs will stay below 25 percent this evening. High temperatures over the central deserts today and Wednesday will stay near seasonal normals due to the elevated humidity, with highs reaching or exceeding 110 over the western deserts where the airmass is drier and there will be more solar insolation. Thursday through Saturday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. We still expect high temperatures to generally stay just below excessive heat warning thresholds during the hottest days such as Friday and Saturday; this is supported by HIL data. By Friday, rain chances in the Phoenix area will struggle to exceed around 10 percent due to the drier air in place. Sunday into Monday...The strong upper high continues to build towards the west, with one high center eventually setting up over central CA. Flow around the high becomes more favorable from the east and monsoon moisture starts to return. As such thunderstorm chances start to rise and we will be seeing lower grade conditions with slight chances for afternoon convection over the lower central deserts, along with 20-30 percent chances across the higher terrain of southern Gila County. Temperatures will trend down slightly as humidity levels rise. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Outside of a slight chance for a shower/weak thunderstorm later tonight as debris clouds from storms over northern Mexico move over the region, the rest of tonight and Tuesday morning should be quiet, with winds mainly out of a southeasterly direction. There is a slight risk of more convective activity on Tue afternoon, but confidence is too low to include it in the tafs at this time. Winds on Tue afternoon to once again become westerly, with speeds mainly in the 8-10 knot range. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east over central AZ. Under mostly clear skies, sfc winds will favor a southerly direction at KIPL and from a southeasterly direction at KBLH. A few higher gusts will be possible at KBLH, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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...Percha/MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Tucson AZ 250 AM MST TUE JUL 19 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Isolated light showers were occurring early this morning east of Tucson. Expect these to continue thru sunrise as they move to the WNW. A weak MCV was over SW Graham county as of 2 am, but shouldn`t be a player today as it continue to move NNW. What could be a player later today is the inverted trof currently over Chihuahua MX. This feature is moving slowly to the NW toward the area. Hi-res models focusing best activity W of Tucson, with potential for blowing dust across Pinal county towards Phoenix, and Cochise county. PW values across the remain above normal for July so locally heavy rain a threat. Can`t rule out a severe storm or two. Highs today will be around normal. Scattered afternoon/evening storms Wednesday with highs slightly warmer than today. Starting Thursday and continuing through the upcoming weekend there will be a gradual decrease in shower and thunderstorm activity as sub-tropical ridge expands over the southern CONUS. Still hanging on to enough moisture to keep isolated to scattered storms in the forecast. Highs temperatures will be above normal through this period, maxing out on Friday. && .AVIATION...VALID THRU 20/12Z. Isolated showers through the early morning hours. Sct-bkn clouds at 6-9k ft agl and bkn-ovc clouds at 10-14k ft agl. Expect isolated to scattered showers and thunderstorms developing during the late morning and afternoon, persisting through the mid evening hours tonight. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Wednesday morning. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .CLIMATE...As the area heats up again, could see a few spots across the western deserts approach record highs later in the week. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Flagstaff AZ 242 AM MST TUE JUL 19 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION...A wide area of high pressure aloft remained centered over the Oklahoma/Kansas border. The models continue to promise little movement in this high pressure feature over the next few days. The position of the high is placing southerly flow over Arizona with not much change in the moisture profile through Thursday. Moving forward the distribution of showers and thunderstorms will remain very similar to Monday. Isolated heavy rain amounts of an inch or more and localized flooding will be possible. More generally, amounts in the trace to quarter inch category scattered about northern Arizona. From Friday onward...Models show the high pressure system centered over Oklahoma essentially splitting. The western portion of the high will migrate across Arizona and eventually become established over the western United States. If this pattern transpires it will open the door to an influx of drier air from the west. Forecast grids reflect a downturn in monsoon activity but moisture looks too entrenched for a complete shutdown in monsoon activity. We`ll keep you updated. && .AVIATION...For the 12Z package....Primarily VFR conditions are expected for the next 24 hours with bkn cigs aoa 14kft msl. til 17z isolated -shra / tsra possible, then btwn 17z-02z sct-nmrs SHRA/TSRA especially mountain areas. Brief visibility reductions and gusty winds possible near storms. Precipitation coverage decreasing after 02z Weds. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect another round of thunderstorms over the forecast area today and Wednesday. Storm motion will generally be from the south to north 5-10 mph. Thursday through Saturday...Scattered thunderstorms will persist across the area on Thursday. Drier air filtering into Arizona from the west will bring a decrease in thunderstorm activity on Friday and Saturday...with minimum RH`s dropping back into the teens to the north and west of Flagstaff. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...McCollum AVIATION...DL For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 934 PM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Showers and thunderstorms across southeast Arizona had diminished significantly in areal coverage late this evening. A few lingering showers and thunderstorms may continue to impact areas near Douglas through midnight, but not much activity expected thereafter. That said, updated the forecast to reflect this decreasing trend. Please refer to the additional sections in this product for more details. && .AVIATION...VALID THRU 20/06Z. A few lingering showers and thunderstorms can be expected tonight near the International Border. Otherwise, scattered to broken clouds at or above 10kft can be expected through Tuesday morning. Expect afternoon cloud build-ups Tuesday afternoon with isolated to scattered showers and thunderstorms developing through Tuesday evening. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA on Tuesday. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Tuesday afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .PREV DISCUSSION...Similar coverage of showers/tstms as today canbe expected Tuesday afternoon/evening as deep (albeit still light)sely flow aloft continues across the area. Scattered mainly afternoon/evening showers/tstms will also occur Wednesday. Thereafter, the 18/12Z GFS/ECMWF/CMC were similar versus their respective solutions in depicting a gradual daily decrease in showers/tstms to begin Thursday and continue into this weekend. Given the continued ely mid-level flow, precip-free conditions area- wide should not occur as earlier this month. However, moisture should remain sufficient for isolated to scattered afternoon and evening showers and thunderstorms Thursday through next Monday. High temps Tuesday will remain quite close to seasonal normals. A warming trend is forecast to begin Wednesday, and based on various 18/12Z guidance, high temps were increased several degs Thur-Sat versus the previous forecast. At this time, appears that Friday will be the hottest day although Saturday should be quite similar. A moderation in daytime temps should then occur Sunday and Monday. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Tucson AZ 934 PM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Showers and thunderstorms across southeast Arizona had diminished significantly in areal coverage late this evening. A few lingering showers and thunderstorms may continue to impact areas near Douglas through midnight, but not much activity expected thereafter. That said, updated the forecast to reflect this decreasing trend. Please refer to the additional sections in this product for more details. && .AVIATION...VALID THRU 20/06Z. A few lingering showers and thunderstorms can be expected tonight near the International Border. Otherwise, scattered to broken clouds at or above 10kft can be expected through Tuesday morning. Expect afternoon cloud build-ups Tuesday afternoon with isolated to scattered showers and thunderstorms developing through Tuesday evening. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA on Tuesday. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Tuesday afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .PREV DISCUSSION...Similar coverage of showers/tstms as today canbe expected Tuesday afternoon/evening as deep (albeit still light)sely flow aloft continues across the area. Scattered mainly afternoon/evening showers/tstms will also occur Wednesday. Thereafter, the 18/12Z GFS/ECMWF/CMC were similar versus their respective solutions in depicting a gradual daily decrease in showers/tstms to begin Thursday and continue into this weekend. Given the continued ely mid-level flow, precip-free conditions area- wide should not occur as earlier this month. However, moisture should remain sufficient for isolated to scattered afternoon and evening showers and thunderstorms Thursday through next Monday. High temps Tuesday will remain quite close to seasonal normals. A warming trend is forecast to begin Wednesday, and based on various 18/12Z guidance, high temps were increased several degs Thur-Sat versus the previous forecast. At this time, appears that Friday will be the hottest day although Saturday should be quite similar. A moderation in daytime temps should then occur Sunday and Monday. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Flagstaff AZ 902 PM MST MON JUL 18 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION... Thunderstorm activity appears to be trending downward this evening, with just a few isolated thunderstorms remaining. Will continue to monitor storms overnight, but the short-term forecast through morning currently looks in good shape. && .PREV DISCUSSION /250 PM MST/... The monsoon circulation has brought plentiful atmospheric moisture back into to the area...with precipitable water values now up to around 1.0" at KFLG. Instability has been somewhat limited...but scattered thunderstorms have formed with a few locally heavy showers, mainly over the higher terrain. Little change in the overall pattern is anticipated through Thursday with the strong ridge of high pressure in place over the Southern Plains and moist southerly flow over Arizona, providing the environment for daily thunderstorm activity across the forecast area. Storms will move a bit slower Tuesday through Thursday, leading to a somewhat greater chance for heavy rainfall accumulations. Friday through Sunday...forecast models continue to show the flattening of the ridge over the southern Rockies, and a decrease in thunderstorm activity Friday through Sunday as drier air filters in from the west. && .AVIATION...For the 00Z package...Only isolated showers and thunderstorms are expected for the remainder of tonight. Storms are likely to become more numerous again after 17Z Tuesday. Expect visibility reductions and gusty winds near stronger storms Tuesday. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Monsoon moisture is increasing across the area. Expect increasing showers and thunderstorm coverage. Gusty outflow winds are probable from any storms or showers, especially today. Storm motion today from south to north about 10 mph. Tuesday through Friday...Monsoon moisture to remain over northern Arizona, with shower and thunderstorm chances each day. Winds may become erratic and gusty near thunderstorms. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...KD/Bohlin AVIATION...KD FIRE WEATHER...BAK For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Phoenix AZ 835 PM MST MON JUL 18 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... A very activity late afternoon/evening for a few selected spots across south-central AZ. The combination of increased moisture levels through the column (KPSR balloon sounding PWAT 1.64 inches) and a weak disturbance that moved northward into southern AZ from northern Mexico triggered scattered showers and thunderstorms late this afternoon over Pima County. Outflow from these storms generated locally dense blowing dust over Pinal County, which contributed to a multi-vehicle accident that shut down I-10 at MP 214 late this afternoon. Outflows from these storms also triggered a few new storms over the greater Phoenix area early this evening. The strongest storm produced 63 mph winds and 0.34 inch of rain at Sky Harbor and localized damaging winds/flooding across central Phoenix. A second storm produced gusty winds and heavy winds over Queen Creek/San Tan Valley. At this hour, all remaining storms are either over Gila County or moved northward into Yavapai County. As far as the forecast for the rest of the night is concerned, although there is still a slight chance of an isolated shower or thunderstorm later tonight as debris cloudiness move northward from the remains of storms south of the international border, it should be quiet over the vast majority of our cwa. with inherited forecasts still looking good. && .PREVIOUS DISCUSSION... Tonight...Elevated amounts of monsoon moisture have now securely covered most of AZ. Athough thermodynamics are there for a few afternoon and evening showers and thunderstorms over our forecast area in south central AZ, this region seems to be in between upper level forcing mechanisms in currently working in northern and southern AZ. With the advent of a fairly strong and unseasonably cold Pacific trof moving into the Pacific northwest, a rather strong southwesterly Jetstream maximum has developed over portions of eastern Nevada and Utah. Accelerating winds aloft, from lighter winds in northern AZ into the Utah flow, has developed an area of upper level speed divergence and resulting convection. To our south near the Mexican border, the approaching massive inverted trof, clearly seen in water vapor imagery over the Mexican state of Chihuahua, is spreading leading edge upper level difluence. Our portions of south central AZ, including areas near Phoenix, are under a relatively stable upper level anti-cyclonic flow regime. Therefore a low grade monsoon forecast is expected for the remainder of this afternoon and evening, i.e. a slight chance of showers and thunderstorms. This forecast is excluding the possibility of copious amounts of convective debris clouds from southern AZ moving north toward Phoenix tonight, and causing the possibility of showers and thunderstorms similar to late Sunday night. So far model forecasts are minimizing this possibility. Tuesday...our office staff eyes are now transfixed on the massive inverted trof seen in water vapor imagery over north central Mexico. Models the past two days have resolved this feature very well at the 300/250 mb level, and latest model forecasts continue the trend of moving the feature bodily into southern AZ, although in a weakened form later Tuesday and Tuesday night. Current model forecast are minimizing the effect of this system in south central AZ, including nearby Phoenix and surrounding areas. From a fundamental stand point this is questionable. Strong differential heating and with weakness aloft normally results in an enhanced threat for storms that can last well into the evening hours. For now we will go with our instincts and raise precip probability a bit in south central AZ for late Tuesday and Tuesday night, with even a slight chance going into Wednesday morning. Wednesday...Monsoon moisture will be still be entrenched over the region. With mid/upper level disturbances should depart the area, resulting in another low grade monsoon forecast for Wednesday afternoon and evening. Thursday through Monday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Outside of a slight chance for a shower/weak thunderstorm later tonight as debris clouds from storms over northern Mexico move over the region, the rest of tonight and Tuesday morning should be quiet, with winds mainly out of a southeasterly direction. There is a slight risk of more convective activity on Tue afternoon, but confidence is too low to include it in the tafs at this time. Winds on Tue afternoon to once again become westerly, with speeds mainly in the 8-10 knot range. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east over central AZ. Under mostly clear skies, sfc winds will favor a southerly direction at KIPL and from a southeasterly direction at KBLH. A few higher gusts will be possible at KBLH, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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...Percha/Vasquez AVIATION...Percha/MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Tucson AZ 325 PM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into this weekend. Expect near normal daytime temperatures Tuesday followed by a pronounced warming trend later this week. && .DISCUSSION...Scattered to numerous showers and thunderstorms were occurring generally from the Tohono O`odham Nation southeastward into far southeast Pima County, Santa Cruz County, and extreme southwest Cochise County at this time. This area is within a northwest-to-southeast oriented axis of greatest instability as per SPC hourly mesoscale analysis of MUCAPE. Other isolated showers and thunderstorms were also occurring from southcentral Pinal County eastward into western Graham County. Storm motions were mainly northwest around 5-10 kts. IR satellite imagery depicted rapidly cooling cloud tops during the past hour with the showers/tstms across central Pima County. Have favored the Univ of AZ WRF-NAM for precip chances tonight. Thus, expect scattered to perhaps numerous showers/tstms across much of the area this evening. The main concern given relatively slow storm motions and precip water values of 1.25"-1.50" will be locally heavy rainfall. Have maintained a slight chance of showers/tstms late tonight for much of this forecast area. Have noted that the WRF- NAM depicts precip-free conditions late tonight into mid-morning Tuesday. Will defer to the evening shift to adjust PoPs perhaps downward as necessary. Similar coverage of showers/tstms is expected Tuesday afternoon/evening as deep (albeit still light) sely flow aloft continues across the area. Scattered mainly afternoon/evening showers/tstms will also occur Wednesday. Thereafter, the 18/12Z GFS/ECMWF/CMC were similar versus their respective solutions in depicting a gradual daily decrease in showers/tstms to begin Thursday and continue into this weekend. Given the continued ely mid-level flow, precip-free conditions area- wide should not occur as earlier this month. However, moisture should remain sufficient for isolated to scattered afternoon and evening showers and thunderstorms Thursday through next Monday. High temps Tuesday will remain quite close to seasonal normals. A warming trend is forecast to begin Wednesday, and based on various 18/12Z guidance, high temps were increased several degs Thur-Sat versus the previous forecast. At this time, appears that Friday will be the hottest day although Saturday should be quite similar. A moderation in daytime temps should then occur Sunday and Monday. && .AVIATION...VALID THRU 20/00Z. Isolated to scattered SHRA/TSRA will occur through the period, with the best chances during the afternoon and evening hours. Brief wind gusts of 35-40 kts and MVFR conditions may occur with the stronger TSRA. Outside of thunderstorm outflows, sfc wind will generally be less than 12 kts through Tuesday afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture will ensure daily chances of mainly afternoon and evening showers and thunderstorms this week. A slight decrease in rain chances will occur late in the week into the weekend along with an increase in daytime temperatures. Outside of gusty thunderstorm/outflow winds, expect typical diurnal 20-ft wind patterns each day at mainly less than 15 mph. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ DISCUSSION...Francis AVIATION/FIRE WEATHER...French Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion National Weather Service Flagstaff AZ 250 PM MST MON JUL 18 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION... The monsoon circulation has brought plentiful atmospheric moisture back into to the area...with precipitable water values now up to around 1.0" at KFLG. Instability has been somewhat limited...but scattered thunderstorms have formed with a few locally heavy showers, mainly over the higher terrain. Little change in the overall pattern is anticipated through Thursday with the strong ridge of high pressure in place over the Southern Plains and moist southerly flow over Arizona, providing the environment for daily thunderstorm activity across the forecast area. Storms will move a bit slower Tuesday through Thursday, leading to a somewhat greater chance for heavy rainfall accumulations. Friday through Sunday...forecast models continue to show the flattening of the ridge over the southern Rockies, and a decrease in thunderstorm activity Friday through Sunday as drier air filters in from the west. && .AVIATION...For the 00Z package...Sct shra/tsra expected to continue through 03z...with isold -shra/-tsra continuing overnight. Sct shra/tsra will redevelop after 18Z Tuesday...with storms most numerous over the higher terrain. Expect visibility reductions and gusty winds near storms. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect another round of thunderstorms over the forecast area Tuesday and Wednesday. Storm motion will generally be from the south to north 5-10 mph. Thursday through Saturday...Scattered thunderstorms will persist across the area on Thursday. Drier air filtering into Arizona from the west will bring a decrease in thunderstorm activity on Friday and Saturday...with minimum RH`s dropping back into the teens to the north and west of Flagstaff. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...Bohlin/BAK AVIATION...BAK FIRE WEATHER...BAK For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Phoenix AZ 200 PM MST MON JUL 18 2016 .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle, and temperatures will increase to above normal levels. && .DISCUSSION... Tonight...Elevated amounts of monsoon moisture have now securely covered most of AZ. Athough thermodynamics are there for a few afternoon and evening showers and thunderstorms over our forecast area in south central AZ, this region seems to be inbetween upper level forcing mechanisms in currently working in northern and southern AZ. With the advent of a fairly strong and unseasonably cold Pacific trof moving into the Pacific northwest, a rather strong southwesterly Jetstream maximum has developed over portions of eastern Nevada and Utah. Accelerating winds aloft, from lighter winds in northern AZ into the Utah flow, has developed an area of upper level speed divergence and resulting convection. To our south near the Mexican border, the approaching massive inverted trof, clearly seen in water vapor imagery over the Mexican state of Chihuahua, is spreading leading edge upper level difluence. Our portions of south central AZ, including areas near Phoenix, are under a relatively stable upper level anti-cyclonic flow regime. Therefore a low grade monsoon forecast is expected for the remainder of this afternoon and evening, i.e. a slight chance of showers and thunderstorms. This forecast is excluding the possibility of copious amounts of convective debris clouds from southern AZ moving north toward Phoenix tonight, and causing the possibility of showers and thunderstorms similar to late Sunday night. So far model forecasts are minimizing this possibility. Tuesday...our office staff eyes are now transfixed on the massive inverted trof seen in water vapor imagery over north central Mexico. Models the past two days have resolved this feature very well at the 300/250 mb level, and latest model forecasts continue the trend of moving the feature bodily into southern AZ, although in a weakened form later Tuesday and Tuesday night. Current model forecast are minimizing the effect of this system in south central AZ, including nearby Phoenix and surrounding areas. From a fundamental stand point this is questionable. Strong differential heating and with weakness aloft normally results in an enhanced threat for storms that can last well into the evening hours. For now we will go with our instincts and raise precip probability a bit in south central AZ for late Tuesday and Tuesday night, with even a slight chance going into Wednesday morning. Wednesday...Monsoon moisture will be still be entrenched over the region. With mid/upper level disturbances should depart the area, resulting in another low grade monsoon forecast for Wednesday afternoon and evening. Thursday through Monday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures would be much higher. Therefore afternoon desert temperatures are forecast to be above the 110 degree mark, but approaching 115 over the driest low humidity area of southeast CA. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Timing wind shifts and the potential for gusty outflow winds and localized blowing dust will be the primary aviation concerns through Tuesday morning. Some variability about a southerly wind direction is likely again this afternoon, though eventually should favor southwest by the evening. Thunderstorms forming over SE AZ should move north towards the Phoenix area late in the afternoon with gusty outflow winds preceding them. While the threat of a storm directly affecting an airport is better than Sunday, probabilities are still quite low with better chances of localized blowing dust and more widespread lofted dust and haze affecting slantwise visibilities. Only modest confidence exists timing outflow wind shifts into terminal sites between 02Z- 04Z. Otherwise, developing cigs in a 10K-15K ft range look likely from decaying storms to the south. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east into central AZ. Under mostly clear skies, sfc winds will favor a southerly direction, though will be more variable at KIPL after sunset. A few higher gusts will be possible, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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 FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Phoenix AZ 1230 PM MST MON JUL 18 2016 ...Updated Aviation and Fire Weather... .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle and temperatures will increase to above normal levels. && .DISCUSSION... Woohoo, the monsoon moisture boundary raced north past Phoenix over night and this morning was seen pushing up against the higher elevations of the Mogollon Rim. In other words the southern half of AZ was in the monsoon moisture soup, and noted by the relatively low afternoon convective trigger temperatures at a few locations. For example, based on this mornings weather balloon soundings, the convective trigger temp at Phoenix is 99 deg F, 97 at Tucson, and 92 deg at Globe/Miami (elevation 3-4 thsd ft msl). Even though the afternoon thermodynamics are there, the flow aloft has, and will remain anti-cyclonic and relatively stable today and tonight. In other words, the situation for today favors low topped afternoon convection, mostly in the mountains with possible outflows toward the deserts sparking an isolated desert storm, with convection dissipating quickly after dark, unless. Unless like last night, a surge of convective debris clouds from southeast AZ spread north, creating a well saturated mid level airmass that a gravity wave sparked a few showers and thunderstorms in the Phoenix area after midnight. The gravity wave conclusion was derived from high speed satellite imagery loops. Beyond today, our office staff eyes are now on the massive inverted trof seen in water vapor imagery over the north central Mexican state of Chihuahua. Models the past two days have resolved this feature very well at the 300/250 mb level, and is forecast to move into southeast AZ on Tuesday. For now the low grade monsoon forecast, meaning slight chance of showers and thunderstorms over the south central AZ deserts and mountains look ok for now. We will see how the new models handle Tuesdays inverted trof since model guidance will have incorporated the Chihuahua weather balloon sounding that is launched once per day at 12z. .Previous discussion...503 AM MST... The weather pattern has finally allowed the typical monsoonal circulation to return to the area as the combination of troffing along the Pacific northwest coast and upper ridging over the central CONUS has allowed southerly to southeasterly flow aloft to set up across Arizona. This favorable flow has advected considerable amounts of monsoon moisture into the lower deserts; the latest Phoenix raob had PWAT up to 1.44 inches and Tucson had 1.5 inches. Despite the ample moisture, much of it was at mid and upper levels through, limiting CAPE values. According to the 2 am SPC mesoanalysis graphic, MLCAPE of consequence (over 500 j/kg) was still over far SE Arizona with very low amounts in the central deserts. 2 am radar continued to show showers spreading into south central Arizona from the southeast and isolated thunderstorms are possible but any convection that develops should stay on the weak side into the morning hours. The convection is likely being aided by weak vort maxes rotating into Arizona around the large scale upper high. Should significant clouds and showers persist well into the morning or the early afternoon, instability will again be limited and storm activity tonight will suffer. For the next few days, operational models such as the GFS and ECMWF as well as GEFS data, call for the monsoonal circulation to remain in place with little change from day to day. Moisture will remain relatively plentiful, at least from a PWAT perspective as values upwards of 1.5 inches will stay over much of the lower deserts to the east of the lower Colorado river valley. Most of the CAPE of consequence however is advertised to stay pretty much from Maricopa county eastward each day, suggesting convective potential over the southwest deserts will be limited, and minimal as you move into the deserts of southeast California. Steering flow each day will stay south to southeast but not overly strong, with 700-300mb layer winds mostly between 10 and 15 knots each day. There will be occasional vort maxes/weak inverted trofs rotating around the main upper high and moving north across the central deserts but due to the small scale of these features, they will not be handled very well by the models and as such there will be low confidence in any particular one of these small scale features. As such we will keep a rather low grade monsoon forecast in place today through Wednesday with slight chances for mainly afternoon and evening showers and thunderstorms over the central lower deserts, with better chances over the higher terrain east of Phoenix. Skies will be partly to mostly cloudy much of the time, with the greatest amounts of sunshine likely during later morning through mid afternoon each day. High temperatures will stay near seasonal normals over south central Arizona today, then gradually creep up each day with Phoenix approaching 110 by Wednesday. It will be hotter over the far western deserts and over SE California as the airmass will be drier there. Thursday through Sunday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures be much higher. The driest areas Thursday through Sunday will be southeast California where afternoon temperatures at Imperial, El Centro, and Blythe will at the 114 degree mark. Ouch! Current forecasts will keep Phoenix at or above the 110 degree mark each day. At the moment it appears high temperature will stay below excessive heat warning thresholds but that could change depending upon just how dry we actually get, and how high the heights become over the lower deserts. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Timing wind shifts and the potential for gusty outflow winds and localized blowing dust will be the primary aviation concerns through Tuesday morning. Some variability about a southerly wind direction is likely again this afternoon, though eventually should favor southwest by the evening. Thunderstorms forming over SE AZ should move north towards the Phoenix area late in the afternoon with gusty outflow winds preceding them. While the threat of a storm directly affecting an airport is better than Sunday, probabilities are still quite low with better chances of localized blowing dust and more widespread lofted dust and haze affecting slantwise visibilities. Only modest confidence exists timing outflow wind shifts into terminal sites between 02Z- 04Z. Otherwise, developing cigs in a 10K-15K ft range look likely from decaying storms to the south. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east into central AZ. Under mostly clear skies, sfc winds will favor a southerly direction, though will be more variable at KIPL after sunset. A few higher gusts will be possible, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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/CB/Vasquez AVIATION...MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Phoenix AZ 1230 PM MST MON JUL 18 2016 ...Updated Aviation and Fire Weather... .SYNOPSIS... An increase in clouds and humidity can be expected during the next few days along with a slight chance of showers and thunderstorms, mainly east of the Lower Colorado River Valley. High temperatures will also be a bit cooler. Storm chances on the lower deserts will be slight, with better chances over the higher terrain and over southeast Arizona. During the latter half of the week, storm chances will dwindle and temperatures will increase to above normal levels. && .DISCUSSION... Woohoo, the monsoon moisture boundary raced north past Phoenix over night and this morning was seen pushing up against the higher elevations of the Mogollon Rim. In other words the southern half of AZ was in the monsoon moisture soup, and noted by the relatively low afternoon convective trigger temperatures at a few locations. For example, based on this mornings weather balloon soundings, the convective trigger temp at Phoenix is 99 deg F, 97 at Tucson, and 92 deg at Globe/Miami (elevation 3-4 thsd ft msl). Even though the afternoon thermodynamics are there, the flow aloft has, and will remain anti-cyclonic and relatively stable today and tonight. In other words, the situation for today favors low topped afternoon convection, mostly in the mountains with possible outflows toward the deserts sparking an isolated desert storm, with convection dissipating quickly after dark, unless. Unless like last night, a surge of convective debris clouds from southeast AZ spread north, creating a well saturated mid level airmass that a gravity wave sparked a few showers and thunderstorms in the Phoenix area after midnight. The gravity wave conclusion was derived from high speed satellite imagery loops. Beyond today, our office staff eyes are now on the massive inverted trof seen in water vapor imagery over the north central Mexican state of Chihuahua. Models the past two days have resolved this feature very well at the 300/250 mb level, and is forecast to move into southeast AZ on Tuesday. For now the low grade monsoon forecast, meaning slight chance of showers and thunderstorms over the south central AZ deserts and mountains look ok for now. We will see how the new models handle Tuesdays inverted trof since model guidance will have incorporated the Chihuahua weather balloon sounding that is launched once per day at 12z. .Previous discussion...503 AM MST... The weather pattern has finally allowed the typical monsoonal circulation to return to the area as the combination of troffing along the Pacific northwest coast and upper ridging over the central CONUS has allowed southerly to southeasterly flow aloft to set up across Arizona. This favorable flow has advected considerable amounts of monsoon moisture into the lower deserts; the latest Phoenix raob had PWAT up to 1.44 inches and Tucson had 1.5 inches. Despite the ample moisture, much of it was at mid and upper levels through, limiting CAPE values. According to the 2 am SPC mesoanalysis graphic, MLCAPE of consequence (over 500 j/kg) was still over far SE Arizona with very low amounts in the central deserts. 2 am radar continued to show showers spreading into south central Arizona from the southeast and isolated thunderstorms are possible but any convection that develops should stay on the weak side into the morning hours. The convection is likely being aided by weak vort maxes rotating into Arizona around the large scale upper high. Should significant clouds and showers persist well into the morning or the early afternoon, instability will again be limited and storm activity tonight will suffer. For the next few days, operational models such as the GFS and ECMWF as well as GEFS data, call for the monsoonal circulation to remain in place with little change from day to day. Moisture will remain relatively plentiful, at least from a PWAT perspective as values upwards of 1.5 inches will stay over much of the lower deserts to the east of the lower Colorado river valley. Most of the CAPE of consequence however is advertised to stay pretty much from Maricopa county eastward each day, suggesting convective potential over the southwest deserts will be limited, and minimal as you move into the deserts of southeast California. Steering flow each day will stay south to southeast but not overly strong, with 700-300mb layer winds mostly between 10 and 15 knots each day. There will be occasional vort maxes/weak inverted trofs rotating around the main upper high and moving north across the central deserts but due to the small scale of these features, they will not be handled very well by the models and as such there will be low confidence in any particular one of these small scale features. As such we will keep a rather low grade monsoon forecast in place today through Wednesday with slight chances for mainly afternoon and evening showers and thunderstorms over the central lower deserts, with better chances over the higher terrain east of Phoenix. Skies will be partly to mostly cloudy much of the time, with the greatest amounts of sunshine likely during later morning through mid afternoon each day. High temperatures will stay near seasonal normals over south central Arizona today, then gradually creep up each day with Phoenix approaching 110 by Wednesday. It will be hotter over the far western deserts and over SE California as the airmass will be drier there. Thursday through Sunday...monsoon moisture is forecast to thin a little as drier air from New Mexico and Colorado mix over the area. At the same time atmospheric height and thickness values increase dramatically over the region, and if it weren`t for remnant monsoon moisture, afternoon temperatures be much higher. The driest areas Thursday through Sunday will be southeast California where afternoon temperatures at Imperial, El Centro, and Blythe will at the 114 degree mark. Ouch! Current forecasts will keep Phoenix at or above the 110 degree mark each day. At the moment it appears high temperature will stay below excessive heat warning thresholds but that could change depending upon just how dry we actually get, and how high the heights become over the lower deserts. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Timing wind shifts and the potential for gusty outflow winds and localized blowing dust will be the primary aviation concerns through Tuesday morning. Some variability about a southerly wind direction is likely again this afternoon, though eventually should favor southwest by the evening. Thunderstorms forming over SE AZ should move north towards the Phoenix area late in the afternoon with gusty outflow winds preceding them. While the threat of a storm directly affecting an airport is better than Sunday, probabilities are still quite low with better chances of localized blowing dust and more widespread lofted dust and haze affecting slantwise visibilities. Only modest confidence exists timing outflow wind shifts into terminal sites between 02Z- 04Z. Otherwise, developing cigs in a 10K-15K ft range look likely from decaying storms to the south. Southeast California/Southwest Arizona including KIPL and KBLH: Minimal aviation concerns through Tuesday morning with storm activity remaining well east into central AZ. Under mostly clear skies, sfc winds will favor a southerly direction, though will be more variable at KIPL after sunset. A few higher gusts will be possible, but speeds should generally remain at or below 15kt. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday... Temperatures will trend back into an above normal range through the weekend as better quality moisture partially scours out.Thunderstorm and wetting rain chances dwindle substantially and become almost exclusively limited to higher terrain north and east of Phoenix. Consequently, afternoon humidity levels near a 15- 30 percent range during the middle of the week will fall closer to a 10-25 percent range into the weekend. Outside of isolated gusty winds surrounding any thunderstorms, directions will favor an upslope component in the afternoon with gustiness around terrain features and light overnight valley drainage. && .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/CB/Vasquez AVIATION...MO FIRE WEATHER...MO
Area Forecast Discussion National Weather Service Flagstaff AZ 1004 AM MST MON JUL 18 2016 .SYNOPSIS...Monsoon moisture will continue to bring a chance of showers and thundertorms through Thursday. Strong high pressure and drier air could result in a downturn in activity toward the end of the week. && .DISCUSSION...The subtropical ridge remains in a favorable position for moisture advection into Arizona through Friday. This translates into a moderate grade Monsoon with good chances for showers and thunderstorms each day. A few storms will develop in the overnight periods as a few upper level 200-300mb disturbances roll across the state. We sent out a quick update to increase shower chances this evening. Otherwise the forecast grids look good. && .PREV DISCUSSION /430 AM MST/... For today through Thursday...Due to the position of the high southerly flow and monsoon moisture will remain over northern Arizona. There should be some increase in moisture values over Sunday so shower and thunderstorm activity is expected to be more widespread. Instability and strength of any storms will be inhibited by general mid to high level cloud cover and the fact that the pattern doesn`t favor a decent push of low level moisture. In other words, precipitation amounts will mostly remain on the low to modest side. From Friday onward...Models show strong high pressure aloft building across Arizona into California. As a result, a drier air mass will filter in from the west. Low to no grade monsoon activity will be the result should this pattern materialize. && .AVIATION...For the 18Z package...sct-nmrs shra/tsra expected to develop this afternoon...continuing through 03z. Brief visibility reductions and gusty winds possible near storms. isold-sct -shra will continue aft 05Z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Monsoon moisture is increasing across the area. Expect increasing showers and thunderstorm coverage. Gusty outflow winds are probable from any storms or showers, especially today. Storm motion today from south to north about 10 mph. Tuesday through Friday...Monsoon moisture to remain over northern Arizona, with shower and thunderstorm chances each day. Winds may become erratic and gusty near thunderstorms. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...Bohlin/McCollum AVIATION...BAK FIRE WEATHER...DL For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion National Weather Service Tucson AZ 915 AM MST MON JUL 18 2016 .SYNOPSIS...Adequate moisture will provide scattered mainly afternoon and evening showers and thunderstorms through Wednesday. A slight decrease in daily coverage of showers and thunderstorms should then occur Thursday into the upcoming weekend. && .DISCUSSION...Isolated showers were occurring in western Pima County east of Ajo at this time. Otherwise, visible satellite imagery depicted mostly clear skies to partly cloudy skies from Tucson westward into western Pima County, and mostly clear skies across eastern sections. Ample moisture exists with dewpoints at lower elevations valid 16Z ranging from the mid 50s-lower 60s. 18/12Z KTWC sounding total precip water value of 1.50" was about 0.15" higher versus 24 hours ago. 18/12Z upper air plots depicted a broad ridge over the southern CONUS, with a 597 DM high centered over northern Mississippi. Meanwhile, a deep upper trough was over the Pacific NW, and deep easterly/southeasterly flow prevailed across southeast AZ. Given the greater extent of clearing skies especially across eastern sections versus Sunday morning, am inclined to expect that shower/ tstm development later this morning will occur across favored ranges such as the Chiricahua Mountains. The 18/14Z HRRR supports this notion, the showers/tstms should migrate wwd/nwwd this afternoon. Quick glance at the 18/12Z Univ. of AZ WRF-NAM suggests shower/tstm development may also occur further westward by 19Z, and favor locales from Nogales to Kitt Peak. Water vapor imagery depicts a cyclonic twist approaching this area from the southeast over central Sonora Mexico. A much larger cyclonic circulation was south of the Texas Big Bend, or far eastern Chihuahua Mexico. This system may have more influence for this forecast area Tuesday. At any rate and without a further recitation of various NWP models, expect scattered to perhaps numerous showers and thunderstorms this afternoon and evening. The lowest coverage should occur across western Pima County where only isolated showers/tstms are expected. The main concern this afternoon/evening will be the potential for locally heavy rainfall and brief strong wind gusts that may approach severe thresholds. A slight chance of showers/tstms continues for much of the area late tonight. High temps this afternoon will be quite similar to temps achieved Sunday, or perhaps generally a couple of degs lower depending upon location. May make some minor PoP adjustments for this afternoon/evening, but this will not affect the overall scenario. Please refer to the additional sections for further detail. && .AVIATION...VALID THRU 19/18Z. Isolated -SHRA mainly west of KTUS this morning, then scattered to numerous -TSRA/-SHRA this afternoon and evening. The favored locales will be from KTUS vicinity east and south to the New Mexico/ International borders. Forecast confidence is sufficiently high to include VCTS in the KDUG/KOLS TAFs this afternoon and evening. VCTS may be delayed at KTUS until after 20/00Z. Isolated -SHRA and possible -TSRA to continue late tonight/early Tuesday morning. Outside of thunderstorm outflows, surface wind will generally be variable in direction less than 12 kts thru the period. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Ample moisture and a favorable flow regime will maintain the daily cycle of scattered to perhaps numerous showers and thunderstorms through Wednesday. The bulk of this activity will occur during the afternoon and evening hours, and a slight chance of showers and thunderstorms will continue during the overnight hours. Thereafter, a gradual decrease in thunderstorm coverage is expected Thursday into the upcoming weekend. Outside of gusty thunderstorm outflows, 20-foot winds will be terrain driven and mostly less than 15 mph. && .PREV DISCUSSION /340 AM MST/...The 330 am radar imagery showed a distinctive circulation just west of Willcox, moving to the WNW. This MCV is associated with decaying MCS that formed over eastern Cochise county last night and produced areas of locally heavy rain. Douglas airport recorded 1.75" last night which set a daily record and also ranks as the 9th wettest July day on record. The MCV will be one of several features that will have an impact on todays forecast. Last nights MCS likely associated with a weak disturbance aloft that moved across northern Chihuahua MX. Water vapor was also showing an inverted trof approaching the Texas Big Bend this morning. A challenging forecast indeed for the next 12-18 hours. One would go with the idea that after the morning activity ends, that there will be lesser activity this afternoon due to debris cloud cover slowly diminishing which cuts down on heating thus being a few degrees cooler than Sunday. However both HRRR and 00z WRF NAM/GFS fire scattered storms this afternoon. Confidence is low will this forecast. Tomorrow likely will be another forecast challenge based on what will transpire today. Again confidence is low. Wednesday through next weekend will see a gradual decrease in moisture and thus areal coverage of storms as the sub-tropical high expands west into the eastern Pacific. Temperature warming up but likely not as hot as the GFS would suggest if going by low-level thickness numbers, which are higher than EC. Something to keep watch. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
317 PM CDT TUE JUL 19 2016 .SHORT TERM...(This Evening through Wednesday) Issued at 315 PM CDT TUE JUL 19 2016 Tonight through Wednesday... An Excessive Heat Warning continues through Saturday. High temperatures this afternoon are ranging from the middle to upper 90s. These hot temperatures coupled with dewpoints in the low to middle 70s are producing heat indices near 105 degrees. A complex of showers and thunderstorms are located across Southern Iowa and Northern Missouri. These will remain well east of forecast area. Otherwise upper level ridging continues across the area into Wednesday. Overnight lows will only "cool" into the middle 70s. Any thunderstorm chances will stay north of KS-NE border overnight as weak 500MB waves ride up and over the ridge, along a stall surface boundary. Temperatures will once again warm into the middle 90s to perhaps 100 degrees Wednesday afternoon. With mid 70 dewpoints remaining in place across much of the area, heat indices will soar to between 105 and 110 degrees during the afternoon and evening. .LONG TERM...(Wednesday Night through Tuesday) Issued at 315 PM CDT TUE JUL 19 2016 Tonight through Wednesday... An Excessive Heat Warning continues through Saturday. High temperatures this afternoon are ranging from the middle to upper 90s. These hot temperatures coupled with dewpoints in the low to middle 70s are producing heat indices near 105 degrees. A complex of showers and thunderstorms are located across Southern Iowa and Northern Missouri. These will remain well east of forecast area. Otherwise upper level ridging continues across the area into Wednesday. Overnight lows will only "cool" into the middle 70s. Any thunderstorm chances will stay north of KS-NE border overnight as weak 500MB waves ride up and over the ridge, along a stall surface boundary. Temperatures will once again warm into the middle 90s to perhaps 100 degrees Wednesday afternoon. With mid 70 dewpoints remaining in place across much of the area, heat indices will soar to between 105 and 110 degrees. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon) Issued at 1240 PM CDT TUE JUL 19 2016 VFR conditions are expected through the period. It looks like the better chances to reach LLWS criteria will be met in central Kansas so have kept them out of the TAFs for now. && .TOP Watches/Warnings/Advisories... Excessive Heat Warning until 7 PM CDT Saturday for KSZ008>012- 020>024-026-034>040-054>056-058-059. && $$ SHORT TERM...Baerg LONG TERM...Drake AVIATION...Heller
Area Forecast Discussion National Weather Service Goodland KS 213 PM MDT TUE JUL 19 2016 .SHORT TERM...(This afternoon through Wednesday) Issued at 147 PM MDT Tue Jul 19 2016 Early afternoon WV imagery and RAP upper level analysis show large scale ridge centered over the plains dominating the pattern across the US. Moist monsoonal plume is wrapping around the western extent of ridge into the Rockies. At the surface; low pressure is in place across eastern Colorado with a trough axis extending from northeast Colorado and across northern Kansas. Southwest flow is in place across much of our cwa. This afternoon-Wednesday: Mean storm track remains well west of our CWA with focus mainly in the central Rockies. A few weak shortwaves may try rotating towards the northwest part of our CWA. West and northwest parts of our CWA (near surface trough) also have better chance to see any thunderstorm activity due to weaker CAP and better instability. Further south and east in our CWA guidance shows a stronger CAP and eventually a significant decrease in CAPE as profiles warm and dry out during the afternoon periods. Strongest precip signal in guidance matches with these trends (northwest). A slightly stronger shortwave and shift in trough axis Wednesday (as indicated by some models) may support a few thunderstorms moving a little further east-southeast Wednesday afternoon (far northwest Kansas). Regarding temperatures/heat indices: Air mass aloft is only expected to become warmer and consensus shows highs 2-4F warmer than today. A major question on heat indices is Tds (which may mix lower in our west). As Tds decrease below 60 heat indices actually decrease from ambient temperature. Td recovery during the nighttime periods we will see overnight heat indices in the 68-76 range (minimum) which is quite mild for our CWA. There may be a few counties along western periphery of current heat advisory that remain below "exact" advisory criteria, but it is close enough and considering the very warm nighttime heat indices and several days in a row of the hot temperatures the decision was made to upgrade watch to heat advisory. Consecutive day requirement is not expected to be met for issuance of heat warning at this time, so advisory was favored. .LONG TERM...(Wednesday night through Tuesday) Issued at 213 PM MDT Tue Jul 19 2016 Overall, not much has changed in the long term. Hot temperatures are still the main story in the midterm while precipitation chances persist throughout the extended. Wednesday night through Friday, high pressure dominates the pattern. Above normal temperatures are anticipated with highs from the upper 90s to the low 100s on both Thursday and Friday, with Thursday being the hotter day for most locations. With dewpoint temperatures in the lower 60s, heat indices will be around 105 generally east of a line from Russell Springs, Kansas to Benkelman, Nebraska. This has warranted a heat headline for these locations. As mentioned in the short term discussion, the watch has been upgraded to a heat advisory (beginning Wednesday afternoon) and extended to cover through Friday afternoon. Expect somewhat dry conditions for the majority of the area, with only slight chances for convection each afternoon/evening as monsoonal moisture filters into the region along the western side of the ridge and disturbances pass through the upper flow. Friday night and the weekend, the ridge across the CONUS breaks down as a trough tracks from the Pacific Northwest and across the northern Plains, sending a cold front south. Will see more seasonal temperatures over the weekend. With a boundary nearby, expect thunderstorm chances through the weekend. Early next week, guidance differs on how the pattern develops. Consensus seems to be that the high pressure retreats to the west, bringing more of a west/northwest flow to the region. Some perturbations round the northern side of the high, traveling from the Rockies to the High Plains. This setup generates an opportunity for additional precipitation as the trough impacting the region during the weekend continues to push towards New England. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1124 AM MDT Tue Jul 19 2016 VFR conditions will continue through the TAF period. Gusty winds (20-25kt) from the south will slowly decrease this evening with loss of daytime heating. A strong LLJ will develop overnight and low level wind shear is expected late tonight through around sunrise. && .GLD Watches/Warnings/Advisories... KS...Heat Advisory from noon Wednesday to 7 PM CDT Friday for KSZ002>004-014>016-028-029. CO...NONE. NE...Heat Advisory from 11 AM MDT /noon CDT/ Wednesday to 6 PM MDT /7 PM CDT/ Friday for NEZ079>081. && $$ SHORT TERM...DR LONG TERM...JBH AVIATION...DR