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.
&&
$$
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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
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www.Facebook.com/nwsbayarea
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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.
&&
$$
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[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.
&&
$$
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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.
&&
$$
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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