Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 07/21/16
Area Forecast Discussion
National Weather Service Flagstaff AZ
330 PM MST WED JUL 20 2016
.SYNOPSIS...Showers and thunderstorms will remain in the forecast
through tomorrow. A drier westerly flow will decrease shower and
thunderstorm coverage across western Arizona Friday into the
weekend. Decent chances for thunderstorms will remain across
southern Navajo and Apache counties.
&&
.DISCUSSION...Widespread showers and thunderstorms continue across
northern Arizona this afternoon. Flash flooding was reported in
Oak Creek Canyon and in the Sedona area where flash flood warnings
were issued earlier this afternoon. Thunderstorms are just now
becoming more widespread across northern Navajo and Apache
Counties. While the flash flood threat has ended across much of
the area from central Coconino County to central Yavapai County, a
heavy rain and possible flood threat will continue elsewhere into
the evening hours. Look for storms to diminish after sunset,
though northern Navajo and Apache counties could see scattered
storms continue until around midnight or so.
Another round of showers and thunderstorms is expected across all
of northern Arizona tomorrow, beginning after 10AM MST. Storms
will initially develop in the higher terrain and slowly work their
way to the lower elevations. The main threat with storms tomorrow
will once again be very heavy rain due to the slow storm movement,
which could lead to localized flash flooding. The stronger storms
will also be capable of producing small hail and gusty winds.
Beginning Friday, drier air will start to move in from the west.
This will reduce storm chances across Coconino and Yavapai
Counties. For the weekend, the greatest storm chances will remain
over southern Navajo and Apache Counties where the highest
moisture remains.
&&
.AVIATION...For the 00Z package...Scattered to numerous showers
and thunderstorms will continue before diminishing around 02Z. A
few showers will develop overnight. Expect MVFR/IFR conditions in
heavy showers. Scattered to numerous thunderstorms will redevelop
around Thursday 18Z. Aviation discussion not updated for TAF
amendments.
&&
.FIRE WEATHER...An active wet Monsoon weather pattern will continue
on Thursday with drier air moving into western Arizona on Friday.
Drier air will reduce chances for showers and thunderstorms starting
on Friday afternoon.
Saturday through Monday...A drier low grade Monsoon pattern will
remain in the forecast. The highest chances for showers and storms
will be across the White Mountains Region.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...Flash Flood Watch until 8 PM
MST this evening FOR AZZ004>008-015- 037-038.
&&
$$
PUBLIC...Mottice
AVIATION...Bohlin
FIRE WEATHER...Bohlin
For Northern Arizona weather information visit
weather.gov/flagstaff
[top]
Area Forecast Discussion
National Weather Service Tucson AZ
112 PM MST WED JUL 20 2016
.SYNOPSIS...A steady decrease in convection will take place Thursday
into the weekend as the air mass over the region dries out. As a
result temperatures will climb to roughly 10 degrees warmer than
average Friday and Saturday. Monsoon moisture will then gradually
return Sunday onward for an overall increase in convection and a
slight cooling of afternoon temperatures.
&&
.DISCUSSION...Convection beginning to fire up pretty much as expected
to our south with the individual cells moving northward. Expect the
activity to increase over the next few hours, primarily south and
east of Tucson over higher terrain then spreading north. This all
should die off tonight earlier than it has lately with a lack of
significant forcing by that time.
A steady drying trend kicks in Thursday and especially Friday and
Saturday with PWs dropping to around an inch (a bit more south and a
bit less north) by Friday and Saturday. This will result in a
significant decrease in convection despite a wave sliding by just to
our south on Friday. Still carrying some precip chances mainly near
the international border where the highest amount of moisture will
exist. Afternoon high temperatures will climb through this period
peaking Friday and Saturday nearly 10 degrees above normal.
Sunday onward the models are suggesting the the upper level ridge
will shift slightly north allowing the easterlies to have a greater
influence on our area with an increase in moisture. This will help to
put us back into the daily rounds of afternoon/evening convection
especially if it ends up more like what the ECMWF is suggesting.
Will also see a decrease in afternoon high temperatures down a bit
closer to average next week.
&&
.AVIATION...VALID THRU 22/00Z.
Showers and thunderstorms are developing and will continue through
at least 03Z. Storms will be in the vicinity of the terminals,
especially KOLS, KTUS, and KSAD through about 01Z. Heavy rainfall,
gusty winds, and some areas of blowing dust will be the biggest
concerns. The expectation is that storms will begin to wane in
coverage after 03Z. Aviation discussion not updated for TAF
amendments.
&&
.FIRE WEATHER...Moisture in place will lead to the daily cycle of
mainly afternoon and evening isolated to scattered showers and
thunderstorms through Thursday. A drying trend will then lead to
reduced coverage of showers and thunderstorms Friday 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.
&&
.CLIMATE...Record high temperatures will be approached at a few spots
Thursday then most of the area will be at or near record highs
Friday and Saturday.
&&
.TWC Watches/Warnings/Advisories...
None.
&&
$$
PUBLIC...CERNIGLIA
AVIATION....CANTIN
FIRE WEATHER...CANTIN
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion
National Weather Service Flagstaff AZ
908 AM MST WED JUL 20 2016
.SYNOPSIS...Monsoon moisture will continue to keep showers and
thunderstorms in the forecast through at least Thursday. Friday
and into the weekend, a drier westerly flow will decrease shower
coverage across northwestern Arizona with decent chances for
thunderstorms across southern Navajo and Apache counties.
&&
.UPDATE...Clouds cleared out nicely in many locations this
morning, which will allow for ample surface heating. Look for
storms to develop between 10 and 11 AM MST, first across Yavapai
County and the Mogollon Rim, then spreading elsewhere across
northern Arizona. Slow storm motion today from south to north will
make for a flash flood threat. The stronger storms may also
contain small hail and gusty winds. The previous forecast looks
good and no significant changes were made.
&&
.PREV DISCUSSION /335 AM MST/...Deep southerly flow continues to
import plentiful moisture into the state this morning. A few light
showers and an occasional lightning strike were noted at 3 am from
around Williams into western Yavapai county and also southern
Apache county. Later this morning through the afternoon, expecting
another round of showers and thunderstorms, most numerous along
the higher terrain though some storms will push northward into
some lower terrain areas. Morning cloud cover could play a role in
where storms develop first and how strong they become. A mid and
upper level disturbance rotating northward across our region today
could also act to enhance storm coverage. The main threats today
will be locally heavy rainfall and flooding, with some hail and
gusty winds with stronger storms as well. Similar conditions are
expected Thursday, then a downward trend in moisture and storm
activity is forecast starting Friday in the northern part of the
state as the ridge axis sinks southward. However, due to the
forecast position of the ridge axis, a tight moisture gradient is
likely to set up across the area, with higher values of moisture
in the southern portion of the forecast area. So we kept a chance
of thunderstorms each day into early next week across the Mogollon
Rim and White Mountains with generally slight chances elsewhere.
There is still some uncertainty with where this moisture gradient
sets up, so watch for updated forecasts as the pattern evolves.
&&
.AVIATION...For the 18Z package...Scattered to numerous SHRA/TSRA
will redevelop between 18z-02z today. Brief MVFR/IFR conditions
in the stronger storms with locally heavy rain, small hail, and
gusty winds. Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Scattered to numerous showers and thunderstorms can
be expected today and again on Thursday. Storms will generally be
moving slowly from south to north.
Friday through Sunday...Drier air will start to filter in from the
west, which will bring a decrease in thunderstorm activity,
especially across the western portion of the state. Minimum RH
values will drop back into the teens generally from Flagstaff north.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...Mottice/JJ
AVIATION...Mottice
FIRE WEATHER...MCS
For Northern Arizona weather information visit
weather.gov/flagstaff
[top]
Area Forecast Discussion
National Weather Service Phoenix AZ
835 AM MST WED JUL 20 2016
.SYNOPSIS...
The dry weather across southeast California and southwest Arizona
will begin to spread eastward today, with chances for showers and
thunderstorms gradually dwindling across central Arizona. By Friday,
just low end chances will be confined to Arizona`s higher elevation
areas. In response, temperatures will warm up with excessive heat
conditions possible Friday. The weather pattern will undergo a
transition during the weekend and it is looking possible that a more
active pattern will become established next week.
&&
.DISCUSSION...
After looking at the regional weather balloon soundings we were
nearly bug-eyed to see the Arizona monsoon moisture boundary had
accelerated north overnight, to Grand Junction Colorado (GJT)? Just
curious to see if this was an early start to the southwest and south
central Colorado monsoon, but after perusing their upper air
sounding climatology (available at SPC), its happened before in mid
July. However todays GJT precip water value was climatologically
high and roughly in the 95th percentile for the day at 1.19 inches.
Monsoon moisture was drawn north with the help of an unseasonably
large scale trof struggling to work its way onto the Pacific
northwest coast.
Back to Arizona. Upper air data showed monsoon moisture was firmly
entrenched over most of AZ. Monsoon moisture was not excessive, but
not minimal either. And a couple of regional AZ differences with
regards to afternoon instability, gleaned from the sounding data,
showed convective trigger temperatures over south central were still
relatively low, 102 deg F in Phoenix and 91 in Globe/Miami. Highs
forecast for today are 108 and 97 degrees respectively. However in
southeast AZ, convective trigger temps were higher (again based on
their morning weather balloon sounding and just for relative
comparison), at 103 degree F. Tucsons high forecast for today is 102.
Therefore the regional difference by comparison was, it was a little
more stable in southeast AZ than in south central AZ. No worries
though because...
most important of all was the inverted trof (IT) that came out of
Chihuahua Mexico, north into southeast and south central AZ late
yesterday afternoon and night, had decayed significantly and was
seen working its way into northern AZ this morning. Earlier this
feature produced a few showers and thunderstorms in the Phoenix area
after midnight.
Despite appreciable monsoon moisture over AZ, most convective
activity should develop north of our forecast area, generally over
the Mogollon Rim and points north. The combination of a weak upper
level shortwave moving into northern AZ from southwest AZ, and
accelerating upper level winds (speed divergence) flowing into a
persistent Jetstream maximum in Utah (again resulting from the slow
moving Pacific Northwest trof) will help to divert most of todays
storms north. Therefore in south central AZ, including Phoenix, we
should be back to the low grade monsoon, meaning a slight chance of
afternoon and evening showers and thunderstorms. Ditto on Thursday.
Our forecast area portions of southeast CA and southwest AZ will
remain relatively dry and hot.
Current forecasts look ok for now. No updates planned.
.Previous Discussion...330 AM MST...
Few showers/thunderstorms moving through central Arizona early
this morning, associated with an upper level low who`s swirl can be
seen in water vapor and infrared satellite images. Operational HRRR
has not handled this feature and resultant precipitation well (just
catching on the past few runs) but the HRRR-X is exhibiting much
better performance. Based on current trends and HRRR-X forecast,
expect shower activity to move north of Maricopa County by around 13
UTC/6 AM MST.
For the rest of the day, mix of clouds in the morning should slow
warming across central Arizona while southwest Arizona and southeast
California enjoy fuller sunshine and quickly warming temperatures.
Preponderance of high-res convective allowing models (CAMs) for
today keep convection confined to the Rim area to our northwest and
sky islands to our south. It does seem possible, especially from the
NCAR Ensemble and SPC Storm-Scale of Opportunity Ensemble, that some
outflow boundaries will make their way into the Phoenix area again
this evening and perhaps touch of a few showers/storms. As usual,
chance of outflows exceed chance of rain. This seems reasonable given
a mixed boundary layer exceeding 700 mb but modest instability (mixed
layer CAPE of around 300 J/kg) and warrants continued low but non-
zero chances for precipitation. Further west...airmass remains too
dry and stable to support any convection.
Moisture really begins to thin out on Thursday as boundary layer
mixing ratio values during the afternoon drop to about 8 g/kg or less
across our entire CWA. Still a fleeting chance for precipitation as
it is possible some lingering moisture could boost instability, but
definitely on the downward trend.
And as usually is the case for our climate this time of year, if the
moisture decreases the temperatures take advantage. GFS/EC and GEFS
point to 850 mb temperatures climbing to around 32C for Friday, which
will yield high temperatures in the 110-115 range for the lower
elevations. Given modest remnant moisture and perhaps nocturnal
debris clouds, low temperatures at-or-above 90F seem quite likely
Friday and Saturday mornings. Given these high end temperatures, we
are issuing an Excessive Heat Watch for Friday focusing on the
Phoenix area where the urban infrastructure will boost overnight
lows. At this point it appears to be a marginal event, and confidence
is moderate at this time for excessive heat conditions to come to
fruition (hence issuance of a watch, which is not a guarantee by
itself of course but highlight the enhanced risk). There is certainly
plausible scenarios where excessive heat conditions persist into
Saturday (or even develop early on Thursday).
As the weekend progresses, the upper level (250 mb) flow pattern
will be adjusting. The heat dome parked over the central CONUS today
will be migrating southwest through Saturday (hence our heat event),
but will become suppressed and weaken Sunday as a trough moves across
the northern tier states. The southern edge of that trough appears as
if it will develop into a shear axis that extends from near southern
California into the Central Plains by the middle of next week. With a
strong upper level anti-cyclone to our northwest, the cloud-bearing flow
across Arizona will become much more easterly. Winds in the 700-500
mb layer will be 10-20 kt and propagation/Corfidi vectors will also
be near 20 kt, all with an easterly flow. At the same time, appears
the Sierra Madre will be lighting up with thunderstorms by next
week, which is a great pumping mechanism to transport moisture into
the Sonora Desert. This all points to the potential for a more active
thunderstorm period beginning Tuesday and, should the heart of the
500 mb anti-cyclone stay in a preferred location to our north,
continuing for well beyond our forecast period.
&&
.AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL:
Weather disturbance that led to overnight showers and isolated
thunderstorms continued to weaken and move north of the area early
this morning and currently expect morning precip to be of the shower
variety. Expect scattered to broken mid/high level debris cloud
decks into mid morning with most bases aoa 10k feet, with additional
clearing by late morning/early afternoon. Another round of
convection is possible this evening but due to the showers that
already occurred and a stabilized boundary layer, they may be
somewhat delayed and not especially vigorous if/when they occur.
Will not mention thunder later on in the upcoming TAFs due to low
confidence in formation/timing of any storms that do occur. Winds to
favor the east this morning, turning to the west by mid afternoon.
Should storms occur this evening, gusty outflow winds will likely
impact the terminals, probably favoring a south to southeast
direction. May see some blowing dust as well but visibilities at the
terminals should stay above 3SM.
Less convective activity is expected Thursday into Friday as monsoon
moisture steadily thins out.
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 day today.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Friday through Tuesday...Temperatures will trend back into a well
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
fall below 15 percent over the lower deserts through Saturday, and
then climb back into the 15-20 percent range Sunday into early next
week as thunderstorms chances slowly increase from east to west.
Higher RH values are expected across the higher terrain locations.
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...Excessive Heat Watch from late Thursday night through Friday
evening for AZZ023.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Vasquez/Iniguez
AVIATION...CB
FIRE WEATHER...Deemer/Iniguez/CB
Area Forecast Discussion
National Weather Service Flagstaff AZ
335 AM MST WED JUL 20 2016
.SYNOPSIS...Monsoon moisture will continue to keep showers and
thunderstorms in the forecast through at least Thursday. Friday
and into the weekend, a drier westerly flow will decrease shower
coverage across northwestern Arizona with decent chances for
thunderstorms across southern Navajo and Apache counties.
&&
.DISCUSSION...Deep southerly flow continues to import plentiful
moisture into the state this morning. A few light showers and an
occasional lightning strike were noted at 3 am from around
Williams into western Yavapai county and also southern Apache
county. Later this morning through the afternoon, expecting
another round of showers and thunderstorms, most numerous along
the higher terrain though some storms will push northward into
some lower terrain areas. Morning cloud cover could play a role in
where storms develop first and how strong they become. A mid and
upper level disturbance rotating northward across our region today
could also act to enhance storm coverage. The main threats today
will be locally heavy rainfall and flooding, with some hail and
gusty winds with stronger storms as well. Similar conditions are
expected Thursday, then a downward trend in moisture and storm
activity is forecast starting Friday in the northern part of the
state as the ridge axis sinks southward. However, due to the
forecast position of the ridge axis, a tight moisture gradient is
likely to set up across the area, with higher values of moisture
in the southern portion of the forecast area. So we kept a chance
of thunderstorms each day into early next week across the Mogollon
Rim and White Mountains with generally slight chances elsewhere.
There is still some uncertainty with where this moisture gradient
sets up, so watch for updated forecasts as the pattern evolves.
&&
.AVIATION...For the 12Z package...Isolated to scattered storms will
continue this morning. Look for scattered to numerous SHRA/TSRA to
redevelop between 17z-02z today. Brief MVFR/IFR conditions in the
stronger storms with locally heavy rain, small hail, and gusty
winds. Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Scattered to numerous showers and thunderstorms can
be expected today and again on Thursday. Storms will generally be
moving slowly from south to north.
Friday through Sunday...Drier air will start to filter in from the
west, which will bring a decrease in thunderstorm activity,
especially across the western portion of the state. Minimum RH
values will drop back into the teens generally from Flagstaff north.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...JJ
AVIATION...MCS
FIRE WEATHER...MCS
For Northern Arizona weather information visit
weather.gov/flagstaff
Area Forecast Discussion...Updated
National Weather Service Phoenix AZ
330 AM MST WED JUL 20 2016
.UPDATE...Updated aviation and fire weather discussions.
&&
.SYNOPSIS...
The dry weather across southeast California and southwest Arizona
will begin to spread eastward today, with chances for showers and
thunderstorms gradually dwindling across central Arizona. By Friday,
just low end chances will be confined to Arizona`s higher elevation
areas. In response, temperatures will warm up with excessive heat
conditions possible Friday. The weather pattern will undergo a
transition during the weekend and it is looking possible that a more
active pattern will become established next week.
&&
.DISCUSSION...
Few showers/thunderstorms moving through central Arizona early this
morning, associated with an upper level low who`s swirl can be seen
in water vapor and infrared satellite images. Operational HRRR has
not handled this feature and resultant precipitation well (just catching
on the past few runs) but the HRRR-X is exhibiting much better
performance. Based on current trends and HRRR-X forecast, expect
shower activity to move north of Maricopa County by around 13 UTC/6
AM MST.
For the rest of the day, mix of clouds in the morning should slow
warming across central Arizona while southwest Arizona and southeast
California enjoy fuller sunshine and quickly warming temperatures.
Preponderance of high-res convective allowing models (CAMs) for
today keep convection confined to the Rim area to our northwest and
sky islands to our south. It does seem possible, especially from the
NCAR Ensemble and SPC Storm-Scale of Opportunity Ensemble, that some
outflow boundaries will make their way into the Phoenix area again
this evening and perhaps touch of a few showers/storms. As usual,
chance of outflows exceed chance of rain. This seems reasonable given
a mixed boundary layer exceeding 700 mb but modest instability (mixed
layer CAPE of around 300 J/kg) and warrants continued low but non-
zero chances for precipitation. Further west...airmass remains too
dry and stable to support any convection.
Moisture really begins to thin out on Thursday as boundary layer
mixing ratio values during the afternoon drop to about 8 g/kg or less
across our entire CWA. Still a fleeting chance for precipitation as
it is possible some lingering moisture could boost instability, but
definitely on the downward trend.
And as usually is the case for our climate this time of year, if the
moisture decreases the temperatures take advantage. GFS/EC and GEFS
point to 850 mb temperatures climbing to around 32C for Friday, which
will yield high temperatures in the 110-115 range for the lower
elevations. Given modest remnant moisture and perhaps nocturnal
debris clouds, low temperatures at-or-above 90F seem quite likely
Friday and Saturday mornings. Given these high end temperatures, we
are issuing an Excessive Heat Watch for Friday focusing on the
Phoenix area where the urban infrastructure will boost overnight
lows. At this point it appears to be a marginal event, and confidence
is moderate at this time for excessive heat conditions to come to
fruition (hence issuance of a watch, which is not a guarantee by
itself of course but highlight the enhanced risk). There is certainly
plausible scenarios where excessive heat conditions persist into
Saturday (or even develop early on Thursday).
As the weekend progresses, the upper level (250 mb) flow pattern
will be adjusting. The heat dome parked over the central CONUS today
will be migrating southwest through Saturday (hence our heat event),
but will become suppressed and weaken Sunday as a trough moves across
the northern tier states. The southern edge of that trough appears as
if it will develop into a shear axis that extends from near southern
California into the Central Plains by the middle of next week. With a
strong upper level anti-cyclone to our northwest, the cloud-bearing flow
across Arizona will become much more easterly. Winds in the 700-500
mb layer will be 10-20 kt and propagation/Corfidi vectors will also
be near 20 kt, all with an easterly flow. At the same time, appears
the Sierra Madre will be lighting up with thunderstorms by next
week, which is a great pumping mechanism to transport moisture into
the Sonora Desert. This all points to the potential for a more active
thunderstorm period beginning Tuesday and, should the heart of the
500 mb anti-cyclone stay in a preferred location to our north,
continuing for well beyond our forecast period.
&&
.AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL:
Weather disturbance that led to overnight showers and isolated
thunderstorms continued to weaken and move north of the area early
this morning and currently expect morning precip to be of the shower
variety. Expect scattered to broken mid/high level debris cloud
decks into mid morning with most bases aoa 10k feet, with additional
clearing by late morning/early afternoon. Another round of
convection is possible this evening but due to the showers that
already occurred and a stabilized boundary layer, they may be
somewhat delayed and not especially vigorous if/when they occur.
Will not mention thunder later on in the upcoming TAFs due to low
confidence in formation/timing of any storms that do occur. Winds to
favor the east this morning, turning to the west by mid afternoon.
Should storms occur this evening, gusty outflow winds will likely
impact the terminals, probably favoring a south to southeast
direction. May see some blowing dust as well but visibilities at the
terminals should stay above 3SM.
Less convective activity is expected Thursday into Friday as monsoon
moisture steadily thins out.
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 day today.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Friday through Tuesday...Temperatures will trend back into a well
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
fall below 15 percent over the lower deserts through Saturday, and
then climb back into the 15-20 percent range Sunday into early next
week as thunderstorms chances slowly increase from east to west.
Higher RH values are expected across the higher terrain locations.
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...Excessive Heat Watch from late Thursday night through Friday
evening for AZZ023.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Iniguez
AVIATION...CB
FIRE WEATHER...Deemer/Iniguez/CB
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
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.
&&
$$
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 Phoenix AZ
940 PM MST WED JUL 20 2016
.SYNOPSIS...
The dry weather across southeast California and southwest Arizona
will begin to spread eastward, with the chances for showers and
thunderstorms gradually dwindling across central Arizona the next
several days. The combination of thinning moisture and a much warmer
atmosphere building into the region, will cause afternoon
temperatures to soar, especially Friday and Saturday. Slight cooling
is expected Sunday through next week, with minimal chances of
thunderstorm activity.
&&
.DISCUSSION...
The main cause of earlier activity over our forecast area was
outflow from numerous storms over Yavapai county which appeared to be
triggered by a small vort max. But now, storm activity across
Arizona and southeast California has pretty much dwindled down for
the night except for some very isolated activity over southeast
Arizona. Activity over Sonora has been minor (better just south over
Sinaloa) so not anticipating a lot of debris clouds later on. Latest
PSR sounding shows meager CAPE and substantial CIN (likewise for
earlier TWC sounding). HRRR supports this as well. One potential fly
in the ointment is what appears to be a subtle circulation evident in
water vapor imagery over southern AZ but with the thermodynamic
conditions previously mentioned, anticipate "quiet" conditions
overnight.
Latest models continue to indicate a downtrend of moisture Thu and
Fri as high pressure centered over the central states shifts
southwestward and a secondary anticyclone becomes established over
and near southern CA. This means even warmer temperatures. We may
flirt with Excessive Heat Criteria in portions of Southeast CA on
Thursday but for now, the Watch remains in effect for Fri and Sat.
&&
.PREVIOUS DISCUSSION...Issued 225 pm MST/PDT...
Upper air data showed monsoon moisture was firmly entrenched over
most of AZ. Monsoon moisture was not excessive, but not minimal
either. For the remainder of the afternoon and evening, most showers
and thunderstorms will be confined to northern and southeast AZ
mostly outside our forecast area. Therefore a slight chance of
afternoon and evening thunderstorms are still expected the remainder
of today and this evening.
Thursday...again, with the absence of any notable upper level
features, thermodynamics will likely control the possibility of late
afternoon and evening convective activity. Another low grade monsoon
pattern will continue in south central AZ, i.e. a slight chance of
late afternoon and evening thunderstorms. Southeast CA and southwest
AZ will remain relatively dry and hot.
Friday and Saturday...latest model forecasts of thinning moisture in
conjunction with increasing atmospheric thickness values, and much
warmer 850 mb temperatures, are helping us bring the magnitude of
warming into focus for Friday and Saturday. Model guidance, and our
experience of dealing with how the surface airmass reacts to a
decrease in humidity, has us concerned about dangerous heat. Our new
Heat Impact Level guidance tools are putting the entire CWA into a
marginal Excessive Heat Event by 1 or 2 degrees. Therefore an
Excessive Heat Watch has been posed for most of our forecast area
except for Joshua Tree National Park CA zone 30.
Sunday through Thursday...afternoon temperatures are forecast to
remain above normal...in the 110-112 degree range, but below
excessive heat criteria. A low grade monsoon is also expected with
a slight chance of showers and thunderstorms over the south central
AZ deserts and mountains, including Phoenix. Southeast CA and
southwest AZ will remain dry.
&&
.AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL:
Storm activity is no longer expected over the metro area tonight.
Surface winds the rest of this evening will trend from northerly to
northeasterly and easterly. Cloudiness the rest of the night will be
mainly cirrus (AOA FL200). Less convective activity is expected
over Arizona on Thursday and thus lower likelihood of outflow winds
from distant storms reaching metro airfields.
Southeast California/Southwest Arizona including KIPL and KBLH:
Northeast and east winds over southwest AZ and the lower Colorado
River Valley will weaken during the rest of the evening and trend
toward southerly overnight (especially Lower Colorado River Valley).
Further west, southeast winds will prevail except for temporary west
winds for the Imperial Valley between about 05Z-11Z. Clear skies
except for minor cirrus.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Saturday through Wednesday...Temperatures are climbing to well above
normal territory through the weekend as moisture levels thin and
humidity values drop. Chances for thunderstorms/wetting rain dwindle
and become almost limited to the higher terrain of eastern Arizona
by Friday and Saturday. Consequently, afternoon humidity levels will
fall below 15 percent over the weekend before increasing to the 15-
20 percent range beginning Sunday and into next week as thunderstorm
chances slowly increase from east to west. Higher humidity values
can be expected in the higher terrain locations. Outside of
thunderstorms, winds will be typical with some afternoon gustiness.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Watch from late Thursday night through Saturday
evening for AZZ020>023-025>028.
CA...Excessive Heat Watch from late Thursday night through Saturday
evening for CAZ031>033.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...AJ
PREVIOUS DISCUSSION...Vasquez
AVIATION...AJ
FIRE WEATHER...Deemer
AREA FORECAST DISCUSSION...UPDATED
NWS LOS ANGELES/OXNARD CA
1012 PM PDT WED JUL 20 2016
.SYNOPSIS...
High pressure over the Southern Plains will expand west and bring
a heatwave for late this week. Fair skies are expected with a
limited marine layer coverage. Gusty northerly winds are possible
across the portions of the area, especially during the night and
morning hours Thursday through Saturday. A cooling trend is
possible early next week as the high weakens and onshore flow
strengthens.
&&
.UPDATE...
Southwest flow aloft and onshore flow continues to weaken this
evening as high pressure aloft over the Southern Plains continues
to strengthen and expand westward. A thin marine layer remains
over the area this evening. KLAX AMDAR soundings indicate a marine
layer depth around 700 feet deep and deepening slightly to near
1000 feet north of Point Conception. A warming trend is forecast
over the next several days with dangerous heat expected late this
week. Marine layer stratus will pretty much be non-existent into
Saturday.
The latest satellite imagery indicates mostly cloud free skies
over the area this evening, except for a few middle and high-
level clouds streaming north from Tropical Storm Estelle. Some
stratus clouds could reform tonight across the coastal sections,
but highest confidence is placed with stratus for the Central
Coast. Any stratus that forms will likely be in the form of dense
fog.
Gusty Sundowner winds with gusts to 35 mph have developed west of
Goleta this evening, but winds will likely strengthen the next
couple night and become more widespread. A Wind Advisory may need
to reissued or extended for Southern Santa Barbara County and
expanded to the Interstate 5 Corridor on Thursday night and into
Friday morning.
&&
.PREV DISCUSSION...
SHORT TERM...The low over the Pacific Northwest that has been
parked there for the last few days is still on track to open up
and move into Canada tomorrow. This will allow the ridge over
Texas to expand and envelope the entire southern half of the
United States with the core shifting directly over southern
California by Friday and Saturday. This change will further weaken
west-to-east pressure gradients and strengthen north-to-south
gradients each day...peaking Friday night. Northwest flow over SBA
County will increase each night as a result...and confidence is
fairly high in the overall picture as the NAM has been doing very
well on the pressure gradient forecast so far. Will issue a low-
end wind advisory (gusts to 35 mph) tonight...with a solid
advisory likely on Thursday night (gusts to 50 mph). Friday night
is looking concerning as the SBA-SMX gradient should dip below
-5.0 mb and SBA-BFL drops to near -3.0 mb...which could translate
to gusts approaching warning levels especially near the Montecito
Hills. These winds on Friday could push temperatures over 100
degrees in some south coast locations with the NAM showing 950mb
temps incredibly over 35C. The I-5 Corridor will also get windy
starting Thursday night and a low-end advisory may be needed
during the Friday night peak. The winds on Saturday look gusty but
weaker and shorter lived than Friday. These winds and very dry air
will also lead to fire weather concerns especially Friday night.
These winds will keep most of the area stratus free through
Saturday...and pace the warming trend higher over SBA and Ventura
Counties. The Central Coast might be the one exception from
either radiation dense fog forming each morning or the narrow band
of stratus off Monterey working down the coast. Localized offshore
flow will increase each morning however which may also keep it all
clear.
With the winds...stratus-lite skies...and building ridge...the
heat is locked in. By Friday...highs in the 95 to 105 range will
be common away from the coast...with coastal areas at the mercy of
the ebbs and flows of what should be a very shallow marine layer.
Overnight low temperatures will also be on the rise...with above
normal lows by Friday morning generally in the 65 to 75 range.
Although the airmass will be dry...these types of temperatures
will bring serious concerns to sensitive populations and those
working outdoors. Decided to put out an Excessive Heat Watch for
the LA and Ventura mountains Friday through Sunday thanks to
their lower criteria. Also put one out for the valleys
but a little less certain that those areas will reach the true
heat index criteria of 105...although it will nevertheless be
hot. Other than Sandberg in the mountains and Santa Barbara (see
above)...all records looks safe thanks to the extreme heat that
occurred at this time 10 years ago when Woodland Hills hit an area
all-time record of 119 on July 22 2006.
The position of the high has set up a window for southerly flow
aloft through Thursday. Although a few high clouds will stream
in, the air below 15,000 feet will remain so dry that convection
chances still look minimal to none.
LONG TERM...The ridge of high pressure should split into two
cores on Sunday with one over New Mexico and one about 600 miles
west of Los Angeles. This subtle pattern change should completely
squash the strong northwest flow over the region by Sunday morning
which will allow a strong coastal eddy to form and onshore
pressure gradients to strengthen. While interior areas will remain
hot Sunday through Tuesday...coastal and valley areas should see a
healthy cool down with increasing marine layer influence. How the
stratus behaves is a tough call but increasing coverage Sunday and
Monday seems like a safe bet.
The middle-to-end of next week is looking hot once more as both
the GFS and ECMWF (with good agreement in the ensembles) show the
core of the ridge settling into Nevada by Wednesday and
strengthening. This is also a textbook monsoonal position for the
high and upper level clouds and convection possibilities may be on
the rise.
&&
.AVIATION...21/0510Z.
At 00Z, the marine layer depth was around 700 feet deep. The top
of the inversion was around 2500 feet with a temperature near 28
degrees Celsius.
VFR conditions are expected throughout the period, except for a
chance of LIFR to IFR conditions at Central Coast and Los Angeles
County Coast Terminals between 08Z and 16Z.
KLAX...VFR conditions are expected throughout the period, except
for a 20 percent chance of IFR conditions between 12Z and 16Z.
KBUR...High confidence in VFR conditions throughout the period.
&&
.MARINE...20/900 PM.
For the Outer Waters, the current Small Craft Advisory has been
extended through Thursday night and will likely need to be
extended through the weekend by future shifts. For Friday and
Saturday, there is a chance that the northwest gusts could reach
gale levels and a Gale Watch may be needed.
For the Inner Waters, moderate to high confidence in the current
forecast. For the waters north of Point Sal, gusty northwest winds
are expected each afternoon/evening through Saturday. A Small
Craft Advisory has been issued for this afternoon/evening and will
likely be needed for the same time periods Thursday through
Saturday. For the waters south of Point Conception, winds are
generally expected to remain below Small Craft Advisory levels
through the weekend. The only exception will be the western half
of the Santa Barbara Channel where there is a 60 percent chance
of gusts reaching Small Craft Advisory levels in the
afternoon/evening hours Thursday and Friday.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 3 AM PDT Thursday For zone 39. (See LAXNPWLOX).
Excessive Heat Watch in effect from Friday morning through
Saturday evening For zones 44>46-53-54-547-548. (See LAXNPWLOX).
Fire Weather Watch in effect from Friday afternoon through
late Friday night For zones 239-252. (See LAXRFWLOX).
Fire Weather Watch in effect from Friday afternoon through
Friday evening For zones 253-254. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect until 9 PM PDT Thursday For
zone 645. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 AM PDT Friday For
zones 670-673-676. (See LAXMWWLOX).
&&
$$
PUBLIC...Hall
AVIATION...Hall
MARINE...Hall
SYNOPSIS...Seto/Hall
weather.gov/losangeles
[top]
Area Forecast Discussion
National Weather Service Phoenix AZ
940 PM MST WED JUL 20 2016
.SYNOPSIS...
The dry weather across southeast California and southwest Arizona
will begin to spread eastward, with the chances for showers and
thunderstorms gradually dwindling across central Arizona the next
several days. The combination of thinning moisture and a much warmer
atmosphere building into the region, will cause afternoon
temperatures to soar, especially Friday and Saturday. Slight cooling
is expected Sunday through next week, with minimal chances of
thunderstorm activity.
&&
.DISCUSSION...
The main cause of earlier activity over our forecast area was
outflow from numerous storms over Yavapai county which appeared to be
triggered by a small vort max. But now, storm activity across
Arizona and southeast California has pretty much dwindled down for
the night except for some very isolated activity over southeast
Arizona. Activity over Sonora has been minor (better just south over
Sinaloa) so not anticipating a lot of debris clouds later on. Latest
PSR sounding shows meager CAPE and substantial CIN (likewise for
earlier TWC sounding). HRRR supports this as well. One potential fly
in the ointment is what appears to be a subtle circulation evident in
water vapor imagery over southern AZ but with the thermodynamic
conditions previously mentioned, anticipate "quiet" conditions
overnight.
Latest models continue to indicate a downtrend of moisture Thu and
Fri as high pressure centered over the central states shifts
southwestward and a secondary anticyclone becomes established over
and near southern CA. This means even warmer temperatures. We may
flirt with Excessive Heat Criteria in portions of Southeast CA on
Thursday but for now, the Watch remains in effect for Fri and Sat.
&&
.PREVIOUS DISCUSSION...Issued 225 pm MST/PDT...
Upper air data showed monsoon moisture was firmly entrenched over
most of AZ. Monsoon moisture was not excessive, but not minimal
either. For the remainder of the afternoon and evening, most showers
and thunderstorms will be confined to northern and southeast AZ
mostly outside our forecast area. Therefore a slight chance of
afternoon and evening thunderstorms are still expected the remainder
of today and this evening.
Thursday...again, with the absence of any notable upper level
features, thermodynamics will likely control the possibility of late
afternoon and evening convective activity. Another low grade monsoon
pattern will continue in south central AZ, i.e. a slight chance of
late afternoon and evening thunderstorms. Southeast CA and southwest
AZ will remain relatively dry and hot.
Friday and Saturday...latest model forecasts of thinning moisture in
conjunction with increasing atmospheric thickness values, and much
warmer 850 mb temperatures, are helping us bring the magnitude of
warming into focus for Friday and Saturday. Model guidance, and our
experience of dealing with how the surface airmass reacts to a
decrease in humidity, has us concerned about dangerous heat. Our new
Heat Impact Level guidance tools are putting the entire CWA into a
marginal Excessive Heat Event by 1 or 2 degrees. Therefore an
Excessive Heat Watch has been posed for most of our forecast area
except for Joshua Tree National Park CA zone 30.
Sunday through Thursday...afternoon temperatures are forecast to
remain above normal...in the 110-112 degree range, but below
excessive heat criteria. A low grade monsoon is also expected with
a slight chance of showers and thunderstorms over the south central
AZ deserts and mountains, including Phoenix. Southeast CA and
southwest AZ will remain dry.
&&
.AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL:
Storm activity is no longer expected over the metro area tonight.
Surface winds the rest of this evening will trend from northerly to
northeasterly and easterly. Cloudiness the rest of the night will be
mainly cirrus (AOA FL200). Less convective activity is expected
over Arizona on Thursday and thus lower likelihood of outflow winds
from distant storms reaching metro airfields.
Southeast California/Southwest Arizona including KIPL and KBLH:
Northeast and east winds over southwest AZ and the lower Colorado
River Valley will weaken during the rest of the evening and trend
toward southerly overnight (especially Lower Colorado River Valley).
Further west, southeast winds will prevail except for temporary west
winds for the Imperial Valley between about 05Z-11Z. Clear skies
except for minor cirrus.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Saturday through Wednesday...Temperatures are climbing to well above
normal territory through the weekend as moisture levels thin and
humidity values drop. Chances for thunderstorms/wetting rain dwindle
and become almost limited to the higher terrain of eastern Arizona
by Friday and Saturday. Consequently, afternoon humidity levels will
fall below 15 percent over the weekend before increasing to the 15-
20 percent range beginning Sunday and into next week as thunderstorm
chances slowly increase from east to west. Higher humidity values
can be expected in the higher terrain locations. Outside of
thunderstorms, winds will be typical with some afternoon gustiness.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Watch from late Thursday night through Saturday
evening for AZZ020>023-025>028.
CA...Excessive Heat Watch from late Thursday night through Saturday
evening for CAZ031>033.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...AJ
PREVIOUS DISCUSSION...Vasquez
AVIATION...AJ
FIRE WEATHER...Deemer
Area Forecast Discussion
National Weather Service Tucson AZ
845 AM MST THU JUL 21 2016
.SYNOPSIS...A decrease in thunderstorms activity will occur over
the next several days as the air mass over the region dries out.
As a result temperatures will climb to roughly 10 degrees warmer
than average Friday and Saturday with record high temperatures
possible both days. Monsoon moisture will then gradually return
Sunday onward for an overall increase in convection and a slight
cooling of afternoon temperatures.
&&
.DISCUSSION...Drying has not started yet in any significant fashion
thus we still have nearly 1.5" PW on the morning sounding with a
little less to the east. Also the sounding has a slightly better
thermal profile compared to yesterday with a touch of cooling aloft
an warming below. The upshot, the atmosphere is ready with plenty of
sunshine to help out. Not much if anything noticeable out there to
help focus or provide extra lift so this will primarily be another
diurnal, terrain driven day much like yesterday. The latest runs of
the HRRR and UA WRF NAM agree so would expect convection to begin to
develop 18-19z over the higher terrain to the south and southeast
then move to the NNW through the day, much like yesterday.
More noticeable drying to take place from the east tomorrow and
Saturday and that is apparent on this mornings water vapor imagery.
This should provide for a reduction in the convection across the
area while also lifting afternoon temperatures to roughly 10 degrees
warmer than average, which means hot but not quite heat advisory
hot. That said we will likely see a few record highs fall over the
next few days.
The moisture will begin to return to the region later Sunday into
next week which will enhance the convection threat and put us back
into a somewhat active pattern once again. Thankfully the extra
clouds and scattered showers will trim a few degrees of the high
temperatures next week. Cerniglia
&&
.AVIATION...VALID THRU 22/18.
Sct-bkn clouds at 6-9k ft agl and bkn-ovc clouds at 10-15k ft agl
developing with isolated to scattered showers and T-storms today
into this evening. Once again, heavy rainfall, gusty winds, and some
areas of blowing dust will be the biggest concerns. The showers and
storms will diminish aft 22/04Z. Aviation discussion not updated for
TAF amendments.
&&
.FIRE WEATHER...Moisture in place will lead to the showers and
thunderstorms again today, developing after 11 am over higher
terrain and drifting to the north. A drying trend will then lead to
reduced coverage of showers and thunderstorms Friday into this
weekend. Moisture will increase again early next week resulting in
an uptick in convection. Outside of gusty thunderstorm outflows, 20-
foot winds will be terrain driven and mostly less than 15 mph.
&&
.CLIMATE...Record high temperatures will be approached at a few spots
today then most of the area will be at or near record highs Friday
and Saturday.
&&
.TWC Watches/Warnings/Advisories...None.
&&
$$
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion
National Weather Service Flagstaff AZ
338 PM MST THU JUL 21 2016
.SYNOPSIS...Scattered showers and storms are expected again Friday
afternoon across much of northern Arizona. Storm coverage will
decrease significantly this weekend as drier air moves in from
the west. Moisture and storm chances could increase again next
week, especially along and south of the Mogollon Rim.
&&
.DISCUSSION...Scattered showers and storms are ongoing late this
afternoon across northern Arizona. The overall intensity is much
weaker than what we have seen the last couple of days. Storm
coverage will decrease after sunset, with some showers and storms
lingering into the overnight hours.
Scattered storms are expected again Friday afternoon. Instability
should be a little greater, so the overall intensity of the
storms may be stronger than what we have seen today. Storms will
be moving more to the east as opposed to the north like we have
seen the past few days. The main threat with any storm will be
heavy rain,.
Saturday and Sunday...Drier air moves in from the west, greatly
reducing storm chances across Yavapai and Coconino Counties.
Southern Navajo and Apache Counties will see the greatest chance
of continuing thunderstorms.
Next week...Models continue to show the ridge lifting back to the
north early next week, which would allow for moisture to make its
way back into northern Arizona. If this happens, thunderstorm
chances would become more widespread, especially from the Mogollon
Rim south.
&&
.AVIATION...For the 00Z package...Expect isolated to scattered
showers and thunderstorms until sunset then diminishing to a slight
chance overnight. On Friday...Look for another round of isolated to
scattered showers and storms. Conditions will remain primarily VFR
but local MVFR in heavy rain is possible in stronger storms.
Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...On Friday and Saturday...a drier westerly flow will
begin a downward trend in thunderstorm activity over much of the
area. The exception...scattered storm activity will continue over
the region of the White Mountains.
Sunday through Tuesday...Expect lower thunderstorm chances and
decreased afternoon humidity on Sunday. Moisture and the chance for
storms may increase on Monday and Tuesday from the Mogollon Rim
south.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...Mottice
AVIATION...McCollum
FIRE WEATHER...McCollum
For Northern Arizona weather information visit
weather.gov/flagstaff
[top]
Area Forecast Discussion
National Weather Service Phoenix AZ
146 PM MST THU JUL 21 2016
.SYNOPSIS...
The dry weather across southeast California and southwest Arizona
will begin to spread eastward, with the chances for showers and
thunderstorms gradually dwindling across central Arizona the next
several days. The combination of thinning moisture and a much warmer
atmosphere building into the region, will cause afternoon
temperatures to soar, especially Friday and Saturday. Temperatures
will cool a bit Sunday, but still remain fairly hot into next week,
as thunderstorm chances return to the forecast.
&&
.DISCUSSION...
Latest satellite imagery shows agitated CU developing across the
higher peaks of Arizona with the strongest storms across the White
Mountains and the Mogollon Rim. Some recent AMDAR flights out of KPHX
show that the mid-level flow continues to veer to the southwest,
which explains the general cloud movement to the north and northeast
in central Arizona. Meanwhile, no well-defined vort maxes or
inverted troughs were evident on WV imagery. Conceptually speaking,
conditions remain unfavorable for organized convection in the lower
deserts for late this afternoon and this evening. However, with PWATs
around 1.4 inches, conditions remain sufficiently moist for scattered
activity across the higher terrain east of Phoenix.
Latest convective allowing guidance continues to suggest that showers
and thunderstorms will develop across Pinal County late this
afternoon. Model consensus indicates that propagation into Maricopa
County is unlikely. However, an outflow boundary is expected to move through
the Phoenix area this evening along with the possibility of blowing
dust. SPC SSEO continues to suggest that strong storms are not
anticipated in the lower deserts, though depiction in the hi-res
guidance points to the possibility of mid-level debris along with
isolated sprinkles/light showers.
Otherwise, focus will be on the warming trend the next few days.
Latest NAEFS percentiles exceed the 90th percentile across
southeastern California by Friday and look to approach the 98th
percentile across the Imperial Valley by Saturday. Much of Imperial
County was upgraded to an Excessive Heat Warning. The Warning
continues for the Phoenix area. Elsewhere, anomalies are not as
extreme and the Watch was cancelled.
&&
.PREVIOUS DISCUSSION...
We`ll start off with the main weather concern over the next seven
days which is a relatively short period of excessive heat. The
sprawling central CONUS 500 mb anti-cyclone will migrate toward the
Southwest States today and hover over us on Friday and Saturday. This
will help quell chances for showers/thunderstorms while temperatures
show a marked upward jump. Temperatures at 850 mb will hover around
32-33C both days, which will put lower desert locations firmly in the
110-115F range. Model range continues to tighten on this solution and
don`t see a lot of wiggling likely as the event arrives.
Climatologically-driven Excessive Heat Warning criteria is being met
in the Phoenix Metro Area both days and in northwest Pinal County
communities. Therefore, upgraded the watch to a warning given our
higher confidence. Of concern will also be the overnight low
temperatures, likely not falling below 90 in the urban areas.
By Sunday, the PacNW trough we`ve been watching in the models for
several days remains in the forecast and is expected to suppress the
ridge overhead, resulting in a noted cool-down in the forecast
(though it will still be fairly hot, just not excessively so).
As for convection, we continue to be on a downward trend today
through Saturday. Boundary layer mixing ratios this afternoon across
most of southern Arizona will barely be above 8 g/kg, which is a good
approximation of enough moisture to translate into positive CAPE
values. We expect to see more shower/storms in the area but coverage
will likely not be impressive. With a deep and well-mixed boundary
layer, outflows will continue to remain a threat along with the
blowing dust they bring. For Friday and Saturday, moisture and
instability values fall further along with precipitation chances.
Once we get past the hottest days of Friday and Saturday, the upper
level (250 mb) flow pattern will re-adjust. It still appears that the
mid-level anti-cyclone will take-up a position just to the north of
Arizona, which will allow deep easterly flow to stretch up the Rio
Grande Valley and across southern New Mexico/Arizona/California.
Boundary layer mixing ratio values climb back into the 9-10 g/kg
range by Monday and remain there through the week. This pattern open
the door for more instability to develop, the transversing of
easterly waves, and favorable propagation vectors to promote storm
movement off the mountains and into the lower deserts. This pattern
could remain in place through the end of the month.
&&
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
Thin high level cirrus will carry through the afternoon with mid-
level CU/CB development popping over the typically favored mountains
well N, E and SE of the Phoenix-area terminals. Midday winds to be
on the lighter side with VRB headings before settling into westerly
directions between 20z-22z. Regionally, moisture is be thinning and
flow aloft is turning less favorable for desert storms so chances of
storms surviving into the Phoenix-metro are low. However, several
hi-res models and observed forecast soundings indicate potential for
outflow driven wind shifts likely from the southeast (anywhere
between 140-170 or so) on the headings post 22/02z for an initial
estimate. Will be able to better time the shifts once storm
development between Casa Grande and Tucson begins in the afternoon.
Debris cloudiness with some very light showers/virga could follow in
the wake of the outflow, with VCSH coverage included generally post
22/04z for the terminals for just a few hours.
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns at the TAF site next 24 hours as thunderstorm
activity will remain well off to the east and to the east of the
lower Colorado River valley. Winds to favor the south next 24 hours
at KBLH with a few afternoon gusts over 18kt possible. Winds to
favor the west at KIPL turning for a spell to the southeast mainly
during the afternoon hours today.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Saturday through Wednesday...Temperatures are climbing to well above
normal territory through the weekend as moisture levels thin and
humidity values drop. Chances for thunderstorms/wetting rain dwindle
and become almost limited to the higher terrain of eastern Arizona
by Saturday. Consequently, afternoon humidity levels will fall below
15 percent over the weekend before increasing to the 15-20 percent
range beginning Sunday and into next week as thunderstorm chances
slowly increase from east to west. Higher humidity values can be
expected in the higher terrain locations. High temperatures will
taper off next week as humidity levels climb but will stay near or
slightly above seasonal normals. Outside of thunderstorms, winds
will be typical with some afternoon gustiness.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning from midnight tonight to midnight MST
Saturday night for AZZ023-028.
CA...Excessive Heat Warning from midnight tonight to midnight PDT
Saturday night for CAZ033.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...Iniguez
AVIATION...Nolte/CB
FIRE WEATHER...Deemer/CB
[top]
Area Forecast Discussion
National Weather Service Tucson AZ
1244 PM MST THU JUL 21 2016
.SYNOPSIS...Hotter and drier conditions are expected Friday into
Sunday with some record high temperatures likely to fall. There will
be just enough moisture around for a few storms near the Mexico and
New Mexico border each of those afternoons. Then moisture will
increase across much of the area early next week for an increase in
storms and somewhat cooler afternoon temperatures.
&&
.DISCUSSION...Convection kicking off across the higher terrain early
this afternoon with individual cells drifting to the NNW. The
convection will continue to develop and expand in coverage through
the afternoon with locally gusty winds with some blowing dust being
the biggest concern. There will be some decent rainers but with
slowly diminishing PWs less of a threat outside of training echoes.
All this activity will die off this evening much like yesterday as
there isn`t any larger scale forcing to keep things going.
Then Friday and Saturday drier air invades the region which is
currently on our door step looking at the water vapor loop. The
overall result of this will be a reduction in the convection and
resultant cloud cover with much of it being limited to our eastern
and southern border areas. The other affect of this will be to allow
afternoon temperatures to increase the next few days peaking Friday
and Saturday afternoons about 10 degrees above average and at or
slightly above records for several locations. I tweaked pops down a
bit a few areas and added a degree to the high temperature to many
areas on Saturday.
On Sunday lower level thickness values begin to drop back with
moisture beginning to increase from the south. This is basically
beginning to occur thanks to a nudge from the tropics but at this
time believe the main push of moisture will be Sunday night into
Monday. So for now only made minor adjustments to the pops Sunday and
went with about 5 degrees of cooling for the afternoon when compared
to Saturday.
For Monday onward nudged pops upward with the current trend in the
models and introduced chance of storms to the western deserts
throughout the week. May need to adjust them up further early in the
week but will wait a bit and see how this begins to unfold. I also
nudged afternoon high temperatures down a couple of degrees but there
is potential to nudge them down further one or two of those days
depending on the moisture surge. Still have a decent amount of
discrepancy in the lower level thickness forecast in the models with
the ECMWF being on the cooler side.
&&
.AVIATION...VALID THRU 23/00.
Scattered showers and thunderstorms will develop through at least
03Z with impacts to terminals including gusty winds, heavy rainfall,
and the potential for reductions in visibility. In general VFR
conditions will be prevalent throughout, unless a storm develops
directly over the airport. Cloud bases will hover around 8 or 9
thousand feet. Storm chances will drop quickly after 03Z. Aviation
discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Daily rounds of showers/thunderstorms will
linger into the weekend with coverage waning Saturday and Sunday.
A greater chance of storms will move into the area 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.
&&
$$
PUBLIC...CERNIGLIA
AVIATION....CANTIN
FIRE WEATHER...CANTIN
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion
National Weather Service Phoenix AZ
1109 AM MST THU JUL 21 2016
.UPDATE...To Aviation Discussion...
&&
.SYNOPSIS...
The dry weather across southeast California and southwest Arizona
will begin to spread eastward, with the chances for showers and
thunderstorms gradually dwindling across central Arizona the next
several days. The combination of thinning moisture and a much warmer
atmosphere building into the region, will cause afternoon
temperatures to soar, especially Friday and Saturday. Temperatures
will cool a bit Sunday, but still remain fairly hot into next week,
as thunderstorm chances return to the forecast.
&&
.DISCUSSION...
Latest morning Phoenix sounding shows that winds in the 700-500 mb
layer have weakened and veered to southerly around the anticyclone in
the southern Plains. Conceptually speaking, this pattern is less
favorable for convection in the lower deserts. Latest convective-
allowing model guidance corroborates this, depicting afternoon
development mainly across eastern Arizona and the higher terrain of
east of Phoenix. Nevertheless, sufficient moisture is present to
trigger isolated activity, particularly across Pinal County this
afternoon. SSEO suggests intense cells are not probable. Other
thunderstorm impacts such as wind and dust are certainly more likely
in these areas. Minor adjustments were made to the short-term
temperatures. Otherwise, the forecast remains on track with well-
above normal temperatures expected.
&&
.PREVIOUS DISCUSSION...
We`ll start off with the main weather concern over the next seven
days which is a relatively short period of excessive heat. The
sprawling central CONUS 500 mb anti-cyclone will migrate toward the
Southwest States today and hover over us on Friday and Saturday. This
will help quell chances for showers/thunderstorms while temperatures
show a marked upward jump. Temperatures at 850 mb will hover around
32-33C both days, which will put lower desert locations firmly in the
110-115F range. Model range continues to tighten on this solution and
don`t see a lot of wiggling likely as the event arrives.
Climatologically-driven Excessive Heat Warning criteria is being met
in the Phoenix Metro Area both days and in northwest Pinal County
communities. Therefore, upgraded the watch to a warning given our
higher confidence. Of concern will also be the overnight low
temperatures, likely not falling below 90 in the urban areas.
Further to the west, while temperatures will be just as warm,
climate in those locations is also warm thus temperatures not as
anomalous. In addition, overnight low temperatures will be several
degrees cooler. Given that confidence remains lower of hitting
excessive heat thresholds, decided to maintain the watch. Next shift
will likely need to make a final go/no-go decision. By Sunday, the
PacNW trough we`ve been watching in the models for several days
remains in the forecast and is expected to suppress the ridge
overhead, resulting in a noted cool-down in the forecast (though it
will still be fairly hot, just not excessively so).
As for convection, we continue to be on a downward trend today
through Saturday. Boundary layer mixing ratios this afternoon across
most of southern Arizona will barely be above 8 g/kg, which is a good
approximation of enough moisture to translate into positive CAPE
values. We expect to see more shower/storms in the area but coverage
will likely not be impressive. With a deep and well-mixed boundary
layer, outflows will continue to remain a threat along with the
blowing dust they bring. For Friday and Saturday, moisture and
instability values fall further along with precipitation chances.
Once we get past the hottest days of Friday and Saturday, the upper
level (250 mb) flow pattern will re-adjust. It still appears that the
mid-level anti-cyclone will take-up a position just to the north of
Arizona, which will allow deep easterly flow to stretch up the Rio
Grande Valley and across southern New Mexico/Arizona/California.
Boundary layer mixing ratio values climb back into the 9-10 g/kg
range by Monday and remain there through the week. This pattern open
the door for more instability to develop, the transversing of
easterly waves, and favorable propagation vectors to promote storm
movement off the mountains and into the lower deserts. This pattern
could remain in place through the end of the month.
&&
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
Thin high level cirrus will carry through the afternoon with mid-
level CU/CB development popping over the typically favored mountains
well N, E and SE of the Phoenix-area terminals. Midday winds to be
on the lighter side with VRB headings before settling into westerly
directions between 20z-22z. Regionally, moisture is be thinning and
flow aloft is turning less favorable for desert storms so chances of
storms surviving into the Phoenix-metro are low. However, several
hi-res models and observed forecast soundings indicate potential for
outflow driven wind shifts likely from the southeast (anywhere
between 140-170 or so) on the headings post 22/02z for an initial
estimate. Will be able to better time the shifts once storm
development between Casa Grande and Tucson begins in the afternoon.
Debris cloudiness with some very light showers/virga could follow in
the wake of the outflow, with VCSH coverage included generally post
22/04z for the terminals for just a few hours.
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns at the TAF site next 24 hours as thunderstorm
activity will remain well off to the east and to the east of the
lower Colorado River valley. Winds to favor the south next 24 hours
at KBLH with a few afternoon gusts over 18kt possible. Winds to
favor the west at KIPL turning for a spell to the southeast mainly
during the afternoon hours today.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Saturday through Wednesday...Temperatures are climbing to well above
normal territory through the weekend as moisture levels thin and
humidity values drop. Chances for thunderstorms/wetting rain dwindle
and become almost limited to the higher terrain of eastern Arizona
by Saturday. Consequently, afternoon humidity levels will fall below
15 percent over the weekend before increasing to the 15-20 percent
range beginning Sunday and into next week as thunderstorm chances
slowly increase from east to west. Higher humidity values can be
expected in the higher terrain locations. High temperatures will
taper off next week as humidity levels climb but will stay near or
slightly above seasonal normals. Outside of thunderstorms, winds
will be typical with some afternoon gustiness.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning from midnight tonight to midnight MST
Saturday night for AZZ023-028.
CA...Excessive Heat Warning from midnight tonight to midnight PDT
Saturday night for CAZ033.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...Iniguez
AVIATION...Nolte/CB
FIRE WEATHER...Deemer/CB
Area Forecast Discussion
National Weather Service Phoenix AZ
1109 AM MST THU JUL 21 2016
.UPDATE...To Aviation Discussion...
&&
.SYNOPSIS...
The dry weather across southeast California and southwest Arizona
will begin to spread eastward, with the chances for showers and
thunderstorms gradually dwindling across central Arizona the next
several days. The combination of thinning moisture and a much warmer
atmosphere building into the region, will cause afternoon
temperatures to soar, especially Friday and Saturday. Temperatures
will cool a bit Sunday, but still remain fairly hot into next week,
as thunderstorm chances return to the forecast.
&&
.DISCUSSION...
Latest morning Phoenix sounding shows that winds in the 700-500 mb
layer have weakened and veered to southerly around the anticyclone in
the southern Plains. Conceptually speaking, this pattern is less
favorable for convection in the lower deserts. Latest convective-
allowing model guidance corroborates this, depicting afternoon
development mainly across eastern Arizona and the higher terrain of
east of Phoenix. Nevertheless, sufficient moisture is present to
trigger isolated activity, particularly across Pinal County this
afternoon. SSEO suggests intense cells are not probable. Other
thunderstorm impacts such as wind and dust are certainly more likely
in these areas. Minor adjustments were made to the short-term
temperatures. Otherwise, the forecast remains on track with well-
above normal temperatures expected.
&&
.PREVIOUS DISCUSSION...
We`ll start off with the main weather concern over the next seven
days which is a relatively short period of excessive heat. The
sprawling central CONUS 500 mb anti-cyclone will migrate toward the
Southwest States today and hover over us on Friday and Saturday. This
will help quell chances for showers/thunderstorms while temperatures
show a marked upward jump. Temperatures at 850 mb will hover around
32-33C both days, which will put lower desert locations firmly in the
110-115F range. Model range continues to tighten on this solution and
don`t see a lot of wiggling likely as the event arrives.
Climatologically-driven Excessive Heat Warning criteria is being met
in the Phoenix Metro Area both days and in northwest Pinal County
communities. Therefore, upgraded the watch to a warning given our
higher confidence. Of concern will also be the overnight low
temperatures, likely not falling below 90 in the urban areas.
Further to the west, while temperatures will be just as warm,
climate in those locations is also warm thus temperatures not as
anomalous. In addition, overnight low temperatures will be several
degrees cooler. Given that confidence remains lower of hitting
excessive heat thresholds, decided to maintain the watch. Next shift
will likely need to make a final go/no-go decision. By Sunday, the
PacNW trough we`ve been watching in the models for several days
remains in the forecast and is expected to suppress the ridge
overhead, resulting in a noted cool-down in the forecast (though it
will still be fairly hot, just not excessively so).
As for convection, we continue to be on a downward trend today
through Saturday. Boundary layer mixing ratios this afternoon across
most of southern Arizona will barely be above 8 g/kg, which is a good
approximation of enough moisture to translate into positive CAPE
values. We expect to see more shower/storms in the area but coverage
will likely not be impressive. With a deep and well-mixed boundary
layer, outflows will continue to remain a threat along with the
blowing dust they bring. For Friday and Saturday, moisture and
instability values fall further along with precipitation chances.
Once we get past the hottest days of Friday and Saturday, the upper
level (250 mb) flow pattern will re-adjust. It still appears that the
mid-level anti-cyclone will take-up a position just to the north of
Arizona, which will allow deep easterly flow to stretch up the Rio
Grande Valley and across southern New Mexico/Arizona/California.
Boundary layer mixing ratio values climb back into the 9-10 g/kg
range by Monday and remain there through the week. This pattern open
the door for more instability to develop, the transversing of
easterly waves, and favorable propagation vectors to promote storm
movement off the mountains and into the lower deserts. This pattern
could remain in place through the end of the month.
&&
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
Thin high level cirrus will carry through the afternoon with mid-
level CU/CB development popping over the typically favored mountains
well N, E and SE of the Phoenix-area terminals. Midday winds to be
on the lighter side with VRB headings before settling into westerly
directions between 20z-22z. Regionally, moisture is be thinning and
flow aloft is turning less favorable for desert storms so chances of
storms surviving into the Phoenix-metro are low. However, several
hi-res models and observed forecast soundings indicate potential for
outflow driven wind shifts likely from the southeast (anywhere
between 140-170 or so) on the headings post 22/02z for an initial
estimate. Will be able to better time the shifts once storm
development between Casa Grande and Tucson begins in the afternoon.
Debris cloudiness with some very light showers/virga could follow in
the wake of the outflow, with VCSH coverage included generally post
22/04z for the terminals for just a few hours.
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns at the TAF site next 24 hours as thunderstorm
activity will remain well off to the east and to the east of the
lower Colorado River valley. Winds to favor the south next 24 hours
at KBLH with a few afternoon gusts over 18kt possible. Winds to
favor the west at KIPL turning for a spell to the southeast mainly
during the afternoon hours today.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Saturday through Wednesday...Temperatures are climbing to well above
normal territory through the weekend as moisture levels thin and
humidity values drop. Chances for thunderstorms/wetting rain dwindle
and become almost limited to the higher terrain of eastern Arizona
by Saturday. Consequently, afternoon humidity levels will fall below
15 percent over the weekend before increasing to the 15-20 percent
range beginning Sunday and into next week as thunderstorm chances
slowly increase from east to west. Higher humidity values can be
expected in the higher terrain locations. High temperatures will
taper off next week as humidity levels climb but will stay near or
slightly above seasonal normals. Outside of thunderstorms, winds
will be typical with some afternoon gustiness.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning from midnight tonight to midnight MST
Saturday night for AZZ023-028.
CA...Excessive Heat Warning from midnight tonight to midnight PDT
Saturday night for CAZ033.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...Iniguez
AVIATION...Nolte/CB
FIRE WEATHER...Deemer/CB
Area Forecast Discussion
National Weather Service Flagstaff AZ
918 AM MST THU JUL 21 2016
.SYNOPSIS...Another round of showers and thunderstorms is expected
from late this morning through early evening. Drier westerly flow
will decrease shower and thunderstorm coverage across western
Arizona Friday into the weekend, though decent chances for
thunderstorms will remain across southern Navajo and Apache
counties. Moisture and storm chances could increase again next
week, especially along and south of the Mogollon Rim.
&&
.UPDATE...Today will be another day of widespread showers and
thunderstorms across northern Arizona. The main threats with these
storms will be very heavy rain, which could lead to localized
flash flooding. The previous forecast is in good shape and no
changes were made.
&&
.PREV DISCUSSION /342 AM MST/...Another round of showers and
thunderstorms is expected across all of northern Arizona today,
beginning after 10 AM MST. Storms will initially develop in the
higher terrain and slowly work their way to the lower elevations.
The main threat with storms will once again be localized very
heavy rain due to the slow storm movement, which could lead to
localized flash flooding. The stronger storms will also be capable
of producing small hail and gusty winds.
Beginning Friday, the axis of strong high pressure will shift over
or just south of the forecast area and drier air will start to
move in from the west. This will reduce storm chances across
Coconino and Yavapai Counties into the weekend. The greatest storm
chances will remain over southern Navajo and Apache Counties where
the highest moisture will linger. Most model guidance shows the
ridge shifting back northward possibly as early as Sunday but more
likely Monday into midweek. This would allow for some better
moisture and storm chances to return, especially for areas along
and south of the Mogollon Rim and White Mountains. Depending on
where the high eventually sets up, we could see some east or
northeast steering flow off the higher terrain which is favorable
for some stronger storms in the late afternoon and evening in Gila
County and the lower elevations of Yavapai County. Far northern
Arizona (along/north of Grand Canyon to Window Rock) often remains
drier in this pattern. With high pressure in place, expect hot
temperatures in this area, 110+ at Phantom Ranch, 102-104 at Page
and near 90 at Grand Canyon south rim.
&&
.AVIATION...For the 18Z package...Expect scattered to numerous
showers and thunderstorms. Conditions will remain primarily VFR but
local MVFR in heavy rain is possible in stronger storms.
Activity should decrease after sunset. Aviation discussion not
updated for TAF amendments.
&&
.FIRE WEATHER...A wet monsoon pattern will remain in place today
resulting in scattered thunderstorms with locally heavy rain
possible. By Friday, a drier westerly flow will begin a downward
trend in thunderstorm activity.
Saturday through Monday...Expect lower thunderstorm chances and
decreased afternoon humidity over the weekend. Moisture may increase
on Monday from the Mogollon Rim south.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...Mottice/JJ
AVIATION...AT
FIRE WEATHER...MCS
For Northern Arizona weather information visit
weather.gov/flagstaff
Area Forecast Discussion
National Weather Service Tucson AZ
845 AM MST THU JUL 21 2016
.SYNOPSIS...A decrease in thunderstorms activity will occur over
the next several days as the air mass over the region dries out.
As a result temperatures will climb to roughly 10 degrees warmer
than average Friday and Saturday with record high temperatures
possible both days. Monsoon moisture will then gradually return
Sunday onward for an overall increase in convection and a slight
cooling of afternoon temperatures.
&&
.DISCUSSION...Drying has not started yet in any significant fashion
thus we still have nearly 1.5" PW on the morning sounding with a
little less to the east. Also the sounding has a slightly better
thermal profile compared to yesterday with a touch of cooling aloft
an warming below. The upshot, the atmosphere is ready with plenty of
sunshine to help out. Not much if anything noticeable out there to
help focus or provide extra lift so this will primarily be another
diurnal, terrain driven day much like yesterday. The latest runs of
the HRRR and UA WRF NAM agree so would expect convection to begin to
develop 18-19z over the higher terrain to the south and southeast
then move to the NNW through the day, much like yesterday.
More noticeable drying to take place from the east tomorrow and
Saturday and that is apparent on this mornings water vapor imagery.
This should provide for a reduction in the convection across the
area while also lifting afternoon temperatures to roughly 10 degrees
warmer than average, which means hot but not quite heat advisory
hot. That said we will likely see a few record highs fall over the
next few days.
The moisture will begin to return to the region later Sunday into
next week which will enhance the convection threat and put us back
into a somewhat active pattern once again. Thankfully the extra
clouds and scattered showers will trim a few degrees of the high
temperatures next week. Cerniglia
&&
.AVIATION...VALID THRU 22/18.
Sct-bkn clouds at 6-9k ft agl and bkn-ovc clouds at 10-15k ft agl
developing with isolated to scattered showers and T-storms today
into this evening. Once again, heavy rainfall, gusty winds, and some
areas of blowing dust will be the biggest concerns. The showers and
storms will diminish aft 22/04Z. Aviation discussion not updated for
TAF amendments.
&&
.FIRE WEATHER...Moisture in place will lead to the showers and
thunderstorms again today, developing after 11 am over higher
terrain and drifting to the north. A drying trend will then lead to
reduced coverage of showers and thunderstorms Friday into this
weekend. Moisture will increase again early next week resulting in
an uptick in convection. Outside of gusty thunderstorm outflows, 20-
foot winds will be terrain driven and mostly less than 15 mph.
&&
.CLIMATE...Record high temperatures will be approached at a few spots
today then most of the area will be at or near record highs Friday
and Saturday.
&&
.TWC Watches/Warnings/Advisories...None.
&&
$$
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
321 PM CDT THU JUL 21 2016
.SHORT TERM...(This Evening through Friday)
Issued at 252 PM CDT THU JUL 21 2016
Not much change to overall forecast for the remainder of today with
heat indices likely above 100 degrees until about 9 pm this evening.
There is currently a weak frontal zone across northwest KS and
central NE. This front is forecasted to drift eastward tonight, but
it will not reach our forecast area. Some of the models suggest that
isentropic lift will increase tonight generally above 850 mb over
central KS late tonight. Although it appears that there will be a
decent amount of dry air below about 700 mb. Therefore if showers or
storms can from it will take some time to saturate the environment.
Have slight chances north central KS for a few hours around sunrise.
Temperatures and dew points are forecasted to be similar tomorrow
with the exception of far northern KS, which will be closer to the
frontal zone and possible precipitation. Again tomorrow afternoon
the heat indices will range from 105 to 113.
.LONG TERM...(Friday Night through Thursday)
Issued at 252 PM CDT THU JUL 21 2016
Excessive heat is very likely to continue into Saturday with
temperatures at the same level or even slightly hotter than
Friday. The question regarding eventual heat indices lies in how
high afternoon dewpoints can hold and if today is any indication
the evapotranspiration will remain a strong contributor to high
level near surface dewpoints. Have thus maintained similar
dewpoint values to today and recent days even through Saturday and
with the higher temperatures expect heat indices in the 105 to 115
range. Have the smallest chance for thunderstorms in north central
KS Friday night with an elevated storm possible within the LLJ
upslope, but this looks like a low probability.
On Saturday night into Sunday, a short wave trough currently off
the Oregon coast will move across the northern Plains and is
likely to be strong enough to bring a surface cold front into
northern KS. This front, while likely to be weak, may be strong
enough to kick off a few storms Saturday night with a limiting
factor being a weak low level jet. Models are consistent in
hanging this front across northern KS on Sunday with very hot
conditions persisting south of the boundary and slightly less hot
but with potentially higher dewpoints north of the boundary. This
leads to a chance of continued excessive heat across much of or
all of the forecast area. However at this time with the chance for
thunderstorms, have opted not to extend any products into Sunday
but just know that the potential exists to once again have 100-110
heat index readings.
Late Sunday into Monday morning may be the best chance for
thunderstorms in quite a while, although still not clear cut as a
widespread rain maker. The surface front is likely to sag a bit
farther south across the area as the ridge flattens and a short
wave trough with associated jet streak comes a bit farther south
than previous storm tracks. This setup should provide favorable
jet dynamics for modest deep vertical motion in the local area and
may pose a locally heavy rain potential although the LLJ intensity
remains lacking during that period for such an event.
The first part of next week seems likely to have temperatures in
the lower 90s with heat indices pushing 100 each day...and each
day depending upon thunderstorm coverage as multiple weak upper
disturbances will cross from the northern Plains southeast.
Wednesday into Wednesday night presents itself as another slightly
better opportunity for thunderstorms as a stronger short wave
crosses the region. This may be another scenario for which
individual MCS development is difficult to predict well in advance
but the ingredients for longer track MCS`s will be in place across
the region for much of the weak and could lead to an unsettled
period of weather.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1248 PM CDT THU JUL 21 2016
VFR conditions are expected through the period. LLWS still looks
to be below criteria at this time.
&&
.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...Sanders
LONG TERM...Barjenbruch
AVIATION...Heller
[top]
Area Forecast Discussion
National Weather Service Goodland KS
220 PM MDT THU JUL 21 2016
.SHORT TERM...(This evening through Friday)
Issued at 220 PM MDT Thu Jul 21 2016
Latest upper air data shows a ridge centered over the Texas and
Oklahoma panhandles. Rotating around the ridge is a short wave
trough currently over the Central Rockies with thunderstorms
accompanying it. At the surface a trough/dry line was located over
the Tri-State Area extending from La Junta and Lamar to Oakley and
Atwood.
For the rest of the afternoon the upper level short wave trough over
the Central Rockies will move onto the Plains bringing thunderstorms
with it. The surface trough/dry line will move very little during
the afternoon. Latest SPC Mesoanalysis indicates the surface
feature is capped, but this may change by late afternoon when the
upper level short wave trough deepens over it. Latest radar shows
storms already developing in southeast Colorado. Am expecting these
storms to continue tracking toward the Tri-State Area and eventually
moving into Cheyenne County Colorado.
Tonight the short wave trough will deepen over the southwest part of
the Tri-State Area. With added lift from the surface trough/dry
line am expecting storm coverage to increase during the evening. By
midnight the short wave trough will begin filling causing storm
activity to diminish. Cannot rule out isolated storms developing
across the rest of the Tri-State Area this evening due to large
scale lift from the short wave trough. The nose of the low level
jet will develop over the southeast part of the area this evening.
This may allow an isolated storm to develop along the elevated CAPE
axis that will form along the low level jet nose.
After midnight storm activity should be confined to the upper level
short wave trough that will be filling over the southwest part of
the Tri-State Area. Any storm activity should end a couple hours
after midnight as the short wave trough continues to fill.
Lows tonight will continue to be above normal.
Friday will be another warm day with heat indices of 100 to 105
across the advisory area. Highs will be very similar to today. The
surface trough will be southeast of the Tri-State Area during the
afternoon. However an upper level short wave trough will deepen
over the center of the Tri-State Area during the afternoon, with
the strongest lift over the northern and southwest part of the
area. Am expecting storm activity to be fairly isolated then
increase in coverage into the evening as the short wave trough
deepens.
.LONG TERM...(Friday night through Thursday)
Issued at 220 PM MDT Thu Jul 21 2016
Temperatures become more seasonal after Saturday in the long term
period. Chances for afternoon and evening thunderstorms persist
through early next week for portions of the area.
Friday night: The ridge over the CONUS breaks down and high pressure
retreats to the west as a shortwave trough advances from the Pacific
Northwest towards the northern Plains. Thunderstorm chances continue
into Friday evening as convection from Colorado moves eastward.
Saturday through Sunday night: The trough travels along the Canadian
border towards the northern Plains on Saturday. Temperatures still
appear to be warm (ranging from the upper 90s to a couple degrees
over 100) ahead of a cold front expected to pass through Saturday
night/early Sunday. At this time, am thinking a heat advisory is not
needed for Saturday due to slightly lower heat indices than previous
days, but will continue to monitor. As the next system nears the
region, afternoon/evening thunderstorm chances return. A few strong
to severe storms are possible across the region. Cooler temperatures
in the upper 80s to low 90s are forecast Sunday behind the front.
Thunderstorms will be possible again Sunday afternoon and evening
with a better chance to the south near the boundary.
Monday through Thursday: High pressure remains over the southwestern
CONUS in the beginning of the extended, with westerly flow over the
northern half of the country. A series of disturbances appear
to pass through the flow and impact the High Plains on Monday and
Tuesday. Ridging starts to rebuild over the western CONUS
towards the later half of the work week. This looks to bring
drier conditions and warmer temperatures back to the area.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1123 AM MDT Thu Jul 21 2016
VFR conditions expected for the TAFs. A surface trough has moved
through KGLD but will be near KMCK most of the day causing light
winds to be variable. Isolated thunderstorms are anticipated along
the surface trough this afternoon which may affect KMCK. Storms
should remain south of KGLD. Variable winds at KMCK will turn
more to the north overnight then become east Friday morning.
&&
.GLD Watches/Warnings/Advisories...
KS...Heat Advisory until 7 PM CDT Friday for KSZ002>004-014>016-028-
029.
CO...NONE.
NE...Heat Advisory until 6 PM MDT /7 PM CDT/ Friday for NEZ079>081.
&&
$$
SHORT TERM...JTL
LONG TERM...JBH
AVIATION...JTL
[top]
Area Forecast Discussion
National Weather Service Wichita KS
306 PM CDT THU JUL 21 2016
.SHORT TERM...(This evening through Sunday night)
Issued at 301 PM CDT Thu Jul 21 2016
The main forecast focus is on temperatures and heat indices into
this weekend.
A strong upper high center over the south-central CONUS will
continue to bake the region with above normal heat into this
weekend, while subtropical moisture circulates around the periphery
of the high. A strong shortwave trough along the Pacific Northwest
Coast this afternoon, is progged to lift east-northeastward across
the Northern Plains Saturday into Sunday, flattening the upper ridge
some. This trough may allow a weak front to sink southward into
Kansas late Saturday night into Sunday, where it could stall out or
perhaps be reinforced some by thunderstorm outflow effects.
Persistent lee troughing and a strong low-level thermal ridge axis
will keep 850 temperatures anomalously warm at least Friday and
Saturday, and possibly into Sunday as well (particularly in south-
central/southeast Kansas). Highs of 98 to 106 are expected Friday
and Saturday, with mid-upper 90s on Sunday. Confidence in heat
indices above 105 degrees is high on Friday and only somewhat
lesser on Saturday, depending on further drying of the ground and
how much dewpoints can mix out. Consensus with adjacent forecast
offices to the west/south was to hold off on extending heat
headlines into Saturday for now, although it may be necessary with
later shifts.
Modest chances for thunderstorms will affect the northwestern part
of Kansas tonight and again Friday night...near the edge of the
monsoonal moisture plume where weak vort lobes are embedded. Storm
chances may increase late in the weekend in our forecast area if the
front can make it this far south.
.LONG TERM...(Monday through Thursday)
Issued at 301 PM CDT Thu Jul 21 2016
The medium range models are tending to show the upper ridge
retrograding to over the Great Basin by Wednesday/Thursday, allowing
more of a west-northwesterly flow aloft pattern over the Central
Plains. A frontal boundary may linger across the Kansas vicinity at
least early in the period. A high precipitable water environment
will exist near and north of this front which may serve as a focus
for thunderstorms Monday-Tuesday. Even if the front washes out by
midweek, developing northwest flow aloft would allow the possibility
of nocturnal storm complexes moving east-southeastward off of the
High Plains. Expecting seasonably warm temperatures during this
period (Highs low-mid 90s), with occasional storm chances.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1237 PM CDT Thu Jul 21 2016
VFR will prevail across the area through the 24-hr period. Breezy
SSW winds will back to the SSE this evening while returning to the
SSW early on Fri.
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 79 103 77 104 / 10 10 10 10
Hutchinson 77 105 77 104 / 10 10 10 10
Newton 78 102 77 103 / 10 10 10 10
ElDorado 77 101 77 102 / 10 10 10 10
Winfield-KWLD 77 102 77 102 / 0 10 0 10
Russell 75 105 77 104 / 20 20 20 10
Great Bend 76 105 77 104 / 20 20 20 10
Salina 79 106 79 105 / 10 10 10 10
McPherson 77 105 77 104 / 10 10 10 10
Coffeyville 76 99 76 99 / 0 10 0 0
Chanute 76 99 76 98 / 0 10 0 10
Iola 76 98 76 97 / 0 10 0 10
Parsons-KPPF 76 99 76 98 / 0 10 0 0
&&
.ICT Watches/Warnings/Advisories...
Excessive Heat Warning until 8 PM CDT Friday for KSZ033-048>053-
067>072-082-083-091>096-098>100.
Heat Advisory until 8 PM CDT Friday for KSZ032-047.
&&
$$
SHORT TERM...JMC
LONG TERM...JMC
AVIATION...MWM
[top]
Area Forecast Discussion
National Weather Service Dodge City KS
235 PM CDT THU JUL 21 2016
...Updated Long Term...
.SHORT TERM...(This evening through Friday)
Issued at 1244 PM CDT Thu Jul 21 2016
High pressure aloft is at its peak intensity at midday, with a
clear sky and temperatures soaring on their way to 100 as of noon.
Heat index values will be most dangerous across eastern areas this
afternoon and early evening, and the heat advisory continues.
NAM forecasts scattered thunderstorms this evening along the
periphery of the ridge, across SE Colorado and SW Nebraska, with a
few storms hugging the northern CWA border overnight. Was about to
ignore this solution, until GFS came in with something very
similar, with isolated convection mainly north of Dodge City
tonight. HRRR also lends support to convection near Hays by late
this evening. Confidence is low on thunderstorm development. Weak
vorticity max rounding the ridge axis appears to be the only
forcing evident. Spread slight chance/isolated wording across
the northern zones overnight.
Friday...Still hot! High pressure remains quite strong, with no
changes in thickness or 850 mb temperatures noted. As such, high
confidence in widespread triple digit heat Friday afternoon.
Afternoon max temperatures from 100-106, with the most dangerous
heat indices again relegated to the far eastern zones and lowest
elevations. Heat advisory continues through evening. Hot and dry
for most, but isolated thunderstorms may find their way into
northern zones by evening where the high pressure ridge`s
influence is weakest.
.LONG TERM...(Friday night through Thursday)
Issued at 235 PM CDT Thu Jul 21 2016
Another hot day on Saturday. Although high pressure aloft will
continue to weaken with lowering heights, the atmosphere remains
hot on Saturday with little to no change in 850 mb temps or
thickness. Afternoon highs from 99-104. Ongoing heat advisory will
likely have to be extended to include Saturday, especially the SE
zones near Medicine Lodge. Isolated to scattered thunderstorm
coverage expected to favor the W/NW zones Saturday afternoon and
evening. Marginal risk of marginal wind/hail from any convection
across NW zones late Saturday. Forcing is nebulous, but should be
able to start pulling in convection from the higher terrain by
Saturday evening.
Sunday...Still expecting a break from the heat. Weak frontal
boundary adds an easterly component to the surface wind fields,
and thicknesses finally relax. Temperatures "cool" a few degrees
back to the 90s, enough to let the heat advisory expire.
Thunderstorms expected to increase in coverage by Sunday evening,
particularly across the western 1/2 of the CWA, as westerly flow
aloft increases a bit, and embedded vort maxes begin pushing
convection eastward from the higher terrain.
Monday through Wednesday...Daily chances of thunderstorms
expected. High pressure ridge will gradually strengthen and remain
stationary over the Great Basin through this period. Expect
nocturnal MCSs to become more likely as NW flow establishes
itself, with 12z ECMWF suggesting this is most likely around
Wednesday.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1200 PM CDT Thu Jul 21 2016
VFR expected to prevail through the TAF forecast. SW winds again
gusting to 25-30 kts this afternoon, with sct to bkn mid clouds
developing by evening. Surface winds weaken at 00z with another
round of modest low level wind shear overnight. 12z NAM/GFS models
are both forecasting scattered -SHRA/-TSRA during the 06-12z Fri
timeframe (especially near HYS), with HRRR solutions also
indicating convection near HYS by 06z Friday. Have low confidence
in these solutions, so only included VCSH/VCTS sparingly in the
TAFs for now.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 102 75 103 75 / 0 10 10 10
GCK 101 72 102 74 / 10 10 20 20
EHA 101 72 103 72 / 0 10 20 20
LBL 102 73 105 71 / 0 10 10 10
HYS 104 74 103 75 / 10 20 20 20
P28 104 76 106 77 / 0 10 0 10
&&
.DDC Watches/Warnings/Advisories...
Heat Advisory until 8 PM CDT Friday for KSZ030-031-044>046-
064>066-079>081-089-090.
&&
$$
SHORT TERM...Turner
LONG TERM...Turner
AVIATION...Turner
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1249 PM CDT THU JUL 21 2016
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 318 AM CDT THU JUL 21 2016
Similar to previous nights across the area, with temperatures still
holding in the low 80s for much of the area at this early hour. A
bit more wind out west has kept middle 80s there. Outflow boundary
has made progress across western Kansas from convection on the high
plains, and may make a run at the north central counties but not
expecting much in the way of a sensible weather impact. Mid level
temps rise 2-4C at 850mb today, and have increased high temps a few
degrees to reflect this. Widespread heat indices around 110F make
for dangerous heat today and the excessive heat warning remains in
place. Also expecting another night with lows well into the 70s. A
few models generate convection late to our northeast or west, but do
not think it will impact our forecast area before sunrise on
Friday.
.LONG TERM...(Friday through Wednesday)
Issued at 318 AM CDT THU JUL 21 2016
The forecast remains on track into at least Saturday. Weak front
washes out in central Nebraska Friday with minor convergence
resulting to the northwest and west. Enough potential for convection
to form and move this way for small pops in the northwest counties
Friday night. Upper ridge breaks down somewhat Friday into Friday
night with upper wave passing well north during the weekend.
Continued south to southwest low level flow however keeps hot air in
place. Models continue to show hottest conditions Friday with 850mb
temps mainly in the 25-30C range. There remains to be some variation
in how hot/mixed western areas will be, but overall combination of
heat and humidity keeps afternoon heat index values in the 103-111
range for the entire area Friday and Saturday. Models continue to
trend a bit slower with front`s passage through the area during the
weekend, with the potential for at least southeastern areas to be in
the warm sector for much of Sunday. Questions on specifics of mixing
depths in the weaker flow, dewpoints, cloud cover, and potential
precip however keep confidence too low for an extension of the
Warning. As for precip chances, weak forcing keeps chances low
Saturday night and Sunday, with better potential in subsequent
periods, mainly Sunday night and Tuesday night-Wednesday -- Sunday
night as the low level jet increases over the old front and Tuesday
night into Wednesday as the next upper wave passes across the
Northern Plains and the jet again responds. Extreme heat is not
anticipated to return in these periods, with highs mainly in the 90-
95 range depending on precip timing/persistence.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1248 PM CDT THU JUL 21 2016
VFR conditions are expected through the period. LLWS still looks
to be below criteria at this time.
&&
.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...67
LONG TERM...65
AVIATION...Heller
Area Forecast Discussion
National Weather Service Dodge City KS
1244 PM CDT THU JUL 21 2016
...Updated Short Term...
.SHORT TERM...(This evening through Friday)
Issued at 1244 PM CDT Thu Jul 21 2016
High pressure aloft is at its peak intensity at midday, with a
clear sky and temperatures soaring on their way to 100 as of noon.
Heat index values will be most dangerous across eastern areas this
afternoon and early evening, and the heat advisory continues.
NAM forecasts scattered thunderstorms this evening along the
periphery of the ridge, across SE Colorado and SW Nebraska, with a
few storms hugging the northern CWA border overnight. Was about to
ignore this solution, until GFS came in with something very
similar, with isolated convection mainly north of Dodge City
tonight. HRRR also lends support to convection near Hays by late
this evening. Confidence is low on thunderstorm development. Weak
vorticity max rounding the ridge axis appears to be the only
forcing evident. Spread slight chance/isolated wording across
the northern zones overnight.
Friday...Still hot! High pressure remains quite strong, with no
changes in thickness or 850 mb temperatures noted. As such, high
confidence in widespread triple digit heat Friday afternoon.
Afternoon max temperatures from 100-106, with the most dangerous
heat indices again relegated to the far eastern zones and lowest
elevations. Heat advisory continues through evening. Hot and dry
for most, but isolated thunderstorms may find their way into
northern zones by evening where the high pressure ridge`s
influence is weakest.
.LONG TERM...(Friday through Wednesday)
Issued at 322 AM CDT Thu Jul 21 2016
Relief from the excessive heat will come by the beginning of the
weekend as the upper ridge begins to break down. It is not
impossible to see a storms across the I-70 corridor Friday night,
as weak shortwave energy rotates over the top of the mid level
ridge. The GFS supports a better opportunity for more widespread
thunderstorm chances by Saturday evening/overnight when the mid
levels become much less stable. Temperatures moderate back toward
normal climatological highs and lows in the extended period
(generally speaking next week).
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1200 PM CDT Thu Jul 21 2016
VFR expected to prevail through the TAF forecast. SW winds again
gusting to 25-30 kts this afternoon, with sct to bkn mid clouds
developing by evening. Surface winds weaken at 00z with another
round of modest low level wind shear overnight. 12z NAM/GFS models
are both forecasting scattered -SHRA/-TSRA during the 06-12z Fri
timeframe (especially near HYS), with HRRR solutions also
indicating convection near HYS by 06z Friday. Have low confidence
in these solutions, so only included VCSH/VCTS sparingly in the
TAFs for now.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 102 74 103 75 / 0 10 10 10
GCK 101 71 102 74 / 10 10 20 20
EHA 101 72 103 73 / 0 10 20 20
LBL 102 72 105 73 / 0 10 10 10
HYS 104 74 103 75 / 10 20 20 20
P28 104 76 106 77 / 0 10 0 10
&&
.DDC Watches/Warnings/Advisories...
Heat Advisory until 8 PM CDT Friday for KSZ030-031-044>046-
064>066-079>081-089-090.
&&
$$
SHORT TERM...Turner
LONG TERM...Russell
AVIATION...Turner