Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/17/23
Area Forecast Discussion
National Weather Service La Crosse WI
1055 PM CDT Mon Oct 16 2023
.UPDATE...
Issued at 849 PM CDT Mon Oct 16 2023
With temperatures already in the mid- and upper 30s in central
Wisconsin and skies expected to remain mostly clear to partly
cloudy overnight, temperatures will likely continue to fall to
around freezing overnight. Due to this, we joined NWS Green Bay
and issued a Frost Advisory for central Wisconsin. This includes:
Adams, Jackson, Juneau, and Monroe counties. With the 2023 growing
season already ended in Clark and Taylor counties, they were not
included in this advisory.
&&
.DISCUSSION...(This evening through Monday)
Issued at 220 PM CDT Mon Oct 16 2023
Key Messages:
- Fog and Frost for some tonight; warming into Wednesday
- Rain chances Wednesday through Friday
Overview:
The latest water vapor satellite imagery/heights/lightning show the
large trough over the eastern U.S. with a mid-tropospheric ridge
over the Rockies/southwest U.S. and the next storm system off the
West Coast. A ridge of high pressure is over the local area at the
surface, however low level moisture weak northeast flow is resulting
in shallow moisture and variable clouds. Where it cleared out this
morning, temperatures varied from the upper 20s to the upper 30s.
Despite a 20kt 900mb wind, dense fog developed over parts of
Minnesota where surface winds decoupled; were calm, and low level
dewpoint depressions were zero.
Fog and Frost for some; Warmer Tuesday:
Overnight into Tuesday, surface high pressure remains over the
forecast area with weak low level warm advection with a subtle
ripple noted in the 925/850mb flow. Forecast soundings from the
HRRR/RAP are quite pessimistic with low level moisture and potential
for patchy drizzle. With the extent of afternoon clearing that
was not handled well, low confidence in the extent of clouds
tonight thus affecting fog/frost/low temperature forecast. The
RAP has backed off on the dense fog, however the HRRR/NAM
continue for parts of southeast MN and northeast Iowa and the
GFSLAMP has increased the fog with dense fog possible. Mid and
high clouds will also be on the increase Tuesday. Where clouds
return, this should help mitigate the fog and frost. low clouds
are forecast to linger Tuesday morning. Highs Tuesday should be in
the lower 50s to the lower 60s with the cooler readings I94
eastward.
Warming into Wednesday:
Upper ridging over the Rockies this afternoon will make a gradual
eastward push toward the region through midweek. Weak surface
ridging out ahead of this feature will traverse the Upper
Mississippi Valley through early Tuesday, with increasing return
flow leading to steady warming into Wednesday.
With the ongoing warm air advection, temperatures by Wednesday are
likely to climb a few degrees above seasonal normals for mid-
October. GEFS and EPS ensembles have been consistently indicating
temps climbing into the low to mid 60s for most of the area Tuesday
and Wednesday.
Light Rain Chances Wednesday through Friday:
A bit of a pattern shift on the docket for the second half of the
week as an upper level low brings a return to cyclonic flow. This
system will come ashore the Pacific Northwest tonight and then
develop into a closed upper low as it migrates over the northern
Great Plains Tuesday evening. Some negatively tilted orientation to
this system with most guidance trending towards a deepening upper
low. Overall pretty limited moisture transport out ahead of this
system with a narrow axis of >1" precipitable water values crossing
the local area late Wednesday. Forecast soundings show some dryness
lingering in the low levels until Wednesday night. Even so, upper
divergence as well as some support from a passing jet streak and
transient low level frontogenesis should tap into this rather
limited moisture to generate scattered shower potential at times
Wednesday into Thursday. ECMWF-based guidance continues to run
higher for QPF amounts than other guidance, with EPS >90%
probabilities for >0.1" now encompassing I-90 northward. By
comparison, GEFS probabilities for >0.1" only range from 20 to 50%
across our forecast area, while CMC ensemble guidance lies somewhere
in between. All in all, not a favorable setup for anyone desiring a
widespread soaking rain.
Additional small rain chances may follow for some areas into Friday
as another progressive shortwave dives through the region. This weak
system looks to mostly favor areas near and east of the Mississippi
River, though probabilities are low (<40%) for more than a few
hundredths of additional rainfall at any given location.
Another weak passing shortwave looks to drop through over the
weekend without much fanfare, followed by a building upper ridge
next week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1056 PM CDT Mon Oct 16 2023
The 16.00z models continued to produce too many low clouds this
evening. Due to this, opted to only go with a scattered mid-deck
of clouds overnight. In addition, removed the MVFR fog at KRST for
late tonight.
As a shortwave approaches the area on Tuesday night from the
Northern Plains, a broken high deck will move into the TAF sites
during the late afternoon and early evening of Tuesday.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Frost Advisory until 7 AM CDT Tuesday for WIZ034-042>044.
MN...NONE.
IA...NONE.
&&
$$
UPDATE...Boyne
DISCUSSION...Zapotocny/Kurz
AVIATION...Boyne
Area Forecast Discussion
National Weather Service Cheyenne WY
853 PM MDT Mon Oct 16 2023
.UPDATE...
Issued at 849 PM MDT Mon Oct 16 2023
No changes are needed for the short term forecast update this
evening. Tranquil weather conditions with weak winds less than
15mph are expected for most locations overnight, with a few
elevated gusts above that possible in the I-80 corridor of the
higher terrain in southeast Wyoming. The approaching weather
disturbance from the north will result in a few mid-level and high
clouds to swing in via northwest flow aloft. Seasonal overnight
lows in the 30s and 40s can be expected, with a couple locations
in the foothills seeing a morning low of only 50 degrees by
daybreak Tuesday.
&&
.DISCUSSION...(Tonight through Sunday)
Issued at 215 PM MDT Mon Oct 16 2023
Key Messages:
1) Well above normal temperatures today and more so Tuesday with
+10 to +20 degrees above normal for high temperatures.
2) Increased wind gusts expected Tuesday afternoon through
Wednesday morning for 8500ft+ plus wind prone/gap wind areas.
High Wind Watch remains in effect. Light/High profile vehicles
should expect challenging driving conditions in select locations.
3) Dry cold front sweeps through Wednesday with returning warmth
and above normal temperatures late week into the weekend. Next
best chance of precipitation will be early next week.
Weather Discussion: RAP analysis combined with latest satellite
water vapor imagery shows ridge of high pressure over the central
and southern Rockies to Intermountain west. This is leading to
pleasant temperatures in the 60s and 70s across the region this
afternoon. Temperatures are expected to be another 5 degrees
warmer tomorrow with slight increase in H7 temperatures in
combination with compressional heating and better downslope wind
mixing ahead of quickly moving Alberta clipper system. Winds will
start to increase as H7-H5 heights tighten quickly Tuesday
afternoon and overnight and ease by Wednesday morning. A High Wind
Watch remains in effect for the Laramie Range/foothills plus
Arlington/Elk Mountain. NBM ensembles indicate a 30-60% chance of
near 50 mph gusts, especially for the higher terrain of the
Laramie Mountains and the Snowys and <10% for gusts greater than
48 knots. NBM 4.2 tends to underforecast winds and looking at the
75 to 90 percentiles, these tend to perform better. Tilted wind
forecast towards these values along with CAG/CPR gradients
increasing above 45-50 dam and peaking in the low 60s. This
typically results in brief wind gusts in the 55-65 mph range.
Deterministic GFS output also indicates a band of 50 knot H7 wind
as well. Will give next shift final word on any possible upgrades
to the High Wind Watch. With the wind component and above normal
temperatures comes elevated to near-critical fire weather
conditions as well. See more below in the fire weather discussion.
Winds will decrease post Pacific cold front that will sweep
through late Tuesday night into early Wednesday morning. H7
temperatures fall from +10-12C to -2C to +2C from Tuesday morning
to Wednesday morning. Highs Wednesday will be 10-15 degrees
cooler but still near average climate wise. The stronger closed
low Alberta clipper system will shift quickly east to the Mid
West and Great Lakes late Wednesday into early Thursday. The
Pacific airmass will not be terribly cold and most of the High
Plains should still remain above freezing through the weekend for
lows. Longwave ridging with weaker NW flow transitioning to more
zonal flow into the weekend will rebound H7 temperatures into the
+8C to +10C range once again with above normal temperatures and
dry conditions persisting. SW flow aloft will more likely early
next week as a deeper trough shifts across the western CONUS per
several deterministic model envelope solutions. To far out for
specifics but next best chance for precipitation and cooler
temperatures will be early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday afternoon)
Issued at 545 PM MDT Mon Oct 16 2023
Upper level ridge axis currently over the Rocky Mountains will shift
east into the Great Plains tonight. The next surface cold front is
forecast to push into Wyoming late on Tuesday, mainly leading to
increasing winds ahead of the front and high clouds.
HAZARDS/WEATHER TRENDS: VFR conditions expected to continue through
Tuesday afternoon. Aviation impacts will be limited to gusty winds
in the afternoon hours (18z to 00z), with gusts up to 35 knots
possible at KRWL, KLAR, and KCYS...and up to 25 knots for the
western Nebraska terminals.
&&
.FIRE WEATHER...
Issued at 215 PM MDT Mon Oct 16 2023
Elevated fire weather conditions today with near-critical
conditions Tuesday. Wind gusts will increase Tuesday afternoon,
especially across the higher terrain above 8500ft and in the
wind prone areas. Sustained winds will increase upwards of 35
to 45 mph with gusts in the 55 to 60 mph range. Relative humidity
values will remain above 15 percent in these areas but still be
in the 20-30 percentiles. No fire weather watches or ref flag
warnings expected at this time but with this wind and cured/dry
grass fuels, a quickly moving fine fuel fire could become an issue
quickly.
A dry cold front will pass through the region Wednesday and
increase humidity values. A warmer and dry trend continues
through the late week into the weekend.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Watch from Tuesday afternoon through late Tuesday
night for WYZ106-110-116-117.
NE...None.
&&
$$
UPDATE...BW
SHORT TERM...JSA
LONG TERM... JSA
AVIATION...TJT
FIRE WEATHER...JSA
Area Forecast Discussion
National Weather Service Grand Rapids MI
1030 PM EDT Mon Oct 16 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 1029 PM EDT Mon Oct 16 2023
A clearing trend is trying to take place from north to south at
this time. A low confidence forecast with regard to clouds
overnight as stated below in the aviation discussion from a few
hours ago. The flow is out of the north tonight which is usually a
drying / scattering out type of flow due to some small downsloping
affects and the fact that it is not off the water directly. So,
trend is currently for some continued clearing, but model data
does not completely support this idea. Based on cloud/RH model
blends input into our gridded database we are using a partly
cloudy forecast for tonight. Removed some very small pops in the
forecast near Lake Michigan as it does not appear we will see any
light rain shower activity overnight. Lows tonight mainly in the
middle to upper 30s.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 250 PM EDT Mon Oct 16 2023
- Challenging cloud forecast tonight
Satellite trends show clearing going on over parts of Northern
Lower MI. With the northerly flow in place, some of this clearing
may make it into mainly northern parts of our forecast area. HRRR,
NAM and HREF forecasts indicate that any clearing should be brief
with the clouds filling back in. However the are not handling the
amount of clearing going on up north very well. If we do clear off
for any period of time, we may generate stratus/fog. Thus we will
maintain the mostly cloudy/cloudy wording in the forecast. Temps
will need to be lowered if the clearing persists for any period of
time.
- Risk for a few sprinkles Tuesday
A band of lake effect clouds/light showers will move inland
Tuesday morning, diminishing as it does. There is a little lift in
the cloud layer seen in the models Tuesday so, a few sprinkles may
occur. Based off of forecast soundings, the inversion height is
shown to be up around 5k ft so the moisture depth will be quite
limited. Most locations will not see measurable precipitation so
POPs will be kept at 20 percent or lower.
.LONG TERM...(Wednesday through Monday)
Issued at 250 PM EDT Mon Oct 16 2023
- Rain Returns through the latter half of the week -
The long range period begins with a positively tilted ridge
building over the region. This will allow for a fairly clear and
cold night into Wednesday morning.
Wednesday will see clouds mix in from the approaching system.
However there will be southerly flow bringing in warm air, allow
for daytime highs into the low 60s.
Any fair weather will be short lived as a deepening upper level
low will move through the Great Lakes through the latter half of
the week. An upper low will move through southern Lower Wednesday
nigh into Thursday amplifying a long wave trough. As that trough
digs through the region expect for some instability which could
allow for some showers and storms Thursday. The upper level jet is
in good position to allow for storm development. Along with this
will be a cold pool aloft behind the previous mentioned warm air
advection. This could allow for a hail risk, especially given the
moisture present.
The upper level low will slowly make its way through the region
making for a dreary second half to the week. Cold moist flow will
persist giving southern Michigan chances for precipitation through
the weekend.
PoPs eventually trend lower by Sunday as the main energy within the
big upper trough shifts toward New England and our low level flow
goes northerly. However strong cold advection pattern with H8 temps
falling to -5C will probably keep some clouds around and support
lake effect showers hugging the coast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 723 PM EDT Mon Oct 16 2023
Over the past few hours, some holes in the MVFR ceilings opened up
between Grand Rapids, Muskegon, and Big Rapids. There have been
more recent patches of cloud redevelopment within this area of
clearing, so it remains an open question how long this clearing
will last and how far south it will spread.
This is a fairly low-confidence forecast regarding the timing for
ceilings to redevelop near and north of MKG/GRR, and also when
exactly the ceilings will be above or below 2000 feet at any
location. Leaning mainly on the HRRR and RAP, it seems more likely
to expect ceilings below 2000 feet tonight through morning (with
temporary improvements above 2000 possible), and optimistically
the prevailing ceiling rises above 2000 feet for Tuesday
afternoon. Though, the opposite could be true near Lake Michigan.
Cloud tops between 3000 and 5000 feet will be right around 0
degrees Celsius, so icing concerns will be pretty low, and any
light precipitation that forms on Tuesday should be more drizzly
than anything.
&&
.MARINE...
Issued at 250 PM EDT Mon Oct 16 2023
The conditions have fallen to under Small Craft Advisory levels
with South Haven now down to 3.0 ft as of 2 pm. We do not
anticipate any increase in the winds or waves this evening. As a
result, the Small Craft Advisory will be cancelled.
The winds and waves will be on the increase Wednesday as a frontal
system approaches from the west. Southerly flow will strengthen
leading to building waves, especially for Little and Big Sable
Points given the longer fetch there. Headlines will likely be
required.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...Duke
SHORT TERM...MJS
LONG TERM...Ceru
AVIATION...CAS
MARINE...MJS
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
955 PM EDT Mon Oct 16 2023
.SYNOPSIS...
Surface high pressure will provide dry weather through the
middle portions of this week. The next frontal system brings
rain back into the forecast Thursday and Friday, followed by a
return to below normal temperatures for the weekend.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Overcast skies will prevail through the near term period area-
wide with just a few sprinkles possible from central through
south-central OH through midnight. With the blanket of
stratus/stratocu and light NW winds around 5kts being
maintained, temps will only dip into the mid 40s.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Surface ridge will be nearly overhead Tuesday, then shift off to
the east Tuesday night. This will bring a southerly wind shift
late. The 12Z HRRR shows a few isolated light showers
associated with a weak shortwave to the north. However, the
preponderance of guidance keeps things dry... so outside of some
river valley fog, expecting quiet weather to continue.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Increasing clouds and breezy conditions can be expected Wednesday as
mid and high moisture arrives and the pressure gradient tightens
between departing high pressure and the next low pressure. Showers
and a few thunderstorms are forecast for Thursday and Friday when
the low and cold front will be sweeping across the Great Lakes and
Ohio Valley. Winds gusting to 30 knots are likely to accompany the
showers on Thursday. Showers undergo a diminishing trend from west
to east on Saturday and Sunday as the low pressure system tracks to
the East Coast. Dry weather may be observed on Monday under high
pressure arriving from the northwest.
Warm advection and favorable mixing ahead of the low will boost
temperatures into mid and upper 60s on Wednesday and Thursday. Highs
will fall back to the upper 50s to lower 60s Friday through Monday
in the cooler flow behind the low.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
While CIGs have transitioned to mainly VFR, some patches of MVFR
clouds will linger about central OH sites of KCMH/KLCK for an
hour or so before conditions trend VFR area-wide for the
remainder of the overnight. There are some indications, however,
for some MVFR clouds to develop after daybreak once again before
transitioning back to VFR by 18z or so. Confidence on this
occurring is not overly high, but given the pattern and depth of
LL moisture availability, do think that at least a several hour
period of MVFR CIGs will once again be possible, especially
between 14z-17z.
Light NW winds around 5-7kts will be maintained for the
overnight before going more westerly past 15z. Light/VRB winds
are expected by/past 00z Wednesday.
OUTLOOK...No significant weather is expected.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...
NEAR TERM...KC
SHORT TERM...
LONG TERM...Coniglio
AVIATION...KC
Area Forecast Discussion
National Weather Service Marquette MI
746 PM EDT Mon Oct 16 2023
.SHORT TERM...(Through Tonight)
Issued at 316 PM EDT MON OCT 16 2023
Key messages:
- A quiet night on the way with uncertain cloud cover affecting low
temps.
Water vapor imagery and RAP analysis show ridging over the Rockies.
Ridging also extending from northern Ontario across Hudson Bay is
the decaying massive positive height anomaly that had been centered
w of Hudson Bay late last week thru the weekend. Combined with
troffing extending from the Canadian Maritimes to the Gulf Coast,
northerly flow once again dominates the Upper Great Lakes today.
Shallow moisture trapped blo inversion based at around 3kft
continues to support low cloudiness, aided by Lake Superior. Despite
the shallowness of the moisture and despite lake sfc to base of
inversion delta-T at around 11C, patchy sprinkly/drizzly pcpn
redeveloped again early this morning into n central Upper MI in a
zone of slightly convergent low-level flow over Lake Superior.
Similar to yesterday, this pcpn began to diminish early in the aftn.
With the shallowness of the moisture, daytime heating is much more
effectively mixing out the stratus today. Skies have almost totally
cleared n and e of Lake Superior and also from s central Upper MI
into far eastern Upper MI. Where sun is making an appearance, temps
have risen into the low to mid 50s F. Under the clouds, temps are in
the mid 40s F.
Expect the last of the drizzly pcpn to end in the next couple of
hrs. How the cloud situation plays out tonight is uncertain. Further
clearing is anticipated over the next few hrs as solar insolation
does its work mixing out moisture. However, once we lose the
heating, stratus will likely expand once again under light low-level
northerly flow backing to nw to w. Conservatively lowered temps
where part of the night should see limited cloud cover s central and
e. If clouds are delayed or fail to redevelop, mid/upper 20s F will
be common. Otherwise, min temps should range thru the 30s F to
around 40F tonight. Winds will fall off to calm for much of the fcst
area as sfc high pres ridge arrives.
.LONG TERM...(Tuesday through Monday)
Issued at 318 PM EDT MON OCT 16 2023
Key Messages:
-Significant weather is not expected this week, although widespread
light rain is expected starting the middle of this week.
-Above normal temps for middle of the week trend to below normal by
this weekend.
-Still some uncertainty in this weekend, but light precip should be
expected from either lake-enhanced/effect showers or passing clipper
systems.
0 and 12z guidance packages continue to suggest good agreement on
the coming pattern this week, but begin to diverge on key features
in time and space for the weekend. The ridge slowly building into
the region today will linger Tuesday before focus shifts to a
clipper diving southeast through CONUS beginning Tuesday night. The
result will be a dry Tuesday with seasonable temps in the low 50s,
but increasing rain chances and warmer conditions Wednesday as the
clipper approaches the Upper Great Lakes. 850mb temps are expected
to climb to 6-8C during the day under southerly flow. With cloudy
skies across the region, daytime highs should climb into the mid-
upper 50s, maybe near 60F in the traditional downslope prone areas.
There are still minor spatial differences in the clipper`s surface
low as it tracks through the Minnesota and the Upper Great Lakes.
This will likely impact precip onset times Wednesday and thus, where
the system`s dry slot ends up as it moves through. Generally though,
increasing isentropic forcing ahead of the low will support showers
spreading across the region Wednesday afternoon or Wednesday night.
The low looks to track somewhere between middle Wisconsin and Lake
Superior Wednesday night and Thursday, followed by a brief period of
lake enhanced and/or effect showers off of Lake Superior Friday.
A cold front embedded in the longwave trough moving through central
North America is progged to immediately follow the clipper, bringing
with it increasing cold air advection. There`s been good agreement
on this general idea, but guidance appears to be flipping back and
forth on how cool the airmass will be. This appears to have a lot to
do with the timing and strength of the next shortwave/clipper that
guidance suggests will drop southeast from Canada into our forecast
area or Wisconsin Friday or Friday night. The faster solutions also
appear to be the most southern and allow 850mb temps to fall to ~-4C
between the systems while the faster while the slower options cool
things to near 1C while bringing the low directly through the UP or
further west. With Lake Superior hovering near 10-11C, this will
likely impact the type of showers to expect on Friday.
Beyond Friday, another clipper/shortwave looks possible Saturday or
Sunday. Much like the preceding system, there`s a good bit of
uncertainty and the degree of cooler air aloft. Where confidence is
highest though is that I`m expecting to trend toward cooler than
normal conditions this weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 735 PM EDT MON OCT 16 2023
A cool northerly flow across Lake Superior will continue to support
lake effect cloudiness, aided by upsloping as MVFR cigs are
likely to prevail at least into Tuesday morning. Light winds
backing to the sw could allow IWD to improve to VFR late
tonight/early Tuesday morning. Advection of drier air probably
won`t clear out the low clouds until mid-late Tuesday afternoon
at CMX and SAW.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 318 PM EDT MON OCT 16 2023
Ridging and calm winds over Lake Superior should be expected into
Wednesday when an approaching system from the west supports winds
increasing to near 20kts by afternoon. Recent guidance suggests the
low could be weaker then previously thought and its possible
stronger winds of 20-25kts won`t be realized on Lake Superior until
Thursday when winds shift around to the north and cooler air aloft
begins filtering in over the warmer lake. At this point, expect
winds to increase to 25-30kts and persist Thursday night, slowly
decreasing from west to east. There`s a good bit uncertainty beyond
this clipper, but its looking like a few more weak clippers may move
through the Upper Great Lakes this weekend with a cooler airmass
aloft. This would likely support winds of 20-30kts through the
weekend.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...JTP
AVIATION...Voss
MARINE...JTP
Area Forecast Discussion
National Weather Service Phoenix AZ
432 PM MST Mon Oct 16 2023
.UPDATE...00Z Aviation Discussion.
&&
.SYNOPSIS...
Well above normal temperatures will continue this week as high
pressure predominates across the Desert Southwest. Near or record-
breaking heat is possible, particularly in the Phoenix area each
day. Cooler conditions are anticipated during the weekend as the
high weakens and shifts eastward, though the above normal
temperatures will likely persist until early next week.
&&
.DISCUSSION...
Latest RAP streamline analysis indicates anticyclonic flow
across the Desert Southwest. Embedded within the ridge are two
smaller features: a vort max near Rocky Point and a weak short-
wave trough approaching the Baja Peninsula. Latest water vapor
imagery reveals somewhat higher mid-level moisture is being pulled
northward around the vort max into southern Arizona.
Nevertheless, the ridge is the predominant feature, resulting in
strong positive height anomalies and well above normal
temperatures. Temperatures this afternoon have already reached 103
degrees at Sky Harbor Airport which breaks the previous record of
102 degrees set in 2020.
After a relatively warm start to the day, slightly cooler
conditions are anticipated Tuesday as the aforementioned upper low
migrates eastward. Meanwhile, steeper lapse rates associated with
the vort max will provide favorable conditions for isolated
convection though latest trends in the HREF indicate any potential
will be relegated to far southeastern Arizona and the Mogollon
Rim.
Latest NBM remains consistent indicating little spread in
temperatures and a continuation of the well above normal
temperatures through at least Saturday. Temperatures will rebound
late in the week as another ridge amplifies across the western
CONUS and there is at least a 50 percent chance of at least tying
the daily record highs in Phoenix Thursday and Friday. Thereafter,
a gradual cooling trend is likely as the ridge weakens and slides
eastward. A return to near normal temperatures is then possible
by Monday as a trough moves into the Great Basin, however there is
some uncertainty with regard to the timing and magnitude of the
cooling.
&&
.AVIATION...Updated at 2325Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
VFR conditions will prevail throughout the forecast period. Winds
will be light and variable this evening, with occasional westerly
winds AOB 5 kts possible. Otherwise, diurnal patterns will resume
with another period of southerly crosswinds expected tomorrow
afternoon before the typical afternoon west shift. Clear skies
will continue until FEW high cumulus clouds begin to build into
the region tomorrow afternoon.
Southeast California/Southwest Arizona including KIPL and KBLH:
VFR conditions will prevail throughout the forecast period. A
brief period of variable winds late this afternoon will be
followed by a westerly component at KIPL and a northwesterly
component at KBLH this evening. Speeds will remain AOB 5 kts.
Clear skies will continue until FEW high cumulus clouds begin to
build into the region tomorrow morning.
&&
.FIRE WEATHER...
Dry conditions will persist through the week as wetting rainfall
chances continue to be absent from the forecast. Temperatures will
hover in a much above normal category this week with readings
around 10F greater than the seasonal average. Cooler temperatures
are not expected to settle into the region until this upcoming
weekend. Minimum afternoon humidity values will generally range
between 15-25% across the high terrain of far eastern districts,
but only 10-15% elsewhere with periods of single digit humidities
likely. Overnight recoveries will mostly be poor to fair at only
20-40%. Winds will mostly remain light with only limited afternoon
upslope gusts.
&&
.CLIMATE...
Record high temperatures this week:
Date Phoenix Yuma El Centro
---- ------- ---- ---------
Oct 16 102 in 2020 106 in 1958 103 in 1958
Oct 17 102 in 2009 104 in 1959 102 in 2009
Oct 18 103 in 2003 103 in 1959 102 in 2003
Oct 19 101 in 2003 105 in 2003 103 in 2003
Oct 20 103 in 2003 105 in 2003 103 in 2003
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Hirsch
AVIATION...Leffel
FIRE WEATHER...Young/18
CLIMATE...Young/18