Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/16/17
Area Forecast Discussion
National Weather Service La Crosse WI
639 PM CDT Mon May 15 2017
.SHORT TERM...(This evening through Tuesday)
Issued at 233 PM CDT Mon May 15 2017
Complex scenario this afternoon into the overnight concerning
thunderstorm coverage and severe potential. As of 15.19Z, there is
a narrow band of showers and thunderstorms from the Twin Cities to
La Crosse to Richland Center along the leading instability gradient.
These storms are producing some pea hail and brief heavy rain,
but are otherwise not expected to produce widespread severe
storms as they lift northeastward this afternoon.
For much of the morning, convection allowing models (CAMs) were
showing additional convective development by mid-afternoon across
south-central MN into northern IA within 1500-2500 J/kg MLCAPE
instability plume (surface dewpoints mid 50s to mid 60s) and 30 to
40 kts of 0-3 km shear as a weak short-wave lifted across the
region. Latest HRRR/ESRL HRRR now appear to be backing away from
that idea somewhat, or least delaying it until late afternoon/early
evening, so overall confidence not as high as preferred this
close to a potential event. If storms do develop, instability/shear
profiles support large hail and damaging winds for areas mainly
south of I-90. Farther north, severe potential is more limited.
A second round of showers and thunderstorms is possible later this
evening and into the overnight as an ill-defined surface warm
front currently draped across central IA is forecast to lift
northward with a strengthening low-level jet. Elevated storms
north of the front could produce hail, but freezing levels around
12-13 kft may be a limiting factor for severe hail. Perhaps a
greater threat will be locally heavy rainfall with training
potential and PWATs around 1.5 inches, although placement of this
precipitation is uncertain and dependent on the evolution of
storms this afternoon. If, and it`s a big if, the warm front can
move far enough north early this evening and encounter a more
unstable/pristine, moisture-rich boundary layer, cannot completely
rule out an isolated tornado or damaging winds. Confidence in
this scenario is very low.
Warm front should lift north of I-90 by 12Z Tuesday, allowing for
some lingering morning convection mainly north of I-94. Still
expect a drying trend into the afternoon with periods of sunshine.
Atmosphere becomes well capped with 925 hPa temperatures rising
to between +21 and +24 Celsius. Assuming there is clean window
with more sun than clouds, temperatures are likely to rise into
the mid to upper 80s, but still cannot rule out some locations
reaching 90 degrees. Tuesday still looking breezy to locally windy
with roughly 30 to 35 kts in the well mixed boundary layer. This
will result in frequent southerly gusts up to 35 mph, especially
west of the MS River.
.LONG TERM...(Tuesday night through Monday)
Issued at 233 PM CDT Mon May 15 2017
Shower and thunderstorm chances return Tuesday night through
Wednesday as a negatively-tilted 500 hPa closed low lifts
northeastward from the Central Plains to the Upper Midwest.
Despite strong shear, severe potential looks iffy at this point
with a dirty warm sector. If substantial clearing/heating can
occur ahead of the eastward advancing cold front, some severe
storms will be possible. Latest GFS/NAM/ECMWF continue to show
that the highest QPF will fall along and north of the surface low
track from central MN into northern WI. Highs Wednesday will be
cooler, generally in the 70s region-wide.
Should see a brief dry period on Thursday with short-wave ridging
aloft, although temperatures will be dropping into the 60s for
highs. Precipitation chances return Friday into the weekend as a
broad trough with multiple short-waves takes up residence across
the the western two-thirds of the CONUS. Instability generally
remains south of the forecast area, so thunder activity is
unlikely. Temperatures will also be unseasonably cool with daily
highs in the upper 50s to lower 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 639 PM CDT Mon May 15 2017
Scattered showers and thunderstorms are expected at the taf sites
tonight. MVFR to IFR conditions are possible in and near any
storms. This activity should lift north of the TAF sites after
10Z. VFR conditions are then expected.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Rogers
LONG TERM...Rogers
AVIATION...Wetenkamp
Area Forecast Discussion
National Weather Service Bismarck ND
919 PM CDT Mon May 15 2017
.UPDATE...
Issued at 912 PM CDT Mon May 15 2017
Weak convective elements are increasing across west central and
southwest North Dakota indicating vertical motion is becoming more
widespread this evening. Updated the POPs with the HRRR time lag
ensemble guidance and this appeared to capture the convective
trends with higher chances across much of central and southwest
North Dakota this evening into the early morning hours.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 150 PM CDT Mon May 15 2017
The main focus for the short term is thunderstorm chances this
evening and overnight.
Strong southwest flow aloft with an upper level jet streak moving
into the Northern Plains and a lee trough will provide the focus
for showers and thunderstorms this evening and overnight. Some
light showers were appearing on radar earlier today and there may
be some light sprinkles reaching the surface, but so far very few
sites have reported any precip at all. cloud bases at or above 10K
feet AGL likely resulting in mostly virga with a very dry low
level atmosphere in place thanks to dry surface high pressure
anchored over central North Dakota.
A more defined mid level trough will eject northeast tonight
across the central Rockies triggering the lee side surface low
to propagate eastward. The track of the mid level wave and sfc
low will favor likely POPs across all far northwest North Dakota
tonight. Far southern ND remains in the marginal risk area for
severe weather, with the more favorable chances across South
Dakota. There may be a narrow window across southwestern North
Dakota late this afternoon where a few strong storms could develop
as instability increases ahead of the approaching wave. Another
round of stronger storms may develop later tonight across
southern North Dakota in association with a strengthening low-
level jet. The main threats are gusty winds and small hail.
.LONG TERM...(Tuesday night through Monday)
Issued at 150 PM CDT Mon May 15 2017
Models have trended more dry as they have moved the storm track
mid to late week farther to our south, with a large surface high
pressure area building south into the Northern Plains Thursday -
Friday. GEFS plume forecasts have also trended towards less QPF
this week. POPs were lowered accordingly. The other impact besides
drier weather will be cool temperatures accompanying the surface
high. Forecast highs will range in the 50s to low 60s. The threat
for frost will also increase as overnight lows are forecast in the
30s Thursday morning through next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 912 PM CDT Mon May 15 2017
Widespread showers and scattered thunderstorms are expected
KDIK-KMOT-KBIS-KJMS through early morning followed by
stratification of the precipitation late tonight. MVFR conditions
expected KDIK-KBIS-KJMS between 10z-14z. Otherwise VFR.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...WAA
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...WAA
Area Forecast Discussion
National Weather Service Cleveland OH
921 PM EDT Mon May 15 2017
.SYNOPSIS...
High pressure will remain in control across the eastern Great Lakes
through tonight. A warm front will lift north through the region
Tuesday afternoon. Low pressure will track northeast across the
western Great Lakes Wednesday night through Thursday, with an
associated cold front sagging south into the area.
&&
.NEAR TERM /THROUGH TUESDAY/...
Just some minor changes to the forecast for the overnight hours.
Latest short term guidance including the HRRR and RUC take the
convection over Lake Michigan just to the north of the area
later tonight. This activity should continue to diminish but a
few stray showers cannot be ruled out. Already had a small
mention for northern areas and have left alone. Temps appear on
track too as clouds will be slow to arrive in the east.
Previous...Relatively quiet near term period as high pressure
remains centered across the eastern Great Lakes. Mainly clear
skies expected through the evening. Some uncertainty remains
with precip potential late tonight into early Tuesday. MCS
expected to propagate eastward from southern WI across southern
lower Michigan this evening through the overnight. Associated
MCV may bring some showers and an isolated thunderstorm to areas
near Lake Erie. Confidence is low at this time, and any
convection should be fairly isolated. Will maintain slight
chance pops late tonight through early tomorrow morning across
NE OH and NW PA.
MCV will exit the area by midday Tuesday, with quiet weather and
mostly sunny to partly cloudy skies expected. No major changes to
temperatures tonight into Tuesday from previous forecast. Mid 80s
are possible across the western half of the area tomorrow as a warm
front lifts north through the area.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
Upper level ridge axis begins to shift east of the area on Wednesday
as a trough lifts out of the Plains towards the western Great Lakes.
The atmosphere will be well mixed on Wednesday with breezy southwest
winds gusting to 25-35 mph. Many sites will experience the warmest
temperatures of the year so far as all areas climb into the mid and
upper 80s.
The surface low will occlude as it approaches Wisconsin then slides
east along the baroclinic zone draped across the central Great lakes
on Thursday. Deep layer moisture will overspread the area on
Thursday and will expect to see at least scattered coverage of
showers and thunderstorms with moderate instability developing. The
clouds and showers will keep temperatures several degrees cooler in
the lower 80s. The associated cold front is expected to push south
into the area on Thursday night before stalling somewhere across
central Ohio. Considerable model spread exists with respect to the
cold advection behind the front on Friday which could lead to a
large error in the temperature forecast. Continued with a middle of
the road forecast and will have to update as we approach based on
later model guidance. Will leave a low chance of showers and
thunderstorms in for Friday as well but this will also depend on the
location of the stalled front.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
Stalled frontal boundary will lift back north on Saturday as another
low pressure system tracks out of the Plains towards the Central
Great Lakes. Chances of showers and thunderstorms will ramp up both
as this boundary lifts north and then along the cold front that will
move through Saturday night into Sunday. Multiple rounds of showers
and thunderstorms will be possible but will need to refine timing.
Temperatures will trend warmer and may approach 80 but kept the
forecast conservative for now with a moist airmass and lots of
opportunities for showers. If we can manage a longer window of time
in the warm sector then temperatures could need to be raised.
&&
.AVIATION /00Z Tuesday THROUGH Saturday/...
VFR will prevail thru Tue as ridge of high pressure over the area
moves off to the east Tue. There is a small chc that some remnants
of convection from the upper midwest could drop ESE into the Lake
Erie area toward daybreak thru 18z Tue but the threat is too small
to mention.
OUTLOOK...VFR with only small chances for convective activity Thu
thru Sat.
&&
.MARINE...
High pressure over Lake Erie today will shift off the mid-Atlantic
coast on Tuesday as a warm front lifts north across Lake Erie. Good
marine conditions are expected through Tuesday with southwest winds
increasing into the 15 to 20 knot range on Wednesday. Should be able
to manage without a Small Craft Advisory through Thursday given the
offshore flow. Winds will shift around to the north/northwest behind
a cold front Thursday night into Friday. Will need to keep an eye on
strength of the front although currently waves are expected to
remain below Small Craft Advisory.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...Greenawalt
NEAR TERM...Greenawalt/Kubina
SHORT TERM...KEC
LONG TERM...KEC
AVIATION...Greenawalt
MARINE...KEC
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1159 PM EDT Mon May 15 2017
.AVIATION...
Increasing ascent north of an approaching warm front will sustain
the potential for shower/thunderstorm develop through the early-mid
morning hours. The limited amount of instability will favor simply
a low coverage of thunderstorms, with the greatest potential
existing from PTK northward. Predominant VFR conditions, exception
within any heavier convective showers/storms where brief IFR/MVFR
will be possible. Clearing skies as a warmer and increasing stable
environment arrives with the frontal passage on Tuesday. Southerly
winds turning gusty within the warm sector and greater daytime
mixing ensues, with gusts in the 20 to 25 knot range attainable by
afternoon.
For DTW...Low probability for TSRA to enter the airspace during the
early-mid morning period. Greater potential will exist north of the
terminal.
//DTW THRESHOLD PROBABILITIES...
* Low confidence in thunderstorms late tonight.
* Low confidence in ceilings aob 5000 feet Tuesday morning.
&&
.PREV DISCUSSION...
Issued at 840 PM EDT Mon May 15 2017
UPDATE...
Northeastward expansion of the burgeoning warm sector slated to
progressively take hold for the midweek period establishing an
extensive corridor of warm air advection from the central plains
into great lakes this evening. Initial wing of mid level
waa/isentropic ascent sustaining a lead band of convective showers,
with a persistent thunderstorm complex anchored on the southern
flank. Recent HRRR guidance steadfast in retaining this precip
shield downstream and into our less receptive/more stable
enviroment. Ambient environment carries virtually no instability at
this stage, so maintainance of a thunder component will likely prove
difficult. Some degree of dimininishing mid level stability as the
accompanying theta-e gradient arrives may still allow for a few
rumbles of thunder.
Elongated zone of forced ascent under moderately unstable conditions
trailing this lead band will continue to support convective
development/expansion from southern WI back through Iowa. Steady
downstream propagation of this activity will sustain at least a
chance of showers/thunderstorms locally during the early-mid morning
hours. Severe thunderstorm risk remains minimal, given the clear
lack of meaningful instability to sustain organize convection and
the overall unfavorable timing. Convective chances diminish
quickly 11z-13z as the warm front lifts through.
Minor update forthcoming to simply tweak the timing and overall POPs
based on latest upstream trends and CAMs guidance.
PREV DISCUSSION...
Issued at 349 PM EDT Mon May 15 2017
DISCUSSION...
Ridge axis over the western Great Lakes will slide through the
region tonight while deepening west coast trough drifts across the
Rockies. The trough then stalls and sends a series of waves up and
around the top of the ridge which will settle over the eastern conus
mid week. One of the first waves tonight will lift through the
midwest with a warm frontal extension lifting through SE lifts
through southern MI later tonight between about 06-12Z. A band of
isentropic ascent and fgen along the front will spread scattered
showers, and possibly elevated thunderstorms, through Lower MI. Best
forcing will be further NW closer to the low whereas the band
extending further SE will be impacted more by the stable ridge. So
question is, how far SE along the front will showers develop? Best
forcing will be over MBS extending down to PTK, though some hires
models do show activity all the way to Detroit. One thing to watch
out for will be upstream activity and possible MCV over IA and
northern IL that will track toward SW Lower MI. Most models show
this following the instability gradient southeastward while
weakening, thus never reaching our CWA. Overall, with lack of much
CAPE, and meager mid level lapse rates, expect band of showers with
possible embedded thunderstorms though these storms are not expected
to be severe.
Warm frontal passage will open the door for deep layer SW flow into
the area on Tuesday. Mixing to near 850mb will have the potential to
mix down winds up to 20 to 30 mph. This will also bring a good surge
of warmer air into the area with 850mb temps rising into the mid
teens. Good mid May sun with WAA should allow temps to reach into
the low 80s for nearly all locations. Area will remain dry with
strong cap in place and all the forcing aligning further west. Low
temps will stay elevated in the low to mid 60s Tuesday night with
lack of decoupling and winds staying elevated.
Wednesday will be even warmer with continued WAA and temps already
starting in the 60s. Clouds will be on the increase later in the day
as upstream waves inches further east. Area will remain dry through
most of Wednesday and Wednesday night but some showers and
thunderstorms could start moving back into the area overnight as the
next shortwave trough rotates up through lower MI.
More active weather period will be in store to round out the second
half of the week into the weekend. A series of shortwaves will move
across the region as troughing moves in starting Wednesday. The
first low will move up across the northern Great Lakes late
Wednesday into Thursday. Weakening of the low will occur through
Thursday bringing slight chances for rain/storms. The next system
looks to have a little better dynamics as it moves up from the
plains this weekend. Temperatures will once again reach into the
lower 80s on Wednesday before cooling back into the 60s Thursday as
cold air filters in behind cold front. Temps then moderate back to
near 70 degrees for the weekend.
MARINE...
Light winds will continue through the evening hours as high pressure
slowly exits East. Southerly flow will then increase somewhat late
tonight into Tuesday as a warm front lifts north through the area.
Showers and thunderstorms will likely accompany the warm front,
particularly over Lake Huron. While south to southwest flow will
gust to around 20 knots on Tuesday, the increasingly warm air will
create a rather stable layer over the cooler waters of the Great
Lakes. The highest gust potential, reaching near 25 knots, will
exist along the immediate shoreline on Wednesday and Thursday as
decent gradient flow leads to gusty conditions over the land.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....MR
UPDATE.......MR
DISCUSSION...DRK/SS
MARINE.......SF
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Grand Forks ND
952 PM CDT Mon May 15 2017
.UPDATE...
Issued at 952 PM CDT Mon May 15 2017
Adjusted POPs and QPF slightly. Latest 00Z NAM as well as the most
recent HRRR and RAP runs have been trending back south with the
heaviest precip amounts. Tweaked amounts a bit back south but will
hold off and let a few more high res runs as well as the 00Z GFS
come in before making huge changes. A few showers are starting to
drift into the far western Devils Lake basin so adjusted POPs
upward in the next few hours in that area.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 320 PM CDT Mon May 15 2017
Challenges over the next 24 hours will be precipitation placement,
intensity, thunder or showers, and amount. Warm frontal boundary
will lift north into the southern forecast area late this evening
and overnight. Along the elevated boundary showers will develop as
850mb wind convergence spreads north and east across the southern
valley and west central Minnesota lifting into the Park Rapids
and Bemidji areas towards dawn.
A second area of convective activity is expected to develop in
the high plains and track to the east reaching the Devils Lake
basin around 12Z and into the valley 15 to 18z. Some uncertainty
exists on placement of the SFC low tomorrow and its strength.
Ahead of the low up to 1k J/kg of cape appears to develop within a
modified warm sector. Hi-res model guidance bring the low across
tech FA and heaviest placement of rainfall along and north of the
highway 200 corridor with the GFS and EC 12z model solns heavier
across the southern FA. Highest amounts look to be around and inch
with upwards of an inch and a half...whereas other areas look to
range from a quarter to half inch.
.LONG TERM...(Tuesday night through Monday)
Issued at 320 PM CDT Mon May 15 2017
Southwest flow aloft will continue to keep things active across the
area for midweek. Some lingering showers will be possible Tuesday
night from the system that moved through the area earlier in the
day. Tuesday night will also bring one last mild night before things
turn much cooler for the remainder of the week and through the
weekend.
On the heels of Tuesday`s system will be another quickly moving into
the Northern Plains. Models are in pretty decent agreement bringing
the main upper low through central/southern Minnesota, keeping the
best forcing and moisture across our far southeastern forecast area
(possibly even further southeast than that). Much of northeastern
North Dakota and the northern Red River Valley should see little
precipitation with this feature while the southern valley and into
west central Minnesota could see a bit more. Will continue to watch
for any northward shifts in the track which would pull rain chances
further north and west. Regardless of precipitation chances for
Wednesday, it will still be a dreary day with plenty of clouds and
wind, along with temperatures struggling to reach the 60 degree mark.
Cool surface high pressure building into the area from Saskatchewan
will gradually push any lingering precipitation chances to the east
by Thursday. The high should bring drier conditions to the area to
end the work week, although remaining cool with highs only in the
50s or lower 60s. Lows could dip into the mid 30s for parts of the
area but enough mixing should keep frost at bay Wednesday night.
Higher chances for frost look to be Thursday night with much less
wind (and clouds).
Another upper low could bring more chances for precipitation late
Friday and into the weekend but plenty of model disagreement remains
on the track of this system. Regardless, it will stay cool before
possibly warming back up to near normal temperatures by next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 647 PM CDT Mon May 15 2017
Some showers early on could impact the KDVL area during the
overnight hours but activity has been mostly mid level and it
should remain VFR. Lower ceilings will move in later tomorrow
along with more showers and a few thunderstorms, although which
TAF sites will be impacted by convection is still uncertain.
Ceilings will drop down to MVFR and then IFR, starting in the KFAR
area shortly after 12Z and spreading northward. Some of the
heavier cells could also impact visibility for brief periods but
too uncertain to put restrictions at this point. All but the
eastern TAF sites should improve back to VFR by the end of the
period. Winds will shift around from the southeast to east and
northeast, then eventually to the northwest as low pressure moves
through. Some of the northwest winds at the end of tomorrow could
gust to around 20 kts.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...JR
SHORT TERM...JK
LONG TERM...Lee
AVIATION...JR
Area Forecast Discussion
National Weather Service North Platte NE
631 PM CDT Mon May 15 2017
.UPDATE...
Issued at 548 PM CDT Mon May 15 2017
Forecast updated for Sheridan County as Severe Thunderstorm Watch
#215 in effect until midnight MDT.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 332 PM CDT Mon May 15 2017
The ACCAS on visible satellite across Scntl Neb represents a
weakness in the 700mb cap. The convection the models are generating
across Wrn KS this afternoon and tonight should develop upscale
along this weakness or "front" tonight. The models vary with the
track of the convection...some due north through Ncntl Neb and
others northeast clipping the eastern edge of Ncntl Neb.
The models in general suggest another area of thunderstorms tonight
across Northwest Neb. The location varies with the models.
Severe weather potential tonight is reasonably good. The SPC outlook
today and tonight is marginal for organized severe storm development
but don`t be fooled. Lapse rates are steep, moisture plentiful and
winds aloft are strong. Thus, it is believed that any organized area
of thunderstorms which forms, could produce severe weather...large
hail and wind damage.
By Tuesday morning the atmosphere should be capped once again. The
models drive another cold front through Wrn and Ncntl Neb in the
morning. This front should lift north in the afternoon and evening
and be the genesis for additional thunderstorm development mainly
affecting areas along and east of highway 83.
The severe weather potential Tuesday is higher. H700mb temperatures
fall into the mid and upper single digits celsius which is weak.
Increasing moisture and strong upper level dynamics emerging from
the upper level low across the Wrn U.S. should support storm
development along and east of a stationary front forecast to lie
somewhere across Cntl Neb. Severe weather could develop anywhere
along and east of highway 61 with the threat increasing eastward.
The models suggest storm development across the Nern Colo plains and
Scntl Nebraska which should lift north into Wrn/Ncntl Neb late in
the afternoon or evening.
.LONG TERM...(Tuesday night through Monday)
Issued at 332 PM CDT Mon May 15 2017
An initial round of strong or severe thunderstorms should move
through Tuesday night. SPC outlooks nearly all areas for marginal
risk of severe weather. The better instability is in just the
eastern edge of Ncntl Neb.
The first of Two upper level lows moves Tuesday night and Wednesday.
Strong cold air advection takes hold Wednesday with highs in just
the 50s and 60s. H700mb temperatures fall from 5C to near 0C
Wednesday and the operative precipe mode is showers. Isolated
thunderstorms might develop given the -15C to -18C temperatures at
h500mb.
A lull in the rain should develop Wednesday and and Thursday
morning. A second colder upper level lows moves across Thursday and
Friday. H700mb temperatures fall to 0C to -5C. Snow will develop in
eastern WY and perhaps a period of wet snow in Western
Nebraska...not unheard of in May. Rain/showers are expected most
areas Thursday and Friday.
Cold air remains in place next weekend with h700mb temperatures
below 0C. The guidance is trending colder Saturday morning with lows
near freezing across the Wrn Sandhills. Skies could clear out at
night and then cloud back up during the late morning.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 627 PM CDT Mon May 15 2017
Forecast challenge is convection as short term models differ in
the focus area and movement of convection overnight. Visual flight
rules expected through the period where model preference is the
RAP where convection in northwest Kansas will lift north into
southwest Nebraska, while additional convection in the northwest
Panhandle moves northeast to bring a chance of thunderstorms
throughout through 08Z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...TLK
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...19
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
903 PM CDT Mon May 15 2017
.MESOSCALE DISCUSSION...
903 PM CDT
Small, but fairly potent MCS continues to propogate east across
southwest WI and into far NW IL. Evening sounding from DVN
depicted some very impressive low-mid level lapse rates, though
boundary layer is cooling/stabilizing now with increasing SB/ML
CINH. Strong book-end vortex associated with this MCS is moving
straight eastward across southern WI. Recent radar observations
seem to depict some weakening/decrease in the organization of the
system, particularly the southern flank of the line over NW IL
where KDVN 88D shows outflow starting to outrun the line, likely
at least partially a result of it starting to encounter increasing
inhibition. Haven`t seen any appreciable warming of cloud tops yet
and given the mesoscale organization, concerned that damaging wind
threat (while slowly lessening) could continue into our CWA,
particularly the WI border counties.
Will continue to closely monitor trends the next 30-45 minutes to
determine whether watch box may need to be extended farther east
into especially northern portions of the Chicago metro area.
- Izzi
&&
.SHORT TERM...
236 PM CDT
Through Tuesday...
Convective chances and the potential for severe weather this
evening remain the primarily forecast concerns. Mid afternoon,
low pressure is analyzed over far western IA with a northward
advancing warm front stretching east to near DVN and then ESE
across VYS towards IND. Across the local area, dew points are
pooling in the upper 50s to low 60s near the warm front which in
combination with very steep mid level lapse rates associated with
an EML spreading east across the region is resulting in moderately
strong instability. Special 18Z RAOBs from DVN indicates around
1000 J/kg MLCAPE (2500+ SBCAPE), though it is well capped with
700mb temps near 10C. This capping inversion is expected to be the
primary limiting factor for convection locally through there
remains potential to overcome this if a sufficient cold pool can
develop this evening from upstream convection.
To our north, an MCV is noted moving ENE across MN into WI which
has been the primary focus for convection thus far today, though
is outrunning the better instability to the south. This wave
shouldn`t be much of a player for the local area, but if anything
may contribute to some weak mid level height rises in its wake
which could reduce or delay precip chances upstream.
Thunderstorms are expected to increase in coverage over north
central and northeast IA this evening as a low level jet begins to
intensify with storms expected to propagate east or east-southeast
along with instability gradient. Earlier runs of the HRRR as well
as the NAMNest indicated the potential for a bowing line of
thunderstorms to race across the northern half of the CWA but have
since backed off on convection altogether or shifted the threat
farther north. As mentioned earlier, moderate MLCIN is in place
across the warm sector and will be strengthened later this
evening as we move beyond our diurnal peak. Confidence in
thunderstorms occurring is not particularly high, and lowering
with each successive CAM run, though given the strong instability
and sufficient deep layer shear, if we are able to overcome the
cap there remains a reasonable risk we could see strong storms
with damaging winds the primary concern.
Warm front is expected to continue north across the Great Lakes
Tuesday with the local area falling well into the warm sector.
Temperature tomorrow afternoon are expected to push well into the
80 under mostly sunny skies. Tightening pressure gradient and
deep mixing will result in very breezy conditions. NAM/GFS
soundings indicate potential for mean gusts to around 30 kt mid to
late in the afternoon, with a few sporadic top of the channel
gusts into the mid 30 kt range.
Deubelbeiss
&&
.LONG TERM...
153 PM CDT
Tuesday night through Monday...
With a well established warm sector in place, focus will shift
back west to the plains, as the upper low (currently over Southern
California) will be shifting northeast into the plains. Tuesday
night remains mild as we maintain breezy southwest winds ahead of
the low. The compact upper low will proceed northeast to Minnesota
by Wednesday night, with a corresponding and seasonally strong surface
low taking a similar track across Iowa into Minnesota. With a deep
and fairly stacked upper low in place, we do expect there to be
ongoing convective activity to our west much of the day. There
will be several waves ahead of the low and an increasing
southerly low level jet that will steer at least a narrow ribbon
of fairly high precipitable water airmass in our direction, with
the most notable wave arriving late in the day. At this point the
more significant forcing may still remain to our west, but there
appears enough forcing at least across north central Illinois for
scattered showers and thunderstorms. As mentioned in the previous
AFD, the kinematic environment is highly favorable for organized
storms given the strength of the wind fields. The threat may be
the highest late in the day/evening as the forcing gets a bit
closer and the low level jet refocuses back southwesterly.
The airmass across our area will also feature dewpoints in the mid
to upper 50s, maybe higher, which if cloud cover from storms to
our west does not inhibit warming, could translate to 1000 J/KG of
CAPE as well. Much hinges on said cloud cover and on how far east
the stronger forcing will get. With the southerly low level jet
initially and better forcing west combined with these
thermodynamic concerns, a broad general thunder area remains in
place. Given the warm start and south winds should reach near or
above 80 in most locations (mid 80s east) even with any clouds,
with less clouds determining how windy we will be. Forecast
soundings suggest 30-35 mph wind gusts are plausible, and could be
higher if mixing is deeper, and in an unfavorable direction from
an aviation perspective.
The region remains under mild southwesterly flow on Thursday,
though high pressure to our northeast will steer a cold front
toward northeast Illinois late in the day, and depending on how
fast the front moves could bring another rapid cool down near the
lakefront. This boundary appears to serve as a renewed focus for
showers and thunderstorms ahead of another deep upper low across
the Rockies and high plains, with chances beginning somewhat low
but progressively increasing Thursday evening through the
weekend. Confidence remains on the lower side in this time frame
given uncertainty in how quickly this low will move east, but with
northeast low level winds expect conditions to feel on the cooler
side of normal at least for a few days, including
Friday/Saturday.
KMD
&&
.AVIATION...
For the 00Z TAFs...
A warm front lifting across the region this evening is resulting
in an isolated thunderstorms just northeast of Rockford early this
evening with more widespread convection blossoming across north
central and northeastern Iowa. Activity over northern Illinois is
expected to remain isolated under a modest capping inversion and
on the edge of any weak synoptic forcing and is not included in
the TAFs. Better forcing is in place across north central Iowa
where a low level jet is starting to intensify. The developing
convective complex in this area is going to be the primary concern
as we head into the late evening and overnight hours and it moves
east-southeast into northern Illinois. How far east and south the
line moves remains in question as it will be moving into a less
unstable and more strongly capped airmass with forcing gradually
waning late this evening as the LLJ veers and weakens. Have once
again pushed back timing of TSRA in the TAF, though did hedge a
little sooner than the extrapolated motion of the upstream storms
to account for some acceleration of the line as a cold pool
becomes better developed. There still remains some potential that
the line may dissipate before it reaches the terminals or may pass
just north of the terminals.
Winds will veer to the south overnight and to the south-southwest
Tuesday as the warm front lifts north of the region. Very gusty
conditions are expected through much of the day tomorrow, peaking
in the high 20 kt to around 30 kt range mid to late afternoon.
Wind gusts should diminish shortly after sunset.
Deubelbeiss
&&
.MARINE...
153 PM CDT
Several southwest to northeastward propagating low
pressure systems will take aim at the western Great Lakes region
this week, leading to a somewhat extended period of gusty south-
southwest winds. Currently high pressure over the central to
eastern Great Lakes will slowly drift to the east coast on
Tuesday. The first low will move form the central High plains to
Lake Superior later Tuesday, with the second later in the week
taking a farther east/southward track either over the upper
peninsula of Michigan or through northern Lake Michigan. Expect
winds to increase to 30 kt or so, with highest wave building on
the northern tier of the lake. Generally stable conditions should
preclude gale force winds most of the time. A trailing cold front
will move southeast on Thursday and clear the south end of the
lake by Thursday night. A period of strong northerly winds is then
expected to develop behind the front Thursday night into Friday
as high pressure builds eastward across Ontario and the northern
Lakes.
For the Illinois and Indiana nearshore waters, small craft
advisories will likely be needed by Tuesday afternoon as gusty
south winds develop. May be a bit of a lull later Tuesday night
though it will be very windy again during the day Wednesday, with
south-southwest gusts off of the warmer land perhaps 30-35 kts at
times.
KMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...3 PM Tuesday to 9 PM Tuesday.
&&
$$
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Area Forecast Discussion
National Weather Service Melbourne FL
1000 PM EDT Mon May 15 2017
.UPDATE...
Tonight...High pressure to the north will maintain an onshore wind
flow which will allow for mild overnight lows mostly in the upper
60s to lower 70s. There have been some cloud lines over the
Atlantic but moisture recovery has only been in the lowest levels,
so no isolated showers are expected yet. The HRRR has been showing
some low visibility across northeast Florida and the local WRF
indicates some over interior of east central Florida. With the
gradually increasing low level wind flow, think our current
depiction of patchy inland fog is okay. Little change to previous
forecast.
&&
.AVIATION...
Some MVFR ceilings and visibilities are possible for the interior
terminals again early Tuesday morning. East winds should gust to
around 20 knots towards midday along the coast and over interior
terminals by mid-late afternoon.
&&
.MARINE...
Tonight-Tue...High pressure to the north will slowly strengthen,
which will gradually increase east winds, with speeds getting near
15 knots by Tue afternoon. Seas 3-4 ft near shore wnd building up
to 4-5 ft well offshore by late Tue.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Forecasts...Lascody
Impact Wx...Blottman
Area Forecast Discussion
National Weather Service Marquette MI
808 PM EDT Mon May 15 2017
.SHORT TERM...(This evening through Tuesday)
Issued at 419 PM EDT MON MAY 15 2017
Large scale pattern features deep trough over western Conus with
flattening ridge downstream over middle Conus. Upper level jet is
present from the Rockies to south central Canada. At the sfc, main
low is in lee of the Rockies with warm front extending to southern
MN and southern WI. H85 trough is farther north across MN to western
Upper Michigan with main edge of higher h85 theta-e just west and
southwest of Upper Michigan. Warm and moist advection has brought
showers and isold tsra to west and southwest Upper Michigan through
much of the day. Parts of Gogebic county have seen over 1 inch of
rain and there was steady lighter rain into Ontonagon and Iron
county as well. Temps in those areas really were impacted with IWD
and LNL still in the 40s even at this hour. Elsewhere mid clouds
have spilled east gradually and temps have reached the 50s to near
70 degrees, warmest and driest over far east closer to departing sfc
high still over the lower Great Lakes.
Following radar trends and various short range convective allowing
models (CAMS), expect the area of showers over western forecast area
to slide toward central forecast area into early this evening.
Greatest elevated CAPE up to 1000 j/kg remains south and west of
Upper Michigan so widesread tsra not expected inot the evening for
most of Upper Michigan. Probably a better chance at seeing more tsra
over far west where upstream convection could slide across and since
that area is closer to higher h85 theta-e and elevated CAPE. Attn
later this evening is on convection lifting east north east out of
eastern MN. THis convection is firing along gradient of elevated
MUCAPE which RAP does show making a run into far scntrl forecast
area this evening. Have increased pops toward Menominee county.
Suppose there could be a few stronger storms make it that far north
but with greatest MUCAPE increase over southern WI instead of
farther north into WI, seems that the line of storms should tend to
weaken at least from a severe standpoint. Heavy rain certainly
possible this evening and heavier cores could also produce pea sized
hail with freezing levels around 10kft.
For later tonight, at least right now, models have trended toward
keeping most concentrated convection anchored closer to sfc warm
front lifting slowly north over southern MN to central WI. This
especially makes sense with the convection in the evening serving
to re- inforce cooling over northern WI which would help hold the
warm front to the south. Trimmed pops back after rain moves
through this evening. Do bring chance pops in late tonight into
Tue morning as the warm front tries to lift back to the north
running into h85 theta-e advection that will be ongoing along h85
front. Eventually whatever works through in the morning should
allow recovery in temps/humidity by Tue aftn with readings well
into the 70s and dwpnts nearing 60F over the west. Large scale
forcing will be minimal but the buildup of instability and any
warm air advection that focuses closer to the low lifting across
MN could lead to additional showers and thunderstorms especially
west in the aftn. SREF probabilities which keep severe probs well
to the south of here tonight show increase over west on Tue aftn.
SPC does have our western forecast area in marginal risk for
severe. Similar to tonight with the increasingly humid airmass,
all the tsra could produce heavy rain and will have to watch out
for any areas where tsra train over same areas.
.LONG TERM...(Tuesday night through Monday)
Issued at 430 PM EDT MON MAY 15 2017
After a quiet first half of May with blo normal pcpn, an active
pattern is setting up, somewhat reminiscent of the active pattern
that led to much above normal pcpn across the fcst area during Apr.
The main difference from Apr will be that the pattern over the next
week will be more transitional rather than being stable/persistent.
Trof currently over the western CONUS will slowly shift e to the
central CONUS this weekend then to the Great Lakes/Mississippi
Valley where it may hang up during next week in response to the
establishement of a ridge/positive height anomaly along the w coast
of N America and also over ne Canada. This trof will consist of two
significant pieces of energy, one currently over southern CA and the
other upstream along the BC coast. The first will lift out, reaching
the Upper Great Lakes on Thu. The second will drop into the
central/southern Rockies by Thu then lift into the Upper Great Lakes
late this weekend. Ahead of the first main wave, combination of the
instability and weaker shortwaves lifting ne will lead to clusters
of shra/tsra across the Upper Mississippi Valley/western Great Lakes
into Wed. The main wave will offer the potential of a more
significant organized pcpn event for the Upper Great Lakes later Wed
night into early Thu. After a dry period for at least part of Fri,
the second main wave will bring another round of pcpn for the
weekend. As for temps, after a preview of warm/more humid summer
type weather over the next couple of days, cool weather/blo normal
temps will return in the wake of the Wed/Thu system. Progression of
the mean trof to the Great Lakes/Mississippi Valley early next week
will then work to maintain an overall blo normal temp regime for the
fcst area thru next week.
Beginning Tue night...it appears warm front will lift n of Upper MI
as a shortwave and associated sfc low move from northern MN into
northern Ontario. Trailing cold front will approach western Upper MI
during the night with axis of instability shifting over the fcst
area. With warm front to the n, best potential of shra/tsra should
be over western Upper MI, closer to approaching cold front. With
mucapes in the 1-2k j/kg range, deep layer shear appears sufficient
for the potential of organized, svr storms. Shear progs, however,
are quite varying from model to model, so low confidence on svr
potential. It will be a warm night with humid air mass, precipitable
water of 1.25-1.5 inches/250pct of normal and southerly winds
limiting temp fall. Expect temps at some locations over the w to
stay above 60F.
Wed/Thu...attention turns to the vigorous shortwave lifting ne thru
the Plains on Wed, reaching southern MN Wed evening and the Upper
Lakes on Thu. Meanwhile, cold front should drift se into Upper MI on
Wed, setting the stage for sfc low pres associated with the
approaching shortwave to lift along the front Wed night/early Thu.
With precipitable water 250+% of normal, placement of the front will
be critical for determining where hvy rainfall will occur as the
wave lifts across the area. While not widely varying among model
guidance, there is enough difference in this critical feature that
pinpointing heavy rainfall area is not certain yet. For now,
consensus suggests front will be setup across central Upper MI,
supporting best chance of hvy rainfall across western Upper MI later
Wed and Wed night. Certainly could see widespread 1-2 inches of
rainfall with some local 3 inch amounts. Instability will be in
question Wed into Wed evening as it appears there may be
considerable cloud cover. Overall signal from all the models is for
less instability to be present on Wed compared to Tue. Still, there
will be the potential of svr storms near the cold front as it drifts
into central Upper Mi, conditional on heating/instability build up.
Lingering rain will diminish Thu and probably end for most locations
by evening. Max temps on Wed may show a large range, depending on
location of the cold front. May turn quite cool along Lake Superior
behind the cold front (temps falling to the 40s) while remaining
warm/humid (70s) ahead of it. Thu will turn much cooler across the
area as low pres/cold front exit. In fact, temps across the w and n
may hold to or fall to the low/mid 40s during the day.
Fri thru the weekend...the GFS/CMC are both quicker in advancing the
Rockies trof out into the Plains with lead ejecting energy bringing
shra back into Upper MI by late in the day on Fri. ECMWF remains
consistently slower, though it has shown a slightly faster trend
with the 12z run. Fcst will lean toward the drier ECMWF solution for
Fri. As the trof shifts to the western Great Lakes by late Sun, sfc
low pres will lift into the Upper Lakes over the weekend, bringing
more shra. Timing/track of the sfc low is not well agreed upon by
the models, not surprising at this time range. This prevents having
any confidence in timing best chc of pcpn. Temps will also be
impacted by sfc low track/timing. If the low track stays se of the
fcst area, it will be a cool weekend, especially chilly near Lake
Superior. Dry weather should then return for Mon.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 737 PM EDT MON MAY 15 2017
Warm front associated with a low pressure system over the Western
Plains is expected to stay south of the area tonight into central
Wi and southern Mn which is where most of the shower activity will
stay focused tonight. A weak disturbance moving through the Upper
Great Lakes will continue to support isolated showers over the TAF
sites into early evening, but then expect showers to end by late
evening. Another disturbance lifting northeast from the Central
Plains late tonight into Tue morning will push the warm front
farther north and could be the focus for another round of showers
and thunderstorms lifting toward the TAF sites on Tue morning
though exact timing is still uncertain. Also coverage of showers
will be uncertain as forecast soundings indicate atmosphere may be
capped by warmer air aloft which could limit shower coverage. The
rain occurring this evening along with nighttime cooling and east
to southeast winds north of the warm front should result in
developing low clouds and possible fog late tonight into Tuesday
morning. MVFR cigs and vsby seem likely in this setup with even a
chance of IFR conditions, especially at KSAW and KCMX with
onshore flow off the Great Lakes. Expect some improvement in
cigs/vsbys Tue afternoon with diurnal mixing and wind direction
taking on a more southerly component.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 430 PM EDT MON MAY 15 2017
Winds thru tonight across Lake Superior should remain mostly under
20kt. Expect winds to increase on Tue as a warm front lifts n toward
the area. Gusts should increase to 25kt over the eastern part of the
lake. As the warm front lifts n of the lake Tue night, stronger
winds up to 25kt should remain over the e half of Lake Superior.
After a period of lighter winds Wed morning as a sfc trof settles
over the lake, winds will ramp up Wed aftn thru Thu morning as low
pres rides up the trof across central Upper MI and eastern Lake
Superior. Expect ne to n winds to increase up to gale force Wed
night/Thu morning over western Lake Superior and late Wed night thru
early Thu aftn over central Lake Superior. Winds will then diminish
to under 20kt into Fri. There may some stronger winds again this
weekend as another low pres lifts into the Upper Lakes.
Finally, combination of showers and increasingly humid air arriving
over the cold lake waters will result in fog developing Tue and then
lingering thru early Thu. This fog may become dense Wed. The fog
will dissipate with the arrival of drier air on northerly winds late
Wed night/Thu.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLA
LONG TERM...Rolfson
AVIATION...Voss
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Pueblo CO
621 PM MDT Mon May 15 2017
.UPDATE...
Issued at 621 PM MDT Mon May 15 2017
Upated to cancel severe thunderstorm watch 213 for Baca and
Prowers counties, with the main threat of storms pushing east
into Kansas.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 338 PM MDT Mon May 15 2017
Dew points have plummeted across the mountains and adjacent
plains this afternoon...however a brief shift to a more southerly
component is advecting lower 50 dew points back into the far
southeast plains. This is still the favored area for isolated
strong to severe convection this afternoon through early evening. In
fact by 00z...most of the activity is predicted by HRRR to shift
eastward into KS as dry line mixes eastward. MLCape will be running
around 20000 J/kg across Baca and southeast Prowers County initially
and with deep layer shears around 35 kts could certainly see a
severe storm or two with main threats large hail and damaging winds.
Threat will end by mid evening.
Some cooling aloft noted tonight so temperatures in the mountains
should be slightly cooler than last night. Meanwhile...westerly
downslope winds along the I-25 corridor should keep the usual warm
pockets on the warm side of guidance.
For Tuesday...closed low over AZ will fill and lift northeast across
CO during the afternoon. Lee trof strengthens and kicks eastward in
response with a windy day in store across much of the area. Given
the moist fuels...conditions are not deemed critical by land
management agencies for a fire weather watch or red flag
warning...but certainly meteorological conditions will be meeting
criteria. Some moisture accompanies the system...though from model
soundings it is all very high based. Some isolated to scattered
high based showers and thunderstorms will be possible...mainly over
and near the mountains where gusty winds and lightning will be the
primary storm threats. meanwhile...timing of the eastward
progression of the sfc trof axis washes out dew points and keeps
severe threat to the east of the area during the late afternoon and
evening. -KT
.LONG TERM...(Tuesday night through Monday)
Issued at 338 PM MDT Mon May 15 2017
...Cooler and unsettled weather pattern expected for mid week
and beyond...
Tuesday night-Wednesday...Latest models in good agreement of old
upper low across the Desert SW weakening as is ejects across
southeast Colorado Tuesday night, with brief short wave ridging
across the area early Wednesday as next system digs into the
Northern Great Basin through Wednesday afternoon. Should see a
isolated to scattered showers and a few embedded storms, associated
with the passing wave, spreading east across the mountains through
the eastern plains Tuesday evening, with a frontal boundary pushing
through the plains into early Wednesday morning. Will see increasing
chances of precipitation across the higher elevations along and west
of the ContDvd late Wednesday morning, with a few showers spreading
east across the high valleys through the eastern mountains into the
afternoon.
Wednesday night-Friday night...Again, models in decent agreement of
closed upper low across the Northern Great Basin on Wednesday,
slowly lifting out across the region through the day Friday. The
movement of this system will bring periods of rain and snow to much
of south central and southeast Colorado through the period, with
widespread precipitation across the Contdvd late Wednesday afternoon
spreading east across the area Wednesday night and Thursday. Best
pops to remain over and near the higher terrain Wednesday night,
with another cold front pushing south and east across the plains
Thursday morning. This system looks to be cold enough to bring snow
levels down to between 7000-8000 feet Wednesday night and early
Thursday morning, and may need late season winter weather advisories
for the higher terrain, especially across the Central Mountains
through the Pike Peak region. Another spoke of energy digs across
the area on Thursday. with an elongated upper trough progged to
slowly lift out across the region Thursday night and Friday. This
will keep chances of rain and snow showers across the area through
Friday afternoon/evening. Temperatures below seasonal levels can be
expected through this period.
Saturday-Monday...A cool northwesterly flow pattern develops across
the region into early next week, keeping chances of showers in place
across the region, especially over and near the higher terrain, with
temperatures expected to be at or below seasonal levels through the
period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 338 PM MDT Mon May 15 2017
VFR conditions expected at the taf sites over the next 24 hours.
Gusty south to southwest winds will decrease at all three terminals
by 02-03z. Best threat of any thunderstorms will be well off to the
east of KCOS and KPUB through this evening. On Tuesday...should see
some increasing mid/high cloudiness with VFR cigs and virga possible
in the afternoon. Erratic gusty winds will be the main threat with
these...with this risk a possibility at all three terminals during
the afternoon and early evening. Otherwise should see gusty
southwest winds increase at all three terminals during the afternoon
with gusts to around 30 kts possible. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...MW
SHORT TERM...KT
LONG TERM...MW
AVIATION...KT
Area Forecast Discussion
National Weather Service San Diego CA
902 PM PDT Mon May 15 2017
.SYNOPSIS...
A trough of low pressure aloft will move into Arizona on Tuesday,
continuing cool conditions and a threat of scattered, light
showers along and west of the mountains, with gusty westerly winds
in the mountains and deserts into Wednesday. A warming trend will
begin on Wednesday, and continue into the weekend as high pressure
off the Coast expands eastward and shrinks the marine layer back to
the coast.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
NWS radar shows an increase in shower activity this evening off the
San Diego County Coast, moving east. These are generally light and
are expected to continue to remain isolated to widely scattered
through the night and into Tue morning. The 00Z Miramar sounding had
a weak inversion near 6500 FT MSL with weak instability below, and
unidirectional winds from about 240 degrees. This favors shower
development in island generated bands, which will likely localize a
lot of the accumulating rain overnight.
A closed low was centered near Death Valley this evening, with a
trailing wave swinging cyclonically south and then SE overnight. This
will keep unstable conditions across the region with a threat of
scattered, mostly light showers into Tue morning. The latest HRRR
guidance has most of the showers in western San Diego County and on
the Riverside County mtn coastal slopes, diminishing by Noon on Tue.
The low will be kicked east rather rapidly on Tue as a stronger wave
fills into the Great Basin from the NW. This system will maintain,
and actually increase the onshore flow, and keep a deep marine layer
over the coastal basin through Wed. Thickness gradually rises after
Thursday, and the marine layer diminishes as the low grudgingly
moves east and high pressure off the Coast expands. This will push
daytime temperatures over the coastal basin back above average by
the weekend, with average temps farther inland.
A Wind Advisory has been posted for the mountains and deserts
beginning 6 PM PDT on Tue. Expect a few gusts over 60 MPH near the
windier passes through Wed morning. Please see LAXNPWSGX for
details.
&&
.AVIATION...
160325Z...Coast/Valleys/Coastal Mountain Slopes...SCT-BKN cloud
layers with bases 2000-5000 ft and tops to 6000 ft will continue
through Tuesday evening, obscuring higher terrain at times. ISO-SCT
light showers continuing through about 15Z, then tapering off during
the day Tuesday.
Desert Mountain Slopes/Deserts...West surface wind gusts 35-45 kt
along the desert slopes, through the passes, and locally into the
deserts through about 10Z tonight and again Tuesday afternoon and
evening. Areas of associated MOD-STG UDDFS and LLWS possible over/E
of the mountains. Otherwise SCT-BKN clouds AOA 20000 FT MSL and
unrestricted vis through Tuesday evening.
&&
.MARINE...
Northwest winds will continue with gusts to 20-25 kt in the outer
coastal waters through tonight before subsiding. A Small Craft
Advisory remains in effect through 3 AM Tue for the outer waters.
Another brief period of stronger winds is possible Wed afternoon
across the outer waters with gusts 20-25 kt.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from 6 PM Tuesday to 8 AM PDT Wednesday for Apple
and Lucerne Valleys-Riverside County Mountains-San
Bernardino County Mountains-San Diego County Deserts-San
Diego County Mountains-San Gorgonio Pass Near Banning.
PZ...Small Craft Advisory until 3 AM PDT Tuesday for Waters from San
Mateo point to the Mexican Border Extending 30 to 60 nm out
including San Clemente Island.
&&
$$
PUBLIC...JAD
AVIATION/MARINE...SS