Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/26/17
Area Forecast Discussion
National Weather Service Bismarck ND
946 PM CDT Mon Sep 25 2017
.UPDATE...
Issued at 946 PM CDT Mon Sep 25 2017
Only change was to adjust POPs a bit based on latest radar imagery
and for collaboration purposed.
UPDATE Issued at 639 PM CDT Mon Sep 25 2017
Upper level low will lift towards and across North Dakota over the
next 24 hours. As this occurs at the very minimum expect isolated
light showers through tonight across my west and central. Models
continue to key in on an enhanced area of showers due in part to
upper level jet dynamics, from across eastern SD into southeastern
ND including the James River Valley developing by mid evening and
persisting through the night. Will maintain elevated POPs here
and will increase/decrease as needed. Other change was to expand
patchy fog to include all of western ND based on latest high res
models runs and where clouds may scatter out overnight allowing
for some fog.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 247 PM CDT Mon Sep 25 2017
Current surface analysis places high pressure stretching across
Manitoba into the northern plains. Upper level analysis places
broad trough from the four corners region up through the central
Rockies, with a compact low spinning over southeast Montana. Some
showers continue to lift through western into south central North
Dakota with this system.
For later this afternoon into this evening...aforementioned
compact low will head into North Dakota and gradually open up as a
variety of weak waves work around it. This will keep shower
chances going over various parts of the area this evening. RAP &
HRRR continue to indicate possibility of some fog over
southern/western portions of the area late tonight, so have added
the mention of patchy fog.
On Tuesday...low precipitation chances linger into Tuesday,
diminishing later in the day as the wave moves easterly.
Temperatures remain on the cool side.
.LONG TERM...(Tuesday night through Monday)
Issued at 247 PM CDT Mon Sep 25 2017
Quiet weather expected through the week as ridge builds into the
region, bringing dry conditions and a return to seasonal
temperatures. Ridge axis expected to push to the east for the
later part of the weekend bringing a return of precipiation
chances into early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 639 PM CDT Mon Sep 25 2017
Low VFR to Mvfr cigs for all terminals through at least mid
morning Tuesday. Not sold on IFR cigs tonight but will monitor
and amend as needed. Isold -shra at times through the period.
Improvements to low vfr commence after 16z Tuesday.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
SHORT TERM...JJS
LONG TERM...JJS
AVIATION...KS
Area Forecast Discussion
National Weather Service Dodge City KS
648 PM CDT Mon Sep 25 2017
...Updated aviation discussion...
.SHORT TERM...(This evening through Tuesday)
Issued at 425 PM CDT Mon Sep 25 2017
A 500 mb shortwave was centered over central Wyoming, and farther
south, a broad area of surface/850mb front overrunning convection
was present over the panhandles and northwest Oklahoma. The
cold front across our region was slowly moving eastward, however
will still be straddled across the area late this afternoon and
evening, to be the focus for continued rounds of shower and
thunderstorms as the strong 850 mb moisture transport over the
panhandles impinges on the boundary. Of the convective allowing
models, the HRRR has been the most well adaptive model to this
evolution for additional rounds of showers/storms through this
evening. Given the high theta-e/moisture content air and low level
forcing, some locations of localized flooding could occur
especially in the southeast counties, enhancing the already 3 to 4
inches across Pratt and Barber counties. High uncertainty exists
with respect to just when the precipitation will end. Light fog and
drizzle may be enhanced behind the surface boundary overnight based
on the northeast unsloped surface winds, stratus and extreme light
precipitation fields lingering in the CAMs. However the models
relegate any dense fog well to the west over the higher terrain in
Colorado overnight.
.LONG TERM...(Tuesday night through Monday)
Issued at 425 PM CDT Mon Sep 25 2017
Normal highs for southwest kansas has fallen into the upper 70s
range now for late September. From mid week forward, we will be
cooler than normal initially with a slow/gradual warming trend
through end of the week as the central Plains surface high shifts
east allowing a return to southerly surface winds by the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 648 PM CDT Mon Sep 25 2017
Light rain is rapidly moving out of southwest Kansas early this
evening and will be moving out of the Hays area by 02z. Only a
very slight chance for showers is expected through the remainder
of the night. There is an area of VFR conditions trailing the
rain shield but IFR to LIFR ceilings are expected to redevelop
this evening. This should continue overnight into Tuesday morning
before ceilings lift into the MVFR category.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 51 63 49 67 / 50 20 20 20
GCK 49 61 47 67 / 30 20 10 10
EHA 47 58 46 64 / 20 20 20 20
LBL 50 59 49 65 / 20 20 20 20
HYS 50 63 48 68 / 50 10 10 10
P28 56 64 55 69 / 80 40 30 30
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...Gerard
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
735 PM CDT Mon Sep 25 2017
.UPDATE...
Deep tropical Pacific moisture continues to stream northeast of the
remnant circulation of what was Tropical Storm Pilar that is now
located over the Mexican state of Durango. This moisture is feeding
a weak MCV centered over Zavala County that is allowing widespread
showers and embedded thunderstorms to persist over much of the Rio
Grande Plains. Although the cold front is still well to the north in
the Texas panhandle, differential PVA ahead of a shortwave trough
associated with Pilar`s remnants should provide ample dynamic forcing
at midlevels to support rainfall continuing well into the overnight
hours. In addition, an intensifying south-southeasterly low-level
jet will continue to feed the southern portions of this MCV.
The aforementioned dynamic factors coupled with precipitable water
values in the 2.0-2.4 inch range should result in new cell formation
to train along the Zavala-Frio and Dimmit-La Salle County borders,
possibly extending into Uvalde and southwest Medina Counties. These
areas should see the heaviest rainfall over the next 3-6 hours with
moderate to heavy rainfall just to their north and west. Widespread
1-3 inch rain amounts with locally higher totals above 6 inches is
likely over these areas. Therefore, we have highlighted 90-100 POPs
with locally heavy rainfall in the forecast for these counties, while
removing that mention further north over the Edwards Plateau and west
into Val Verde County as these areas should be deprived of the best
low-level inflow. Current hi-res and global model guidance is too
far north and west with these features, so our forecast has shifted
south and east of this guidance.
The forecast is a bit more uncertain for the overnight hours as it
will largely depend on how convection evolves this evening and where
any quasi-stationary or progressive boundaries set up. The 22Z HRRR
run that appears to have initialized relatively well suggests this
convection will begin to decrease in intensity after about 1-2 am
with the MCV slowly retrograding to the west-southwest. If this
verifies, flooding impacts should stay well to the southwest of the
San Antonio metro area as the heaviest rainfall would stay south of
Highway 90 and along and west of Interstate 35. Therefore, the
eastern border of the Flash Flood Watch appears to be good for now
and we will only need to reevaluate this if this complex progresses
further east than anticipated. Heavy rainfall is expected once again
over the Rio Grande Plains, Edwards Plateau, and possibly a bit
further east as the shortwave associated with Pilar`s remnants
crosses the Rio Grande to provide additional dynamic forcing aloft.
&&
.PREV DISCUSSION... /ISSUED 647 PM CDT Mon Sep 25 2017/
UPDATE...
00Z Aviation Update Below.
AVIATION...
A weak MCV appears to have developed between DRT and COT where a
complex of SHRA and embedded TSRAs currently resides. This is farther
east than what models indicated earlier this afternoon. Through the
next 6 hours went closer to recent runs of the HRRR that appears to
have a better handling on position of the MCV and its continued
slight eastward drift. As such removed VCTS at DRT this evening as
low level flow and forcing have been disrupted.
The complex of SHRAs and TSTMS could maintain itself eastward to
near HDO through the late evening, aided by low level jet
strengthening. Less certain on SAT, but HRRR does suggest some
possible stratiform RA advecting northeast into the area overnight as
the complex possibly weakens. Have shown -RA in both the SAT and SSF
TAFs after 04Z. Ceilings are tricky where convection in ongoing, but
in general will maintain VFR conditions through the evening hours at
all TAF sites, with MVFR deck developing at SAT/SSF after 04Z and
DRT/AUS 06Z-08Z. Appears ceilings could lower further into IFR
criteria at SAT/SSF/AUS after 10Z.
PREV DISCUSSION... /ISSUED 329 PM CDT Mon Sep 25 2017/
SHORT TERM (Tonight through Tuesday Night)...
The effects of Tropical Depression Pilar will provide initially much
needed rain over our western counties, then a flash flood threat for
some areas as early as this evening. Streamer showers continue to
affect areas generally along and just east of the Hwy 281 corridor
with brief heavy downpours of 0.5 to 1 inch. Most of this activity
will be diurnally driven, starting in the predawn hours and wrapping
up by sundown. West of Hwy 281, rain chances will be around the
clock, and the Watch issued early this afternoon for areas west of a
Kerrville to Dilley line kicks in at 00Z this evening. Moderate to
occasional heavy rain has targeted the Del Rio and Brackettville
areas early today but only slow accumulations to around 2.5 inches
have been noted so far.
Mesoscale features ejecting off the higher terrain of Mexico will
make specific focal points for convection difficult to define in
terms of timing and amounts. Based on some patterns shown by many of
the non-gfs runs, the heaviest rains are expected to fall between
06Z and 18Z over the next two nights/mornings. The mcv that moved
into the Brackettville this morning and weakened still brings a focal
point for afternoon convection over the Rio Grande Plains. Pwat
values near the Rio Grande remain around 2-2.1 inches according to
the SPC mesoanalysis, but the NAM suggest values in excess of 2.5
inches possible by early Tuesday morning. The fact that the mcv`s
are tracking almost due east would suggest the heavy rain focal point
could shift east with time and erode the ridging aloft that has
models limiting higher rainfall total east of I-35 for now.
Localized 4 to 6 inch rains will be possible each morning period
with more common amounts of 0.5 to 1.5 inches expected closer to Hwy
281.
LONG TERM (Wednesday through Monday)...
A cold front is expected to slip into the area during the day
Wednesday although gradually shifting winds may make it difficult to
notice a fropa. The front will be initially shallow as well, so
continued heavy rain will become more broad covering for late
Wednesday into Wednesday night. Pwat values are suggested to be at or
above 2.5 inches through Wednesday night, with lowering values
expected by daytime Thursday. Rainfall rates are expected to decrease
by this time, but the continuing feed of heavy rain will likely mean
continuing flash flooding possible through Thursday afternoon, and
river flooding for another day or two beyond that.
Storm total qpf amounts still are well shy of the synoptic models
that suggest all the rain will pile up in the same areas west of Hwy
83, but due to the presence of Ewd moving mcv`s, expect more areas
east of Hwy 83 to see a heavy rain threat that will hopefully be
handled better in later model runs. Storm total rains from this
afternoon through Thursday afternoon remain fairly conservative with
widespread 4 to 6 inch storm total amounts in the watch area with
isolated amounts around 1 foot through midday Thursday. Afterwards,
rains should be more spotty and light as the frontal layer deepens
and the amount of perturbations coming out of Mexico dwindle. Storm
total rains over the more populated areas of Austin/San Antonio are
currently expected to be more in the 1-2 inch range with less than 1
inch expected over our far eastern counties.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 74 88 73 85 72 / 30 50 40 40 30
Austin Bergstrom Intl Airport 74 88 72 86 71 / 30 50 40 30 30
New Braunfels Muni Airport 74 85 73 86 70 / 50 70 50 40 30
Burnet Muni Airport 72 83 70 81 67 / 40 50 50 50 30
Del Rio Intl Airport 73 83 72 82 70 / 60 90 100 80 80
Georgetown Muni Airport 73 87 72 84 70 / 20 40 40 40 30
Hondo Muni Airport 75 88 73 86 70 / 80 80 80 70 60
San Marcos Muni Airport 74 86 72 86 70 / 40 60 40 40 30
La Grange - Fayette Regional 74 89 73 88 72 / 30 30 20 20 20
San Antonio Intl Airport 75 85 74 85 72 / 50 70 60 50 40
Stinson Muni Airport 76 86 74 84 72 / 50 70 60 50 40
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Thursday evening for the following
counties: Bandera...Dimmit...Edwards...Frio...Kerr...Kinney...
Maverick...Medina...Real...Uvalde...Val Verde...Zavala.
&&
$$
Mesoscale/Aviation...Runyen
Synoptic/Grids...LH
Public Service/Data Collection...33
Area Forecast Discussion
National Weather Service Grand Forks ND
917 PM CDT Mon Sep 25 2017
.UPDATE...
Issued at 914 PM CDT Mon Sep 25 2017
Weak echoes now spreading northward into the southern Red River
Valley and west central Minnesota appear to be mid clouds as it is
difficult to find any ground truth for rain via METARs. Latest hi
res guidance is indicating rain. Think things should saturate
enough by 03Z for some rain to start and generally went with a
HRRR and continuity blend, maybe increasing the higher POPs by
about an hour or two. Overall fairly insignificant changes and no
changes made to ongoing temp curve. Adjusted sky trends in the NW
for some breaks earlier this evening, but expect that to fill in
overnight.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 255 PM CDT Mon Sep 25 2017
Upper low to propagate east from the northern high plains across
the forecast area overnight and Tuesday. As it does an associated
surface low will lift ne along the boundary to our east from IA
to the western great lakes. Question will be how far west wrap
around -ra gets into our forecast area. CAM guidance in
reasonable good agreement in bringing -ra back into the east and
south between 03-06z time frame then slowly spreading north and
west. Model guidance indicating best potential across the
remainder of the forecast area from 12-18z Tuesday with upper low
passage. With the track of the upper low over the fa and surface
high ridging into the dakotas rain coverage somewhat in question
so will go with chance pops at this point. Will keep higher pops
across the east closer to surface inverted trough. Clouds will
keep temperatures close to what we have seen the past couple of
days.
.LONG TERM...(Tuesday night through Monday)
Issued at 255 PM CDT Mon Sep 25 2017
Rain should gradually diminish Tuesday night as upper low
continues to propagate northeast. Clearing will have an impact on
how low temperatures get however overall minimum temperatures
should be a few degrees either side of 40.
Improving conditions Wednesday with high pressure building into
the northern plains. Low level westerly flow and potential for
solar should allow temperatures to recover into the 60s and could
reach 70 over the west. At this point with warmer column and light
westerly flow not anticipating any frost potential.
Guidance has come into better agreement with the upper level system
moving into the Great Lakes region along with the cold front moving
through from the north Thursday. However, a drier scenario is now
being forecasted by guidance. Still leaving some chance for rain
mainly in Minnesota counties. The Manitoba/Ontario surface high will
drop into the area behind Thursday`s cold front with its dry
influence lasting through Friday into the weekend. There remains
some chance of patchy frost Friday morning in northern Minnesota,
although confidence still remains low with this potential. As the
surface high moves to the southeast, southerly return flow will
allow for milder temperatures this weekend with highs in the 60s,
possibly 70s for counties closer to the tri-state area. As the
surface high strengthens to the southeast, gusty southerly winds
will be felt mainly during afternoons over the weekend. Guidance
indicates a cold front approaching from the west around the Sunday
into early Monday timeframe. This will increase rain chances. It is
too far out into the period to confidently say if there will be
thunderstorms with this front. Overnight lows throughout the period
will generally be in the 40s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 636 PM CDT Mon Sep 25 2017
Widespread MVFR cigs continue across the northern tier tonight
with cigs across NW Minnesota slowly becoming IFR this evening.
There are some breaks north and west of DVL that will likely fill
back in overnight...and the VFR cigs will fall into the MVFR
range. Much like the last two nights, all sites may improve one
cig category for short durations at best.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Speicher
SHORT TERM...Voelker
LONG TERM...CJ/JK/Voelker
AVIATION...Speicher
Area Forecast Discussion
National Weather Service Midland/Odessa TX
619 PM CDT Mon Sep 25 2017
.DISCUSSION...
See 00Z aviation discussion below.
&&
.AVIATION...
There is scattered TS across the area, though the only TAF
locations in immediate threat is INK and FST which have TEMPO
groups the next few hours. MVFR CIGs will once again move in
tonight and will remain through the end of the TAF period as a
cold front arrives around 18Z Tuesday shifting winds from the
northeast and bringing more moisture and rainfall.
Hennig
&&
.PREV DISCUSSION... /issued 325 PM CDT Mon Sep 25 2017/
DISCUSSION...
WV imagery shows the upper trough has moved NE over the past 24
hours, and is now centered over SE MT. This is still scheduled to
move into Canada by 00Z Wed, at which time a secondary trough will
be taking its place over srn NV. This will maintain SW flow aloft
over West Texas and Southeast New Mexico at least until the weekend.
To the far south, T.S. Pilar is just entering the Gulf of CA, and
with a little luck, some of its tropical moisture will get entrained
into the SW flow into the region.
Of more immediate concern is a cold front that has just entered the
NW Texas Panhandle. Models are in general agreement in bringing it
into the nrn zones by 12Z Tuesday, and thru KMAF around 20Z. Cloud
cover should keep the front from stalling diurnally, and convection
to the north may give an assist driving it south. Models suggest
gap winds may be a problem thru KGDP Tuesday night, we`ve issued a
wind watch for this. Isentropic lift will begin increasing Tuesday,
especially over the NE zones. Ensembles indicate anomalous PWATs of
2 std devs or better running just left of central Texas, up thru the
Panhandle, coincident w/a low-lvl theta-e ridge, all of which should
help maximize rainfall potential efficiency. To top it all of,
models put the RR quadrant of a 250mb jet streak over the region
much of the day Tuesday. For all these reasons, we`ve issued a
Flash Flood Watch for the eastern half of the CWA beginning tonight,
and continuing thru 12Z Thursday, as soils saturate and the pattern
won`t change much thru then. This will alleviate confusion, rather
than issuing new FFAs every 12-24 hrs. Further shifts can expand
westward if the situation warrants.
Thursday or so, the secondary trough begins ejecting up thru the
Rockies, w/upper flow transitioning from SW to zonal over the
weekend. This will result in POPs gradually tapering off,
especially Sun/Mon. Temps will try to rebound by then, but should
stay just below normal.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 66 75 61 68 / 70 90 90 80
Carlsbad 62 77 59 65 / 40 70 70 70
Dryden 71 79 68 75 / 60 60 80 60
Fort Stockton 67 79 62 70 / 30 60 90 80
Guadalupe Pass 60 71 55 61 / 30 50 60 50
Hobbs 62 72 56 62 / 60 70 70 80
Marfa 58 78 57 69 / 40 50 60 50
Midland Intl Airport 67 75 61 67 / 50 80 80 80
Odessa 67 75 60 67 / 50 70 80 80
Wink 66 78 61 69 / 30 70 80 80
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...Flash Flood Watch through Thursday morning for Andrews-Big Bend
Area-Borden-Crane-Dawson-Ector-Gaines-Glasscock-Howard-
Martin-Midland-Mitchell-Pecos-Reagan-Scurry-Terrell-Upton-
Ward-Winkler.
High Wind Watch from Tuesday evening through Wednesday morning
for Guadalupe Mountains.
&&
$$
99/99/10
Area Forecast Discussion
National Weather Service Marquette MI
755 PM EDT Mon Sep 25 2017
.SHORT TERM...(This evening through Tuesday)
Issued at 401 PM EDT MON SEP 25 2017
Water vapor imagery and RAP analysis show that pattern progression
is beginning. Deep trof that has been over the western CONUS is
weakening and shifting downstream. Strong ridge that has been over
eastern N America remains. However, main positive anomaly center
that had been s of James Bay has started to weaken and drift se.
Btwn the trof and ridge, deep sw flow is continuing into the Upper
Great Lakes today. At the sfc, nearly stationary front that has
lingered generally just w of Upper MI for the last couple of days
has slipped e into western Upper MI. Lake breeze component has also
assisted the front in dropping s into n central Upper MI this aftn.
Under mostly sunny skies ahead of the front, MLCAPES have increased
to 500-1000j/kg over central Upper MI per latest SPC mesoanalysis.
The instability and low-level convergence provided by front will set
the stage for convection, which is just starting to develop, to
expand over the next few hrs. Farther w behind front, areas of shra
have been spreading from IA to western Lake Superior today. Ahead of
the front, temps are again unseasonably warm with mid/upper 80s away
from Lake Michigan moderation. Behind the front, current temps are
in the 60s far w.
Instability along with convergence provided by frontal boundary will
generate sct to nmrs shra/tsra in the vcnty of the front this
evening across basically the nw half of the fcst area. With deep
layer shear on the order of 25-35kt and mlcape upwards of 1000j/kg,
an isolated svr storm or two will be possible for the next few hrs.
Otherwise, very hvy rainfall is likely with any of the storms thru
the evening due to precipitable water around 1.5 inches (upwards of
250pct of normal) and freezing level at 12000ft or higher. The
evening convection will tend to fade away late evening into the
overnight as instability diminishes. Focus of shra should then tend
to shift farther w where fgen and better deep layer forcing will
provide support for pcpn just ahead of and w of sfc low pres wave
which will be tracking nne toward nw WI late tonight.
On Tue, as sfc low pres lifts across far western Upper MI and out
over Lake Superior, cold front will sweep e thru the day. Thru the
morning, shra will continue to be most widespread over far western
Upper MI along and w of sfc low track. If there is enough heating
ahead of the front, isold svr storms are not out of the question
over the eastern fcst area in the aftn given 30-40kt of deep layer
shear. Will be something to keep in mind if there isn`t much in the
way of cloud cover thru the morning to hold temps/instability down.
High temps should range from the 60s w to the upper 70s/around 80F
east.
.LONG TERM...(Tuesday night through Monday)
Issued at 242 PM EDT MON SEP 25 2017
Nam shows a shortwave over the upper Great Lakes 00z Wed and the
area remains in upper level troughing through 00z Fri. Nam shows
some 850-500 mb q-vector convergence and some moisture moving
through the area on Thu. Will keep some pops in for Tue night
through Wed morning and again for Thu afternoon.
In the extended, GFS and ECMWF show a 500 mb trough over the ern
U.S. with a ridge over the plains and a trough off the west coast
12z Fri. Ridging moves into the upper Great Lakes 12z Sat with
troughing in the western U.S. 12z Sat. Troughing moves into the
Rockies and northern plains 12z Sun and into the upper Great Lakes
12z Mon. Looks dry for most of the extended period with temperatures
starting to below normal and warming to above normal. Chances for
pcpn look to be Fri morning and again on Mon.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 755 PM EDT MON SEP 25 2017
High confidence in sites seeing primarily IFR to LIFR conditions as
ample low level moisture lingers ahead of a low pressure system.
Periods of thunderstorms are expected, but confined thunderstorm
mention to the first few hours of the TAF given confidence of
coverage and probability.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 401 PM EDT MON SEP 25 2017
A wave of low pres will lift nne late tonight/Tue along a frontal
boundary extending from the Plains to the Upper Great Lakes. This
will result in ne wind increasing to 20-30kt over western Lake
Superior tonight into Tue morning before diminishing in the aftn.
Winds will remain lighter over eastern Lake Superior. As the low
lifts ne of Lake Superior Tue evening, nw winds will increase to 20-
30kt across the lake Tue night into Wed with the strongest winds
over eastern Lake Superior. Winds will diminish to mostly under 20kt
Wed night into Thu. A low pres trof swinging se across the Upper
Great Lakes Thu night will usher in another round of 20-30kt winds
on Fri. Not out of the question that there could be a few gale force
gusts to 35kt over mainly the central portion of Lake Superior.
Winds will then diminish to under 20kt for Sat.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...07
AVIATION...Titus
MARINE...Rolfson
Area Forecast Discussion
National Weather Service San Diego CA
120 PM PDT Mon Sep 25 2017
.SYNOPSIS...
High pressure over the Great Basin will bring Santa Ana conditions
through Wednesday with sunny, warm days and clear nights. Winds
will be gusty at times in the mountains, foothills and the Inland
Empire. Warmer Thursday and Friday with lighter offshore winds.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
No changes in the outlook for the ongoing Santa Ana weather pattern
with warm days, clear nights, and gusty winds in the mountains
passes, foothills and I.E. at times through Wednesday morning. Winds
at Noon today were blustery at the usual offshore wind locations
including Corona (18G24 mph), Riverside (13G23 mph), and Campo
(15G24 mph). It was cool in the mountains (Big Bear 54 degrees), and
warm in the coastal and valley zones (87 at Corona, 86 at Fullerton,
and 85 at Escondido). Palm Springs matched Corona with 87 degrees.
The winds will diminish through evening, then a second burst of
similar intensity offshore winds will pick up again early Tuesday
morning.
Tonight the WRF is advertising a moderately strong coastal eddy
spinning up over the coastal waters, but the HRRR is much weaker
with the eddy circulation. Considering the model disparity, have
used a model blend and projected some low clouds/patchy fog over the
coastal waters later tonight into Tuesday morning, but with
uncertainty as to how widespread it will be. Coverage will likely be
limited to the coastal waters tonight or the immediate coast
tonight. The eddy continues Tuesday night into Wednesday morning
when the coverage should be a little greater, and the marine
layer a couple hundred feet deeper.
*From Previous Discussion*
Santa Ana conditions produced locally gusty winds in the mountains,
foothills and passes this morning, strongest San Bernardino and
Riverside Counties, and the Santa Ana Mountains where 10-20 mph
winds were gusting to 30-35 mph. Winds were lighter in San Diego
County. The Santa Ana airmass has reached all the way to the coast
this morning where dewpoints were in the 30s and low 40s. Farther
inland the dewpoints were lower, ranging from the teens to the low
30s.
Both the ECMWF and GFS model are consistent with the Santa Ana
weather pattern this week. A longwave trough over the West will be
reinforced by a shortwave dropping south over NV tomorrow. This
shortwave will develop into a cut-off low over the Lower Colorado
River Valley Wednesday. The trough then lifts NE on Thursday and
Friday with higher heights resulting in even hotter days to end the
week. The coastal areas may not see a significant temperature change
Thu or Fri though, as the marine layer returns in response to a
coastal eddy that will form on Wednesday. Increasing boundary layer
RH will likely bring some marine layer clouds and patchy fog back
into coastal areas during that time.
Long Range outlook for the weekend and beyond: The ECMWF and GFS are
at odds with each other. The GFS is forecasting a mean ridge pattern
through early next week, while the ECMWF is suggesting a trough for
stronger onshore flow and a hint of cooling. In either case,
precipitation is unlikely, and the main challenge will be if
temperatures will be average or above average.
&&
.AVIATION...
251945Z...Mostly clear skies through Tuesday. Local northeast winds
in foothills and below canyons into valleys with Local mdt
up/downdrafts and LLWS west of the mtns. KONT and KSBD are most
likely TAF sites to be impacted by these winds and LLWS. A similar
offshore wind pattern will continue Tuesday.
The southern coast of San Diego county could see periods of SCT-BKN
low clouds with bases 1000 ft MSL or lower and vis 3SM or less
between 09Z and 16Z Tue. KSAN could be impacted but confidence is
low.
&&
.MARINE...
No hazardous marine weather is expected through Friday.
&&
.FIRE WEATHER...
North-northeast winds in the mountains and foothills ranged from 10
to 20 mph through early afternoon with gusts between 20-30 mph. The
windiest site had gusts above 35 mph including Fremont Canyon (45
mph at 9 AM), Crestline Ridge (41 mph at 2 AM), and Santiago Peak
(40 mph at 1 AM). Campo had a wind gust of 24 mph at 1 PM. The
winds will drop off through the evening, then increase again
Tuesday morning. Strongest winds will be in and below the Cajon Pass
and over the Santa Ana Mts/canyons, with lighter winds over
San Diego County. On Wednesday the winds will a little weaker.
Afternoon humidities will bottom out between 10-15% tomorrow and for
increased wildfire risk, but limited areal coverage of these
conditions will be too small to require any fire weather products.
The will be a small increase in RH Wednesday through Friday, but
overall it will remain fairly dry with afternoon humidities below
25%. It will be dry and very warm days through next weekend,
creating an elevated wildfire risk region-wide. Winds may be gusty
both off and onshore at times, but should be localized and not over
any extended period.
&&
.SKYWARN...
Skywarn activation will not be needed today.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC/FIRE WEATHER...Moede
AVIATION/MARINE...PG