Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/10/17
Area Forecast Discussion
National Weather Service Burlington VT
752 PM EDT Sun Apr 9 2017
.SYNOPSIS...
Another dry day is expected on Monday with plenty of sunshine
and even warmer temperatures with highs in the mid 60s to lower
70s. A front will approach the region Tuesday and enhance the
potential for showers in the afternoon and evening hours. A
slight chance of a thunderstorm will also exist. Above normal
temperatures will continue for Tuesday as well.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 623 PM EDT Sunday...Adjusted sky cover upward somewhat
across the north this evening per latest satellite/rh model
trends. Mid level moisture spilling east/southeast on the front
side of eastern Great Lakes ridge axis is producing an area of
warm advection-driven light showers/sprinkles across southern
Quebec per latest MRMS radar output. As such, I`ve also
introduced a low threat of scattered sprinkles across our
northeastern tier of counties through midnight or so. HRRR
output showing this quite nicely and have leaned in its
direction accordingly. All and all not a big deal with most
areas remaining dry overnight. Current low temperature forecast
of upper 30s to mid 40s still appears on track. Have a great
evening.
Prior discussion...
On Monday...even warmer temperatures are expected than we saw
on Sunday with pronounced southwest flow at the low and mid
levels to bring the warmer conditions. Highs will be in the mid
60s to lower 70s. No precipitation is expected and we should see
lower relative humidities once again with many locations down
in the 25 to 35 percent range and a few spots in the 20 to 25
percent range. South and southwest winds will be increasing
across the area at speeds in the 8 to 15 mph with some higher
gusts.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 347 PM EDT Sunday...Clouds will be on the increase Monday
night and Tuesday as a shortwave trough approaches the region.
Still feel little in the way of forcing will exist over the area
Monday night for a mention of precipitation...but could see
something maybe getting into northern New York by the morning
hours on Tuesday. Have kept it dry until this time period. The
clouds and persistent southwest flow will keep overnight lows
generally in the 50s. The best chance for showers and a few
thunderstorms will be Tuesday afternoon and evening as shortwave
trough and its associated cold front move into the region.
Instability just enough to keep the mention of thunder in the
forecast...but strongly sheared environment that develops might
limit the convection from getting organized. Nevertheless there
is a threat...especially from the northern Adirondacks eastward
Tuesday afternoon and evening. Will continue in the forecast
along with the likely wording on showers for this event. The
showers should taper off quickly as the night wears on Tuesday
night. High temperatures will be in the 60s across northern New
York and in the 70 to 75 degree range across Vermont.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 347 PM EDT Sunday...A cold front will swing through the
North Country on Wednesday and will end the string of temps in
the upper 60s to 70s. Expect temps to fall back to near normal
in the 50s on Wednesday depending on cloud cover. As the front
exits to our east there will be some lingering low and mid level
moisture which when combined with northwest flow aloft will
mean some isolated mountain showers will linger around through
the afternoon on Wednesday.
The cooling trend will continue into Thursday and Friday as a
building ridge moves over the area. Expect highs in the 50s
with lows in the 30s through the rest of the week. The latest
trends in the guidance indicate the ridge may end up being a bit
stronger leading into Friday. This pushes the energy from an
advancing shortwave trough south of the North Country and keeps
the forecast area dry heading into the weekend. I backed off the
chance for precip to just slight chance given the trend over
the last couple of forecast runs. High pressure continues into
the weekend until Sunday as an upper level trough looks to bring
a more robust system into the North Country in the form of
light to moderate rain.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Through 00Z Tuesday...Ceilings and visibilities will be in the
VFR category through the entire period. Winds will generally be
under 10 knots through 12z...then increase from the south and
southwest. Only other wind note will be some low level wind
shear between 06z and 12z at KMSS and KSLK with stronger
southwest winds at 2000 feet in the 35 to 40 knot range.
Outlook 00Z Tuesday through Friday...
Through 12Z Tuesday...VFR. S-SW Wind gusts to 25kts daylight
hours Monday.
Tuesday onward...Cold front brings MVFR rain showers later
Tuesday into Tuesday night then MVFR/VFR conditions exist for
Wednesday and Thursday.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Evenson
NEAR TERM...Evenson/JMG
SHORT TERM...Evenson
LONG TERM...Deal
AVIATION...Neiles
Area Forecast Discussion
National Weather Service Cheyenne WY
950 PM MDT Sun Apr 9 2017
.UPDATE...
Issued at 947 PM MDT Sun Apr 9 2017
Made a few phone calls in Converse county and snowfall amounts are
ranging from 1 to 2 inches in the lower elevations around Douglas
with snow melting on the roadways. Meanwhile, there is nearly 3
inches in the higher elevations along with some accumulation on
the roadways. As a result, we are including Converse county in the
Winter Weather Advisory until 12z.
UPDATE Issued at 858 PM MDT Sun Apr 9 2017
We are sending out quick update to cancel the high wind warning
for everything except for the summit and the foothills. Latest
look at the water vapor loop was showing some mountain wave
activity this evening. across the I-80 summit and the foothills
and even less mountain wave activity near Arlington. In addition,
surface temperatures have really cooled off this evening which is
tending to weaken the low level lapse rates in the
Wyoming/Nebraska Plains. The HRRR is still showing some strong low
level winds trying to push into the Nebraska panhandle overnight,
but it appears like the lapse rates and minimal subsidence will
keep the high winds at bay.
Further north, we are still watching on the web cams the snowfall
moving through Douglas and Glen Rock, but this band appears to be
dissipating according the GOES-R IR loop. Therefore, we are
holding back on any Winter Weather advisory there. However, we
are watching cold conveyor belt on the mid level water vapor loop
wrapping into northeast Niobrara county. This will certainly bring
some snow to Niobrara County, Sioux and Dawes Counties as this
wave slowly rotates to the southeast. &&
.SHORT TERM...(This evening through Monday Night)
Issued at 247 PM MDT Sun Apr 9 2017
Powerful upper shortwave traversing the CWA late this afternoon.
Strong gradient combined with afternoon mixing of higher momentum
has produced widespread sustained wind speeds of 40-45 mph with a
few gusts to 60+ mph over the wind prone areas as well as Cheyenne
proper. These winds should continue to spread eastward through the
early evening as rapid surface cyclogenesis takes place near Rapid
City.
The question then becomes, how strong will the winds be after peak
mixing? Low level flow between 700 and 800 mb increases rapidly
over eastern WY and western NE panhandle this evening in response to
and upper level PV max and the consolidating low level cyclone over
western SD. Model soundings continue to show decent low level lapse
rates through early evening mainly south of the Pine Ridge. Decided
to keep the current high wind warnings as is and upgrade Box Butte
County to a warning through 6z as well. To the north, the winds
should still be quite gusty but think verifying a high wind warning
may be difficult as more clouds and precip later this evening will
limit mixing potential. All the models indicate a 4 to 6 hour period
of frontogenesis in the 850 to 700 mb layer combined with decent
wraparound moisture. Temperatures will also be cooling rapidly with
the low level cold advection to the west of the SFC low. Decided to
go with a winter weather advisory for Niobrara, N Sioux, and Dawes
Counties which will replace the high wind watch previously in
effect. While snow amounts will probably fall just short of
advisory criteria, think the combination of strong winds and
snowfall will cause travel impacts in this area late tonight, enough
to warrant an advisory.
The low will pull away from the area early Monday morning with winds
diminishing and skies clearing over the north. Should be a
pleasantly cool day with high temperatures ranging from upper 40s
west to mid 50s east.
.LONG TERM...(Tuesday through Saturday)
Issued at 247 PM MDT Sun Apr 9 2017
Weak zonal flow aloft will be in place on Tuesday/Wednesday with
gradually warming temps. The gradients are rather weak (CAG-CPR
below 25 meters), so winds will be relatively light. The models
continue to show a shortwave lifting northeastward from the Great
Basin into Montana on Thursday. With pressure falls across
Montana, south to southwest winds will increase on Thursday, and
temps will warm into the upper 60s to mid 70s over lower
elevations. Sfc trough will shift into the western Nebraska
Panhandle by Friday. Could see isolated showers develop in the
convergence along the trough/weak cool front. Overall, little
impacts are expected through the week.
&&
.SHORT TERM...(This evening through Monday Night)
Issued at 247 PM MDT Sun Apr 9 2017
Powerful upper shortwave traversing the CWA late this afternoon.
Strong gradient combined with afternoon mixing of higher momentum
has produced widespread sustained wind speeds of 40-45 mph with a
few gusts to 60+ mph over the wind prone areas as well as Cheyenne
proper. These winds should continue to spread eastward through the
early evening as rapid surface cyclogenesis takes place near Rapid
City.
The question then becomes, how strong will the winds be after peak
mixing? Low level flow between 700 and 800 mb increases rapidly
over eastern WY and western NE panhandle this evening in response to
and upper level PV max and the consolidating low level cyclone over
western SD. Model soundings continue to show decent low level lapse
rates through early evening mainly south of the Pine Ridge. Decided
to keep the current high wind warnings as is and upgrade Box Butte
County to a warning through 6z as well. To the north, the winds
should still be quite gusty but think verifying a high wind warning
may be difficult as more clouds and precip later this evening will
limit mixing potential. All the models indicate a 4 to 6 hour period
of frontogenesis in the 850 to 700 mb layer combined with decent
wraparound moisture. Temperatures will also be cooling rapidly with
the low level cold advection to the west of the SFC low. Decided to
go with a winter weather advisory for Niobrara, N Sioux, and Dawes
Counties which will replace the high wind watch previously in
effect. While snow amounts will probably fall just short of
advisory criteria, think the combination of strong winds and
snowfall will cause travel impacts in this area late tonight, enough
to warrant an advisory.
The low will pull away from the area early Monday morning with winds
diminishing and skies clearing over the north. Should be a
pleasantly cool day with high temperatures ranging from upper 40s
west to mid 50s east.
.LONG TERM...(Tuesday through Saturday)
Issued at 247 PM MDT Sun Apr 9 2017
Weak zonal flow aloft will be in place on Tuesday/Wednesday with
gradually warming temps. The gradients are rather weak (CAG-CPR
below 25 meters), so winds will be relatively light. The models
continue to show a shortwave lifting northeastward from the Great
Basin into Montana on Thursday. With pressure falls across
Montana, south to southwest winds will increase on Thursday, and
temps will warm into the upper 60s to mid 70s over lower
elevations. Sfc trough will shift into the western Nebraska
Panhandle by Friday. Could see isolated showers develop in the
convergence along the trough/weak cool front. Overall, little
impacts are expected through the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 543 PM MDT Sun Apr 9 2017
Latest water vapor loop was showing a very well defined dry slot
now moving through the western Nebraska panhandle. This is
indicating strong subsidence which will be favorable for strong
wind speeds mixing down during the next couple of hours at Sidney
and Alliance. In the meantime, there is mvfr clouds and snowfall
starting to push into the northern Nebraska panhandle. Lusk is
even reporting IFR conditions. It is possible that some of these
clouds and snow will spread into the Chadron TAF site by 04z. We
did bump up the timing a bit from the previous TAF to account for
this. These low clouds may also spread towards Alliance by 08z
with the potential for a rain/snow mix. We will have to keep an
eye on how things evolve this evening.
Otherwise, the rest of the taf sites will see the strong winds 25
to 35kts continue through much of the evening due to strong
subsidence. The wind speeds should begin to diminish towards
daybreak with much lighter wind speeds anticipated on Monday.
&&
.FIRE WEATHER...
Issued at 247 PM MDT Sun Apr 9 2017
Minimal fire weather concerns through the middle of next week.
Strong west to northwest winds will continue through the remainder
of the afternoon behind the cold front, however the relative
humidity will remain above 20 percent. Although minimum humidity
values will fall to 15-25 percent across portions of the area each
afternoon through Wednesday, the winds will be relatively light.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory until 6 AM MDT Monday for WYZ101-102.
High Wind Warning until midnight MDT tonight for WYZ116-117.
NE...Winter Weather Advisory until 6 AM MDT Monday for NEZ002-095.
&&
$$
UPDATE...REC
SHORT TERM...DEL
LONG TERM...ZF
AVIATION...REC
FIRE WEATHER...ZF
Area Forecast Discussion
National Weather Service Hastings NE
647 PM CDT Sun Apr 9 2017
.SHORT TERM...(This evening through Monday)
Issued at 227 PM CDT Sun Apr 9 2017
The short-term forecast revolves around the chances for
thunderstorms this evening. Current analysis indicates an area of
low pressure along the MO/IA border with a cold front moving
through the far SW part of our CWA now. To the west of these
features, there is an area of enhanced 850mb moisture in west-
central NE. Mesoanalysis shows ~500 j/kg of elevated CAPE along
with 40-50 kt of bulk shear - enough for organized convection
given sufficient forcing. We`ve already seen thunderstorms develop
in eastern CO, and the current expectation is that these storms
continue to move east into our area and possibly expand in
coverage.
The most likely timeframe for thunderstorms will be 6-11pm,
across south-central Nebraska, and a few strong to marginally
severe storms remain possible. Up to quarter size hail appears to
be the primary threat. Can`t completely rule out a severe wind
gust, but wind aloft aren`t particularly strong and delta theta-e
doesn`t look particularly impressive either.
Late tonight, a few showers may re-enter northern parts of the
area as the upper level low moves through the area from west to
east.
.LONG TERM...(Monday night through Sunday)
Issued at 227 PM CDT Sun Apr 9 2017
A few showers may linger north of the tri-cities into Monday
morning. Otherwise a dry, but noticably cooler, day is expected.
I continued the mention of frost in the forecast Monday night as
temperatures will be falling into the low 30s for the entire area.
The next opportunity for rain and storms arrives on Wednesday, although
it still appears that the best of the instability will remain
south of the area across Kansas.
Most of the area will stay dry on Thursday, with only a slight
chance for rain/storms in KS. Late thursday night through Saturday
morning like another decent chance for thunderstorms, especially
Friday night into Saturday morning as a cold front pushes
southwest across the area.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday evening)
Issued at 641 PM CDT Sun Apr 9 2017
Line of thunderstorms currently impacting the TAF sites will clear
the area over the next couple hours. Expect northwest winds to
remain elevated for the next couple hours behind the line of
storms before calming down late tonight.
RAP Bufkit soundings indicate that northwest winds will become
breezy again by mid morning as mixing increases. At the same time,
mid-level cloud cover (MVFR cigs) will increase as the upper-
level low passes through the area.
&&
.FIRE WEATHER...
Issued at 227 PM CDT Sun Apr 9 2017
A red flag warning remains in effect until 7pm this evening for
Phillips, Rooks, Osborne, and Smith Counties. RH values are
expected to dip to around 20 percent across this entire area,
although the best chances for reaching the 3-hour criteria appears
to be in Rooks County only. Nevertheless, increasing westerly
winds and low RH will make outdoor burning dangerous.
Fire conditions will improve tonight and should stay below
critical thresholds into next week.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...Red Flag Warning until 7 PM CDT this evening for KSZ005-006-017-
018.
&&
$$
SHORT TERM...Mangels
LONG TERM...Mangels
AVIATION...Mangels
FIRE WEATHER...Mangels
Area Forecast Discussion
National Weather Service Grand Junction CO
615 PM MDT Sun Apr 9 2017
.SHORT TERM...(Tonight through Monday night)
Issued at 100 PM MDT Sun Apr 9 2017
Afternoon surface analysis over the western CONUS reveals low
pressure departing the region through the high plains, while high
pressure settles in from the Great Basin. Aloft, 500mb flow is
relaxing over the region with surface wind speeds finally easing
up in the north. Visible satellite imagery shows lingering
shallow convective cloud cover in the central and northern ranges
of central Colorado, and similar conditions along and to the south
of the Uintas in northeast Utah. Near-term forecast soundings
indicate this lingering moisture in the lowest 5000 feet or so of
the atmosphere this afternoon. RAP mesoanalysis indicates mid-
level lapse rates in the 7.5-8 range this afternoon in the
mountains. These two factors have helped sustain the lingering
precipitation in the higher terrain. As surface heating wanes
later today, expect to see a sharp drop-off in shower activity in
the mountains toward sunset. Surface winds will also decrease
markedly later today as the gradient aloft relaxes and surface
mixing shuts down. Will continue to monitor wind speeds this
afternoon for a possible early drop of the Wind Advisory. As it
stands now, the advisory remains in effect until 6pm MDT.
Overnight...clearing skies, light winds, and dry air in the low
levels will result in a rapid drop off of temperatures in the
valleys. Freeze Advisory remains in effect for Monday morning and
min temperatures have been nudged slightly lower in line with
slightly cooler guidance today (especially the MAV). The northern
mountains may hang on to a bit of cloud cover as well as a
westerly breeze, however it will still be a cold morning on
Monday. Low temperatures across eastern Utah and western Colorado
will run about 10 degrees below average for early April.
A dry day with mostly sunny skies is expected on Monday afternoon.
High temperatures will top out around average across the region.
.LONG TERM...(Tuesday through Sunday)
Issued at 100 PM MDT Sun Apr 9 2017
Light zonal flow will continue over the Four Corners region
through Thursday. A very weak ripple in this westerly flow will
pass through early on Wednesday, resulting in an increase in
cloud cover overnight and in the morning hours. Guidance has
trended even drier with this moisture-starved system. As a result
PoP values have been lowered even further in this forecast
package, even in the higher terrain. This system will quickly
scoot east of the Rockies on Wednesday afternoon, with rising
heights and warming temperatures expected on Thursday. In fact,
many locations may take a run at 80 degrees on Thursday from Moab
through Grand Junction, as well as in locations farther south
such as Delta and perhaps Montrose.
By Friday of this week, guidance is in relatively good agreement
showing a new trough digging into the west coast. As of the 12z
forecast cycle this Sunday afternoon, all major global models keep
any significant moisture with this system far to our north. The
primary impact in eastern Utah and western Colorado will be an
increase in cloud cover for Thursday night and the day on Friday,
as well as cooler temperatures on Friday afternoon. That being
said, highs will still run around 5-10 degrees above average,
likely in the low 70s in the valleys with 50s in the mountains on
both Friday and Saturday. While a lot can change over a week, an
early look at GEFS and EPS ensemble guidance for next weekend
reveals another trough approaching the west coast, and mostly dry
weather for the Four Corners region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 529 PM MDT Sun Apr 9 2017
Cold northwesterly flow will prevail overnight supporting gusty
winds into the evening hours. This cold northwesterly flow will be
dry which will result in VFR conditions through the next 24 hours.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Freeze Warning from midnight tonight to 9 AM MDT Monday for
COZ006-011.
UT...Freeze Warning from midnight tonight to 9 AM MDT Monday for
UTZ027.
&&
$$
SHORT TERM...MAC
LONG TERM...MAC
AVIATION...Larry
Area Forecast Discussion
National Weather Service Green Bay WI
913 PM CDT Sun Apr 9 2017
Updated aviation portion for 06Z TAF issuance
and new information added to update section
.UPDATE...
Issued at 858 PM CDT Sun Apr 9 2017
The first round of storms has now shifted into Upper Michigan, but
additional develop was occurring back to the west over eastern
Minnesota, northeast Iowa, and western Wisconsin. That should
shift northeast into the area later tonight. The focus is again
likely to be across the north. Since the combo outflow
boundary/cool front has sagged south to around highway 29, the
storms should be elevated by the time they arrive in the area.
That will make hail the primary threat.
There is also concern that a flooding threat could develop over
the portions of north-central Wisconsin that got significant rain
during the late afternoon. The RHI ASOS reported 1.56 inches of
rain during the afternoon and early evening. The rains so far
have basically fallen within an area bounded by Rhinelander,
Argonne, and Iron Mountain on the north and Merrill, Antigo, and
Wausaukee on the south. Although northern Wisconsin has been
fairly dry recently, if additional rains fall in the same area
area, some localized flooding could develop. The RAP and HRRR
suggest another substantial round of rains will move through the
north between 1100 pm and about 300 am, with yet another possible
mid-morning Monday. Will be closely monitoring the mesoscale
structure of the additional convection for training storms and an
increased flooding potential.
Updated product suite will be out withiin about 1/2 hour.
&&
.SHORT TERM...Tonight and Monday
Issued at 302 PM CDT Sun Apr 9 2017
Main forecast focus to be on thunderstorm chances late this
afternoon into the overnight hours and the potential for any of
these storms to become severe.
The 19z MSAS analysis showed an area of low pressure on the
Nebraska/Iowa border with a warm front extended northeastward
through central IA into north-central WI. Dew points have climbed
into the upper 40s to lower 50s across northeast WI and the radar
mosaic now picking up a band of showers and thunderstorms along
the warm front. Some of these storms have become strong and will
need to be watched.
The warm front is forecast to stall near its current location
tonight as the low pressure rides northeast along the stalled
boundary. The strongest frontogenetical forcing/baroclinic zone
would then set-up along and north of the boundary and it is this
location that should see the highest precipitation chances.
Furthermore, northern WI will reside on the edge of a mid-level
cap, thus a better chance of seeing thunderstorms continue through
most of the night. Best severe potential should also be across the
north where shear is the strongest (> 50 kts) and provide
sufficient updrafts to possibly allow a few storms to approach
severe limits. For central and east-central WI, it may take until
the approach of the surface low to allow for showers or
thunderstorms to move into this part of the state, mainly after
midnight. While central/east-central WI to have more instability,
the shear is not as strong compared to northern WI (40 kts). The
key to any severe potential here is the capping inversion which
may not break. Anticipate thunder chances to diminish later
tonight, but showers to persist into Monday. Min temperatures to
be in the upper 30s to lower 40s north, lower to middle 50s south.
The surface low is forecast to ride the stalled boundary across
central/east-central WI Monday morning and will continue to bring
rain showers to northern WI and a good chance of showers/isolated
thunderstorms to central/east-central WI. As the surface low exits
Monday afternoon, this will allow the frontal boundary to start
sagging south and exit the forecast area by late afternoon with
additional rain showers possible due to the deformation axis
rotating through the area. Colder air is expected to get pulled
into northern WI later in the day and may allow for some snow to
mix with the rain over Vilas county toward evening. A wide range
in temperatures can be expected on Monday with north-central WI
essentially seeing steady or slowly falling temperatures into the
middle 30s to around 40 degrees, while southern sections of the
forecast area reach the lower 60s.
.LONG TERM...Monday Night Through Sunday
Issued at 302 PM CDT Sun Apr 9 2017
Primary issue Monday night is the rain to snow or mix transition
as compact low pressure system tracks across the state. Colder air
in the wake of the system will produce some snow accumulation,
especially on grassy areas. How far southeast to mention this
snowfall and snow accumulation varies from model to model. The
colder NAM and ECMWF bring a minor snow accumulation all the way
to the fox cities, while the warmer GFS confines the snow further
northwest. Several inches of accumulation still likely across
North central Wisconsin, in the deformation area of the nearly
stacked 850 to 700mb low system. The stacked system may also tend
to have a slow departure Tuesday morning with additional small
mixed pcpn chances.
Eventually dry weather will return Tuesday into Wednesday with
weak upper ridging. A weak short wave and cold front passage
Wednesday night may produce a chance of showers, possibly mixed
across the north.
Upper ridging resumes for the rest of the week with a gradual
warming trend. Next frontal system arrives for the start of next
weekend.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 858 PM CDT Sun Apr 9 2017
Still expect lower clouds and visibilities to expand southeast
across the area in the wake of a cold front/outflow boundary
sagging south across the area, although that has been slow to
occur thus far. Perhaps it will start to happen faster once the
next round of convection arrives in the area later tonight. Still
expect LLWS for a time in advance of the front over east-central
Wisconsin tonight.
&&
.HYDROLOGY...
Issued at 302 PM CDT Sun Apr 9 2017
Potential of an inch to two inches of rainfall roughly northwest
of line from Marshfield to Crivitz. A warm front positioned
across northern Wisconsin will be the primary focus of showers
and storms tonight into Monday. Monday into Monday night, rain
will become more widespread as a low pressure system tracks across
central and northeast Wisconsin. The previous warm front is
expected to shift south a bit as near stationary front and will be
the primary focus of more rainfall. The greatest rainfall amounts
are expected to be associated with this frontal boundary. Will
issue an ESF due to the potential of 1 to 2 inches of rainfall and
some river rises. But due to dry conditions across the north, the
rainfall will also serve as welcome relief for high fire danger.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........Skowronski
SHORT TERM.....AK
LONG TERM......TDH
AVIATION.......Skowronski
HYDROLOGY......TDH
Area Forecast Discussion
National Weather Service Lincoln IL
904 PM CDT Sun Apr 9 2017
.UPDATE...
Issued at 904 PM CDT Sun Apr 9 2017
Have made a few minor changes to the forecast for the rest of the
night. Overall current forecast looks good but needed to adjust
pops overnight as HiRes models showing some slowing trends and
decreasing in coverage/pop. Will take a look at winds as well to
make sure gridded forecast winds match current trends/reality.
Update will be out shortly.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 317 PM CDT Sun Apr 9 2017
A tight gradient between high pressure anchored along the East Coast
and a frontal boundary over the Plains is creating strong southerly
winds across central Illinois this afternoon. Winds have been
gusting to 30-40mph...with the highest gusts concentrated along/east
of I-57. While the gusts will diminish somewhat after sunset,
sustained southerly winds of 10-20mph will continue through the
night. As the front begins to approach from the west, scattered
thunderstorms are expected to develop across parts of Iowa and
Missouri late this evening, then track into the Illinois River well
after midnight. Boundary layer moisture will be plentiful as
surface dewpoints have climbed well into the 50s: however, forecast
soundings continue to show plenty of dry air aloft. As a result,
think any storms that develop west of the Mississippi River this
evening will be in a diminishing state as they arrive across the
western KILX CWA toward dawn. HRRR seems to have a reasonable grasp
on the situation, so have followed its solution closely for the
immediate short-term. Have kept the entire area dry through the
evening, then have brought low chance PoPs into the Illinois River
Valley overnight. Further east, have kept locations along and east
of I-57 dry through dawn Monday.
This initial push of convection will dissipate across west-central
Illinois early Monday morning followed by a lull in the rain chances
til around midday. All models suggest the most widespread
convection will develop well ahead of the approaching front across
the E/SE CWA after 18z: however, the 12z WRF-ARW offers a bit more
detail...showing scattered storms initially forming between the
Illinois River and I-55 between 18z and 21z. Have trended toward
its timing solution, with likely PoPs along/east of I-57 after 21z.
Severe parameters remain modest, with SBCAPE values of 1500-2000J/kg
and 0-6km bulk shear of 40-50kt. Think ample cloud cover will limit
the instability even further...and with the front having very little
forward momentum, convergence along the boundary will be weak.
Forecast soundings show mainly unidirectional speed shear, so
organized long-lived updrafts are unlikely. May see a few strong
cells with gusty winds and small hail across the east during the
afternoon, but severe threat appears minimal.
.LONG TERM...(Monday night through Sunday)
ISSUED AT 317 PM CDT Sun Apr 9 2017
Showers and thunderstorms will linger across east-central and
southeast Illinois Monday evening before quickly pushing into
Indiana. A cooler and less humid airmass will filter into the
region behind the departing front for the middle of the week, with
high temperatures dropping into the lower to middle 60s for Tuesday
and Wednesday.
The next approaching boundary will come into the picture late
Wednesday night into Thursday: however, deep-layer moisture and
instability will be lacking...so will only mention scattered showers
at this time. After that, models continue to disagree on how far
south the boundary will drop before becoming parallel to the upper
flow and stalling. No matter the exact location of the front,
overall synoptic pattern featuring prevailing upper ridging and a
stationary frontal boundary somewhere in the vicinity, will lead to
a period of warm and unsettled weather for the end of the week. As
a result, rain chances will return across the entire area for Friday
and Saturday...with high temperatures climbing back into the 70s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 710 PM CDT Sun Apr 9 2017
VFR conditions will continue this evening ahead of the weather
system still expected to move into the area and effect the TAF
sites after midnight. Based on the HRRR model, scattered precip
will begin to move into the area and get to PIA around 09z. Will
have VCTS at PIA, but model indicates that things dissipate during
the early morning hours, so will just have VCSH everywhere else.
Believe any precip will be short live and then dry weather will be
around during the remainder of the morning. Since have PIA as site
most likely to have thunder, will have MVFR cigs around 2.5kft
during the morning hours and then improvement in the afternoon as
the front begins to move through the area. The active front will
slide to the east during the morning and looks to refire in the
early afternoon. Will have VCTS at all sites, except PIA for the
afternoon with VFR cigs around 3.5kft. The threat of convection
will end in late afternoon, but will not include an additional
line for fropa, which will be just before 00z at SPI and BMI.
South winds will be breezy again, with strongest winds during the
morning hours before the active front moves in and storms refire.
Tonight will also see LLWS again at all sites at 45-50kts possible
based on the BUFKIT data.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Auten
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Auten
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
918 PM CDT Sun Apr 9 2017
.UPDATE...
Issued at 915 PM CDT Sun Apr 9 2017
Updated forecast to push chance of showers and thunderstorm back
until after midnight. Surface observations have shown no rain reports
underneath the radar returns currently over southwest Missouri.
Latest runs of the RAP show that there will be some weak low level
moisture convergence moving into the area between 06-12Z, so will
leave a slight chance of showers and thunderstorms over the area
overnight.
It is another warm evening, and with the clouds over the area and
the winds staying up, still expect lows to only fall to around 60
degrees overnight.
Britt
&&
.SHORT TERM... (Through Late Monday Afternoon)
Issued at 344 PM CDT Sun Apr 9 2017
Main focus will be chance for TSRA, possibly severe, during two
different periods.
Approaching trof across the Central Plains shud help erode a
rather strong cap in place this afternoon and evening. It appears
there will be two areas of convection this evening that may
eventually impact the CWA. One area further south across srn
KS/nrn OK that is expected to remain just south of the CWA if it
develops. The other is further north impacting mainly the nrn
third of the CWA, but possibly further south into central MO. Mdl
solns differ on timing, placement and coverage of any convection
this evening. Have therefore kept PoPs on the low side due to many
questions. Some of these storms may be strong to possibly severe
capable of producing hail and strong winds.
Focus then shifts to TSRA chances on Mon. An approaching mid
level vort max will help storms initiate Mon ahead of a cdfnt
expected to be draped thru the CWA. After TSRA diminish during the
morning hrs, expect a brief lull before TSRA redevelop, most
likely during the early afternoon.
Mdls prog around 40 kts of deep layer shear and increasing during
the afternoon with around 1500 J of MLCAPE. Progd hodographs for Mon
afternoon are unidirectional for much of the area. While storms may
initially be supercells briefly, wud expect these to evolve to small
bowing segments. While shear is somewhat limited, steep lapse rates
and location of CAPE shud allow for at least a large hail threat.
Main question will be where and when the TSRA develop. Currently
believe development will be roughly along a KPPQ to KVIH line with
coverage increasing as storms move ewd during the afternoon.
Raised temp forecast by some 5 degrees based on what happened today.
Convection may hinder warming during the afternoon, but expect temps
to warm quickly thru the morning hours.
Tilly
.LONG TERM... (Monday Night through Next Sunday)
Issued at 344 PM CDT Sun Apr 9 2017
As discussed above, the threat for strong to severe thunderstorms
may persist into the late afternoon and early evening hours on
Monday until the cold front has moved through the area. High
temperatures on Tuesday will likely remain in the 60s across the
area within the cooler post-frontal air mass. Temperatures then
warm back into the upper 60s to mid/upper 70s for the rest of the
extended forecast period.
Dry weather is expected on Tuesday and Wednesday beneath either
weak ridging or quasizonal flow aloft. Meanwhile, a disturbance
will attempt to undercut a sharp upper ridge which will be
building across the west central CONUS. This feature may bring a
chance of SHRA/TSRA to the area during mid/late week. A
disturbance on the eastern side of the upper ridge will move
through the Great Lakes, and this feature may also affect sensible
weather across MO/IL. There is low confidence in precipitation
trends beyond Wednesday because models have shown poor
day-to-day continuity over the last several days regarding the
speed, evolution, and existence of important features.
Kanofsky
&&
.AVIATION... (For the 00z TAFs through 00z Monday Evening)
Issued at 638 PM CDT Sun Apr 9 2017
Mainly dry and VFR conditions are expected through 06Z. Then
scattered showers and thunderstorms will enter central and
northeast Missouri and west central Illinois including KUIN and
KCOU. This may cause brief MVFR or IFR conditions. Additional
showers and thunderstorms will be possible midday on Monday across
east central Missouri and southwest Illinois as a cold front moves
southeast across the area. MVFR conditions are expected with the
passage of this front.
SPECIFICS FOR KSTL: Mainly dry and VFR conditions are expected
tonight and Monday morning. Then scattered showers and
thunderstorms are expected by midday on Monday as a cold front
moves across the terminal. MVFR conditions are expected during the
afternoon and early evening.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
856 PM EDT Sun Apr 9 2017
.SHORT TERM...(This evening through Monday)
Issued at 426 PM EDT SUN APR 9 2017
Water vapor imagery and RAP analysis show split flow across N
America. Northern stream troffing extends from nw of Hudson Bay into
Manitoba/northern Ontario while a southern stream shortwave trof is
over WY/CO. Lead energy ahead of the latter trof is over the central
Plains/Upper Mississippi Valley and is aiding a band of shra from SD
into nw Upper MI. At the sfc, a trof, aided by lake breeze, has
settled across Upper MI today and currently extends from eastern
Lake Superior across central Upper MI to low pres over ne Nebraska.
Cold front associated with the northern stream trof extends from
James Bay to SD. All of these features will be involved in a
complicated fcst for Upper MI during the short term. In the last hr
or so, convection has fired in the vcnty of the sfc trof from w
central WI into the eastern fcst area, pretty much as a number of
models had indicated. Although latest SPC analysis shows mlcapes of
less than 100j/kg, mucape values are now up around 500j/kg from
Menominee to Manistique.
Tonight, sfc trof across the area may drift se a bit during the
night. The approaching cold front to the nw will catch up to it by
12z Mon with the new consolidated boundary located roughly from far
eastern Upper MI to near Menominee. Meanwhile, stronger deep layer
forcing ahead of the approaching southern branch shortwave/sfc low
pres wave riding ene along the sfc trof will overspread the area. In
addition, right entrance of upper jet over northern Ontario and
sharpening low-mid level fgen down below will come into play. As a
result, ongoing expansion of pcpn will continue thru tonight. Taking
advantage of building instability from IA to ne WI, stronger
convection will be tied to the vcnty of the sfc trof while
strengthening fgen will support pcpn to the nw of the main
convective area. Mucapes of at least 1000j/kg nosing into southern
Upper MI tonight along with effective shear of at least 30kt will
support potential of organized storms. With wetbulb zero heights aob
10kft, there will be the possibility of large hail with the
strongest storms. With passage of cold front and strengthening n to
ne winds, it will turn sharply colder with temps falling back to the
mid 30s across the w and n central.
On Mon, cold front will only drift s as main southern stream
shortwave will still be off to the sw, moving from Nebraska in the
morning to the Upper Mississippi Valley by evening. This results in
another area of sharper deep layer forcing approaching in the aftn.
While better isentropic ascent/fgen shifts off to the ene,
approaching shortwave should work to maintain areas of -ra thru the
day. With cold front s of the fcst area by mid morning, temps will
generally remain steady thru the day. Brisk n to ne winds will add
to the chill. Column may become cold enough to support a mix with
snow over the w and nw in the aftn.
.LONG TERM...(Monday night through Sunday)
Issued at 319 PM EDT SUN APR 9 2017
Focused in on Mon night into Tue morning when mixed precip may be an
issue. Otherwise, left blended initialization unchanged as it
handled uncertain/insignificant weather satisfactorily.
For Mon night and Tue morning, an upper level disturbance will move
across the area, bringing forcing for precip to much or all of the
CWA. There is uncertainty in the strength, track and timing, which
then lead to uncertainty in precip time, timing, amounts, and
coverage. General idea is that better chances of a light
snow/freezing rain threat will exist over the northwestern half of
Upper MI, while the southeastern half will see better chances of a
rain/freezing rain mix. Confidence in thermal profiles, SFC temps,
and ice crystal presence make forecasting ptype quite difficult.
While elevated surfaces over the NW half could see around 0.10
inches of freezing rain Mon night into Tue morning, think that any
accumulations will largely non-impactful especially given that warm
ground temps will limit frozen precip accumulations on the ground.
Still plenty of uncertainty with amounts, so keep updated with later
forecasts.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 849 PM EDT SUN APR 9 2017
VFR conditions will prevail initially at KIWD/KCMX/KSAW. Trof
stalling out over the Upper Great Lakes will be followed by a cold
front that will drop se, settling to the s of the area late tonight.
These features will bring deteriorating conditions to all terminals,
beginning first at KSAW this evening when MVFR cigs and sct -shra
should begin to develop in the vcnty of the trof. Drier low-
level air to the nw should allow VFR conditions to linger at
KCMX/KIWD even though shra should begin to develop in that area as
well. Following passing of cold front and arrival of shallow cold
air, conditions at KIWD/KCMX will fall to low MVFR or IFR
overnight thru Mon morning. At KSAW, IFR conditions should develop
by early overnight, then LIFR late tonight/Mon morning under
upsloping northerly winds. Isold TS will be possible tonight,
mainly at KSAW, closer to greater instability near and south of
trof. Included a mention of VCTS early this evening at KSAW but
otherwise left in out of the rest of the TAF sites. Winds will be
gusty to 20-30kt on Mon.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 426 PM EDT SUN APR 9 2017
A low pres trof that has settled across Lake Superior will maintain
light winds under 15kt thru the evening. A cold front will then drop
across Lake Superior overnight with low pressure then tracking along
the front. This will result in quickly strengthening northeast winds
late tonight with gales to 35 knots likely late tonight into Mon
afternoon over at least the west half of Lake Superior. Over the
east half, expect occasional gusts to gale force. Winds will begin
to diminish slightly Mon night and then much more so on Tue as a
high pressure ridge approaches and then arrives Tue night. By Tue
evening, winds should be under 15kt across the lake. Although a low
pres trof should move across the area Wed night or Thu morning, it
will be weak, and winds may remain light, mostly under 15kt Wed/Thu.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning from 2 AM EDT /1 AM CDT/ to 8 PM EDT /7 PM CDT/
Monday for LSZ162-240>243-263-264.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...Titus
AVIATION...Voss
MARINE...Rolfson
Area Forecast Discussion
National Weather Service San Francisco Bay Area
853 PM PDT Sun Apr 9 2017
.SYNOPSIS...Dry and seasonably cool weather is forecast through
Monday except in the North Bay where there is a chance of light
rain tonight and early Monday. The weather pattern will become
increasingly unsettled through mid week, with rain chances
developing in the northern part of our area on Tuesday and then
across our entire forecast area by late Wednesday.
&&
.DISCUSSION...as of 8:53 PM PDT Sunday...A weakening low pressure
area was located several hundred miles off the Washington coast
this evening. A moderate to strong cold front attached to this low
extends southward along the Oregon coast to just off the northwestern
California coast. This front will continue to press southeastward
overnight into Monday causing cloud layers to increase then eventually
a little light rain to develop over the North Bay by early Monday
morning. The latest HRRR and 00z NAM forecast up to 0.10" rain over
Sonoma and Marin counties and are dry elsewhere over the remaining
county warning area through Monday morning. Winds may temporarily
pick up in the vicinity of frontal passage Monday.
The combination of the aforementioned incoming cold frontal boundary,
increasing relative humidity, and sustained winds of 5-15 mph
through much of this evening should all greatly help mitigate the
amount of total cooling through tonight; pockets of mid 30s are
possible over southern interior counties otherwise lows will
mostly be in the 40s Monday morning. To be sure it was cold/chilly
for April this morning with many reports of 30s over inland valleys
and away from the Bays; Valley Ford in Sonoma county reached 33 F.
San Rafael with a low of 38 F this morning was within 1 degree of
tying their record (37 in 1953).
The next upstream surface low pressure wave developing is located
approx 1500 miles west of the Bay Area. This low will approach
northern California through Tuesday advancing a newly developing
occluded front toward the coast Tuesday evening. An ill-defined
cooler air mass then advances into the area Wednesday followed by
a more defined cold front Wednesday night. With this arrangement
the models are indicating mainly sporadic light to very light rain
throughout the day Wednesday followed by steadier light maybe
briefly isolated moderate rain Wednesday night into early Thursday
morning with the cold frontal passage. Showers then persist into
Thursday afternoon, but there should be noticeable down-trend in
shower activity by evening as most if not all of the activity
shifts eastward to the Central Valley. Temperatures then are expected
to stay mainly under April averages through late week (and probably
through much of next week as well).
Dry weather returns Thursday evening lasting through Saturday with a
modest recovery in temperatures especially as clearer skies and a
higher April sun angle helps make it feel warmer during the day, in
direct sunlight anyhow. An active jet stream will continue to
advance another low pressure system toward the west coast next
Sunday-Monday, however, there`s a great deal of disagreement between
the ECMWF and GFS on location/track of this low center. Disagreement
in the low center track throws off the qpf forecast thus it`s a low
confidence forecast for this time period. A period of drier weather
is possible early-middle of next week then another rain producing
system may arrive mid-late next week.
Forecast looks good, updates are not anticipated this evening.
&&
.AVIATION...as of 4:30 PM PDT Sunday...VFR conditions expected
this evening and overnight at most terminals. Chance of IFR/LIFR
visibilities at KSNS on early Monday morning.
Vicinity of KSFO...VFR conditions expected with moderate to high
confidence. Likely will see SCT-BKN midlevel clouds early Monday
as a weak front passes through the area. Winds will decrease
after sunset Sunday, then increase again on Monday afternoon.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR conditions expected to prevail over
the next 24 hours.
&&
.MARINE...as of 8:42 PM PDT Sunday...Relatively light winds will
prevail for the coastal waters tonight and continue Monday. Winds
become southerly and increase on Tuesday as a low pressure system
approaches the northern California coast.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...None.
$$
PUBLIC FORECAST: Canepa
AVIATION: Rowe
MARINE: Rowe
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Area Forecast Discussion
National Weather Service Portland OR
249 PM PDT Sun Apr 9 2017
.SYNOPSIS...A strong cold front is nearing the Pac NW coast, and
is expected to spread rain and gusty winds onshore late this
afternoon into this evening. The colder air behind the front will
bring a quick drop in the snow level from around 4500 ft ahead of the
front this afternoon to around 2500 ft behind the front later tonight
into Monday. The cold upper trough behind this system will also bring
a decent amount of instability to the coast tonight, with some fairly
strong thunderstorms possible. A few of these storms may hold
together long enough to bring a couple rumbles of thunder inland as
well tonight and Monday. Higher pressure will build in from the
southwest for decreasing showers Monday night and a mostly dry and
mild day Tuesday. The next system is expected to develop off the
California coast Tuesday, spreading rain and perhaps gusty winds
northward across the forecast area Tuesday night and Wednesday.
Unsettled weather will continue through the remainder of the week.
&&
.SHORT TERM...Tonight through Wednesday...Not much has really changed
over the past few hours since the previous short term discussion was
written. Cold front is coming in according to plan, with
precipitation echoes beginning to show on klgx/krtx radars. The
frontal signature is even better sampled with by the Eureka, CA radar
(kbhx), with a decent swath of moderate rain about 70 miles wide. A
narrow rope-like signature can be seen along the actual surface
front, likely indicating a sharp contrast in air mass along the
front. This shows how dynamic this front is down toward the OR/CA
border...and it is likely only stronger along the Oregon coast.
Unfortunately, while being closer to the Oregon coast (only about 50
miles W of Newport at the moment), the bulk of the front is still not
being sampled by klgx, krtx, and kmax radars. Still, given the
signature off the S OR/N CA coast, expect a shot of heavy rain and
wind gusts 40-45 mph in the well-mixed environment along the Oregon
Coast as the front moves onshore between 4-7 PM. Winds are picking up
a bit inland as well, with a recent gust to 33 mph at Eugene Airport.
This despite general easterly gradients across the forecast area,
which also shows how well mixed the environment is out ahead of the
front.
There were a few lightning strikes along the front earlier today, but
no lightning has shown on lightning detection over the last couple
hours. That said, given the frontal signature and the bump in solar
heating due to a 2-4 hour period of partly to mostly sunny skies, it
is not out of the question that a bit of lightning may occur with the
front itself. However, the cold front, while being very dynamic, will
not be the biggest lightning threat over the next 12-18 hours.
The greater concern is with the upper level cold pool behind the
front, where 500 mb temps reach as low as -34 deg C per the latest
RAP analysis. This is the compact cluster of convection approaching
44N/130W as of 230 PM PDT this afternoon...which has shown a handful
of lightning strikes each hour despite being beyond 130W. Modifying
surface parcels to our current sea surface temp of 50-52 deg F yields
around 400-600 J/kg of CAPE tonight...along with good synoptic lift.
We will still be under diffluent flow aloft, and NAM 0-3 km shear
values look fairly impressive along the coast tonight...35-45 kt or
even greater in some cases. The result may be some fairly strong and
sustained thunderstorms along the coast tonight...capable of
producing strong, gusty winds, and small hail. With very steep
low-level (0-1 km) lapse rates and decent shear in the low levels,
this is also the classic pattern to support waterspouts along the Pac
NW coast. Would not be surprised to see a report or two of
waterspouts along the coast tonight/Monday morning, though these
would of course be very difficult to see at night. Based on all this,
we opted to issue a Special Weather Statement highlighting the
convective potential along the coast and in the Coast Range
tonight/early Mon morning. Models still support this... 12z WRF and
20z HRRR reflectivity continue to show a little bit of organization
to the coastal convection...with some discrete cells but also a few
clusters/lines. Given the shear, some thunder may hold together east
of the Coast Range, where NAM convective temps are as low as 43-45
deg F tonight. So at the very least, the environment will be
conditionally unstable even inland tonight. Therefore the thunder
mention inland tonight looks good as well.
In addition to the convection in the lowlands, there will be a decent
amount of snow in the Cascades from this system. Snow levels will
start out near the Cascade passes, but will quickly drop to around
2500 ft with the passage of the front tonight. The cold onshore flow
pattern behind the front is a classic snowbuilding pattern for the
Cascades...especially Santiam Pass northward. Would not be surprised
to see a few reports over a foot Santiam Pass northward by the time
all is said and done Monday evening. Pass level accumulations will
probably be a bit more modest...on the order of 5-10 inches. However
anyone planning to travel across the Cascades tonight may want to
consider moving up their plans by a few hours, as conditions will
likely deteriorate quickly across the passes tonight. All of this
prompted the issuance of a winter wx advisory for the Cascades this
evening into Mon.
Otherwise, lowlands will just be showery and unsettled as the upper
low moves across the region Monday. Additional destabilization from
daytime heating may bring another spike in convection for our
northern inland zones Mon midday/afternoon. High pressure builds in
from the southwest Mon night/Tue AM, bringing an end to the showers.
By then, low pressure will likely be developing off the northern CA
coast, and is expected to spread another round of rain northward late
Tue/Tue night. Recent model consensus has been to lift this low
northward 50-100 miles off the coast, but with large variations
between models in the intensity of the low. The low then dumbbells NW
around another strong low near 130W, very much like the Fujiwhara
effect, off the Pac NW coast. The 12z ECMWF offered a stronger
solution, perhaps strong enough to clip the coast with strong winds.
That said, the GFS/NAM have been trending weaker with this low,
favoring the western low. Regardless of which solution wins out,
Tuesday night and Wednesday will likely be wet and/or blustery, but
we will have to wait for better model agreement in order to pin down
the details. Weagle
.LONG TERM...(Wednesday night through Sunday)...Persistent
upper-level troughing over the Pacific Northwest will keep
temperatures below normal through next weekend. Westerly flow behind
the front on Wednesday will keep orographically enhanced showers
over the area Wednesday night into Thursday. Showers continue into
Friday. High pressure sliding up the Coast from the south-southwest
could help to dry us out Friday night into Saturday. Much
uncertainty on Sunday as the models diverge significantly, but it
does appear there is a good chance rain returns midday Sunday. Snow
levels stay fairly low this week for this time of year, hovering
around 2500 to 3000 feet. -McCoy
&&
.AVIATION...Expect predominantly VFR conditions through 00z
Tuesday as a front ushers in a cool and showery airmass into the
region tonight and Monday. A brief burst of heavier rain
associated with the front will likely produce some MVFR
restrictions, particularly along the coast between 00-03z Monday
and possibly in the Willamette Valley between 03-06z Monday. A
weak low pressure behind the front will then move northeastward
towards Astoria between 12-18z Monday. This may also produce some
steadier showers, particularly along the coast and a temporary
uptick in MVFR restrictions across the area. In addition, there
may be enough instability behind the aforementioned front that
there is a decent chance for a thunderstorm impacting a coastal
taf site tonight.
KPDX AND APPROACHES...Expect predominantly VFR conditions through
00z Tuesday as a front ushers in a cool and showery airmass into
the region tonight and Monday. A brief burst of heavier rain
associated with the front may produce some temporary MVFR
restrictions, particularly between 03-06z Monday. A weak low
pressure moving northeastward towards Astoria between 12-18z
Monday may also result in some steadier showers producing
temporary MVFR conditions. /Neuman
&&
.MARINE...A strong front is currently beginning to push across
the waters with Gale Force wind gusts of 35 to 40 kt. The front
looks like it will push ashore late this afternoon or early this
evening so the current end time for the Gale Warnings looks safe.
Seas should climb into the low to mid teens as a result of the
higher winds, but should subside rather quickly to near 10 ft towards
midnight. However, a weak surface low pressure will reinforce gusty
southerly winds of 20 to 30 kt later tonight. Also issued a Marine
Weather Statement to highlight the thunderstorm threat across the
waters overnight.
Weaker pressure gradients Monday night and Tuesday should result
in winds to subside, and subsequently seas. Models continue to
waver on the strength, timing and track of a low pressure system
that will move northward off the coast late Tuesday and Wednesday.
Continued a model blend to come up with the wind and sea forecast
during this time period given considerable differences between
models continue to exist. Gale Force winds appear possible across
the waters during this time. Regardless of what happens midweek,
models continue to suggest high pressure may build across the
northeast Pacific late in the work week, which should ultimately
bring much quieter weather to our waters towards next
Friday/Saturday. /Neuman
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory from 8 PM this evening to 8 PM PDT
Monday for Northern Oregon Cascades.
Winter Weather Advisory from 8 PM this evening to noon PDT
Monday for Cascades in Lane County.
WA...Winter Weather Advisory from 8 PM this evening to 8 PM PDT
Monday for South Washington Cascades.
PZ...Gale Warning until 10 PM PDT this evening for Coastal Waters
from Cape Shoalwater WA to Florence OR out 10 nm.
Gale Warning until 9 PM PDT this evening for Waters from Cape
Shoalwater WA to Florence OR from 10 to 60 nm.
Small Craft Advisory for Rough Columbia River Bar until 8 PM
PDT this evening.
Small Craft Advisory for Rough Columbia River Bar from 3 AM to
7 AM PDT Monday.
&&
$$
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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. The area is
commonly referred to as the forecast area.