Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/25/17
Area Forecast Discussion
National Weather Service Taunton MA
1019 PM EDT Mon Apr 24 2017
.SYNOPSIS...
Low pressure will slowly track up the east coast Tuesday and
Wednesday, bringing periods of rain, gusty winds and the risk
of minor coastal flooding. Drier and milder conditions will
briefly return Thursday. A cold front may bring scattered
showers and possibly a few thunderstorms Friday into early this
weekend, but may waver across the region into early next week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
No major changes to the forecast this evening. Mainly had to
tweak rainfall chances this evening, as a precursor band of very
light rainfall made it all the way to the southern coast of New
England. Latest few runs of the HRRR seemed to have the best
handling of this light rainfall heading into early Tuesday
morning.
Dew point depressions across the northern half of MA remain
large, and will take some time to overcome. Thus, still thinking
rainfall will hold off across most of our region tonight.
Minor tweaks to temperatures and dew points to reflect observed
trends.
650 PM Update...
Northern fringe of high cloud deck moving slowly across southern
areas at 22Z as seen on latest IR satellite imagery as well as
OBS. Thin band of precipitation seen across S coastal areas on
NE regional 88D radar mosaic, but no rain is reaching the ground
due to continued very dry low level layer across the region.
Dewpts at 22Z were in the lower-mid 30s across N central and NW
Mass with temps hovering at 70-75 degrees. Very high dewpt
depressions indeed. With E-SE winds in place, T/Td spreads along
the S coast are much lower, though still dry enough to allow for
evaporation of the precip aloft before reaching the ground.
Have updated to bring conditions current and incorporated trends
into the evening forecast. This did lower dewpts a bit, but
should start to see them rise during the night.
Previous Discussion...
Deep moisture plume will slowly lift northward into SNE tonight
resulting in lowering cigs. Band of light rain across northern
NJ and NYC area will struggle to move north through this evening
due to presence of dry layer in the low levels so expect dry
conditions into this evening. Eventually expect some spotty
light rain to move up from the south and west after midnight
as low level jet moves into the region along with increasing
low and mid level frontogenesis which induces modest forcing for
ascent. Best chance of rain will be from western New Eng to the
south coast region where low levels eventually moisten up.
However, it may remain dry through the night further north
across northern and especially NE MA where low level dry air
persists through 12z.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Tuesday into Tuesday night...Closed/vertical stacked low off
the SC coast lifts slowly northward to the Mid Atlc region Tue
night. With high pres locked over the north Atlantic, this
results in a deep moist easterly flow into New England with low
level wind and PWAT anomalies increasing to 2-3SD above normal.
This will bring periods of rain, heavy at times through Tue
night. The rain will gradually spread north across SNE through
the morning and into the afternoon as low levels moisten and
easterly low level jet moves north across the region. Rainfall
during Tue should be mostly light to moderate. But a second
period of heavier rainfall is likely Tue night, as a SSE low
level jet approaches with increasing PWATS over 1.5". Expect a
period of heavy rain along with chc of a few thunderstorms along
the coast after midnight as elevated instability increases at
the nose of the low level jet. Rainfall of 0.75-1.5" is expected
with locally up to 2 inches in any heavier convective
rain/t-storms. This will not produce river flooding but minor
urban and poor drainage flooding is possible, especially Tue
night.
It will be a chilly and raw day Tue with gusty NE winds and
temps in the mid 40s to lower 50s, mildest near the south
coast. NE winds will occasionally gust to 20-30 mph near the
coast with highest gusts over the Cape/Islands. Temps should
rise into the mid 50s Tue night across RI and SE MA, with slowly
rising temps overnight in the interior. Gusty easterly winds
will continue Tue night along the coast. 50+ kt low level jet
approaches the south coast late Tue night but inversion will
likely prevent these winds from mixing down.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Overview...
As cutoff H5 low pres and associated surface system moves up
the eastern seaboard Wed, it will slow and tend to weaken near
or just S of the region through Thu night. Band of heavy rain
moves across through midday Wednesday ahead of this system,
along with gusty E-SE winds that will slowly shift to S as
remnants of the surface low linger. Will likely see lingering
light showers, areas of drizzle and fog. Can not pinpoint when
or where the showers will occur, but suspect mainly across
central and eastern areas with the good low level moisture will
continue to feed into these areas with the onshore winds, albeit
diminishing as the low weakens.
Digging H5 trough across the Plains states will slowly shift E
as large subtropical high pres (Bermuda high) looks to set up
off the SE U.S. coast by the end of the week. This will make the
progression of the H5 trough difficult while mainly zonal flow
sets up across New England N of the high. A cold front may try
to make a run across the region, but appears will get hung up in
the W-E flow. Not seeing a whole lot of moisture or instability
with this front, especially as it wavers across the region by
this weekend. Will likely see S-SW winds late this week through
the weekend, which may shift to W at times depending where the
front lies. A lot of uncertainty with this portion of the
forecast.
Details...
Wednesday...Moderate confidence.
As weak low moves up the eastern seaboard, heaviest precip will
occur during the morning into midday hours. Some question as to
how quickly the precip exits the region late Wed into Wed
night. 12z NAM/GFS tend to be quickly in pushing heavier precip
out, while the GGEM/ECWMF linger it a bit later as the low
lingers S of the region.
With the low lingering, could see some marginal instability work
into S coastal areas. Noted LIs around zero to -1 along the S
coast and over the southern waters, as well as K indices around
30. Have kept mention of isolated thunder across the immediate S
coast and adjacent coastal waters through midnight, but not
confident.
The more certain part of this forecast will be the lingering
showers, areas of drizzle and fog through Wed night. May see
visibilities locally reduced below 1 mile, less along the
immediate coast early Wed morning and again Wed night. Will also
see E-SE winds gusting up to 25-30 mph mainly across Cape Cod
and the islands where a strong low level jet will pass across.
Winds at 2Kft running in the 50-60 kt range, but not seeing a
lot of good mixing with an inverted layer aloft. Winds will
diminish as pres gradient slackens and winds start to shift to
more southerly during the afternoon or Wed night.
Thursday...Low to moderate confidence.
As weakening surface and upper low meander near or just off the
coast, will see some more scattered showers, patchy drizzle and
fog in place. The drizzle and fog will mainly occur during the
overnight and early morning hours, then return late Thu night.
With the lack of a strong onshore flow, though, looks like temps
should become milder as winds start to shift to a more
southerly direction, though they will remain light. Just seeing
a lot of low level moisture lingering through Thu night.
Friday...Low confidence.
Will start to see a more S-SW wind flow in place as surface and
upper low finally flattens out and a cold front starts to
approach. However, noting the SW H5 steering currents tend to
become more W-SW during the day and especially Fri night. So, as
the front approaches, will get caught in this flow and slow its
progression. Some showers may move into N central and western
areas ahead of this front as it tries to sag S across the region
Fri night or early Sat morning.
Saturday-Monday...Low confidence.
A lot of uncertainty with remnants of the front lingering
across the region. At this point, have kept slight chance to low
chance POPs across the region. Exact timing and position of the
precip still in question though. As the H5 long wave trough
tries to shift E, may see the front lift around the late Sunday
or Monday timeframe, but this timing is uncertain. Temperatures
should run warmer than seasonal normals for late April.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Tuesday Night/...
Through tonight...High confidence. VFR cigs trending downward
to MVFR/IFR along the south coast towards daybreak with patchy
-RA developing.
Tuesday and Tuesday night...Moderate confidence.
Conditions lowering to IFR/LIFR in the morning with widespread
rain, stratus and patchy fog, lingering through Tue night. E
wind gusts to 25 kt developing over Cape/Islands Tue with winds
veering to SE Tue night with similar gusts. LLWS developing
Cape/Islands after midnight as SE/S low level jet at 50+ kt
develops.
KBOS TAF...Moderate confidence.
KBDL TAF...Moderate confidence.
Outlook /Wednesday through Saturday/...
Wednesday...Moderate confidence.
MVFR-IFR CIGS with -RA/RA and patchy fog. Reduced VSBYS likely,
down to IFR in spots. May see areas of LIFR CIGS across the
higher inland terrain and along the coast. SE winds gusting up
to around 25 kt mainly across Cape Cod and the islands Wed,
should diminish Wed night. Low risk of TSRA along S coastal
terminals. LLWS impacts for coastal terminals with 40-50 kt S
winds 2 kft agl, possibly approaching 60 kt on the outer Cape
and Nantucket, shifts offshore late in the day.
Wednesday night...Moderate confidence.
Mainly IFR in areas of -RA, -DZ and FG. Areas of VLIFR along
the coast and across higher terrain. Light/variable winds,
except SE-S up at 5-10 kt across Cape Cod and the islands.
Thursday-Thursday night...Low to moderate confidence.
Drizzle and fog move offshore early Thu, but isolated showers
linger with local MVFR VSBYS. CIGS should improve to VFR across
western terminals, but will likely remain MVFR-IFR for central
and eastern areas. IFR-LIFR conditions may return in patchy fog
and low clouds Thu night with light winds.
Friday-Saturday...Low confidence.
Brief MVFR-IFR VSBYS early Fri, then improving. May see
scattered -SHRA across N central and W Mass early Fri. CIGS
should be mainly VFR, though areas of MVFR return Fri night and
early Sat. SW winds shift to W late Fri or Sat, though timing
very much in question.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Tuesday Night/...High confidence.
Tonight and Tuesday...
Increasing pressure gradient between low pres to the S and high
pressure to the N will lead to increasing easterly winds
spreading north across the waters late tonight and especially
Tue. Gusts to 25-30 kt expected with building seas. Reduced
vsbys in rain and fog Tue.
Tuesday night...
E winds veering to SE overnight. Wind gusts may briefly
diminish for a time Tue evening but increase again after
midnight with gusts 25-30 kt, especially south coastal waters
as SSE low level jet approaches. Reduced vsbys in rain and fog.
Outlook /Wednesday through Saturday/...
* Small craft advisories likely for a majority of the period.
Wednesday...Moderate to high confidence.
E-SE winds at 15-20 kt will continue, with gusts up to around
30 kt during the day. Seas continue to build up to 8-12 ft
during Wed, highest along the outer waters south and east of
Cape Cod and Nantucket. Winds and seas will slowly diminish Wed
night, though wind will remain onshore. Reduced visibilities
possible during the day, more likely at night in patchy rain,
drizzle and fog. Low risk of thunderstorms on the southern
waters through midnight Wed.
Thursday-Thursday night...Moderate confidence.
Light winds in place, mainly S across the southern waters and
E-SE on the eastern waters. Seas remain high, up to 6-8 ft on
the outer waters early and slowly subsiding but remain at or
above 5 ft over the open waters. May see local visibility
restrictions in patchy fog mainly after dark. Patchy rain and
drizzle may also linger.
Friday-Saturday...Low to moderate confidence.
Light S-SW winds early Fri will increase, gusting up to around
20 kt. Winds may shift to W as a cold front may approach
sometime Sat. Seas remain around 5 ft on the outer waters
Friday, though may subside Fri night or early Sat. Patchy fog
with locally lower visibilities early Fri. May see a few showers
late Fri into Sat if cold front approaches.
&&
.TIDES/COASTAL FLOODING...
* Potential minor flooding impacts during astronomically high
tides Tuesday night through Wednesday along the east and south
coasts
Not anticipating any flooding impacts for the Tue high tide as
winds, surge and seas will not have built up enough.
Minor flooding possible during the Tue night and Wed high tide
cycles along both coastlines. A storm surge around 1 ft with low
risk of 1.5 ft surge on top of high astronomical tides and
building seas may lead to minor inundation of vulnerable
shoreline roads. Some beach erosion is also possible, especially
for east and SE facing beaches.
Boston High Tides (flood stage 12.5 feet)...
11.47 feet / Tuesday 11:20 pm
11.15 feet / Wednesday 11:50 am
Providence High Tides (flood stage 7 feet)...
5.98 feet / Tuesday 8:11 pm
5.53 feet / Wednesday 841 am
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 4 AM Tuesday to 8 AM EDT Wednesday
for ANZ232>235-237-255-256.
Small Craft Advisory from 8 AM Tuesday to 8 AM EDT Wednesday
for ANZ231-250-251-254.
&&
$$
SYNOPSIS...KJC/EVT
NEAR TERM...Belk/KJC/EVT
SHORT TERM...KJC
LONG TERM...EVT
AVIATION...KJC/EVT
MARINE...KJC/EVT
TIDES/COASTAL FLOODING...Staff
Area Forecast Discussion
National Weather Service Billings MT
828 PM MDT Mon Apr 24 2017
.UPDATE...
Latest upper air analysis shows 100+ kt H3 jet nosing from the
great basin toward the central Rockies, with increasingly
divergent flow extending thru WY into our cwa. The combination of
increasing synoptic scale ascent and deepening upslope winds in a
moist and unstable airmass has allowed for plenty of showers
across our western cwa this evening. There has been some lightning
but that is diminishing since sunset. Cold advection associated
with Canadian surface high to our northeast has dropped temps to
the 40s...with low-mid 30s noted in NE MT already.
Upper and surface lows will become stacked later tonight in
northeast WY, allowing for significant precipitation along the
easterly upslope side of the Bighorns, extending across our far
southeast. Trailing convergent axis in central MT will keep pcpn
going in our west tonight into early tomorrow as well. Our
northeast parts from Miles City to Baker will remain dry with this
system.
Have made no changes to the inherited winter highlights, which
include a Winter Storm Warning for the Beartooth/Absarokas and
advisories for the Sheridan Foothills and across our far
southeast zones. Low level cooling will be a result of advection
and dynamics, and latest RUC wet bulb zero height forecasts
suggest a change to snow overnight, perhaps not til after 09z for
the lower elevations of Sheridan County. So, these areas will see
a good dose of rain before snow becomes a concern. Further west,
the Beartooth/Red Lodge foothills will also see a change to wet
snow late tonight or early Tuesday, but moisture will begin to
lessen by then. So although some wet accumulation is possible in
the Paradise valley and at Nye and Red Lodge, believe these areas
will see most of the precipitation in the form of rain. Melville
on the east side of the Crazy Mtns should also see some wet
accumulation. Accumulations of 3-6 inches still seems a good call
for our far southeast, especially over the hills and near the WY
border. Will need to keep an eye on Sheridan County per the
upslope. If Sheridan/Dayton/Big Horn change over earlier than
expected, higher snow amounts are possible. Also, the Bighorns
will see heavy snowfall and this looks to be a high end advisory
with up to a foot of snow above 6kft. Travel on I-90 thru Sheridan
and on Highway 212 thru southeast MT will be messy tomorrow
morning.
JKL
&&
.SHORT TERM...valid for Tue and Wed...
A few showers were moving E through the forecast area early this
afternoon. Abundant cloud cover was keeping thunder at bay.
A Pacific jet, seen on water vapor, was diving SE into the four-
corners region and will bring upper divergence to the region
through Tuesday as it carves out a deep trough. An upper low will
form over NE WY by 12Z Tue. and will push E into the Dakotas Tue.
evening. Associated surface low will deepen over E WY tonight.
Models agreed that a bullseye of QPF would develop N of this low
and affect areas from the Sheridan Foothills N and NE into SE MT
tonight through Tue. morning. Strong ENE winds will wrap around
this low into the forecast area. Backdoor cold front will push W
into the area bringing negative 850 mb temperatures as far W as
Yellowstone and Musselshell County Tue. morning. QPF amounts will
be greater than a half inch in some areas around the low.
Soundings showed the precipitation changing to snow around the low
by 12Z Tuesday. Snow ratios combined with expected QPF will allow
for several inches of snow. The snow, although wet, will combine
with the winds to support Advisory conditions. Therefore will have
an Advisory for snow tonight through Tuesday in SE MT and the
Sheridan Foothills.
Time-height cross sections continued to support high snowfall
amounts in the Beartooths/Absarokas and NE Bighorns into Tuesday.
The Bighorns may see Warning criteria snow, but will leave the
Advisory in place for now. Otherwise, rain will mix with snow
across the area overnight through Tue. morning. Some rain/snow mix
will linger in the SE Tue. afternoon. Snow amounts looked too
light to support an Advisory over remaining areas, but this will
need to be watched in subsequent shifts. Highs will reach only the
40s on Tuesday. Did mention some thunder over western zones Tue.
afternoon and evening with LI`s below zero degrees C.
Precipitation winds down Tue. night into early Wednesday under WNW
flow/weak ridging. Another Pacific jet dives SE into the western
U.S. Wed. afternoon through the end of the period, lowering
heights and bringing more showers. Wednesday will be a bit warmer
than Tuesday with highs in the 50s. Arthur
.LONG TERM...valid for Thu...Fri...Sat...Sun...Mon...
Extended period Thursday and Friday is cool with upslope flow
with low heights aloft but fairly disorganized structure to the
upper trough over the region. This will yield a couple of days
with modest precipitation and persistent cold temperatures with
accumulating mountain and likely foothill snowfall. But
accumulation rates will be slow and daytime melting could occur
below 6000 feet so impacts may be limited from a winter
perspective. The amount of precipitation will cumulatively cause
sloppy conditions for non paved roads and will continue to
increase the amount of moisture in the ground and in the snowpack
so streams and rivers will remain at elevated levels for this time
of year.
Upslope flow breaks on Saturday and a transition to an unsettled
northwesterly flow sets up for the remainder of the extended. This
will allow for a minor warmup but with still below normal
temperatures and more shower chances but amounts will not be as
great as the early week or late week events. borsum
&&
.AVIATION...
Increasing upslope flow this evening and overnight will cause
widespread low clouds and a mix of rain and snow. Mountain and
foothill obscurations will become widespread and all terminal
sites will encounter IFR conditions or worse tonight in low cigs
and reduced vis. AAG/borsum
&&
.PRELIMINARY POINT TEMP/POPS...
Tue Wed Thu Fri Sat Sun Mon
-----------------------------------------------------------
BIL 037/047 035/056 039/049 036/046 034/052 036/058 040/058
85/O 32/T 45/W 75/R 32/O 11/B 33/R
LVM 036/050 032/054 035/047 030/046 029/051 030/056 034/055
87/T 46/T 75/W 55/O 42/O 22/R 33/R
HDN 037/049 034/058 039/050 037/048 035/054 035/060 039/060
85/O 21/E 45/W 56/R 32/R 11/B 33/R
MLS 033/046 031/055 036/053 036/050 035/055 036/060 041/060
11/E 11/B 23/W 33/R 21/B 11/U 23/R
4BQ 033/044 027/053 032/048 034/046 032/050 033/057 037/059
77/O 11/B 24/W 44/O 33/O 21/B 33/R
BHK 027/043 024/051 028/051 030/050 031/053 031/057 035/057
01/E 11/B 12/W 12/O 11/B 11/B 24/R
SHR 034/043 030/052 035/045 034/042 030/046 030/053 036/054
++/O 22/T 45/W 66/O 43/O 11/B 32/R
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory in effect until 6 PM MDT Tuesday FOR
ZONES 36>38-58.
Winter Storm Warning in effect until 6 PM MDT Tuesday FOR
ZONE 67.
WY...Winter Weather Advisory in effect until 6 PM MDT Tuesday FOR
ZONES 98-99.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Charleston SC
1127 PM EDT Mon Apr 24 2017
.SYNOPSIS...
A low pressure system will affect the area tonight, before pulling
away Tuesday. Although a short wave could impact the area late
Thursday, high pressure will prevail most of the time into the
weekend. A cold front could affect the area early next week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
The Flash Flood Watch for Inland Berkeley County will be allowed
to expire at midnight. Showers will continue to diminish through
the night. Updated pops to reflect current trends.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Tuesday: The separation between the surface low and it`s
accompanying cyclone aloft with shrink as the associated surface
warm and cold fronts occlude and the resulting vertically stacked
low pulls away to the NE. The last lobe of vorticity spinning
counter-clockwise will pull through the area in the morning, and
with considerable wrap-around moisture to continue across our
northern zones, we still have a slight chance to chance of showers
for the Charleston quad-county area through 1-3 pm. Widespread low
stratus to start the day will lift into an extensive cumulus deck,
and will be slow in diminishing in coverage until late morning south
and not until mid to late afternoon north. Depending upon this
transition, it will have huge implications on max temps. For now we
have mid 70s north of I-26 where cloud cover will last longest,
upper 70s over the rest of SC, and 80-83F across our GA counties
where insolation will b most prevalent.
Tuesday: Mid and upper level will develop and the W-NW extension of
Atlantic high pressure pokes in behind the departing stacked low
pulling through the Great Dismal Swamp and VA Tidewater to the
nearby Atlantic off the Delmarva. Winds will decouple and with
mostly clear skies south and partly cloudy north, there will be
enough radiational cooling to get lows down to the upper 50s-lower
60s inland from the warmer beaches.
Wednesday: Deep-layered high pressure with rising surface pressures
and climbing heights aloft will provide the region with plentiful
sunshine and dry conditions. Temps at 850 mb are as high as 14-16C,
or between the 75th and 90th percentile for late April, and equates
to temps reaching the mid and upper 80s. Coastal sections will
experience a resultant sea breeze, so highs will generally be held
below 80F.
Thursday: Sub-tropical ridging at the surface and low levels, and a
W-SW flow aloft will dominate. The resulting subsident cap around 5-
6K ft looks to keep the majority of the area rainfree, but a
dampening mid level short wave situated in the Pacific NW as of late
Monday, will skirt the region late in the day, actually taking on a
slight negative tilt. This could spark a few showers and t-storms
far inland sections before dark. Despite a little greater cloud
cover than Wednesday, similar 850 mb temps will produce highs again
the in the mid or upper 80s inland from the barrier islands.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A strengthening upper ridge and strong Atlantic high pressure
will maintain above-normal temperatures and mainly dry weather.
Friday and Saturday will probably reach the lower 90s across
inland southeast GA with upper 80s elsewhere. A cold front is
expected to approach next Monday, possibly bringing some rain.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Expect IFR cigs to fill in behind the upper low tonight,
especially at KCHS. KSAV is a bit more questionable as to how
low cigs will get. Latest RAP soundings suggest low-end MVFR,
but IFR is possible. Expect prevailing IFR or lower at KCHS, but
opted to limit cigs to alternate minimum thresholds for now.
Extended Aviation Outlook: No significant concerns.
&&
.MARINE...
Tonight: Winds expected to turn westerly behind departing low
pressure, mainly reaching 15-20 kt with seas 3-5 feet, except
up to 6 feet in the Charleston County waters and the outer
Georgia waters where an Advisory remains in effect.
Tuesday: There remains a cyclonic flow around low pressure off to
the north through the day to hold any resultant sea breeze
circulations at bay until maybe late in the day. Winds and seas will
be below any advisory levels on all waters, with one exception, the
outer GA waters, where the SCA continues into the afternoon.
Wednesday through Saturday: Atlantic high pressure will dominate
with a S-SW synoptic flow to prevail. Despite some boost from the
sea breeze, winds won`t be any higher than about 15-18 kt and seas
will be capped at 3 or 4 ft.
&&
.TIDES/COASTAL FLOODING...
Astronomically high tides will prevail during the middle of the
week due to the Perigean Spring Tides, likely resulting in the
risk for shallow coastal flooding along at least parts of the
coast with the evening high tides Wednesday and Thursday.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 2 PM EDT Tuesday for AMZ374.
Small Craft Advisory until 6 AM EDT Tuesday for AMZ350.
&&
$$
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
705 PM CDT Mon Apr 24 2017
.AVIATION.../00Z TAFS/
VFR conditions are expected to continue at all sites until MVFR
ceilings develop at the I-35 sites around 11Z as southerly 10 knot
winds bring Gulf moisture back into the region. Some models are
indicating that ceilings may lower to IFR at SAT/SSF, but given that
this is the first day of moisture return we have stuck with higher
ceilings for now. Ceilings should lift to VFR by 17Z at all sites
with southerly winds gusting to 20-25 knots tomorrow at AUS.
&&
.PREV DISCUSSION... /ISSUED 256 PM CDT Mon Apr 24 2017/
SHORT TERM (Tonight through Tuesday Night)...
A compact mid level impulse crossing the Mexican mountains will
generate isolated showers and thunderstorms there this afternoon.
Only the HRRR shows any of this moving across the Rio Grande into our
area this evening. Also, previous runs of TTU-WRF showed some moving
into our far western counties. Have a 5 POP for Maverick and Dimmit
Counties where steering flow would take them.
As an upper level trough moves across the Rockies and out into the
High Plains, a surface low drifts to the northeast across the
Southern Plains. South to southwest lower level flow will result.
This increases moisture for stratus formation later tonight into
Tuesday morning, then it mixes out by midday. The main impact of
this will be a rapid strong warmup as 850 MB temperatures warm to
21C-27C and 925 MB to 27C-33C on Tuesday. High temperatures Tuesday
will be about 10 degrees above normal, with some approaching 100
along the Rio Grande. A dryline moves into western areas late Tuesday
night. There may deep enough moisture below a strong cap for patchy
drizzle along and east of Highway 281 by Wednesday morning. Have
silent 10 POPs for this.
LONG TERM (Wednesday through Monday)...
The upper level trough moves out across the Plains on Wednesday with
the dryline moving across the remainder of our area by midday. In
spite of a right entrance region of an upper level jet passing
overhead, moisture will be confined to below a strong cap with only
patchy drizzle for only silent 10 POPs east of I-35. Should moisture
become deeper and linger longer, then isolated showers and perhaps a
thunderstorm are possible along the Highway 77 corridor around
midday. Downslope flow will keep temperatures above normal Wednesday.
Strong mixing and a tight pressure gradient will result in breezy
conditions. Some guidance shows speeds near advisory levels. Low
humidities combined with the winds mentioned above will create
elevated to near critical fire weather conditions with best chances
for these conditions west of San Antonio along and southwest of the
Escarpment to the Rio Grande. A cold front moves across our area late
in the afternoon into evening after peak heating. No rain is
expected with the front as moisture will have been scoured out by the
dryline. Cool surface high pressure settles into our area Wednesday
night for a return to below normal low temperatures. Cool down will
be short lived as south to southwest lower level flow quickly returns
on Thursday with high temperatures back above normal. The surface
high moves off to the east as surface pressures lower in the Plains
as an upper level trough takes shape over the western states. Another
strong warming trend is expected for late week into next weekend as
850MB and 925MB temperatures rise again. There are good chances for
100 degree high temperatures along parts of the Rio Grande on Friday
and Saturday as 925MB temperatures near 35C.
The western states upper level trough moves across the Plains next
weekend with a dryline/pre-frontal trough and a cold front moving
across South Central Texas. Timing and consistency issues have been
noted in the models and run to run. The 12Z runs show slightly better
agreement and for now, have gone with a Saturday night frontal
passage and a Sunday upper trough passage. Expect isolated showers
and thunderstorms on Saturday to become more numerous Saturday night
and then end on Sunday. There is a potential of strong to severe
storms as forecast soundings indicate high CAPE and shear.
Temperatures fall below normal in the wake of the front and remain
below normal into next Monday due to cool surface high pressure.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 63 89 72 89 55 / 0 - 10 10 -
Austin Bergstrom Intl Airport 61 88 72 88 52 / 0 - 10 10 -
New Braunfels Muni Airport 61 88 71 90 53 / 0 - 10 10 -
Burnet Muni Airport 60 89 68 84 51 / 0 0 10 - -
Del Rio Intl Airport 62 97 67 91 58 / 0 0 0 0 0
Georgetown Muni Airport 63 88 71 86 52 / 0 - 10 10 -
Hondo Muni Airport 60 92 66 91 53 / 0 0 0 - 0
San Marcos Muni Airport 61 88 71 89 53 / 0 - 10 10 -
La Grange - Fayette Regional 61 87 72 89 54 / 0 - 10 10 -
San Antonio Intl Airport 63 89 72 90 55 / 0 - 10 - 0
Stinson Muni Airport 62 90 71 91 56 / 0 - - - 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...LH
Synoptic/Grids...05
Public Service/Data Collection...Treadway
Area Forecast Discussion...UPDATED
National Weather Service GLASGOW MT
832 PM MDT Mon Apr 24 2017
.SHORT TERM...for northeast Montana...tonight through Wed...
Sent an update tonight to fine tune the immediate near short term
grids to fall more in line with recent observations and satellite
and radar trends. Precipitation will continue to be shunted away,
barely clipping our CWA along our west and southwest edges. Will
be a cold night with persistent cloud cover and breezy easterly
winds.
BMickelson
Previous short term discussion: Following a thunderstorm that
developed east of Flatwillow, MT just after noon today, convective
showers have continued across the southwest zones of the CWA this
afternoon. Additional convective development appears to be
occurring based on radar reflectivity across Fergus County with a
few lightning strikes, just upstream of the forecast area.
As RAP analysis shows MUCAPE supportive of thunder in the
southwest zones this afternoon and perhaps early evening, thunder
was maintained in the weather grids for now. Additional support
does come from mesoscale simulated reflectivity over the next few
hours. This seems collaborated with SPC which has a general
thunderstorm outline for portions of Petroleum County. The actual
forecast brings slight chance of thunder a little further north
and east based on radar trends. Cloud cover from incipient showers
may be a limiting factor however, and conditions will continue to
be monitored over the next few hours.
An upper level shortwave tracking across southern Alberta and
Saskatchewan into Tuesday will provide enough forcing for ascent
to justify at least slight chance to chance pops in western
portions of the CWA through this time period. Thus, a continued
cool and active weather pattern looks to prevail into the short
term period.
Maliawco
.LONG TERM...Wed night through Mon...
System that brings showers over central Montana should weaken and
not affect our western zones late Tuesday/Tuesday Night but left
higher pops for mainly collaboration purposes.
Rest of forecast looked good and agreed with model consensus.
TFJ
Previous Discussion...
Longwave trof over the western/central CONUS will dominate the
weather pattern for the extended period. Shortwaves diving into
the trof will generate showers along the front range, and
possibly extending into the plains through the middle of the week.
With the cold trof overhead and plenty of cloud cover,
temperatures will remain below normal, with showers turning to
snow in the overnight periods possible.
Late in week the development of a stronger storm system in the
desert southwest will cut off much of the moisture into the
northern plains. Should see showers ending and some sun peeking
through to warm temperatures closer to normal for the weekend.
As a storm system lifts toward the Great Lakes early next week,
showers are expected to return to the state with next shortwave
diving into the lingering trof.
Ebert
&&
.AVIATION...
SYNOPSIS: SFC High pressure will bring a dry and stable ENE flow
to NE MT over the FCST period. Due to a departing low over the
Great Lakes and another low over E WY, most of the area will be
covered in low stratus for the next couple of days.
Flight Conditions: MVFR CIGS.
CIGS: Generally 1500 to 2500, with CIGS slowly rising farther west
into Philips County. Cigs are FCST to gradually improve toward
the end of the FCST period, 00z 4/26.
Weather: No SIG WX FCST thru the period.
tec
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Green Bay WI
1032 PM CDT Mon Apr 24 2017
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Tuesday
Issued at 255 PM CDT Mon Apr 24 2017
The latest rap analysis and satellite/radar imagery show a surface
warm front losing definition over central Wisconsin early this
afternoon. Despite a influx of dry air above the inversion and
increasing south winds aloft, relative humidity values have been
behaving so far, with only a few locations over north-central WI
below 25 percent. Will still have a few hours to tap into the vast
reservoir of dry air above the inversion, but southeast winds will
likely prevent that from happening over eastern WI. Looking to the
west, a cold front is traveling east over the eastern Dakotas, while
a shortwave is producing showers from eastern Nebraska into southern
Minnesota. Forecast concerns revolve around precip chances as
moisture pushes in ahead of the cold front and shortwave trough.
Tonight...As a shortwave trough swings northeast across the region,
a cold front will slowly slide into the northern Mississippi Valley.
Southerly flow aloft and southeast winds at the surface will provide
a steady influx of dry air below 10 kft which should hold off
precip. Could be some virga though over north-central WI as the
shortwave moves through. Otherwise the combo of mid and high clouds
overhead and a breezy southeast wind should keep temperatures mild.
Went slightly above the multi-model blend with low temps mainly in
the middle to upper 40s.
Tuesday...The cold front will not make much progress eastward, but
will see a weak shortwave impulse move across the state during the
afternoon. This shortwave will have more moisture to work with than
the impulse arriving tonight, so will see the first decent chance of
showers over central and north-central WI, mainly during the middle
to late afternoon hours. Eastern WI should remain protected by
lingering dry air. Otherwise, should see periods filtered sunshine
and broken cloud cover through the day. Temps warming into the
middle 60s to near 70 degrees.
.LONG TERM...Tuesday Night Through Monday
Issued at 255 PM CDT Mon Apr 24 2017
Southwest upper flow and lots of upper jet action
will provide at least a few periods of significant precipitation
this week. It will also turn much cooler with some chance of
winter precipitation across northcentral Wisconsin late Wednesday
night and Thursday, and again possibly Saturday.
The first round of precipitation will begin Tuesday afternoon or
evening and continue into Thursday as upper troughs approach from
the northern and southern Plains. They will combine to produce
surface lows that track northeast along a nearly stationary front
from Oklahoma to Lake Michigan. As colder air arrives late
Wednesday night the rain may change to freezing rain or sleet in
the far north. WHile not a climatologically favorable time of the
year for freezing rain, forecast soundings support it as the most
likely precipitation type if the temperatures aloft are as
forecast.
Another synoptic scale weather system with possible significant
precipitation will arrive at the end of the week. A 1032mb surface
high is forecast to be north of the Great lakes, which could
deliver enough cold air in the low levels to produce some winter
precipitation in the far north, depending on the track and timing
of course.
Rains from these systems will likely cause rivers and streams to
rise again later this week, with possible minor flooding i some
areas.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1024 PM CDT Mon Apr 24 2017
LLWS will continue overnight, then subside toward daybreak.
Otherwise, broken mid-level clouds and virga can be expected
through Tuesday morning.
A cold front will approach the region Tuesday afternoon and
evening, and bring rain showers and lowering ceilings. Flight
conditions should deteriorate to MVFR over much of central,
north central and far northeast WI Tuesday evening.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1050 PM EDT Mon Apr 24 2017
.SYNOPSIS...
A deep and vigorous low pressure system will slowly move from
the South Carolina coast to near Cape Hatteras by late Tuesday.
Expect drier and warmer weather Tuesday and Wednesday. A
dissipating cold front crosses our region Thursday and Friday.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 1040 pm EDT, recent HRRR runs continue to bring the relatively
good coverage of persistent light to moderate showers westward into
the I-77 corridor from the NC central piedmont through the early
overnight hours. The current FFA will be maintained although the
threat of additional flooding continues to slowly diminish as rates
fall and the banding focuses more on I-40 than CLT metro late this
evening.
Otherwise, the forecast remains generally on track with the area
entrenched in an unseasonably cool wedge, well removed from the sfc
based unstable air which is mainly east of I-95. Banded forcing
northwest of the departing low pressure circulation will keep
intermittent bands of showers pivotting west into the Piedmont
overnight. An additional half inch to inch of rain will be possible
in some areas east of I-77 through the early morning hours.
A much improved day is on tap for Tuesday with the flow through a
deep layer backing to the NW as the sfc/upper flow wobbles toward
the mid-atlantic. Maximum temperatures are expected to be 12-15 deg
F milder than today`s chilly readings.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 100 PM Mon: Heights rise Tue night and Wed as a shortwave
upper ridge moves overhead. A strong subsidence inversion accordingly
will develop. With weak warm/moist advection occurring in the low
levels, as well as saturated soils across the area, there is
potential for low stratus and perhaps some dense fog to develop early
Wed morning, particularly over the Upstate and NE GA. That afternoon,
the same inversion should be strong enough to stifle convection
across the whole CWFA, so PoPs will be kept below slight chance. Max
temps are expected to be 6 to 9 degrees above normal.
Wed night into Thu, the upper ridge axis will be just to our east. A
full-latitude trough will be hot on its heels, centered near the
Mississippi River at 12z Thu. This trough will be associated with a
low over the western Great Lakes, and a frontal zone that will
impinge on the western CWFA by 00z Fri. A plume of midlevel moisture
preceding the trough suggests increasing clouds/PoPs. Elevated tstms
will be possible in the aftn, but sfc-based convection continues to
be suppressed by poor lapse rates resulting from either the ridge or
from the moisture aloft. The best-verifying blend of guidance
suggests max temps will top out 5 to 8 degrees above normal, held
down a bit more by the cloud cover.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 200 PM Mon: Friday and Saturday will see the resurgence of a
late-spring pattern over the Carolinas and Georgia, as the upper
pattern amplifies. Temps will trend upward under continued
southwesterly flow; the warmest day looks to be Saturday, when a few
spots may hit 90. Convection will be limited by a weak capping
inversion on Friday, but the warming temps overcome that Saturday.
By Sunday the ridge will have drifted east slightly, allowing
slightly better lapse rates and still greater instability. Given the
pattern, we`ll maintain diurnally driven PoPs, with chances trending
up from day to day. As one might expect, weak wind profiles result in
little shear, and sfc-to-midlevel theta-E differences are high.
Together these findings suggest pulse storm threats from the stronger
cells.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
At KCLT: Occasional showers will impact the airfield through the
early overnight before gradually becoming more scattered in nature
through daybreak. Ceilings have bounced around quite a bit this
evening in the MVFR range but should settle quickly back into the
IFR to LIFR range overnight. Expect slow recovery through the day on
Tuesday as abundant low level moisture persists and the departing,
stacked low pressure system wobbles only slowly to the coastline.
NNE winds will vary back toward NW through the period, generally at
less than 10 kt going forward.
Elsewhere: Shower coverage will steadily diminish across the
mountains and foothills as the low pressure system migrates toward
the coast through the period. Shower chances will be best at KHKY
through the early morning hours. Ceilings may bounce around a bit
this evening but should settle into IFR then LIFR most areas
overnight. Slow recovery is expected Tuesday morning, but weak
downsloping will aid lifting and scattering through Tuesday
afternoon. Expect northerly winds to turn more NW with time, and
possibly WSW at KAND late in the period.
Outlook: Conditions should continue to improve through Wednesday
dry air works in behind the departing low. Return flow moisture
ahead of the next system will develop late in the week.
Confidence Table...
03-09Z 09-15Z 15-21Z 21-00Z
KCLT Low 51% Med 66% Med 72% High 83%
KGSP Med 70% Med 70% Med 66% High 85%
KAVL Med 66% Med 72% Med 78% High 100%
KHKY Low 53% Med 66% Med 61% Med 77%
KGMU Med 66% Med 64% Med 61% High 85%
KAND High 85% Med 61% Med 70% High 85%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Flood Watch until 8 AM EDT Tuesday for NCZ035>037-056-057-
069>072-082.
SC...Flood Watch until 8 AM EDT Tuesday for SCZ009.
&&
$$
SYNOPSIS...DEO
NEAR TERM...CSH/HG
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...HG
Area Forecast Discussion
National Weather Service Jacksonville FL
920 PM EDT Mon Apr 24 2017
.UPDATE...
For tonight...deep west to northwest flow will continue as the large
low pressure just to our north slowly lifts out to the northeast.
Wrap around clouds will continue tonight...over parts of northeast FL
through late this evening and continue on and off over southeast GA.
Smoke from the West Mims wildfire expected to move into portions of
Nassau and Duval County tonight through Tuesday under the prevailing
westerly flow. May need a special weather statement for low vsby and
smoke potential tonight into Tue morning. Otherwise...only slight
tweaks to the cooler overnight lows in the lower to mid 50s...with
upper 50s to near 60 northeast and eastern most areas.
&&
.AVIATION...VFR conditions will prevail through the period though
some caveats due to smoke from wildfire. Smoke may move into the
Duval County TAF sites overnight or Tuesday morning first with
scattered deck at 1-2 kft. Some light smoke mentioned for KJAX, KCRG
and KVQQ tonight for into Tuesday for the expected smoke. Certainly
can`t rule out lower conditions briefly down to IFR at JAX but more
likely MVFR vsby/cig. Westerly winds about 5-10 knot winds tonight.
Westerly winds around 8-12 knots gusting up to 17-20 kt forecast on
Tuesday.
&&
.MARINE...SCEC headlines continue tonight and Tuesday due to
strong pres gradient south of primary sfc low located off the coast
of SC. Only slight tweaks to winds and seas for the update.
Rip Currents: Low to Moderate risk of rip currents through
Wednesday.
&&
.FIRE WEATHER...Light westerly flow tonight with LVORI values
possibly around the 6 to 9 range after 4 am. Smoke from West Mims
fire will be pushed east-southeast tonight through early Tue morning
based HRRR guidance and model trajectories.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 56 84 60 88 / 0 0 0 0
SSI 60 79 66 80 / 0 0 0 0
JAX 57 85 62 86 / 0 0 0 0
SGJ 55 82 64 81 / 0 0 0 0
GNV 52 83 58 85 / 0 0 0 0
OCF 53 82 59 85 / 0 0 0 0
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$
Shashy/Peterson/Corless
Area Forecast Discussion
National Weather Service North Platte NE
629 PM CDT Mon Apr 24 2017
.SHORT TERM...(This evening through Tuesday)
Issued at 255 PM CDT Mon Apr 24 2017
The latest NAM12, GFS and HRRR solutions develop some convection
into the Panhandle and western Nebraska this evening, lifting it
to the east and northeast overnight. Main area of precipitation
should track as far south as the the I80 corridor. The mention of
thunder maintained overnight mainly near and south of highway 2.
Looking at instability, lifted indices, both surface based and
elevated, were slightly negative within this area. Overnight lows
will range from the upper 30s in the north to mid 40s south.
On Tuesday, much cooler with rain showers likely east of Cody
through Broken Bow. Still a chance for isolated thunder south of
highway 2 until 10 am cdt. Still a chance for showers for western
sandhills and southwest with chances decreasing through the day.
Models have been fairly consistent in tracking a 500 mb low center
from northeast Wyoming across South Dakota. Cold air aloft will
push southward Tuesday afternoon, with highs nudged colder due to
influence of stratus from only the low to mid 40s north central to
the mid 50s southwest.
.LONG TERM...(Tuesday night through Monday)
Issued at 255 PM CDT Mon Apr 24 2017
A 20 to 30 percent chance for lingering showers Tuesday evening. 850
mb temperatures fall to 0 to -5 degrees Celsius. Lingering light
rain may mix or change to wet snow n the north central, but
precipitation by this point will be very light and no accumulation
is expected. Some clearing late to allow lows to fall below
freezing from the upper 20s to lower 30s.
Wednesday will be a breezy and continued chilly day. Northwest winds
of 15 to 25 mph are expected. 850 mb temperatures do recover to
around 8C across southwest Nebraska by afternoon, but remain below
zero all day across the northeast portion of the forecast area.
Some sun will help highs climb into the 50s across southwest
Nebraska, but across north central Nebraska, lingering clouds and
colder air aloft will limit highs to the upper 40s.
The next chance for showers will arrive Thursday afternoon,
continuing Thursday night and Friday. This will be in response to
an upper trough pushing into the Central Plains. Likely pops most
areas during this timeframe. With colder air aloft, and
temperatures falling into the low to mid 30s in the northwest,
some snow may mix in. Highs Friday only in the 40s to low 50s.
For Friday night through Saturday night, there will be a
continued chance for rain showers, and even a chance for snow
showers on the backside of the system Saturday night. Operational
models have been struggling with the evolution of this system.
Model consensus is for the main system to track from Colorado and
Kansas into central and eastern Nebraska, where the higher chances
to reside. Highs in the 40s to lower 50s Saturday, moderating to
the lower 50s Sunday, and upper 50s to lower 60s Sunday, as
northwest flow still influences the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 625 PM CDT Mon Apr 24 2017
Models in good agreement with high confidence clouds will lower
overnight and beyond 09z marginal visual flight rules to be
expected west of Highway 83, east through north central visual
flight rules overnight with clouds lowering beyond 12z to marginal
visual flight rules throughout. Clouds will lower further across
the far north overnight to include KVTN where overnight Instrument
Flight Rules will be seen into the afternoon Tuesday.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Roberg
LONG TERM...Roberg
AVIATION...Keck
Area Forecast Discussion
National Weather Service Marquette MI
750 PM EDT Mon Apr 24 2017
.SHORT TERM...(This evening through Tuesday)
Issued at 317 PM EDT MON APR 24 2017
12Z raobs/latest wv imagery and RAP analysis show a wsw flow alf
over the wrn Great Lks to the e of upr troffing dominating the wrn
CONUS/sw Canada. The ese flow arnd a retreating sfc hi pres rdg
extending fm nw Ontario into the se Great Lks is advecting dry llvl
air shown on the 12Z APX, GRB and MPX raobs into Upr MI. But there
are plenty of hi clds streaming into the cwa ahead of a shrtwv/sfc
lo pres in the nrn Plains lifting toward MN within the wsw upr flow.
Despite this hi cld, temps have risen well aoa normal, especially
over the w with downslope flow away fm lk moderation.
Tngt...Shrtwv in the ncentral Plains will move ne, reaching wrn Lk
Sup late tngt. Since this disturbance is fcst to shear out a bit as
it enters a more confluent upr flow and the ssw lo-mid flow wl still
be tapping the dry air to the s, the bulk of the models indicate no
more than isold-sct showers wl impact only the nw portion of the
cwa. Plenty of hi clds and steady winds wl limit the diurnal temp
fall.
Tue...A shrtwv rdg axis is fcst to aprch following the exiting
shrtwv to the ne. So any pops over the nw cwa wl tend to diminish
until later in the day, when another shrtwv and some large scale
forcing/hier pwat aprch fm the sw as the lo-mid flow grdly taps a
moister airmass. The best chc of some showers mainly in the 21-24Z
time frame wl be over the w closer to the aprchg forcing/deeper
moistening and along a slow moving frontal bndry that wl push slowly
into the far w during the day in the wake of the first passing
shrtwv to the ne. Many of the short term guidance also indicate the
llvl moistening wl be sufficient to bring a return of some lo clds
over at least the e half. Despite the incrsg clds, expect temps to
top out as hi as the 60s, warmest over the central away fm Lk MI
moderation and some thicker clds/late arriving cold fnt over the w.
If there is more sunshine, a few places in the downslope regions
near Baraga could see 70 degree max temps.
.LONG TERM...(Tuesday night through Monday)
Issued at 337 PM EDT MON APR 24 2017
Still expecting an active weather week with multiple chances for
precipitation across the area.
As longwave troughing digs across the plains, numerous weak
shortwaves embedded within the southwest flow aloft will traverse the
area. This will also allow warm and moist air to stream northeast
ahead of the slow moving surface trough expected to extend northeast
into western portions of Upper Michigan by Tuesday night. The
combination of increasing upper-level support and warm air advection
should allow for fairly widespread rain showers to spread across the
much of Upper Michigan Tuesday night through the day on Wednesday.
With the first round of moisture transport lifting northeast across
the area, expect the focus for moderate to heavy rain to remain
across the west and central, where surface convergence will be
maximized. During the day on Wednesday, expect rain showers to
linger across the area as moisture transport continues to linger.
There are some differences among the model QPF, likely due to how
they each are handling the timing and strength of the mid-level
baroclinic zone. Therefore, there is some uncertainty as to what
locations will see the highest rainfall totals during the day on
Wednesday, but some locations may see over an 1 inch of rain.
Impact wise, Wednesday is a challenge. We could be looking at a day
where we have showers and thunderstorms across the central and east,
and wintry precipitation across the west. It will all be dependent
on how the surface trough traverses Upper Michigan, and on how much
unstable air can lift northward and how much shallow cold air can
undercut the warm, moist air ahead of and behind the surface trough,
respectively. Based on the current model guidance and trends, looks
like the potential for any freezing rain across the west will be
Wednesday night into Thursday morning. As colder air arrives into
Thursday morning, cloud ice will dissipate and leave behind freezing
drizzle before possibly transitioning over to snow in the west. Ice
accumulations from the forecast builder are showing upwards of a
quarter of an inch in some locations across the far west in the
higher terrain. Thinking this is overdone a bit considering the
increasing ground temperatures over the past few weeks. While ice
accumulations will be possible, elevated surfaces should have much
better chances at seeing any accumulations.
The big question on Thursday will be if any locations see any system
snow. There is still quite a bit of uncertainty in regards to the
track of low pressure with the Canadian now tracking the low north
across western and central Upper Michigan, leaving any chances for
system snow across the far southwest. The GFS is the most
progressive and lifts the low across eastern Upper Michigan and up
into Southern Ontario. Precipitation wise, the models remain
different, with the GFS being the less robust QPF wise as the system
is less wrapped up compared to the other deterministic models.
Therefore, confidence still does not remain high in regards to where
precipitation will track on Thursday. However, given the fact that
upper-level energy is progged to become negatively tilted, as a
stout shortwave lifts across the region, leaning towards the
ECMWF/Canadian solutions at this time. That being said, we`re still
looking at the potential for freezing rain to transition over to
snow across the far west and additional rainfall across the central
and east on Thursday.
Depending on when the system lifts out of the area, precipitation
will come to an end sometime Thursday night through early Friday
from south to north. We will see a break Friday and Saturday from
precipitation chances as high pressure clips the region. However,
towards the end of the weekend and into the beginning of next week
precipitation chances will return across Upper Michigan as yet
another system ejects out of the Plains and up across the Great
Lakes.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 749 PM EDT MON APR 24 2017
Under considerable mid and high clouds, a dry low-level air mass
will dominate the area thru Tue aftn, allowing VFR conditions to
prevail at KIWD/KCMX/KSAW. As near sfc layer cools this evening and
increases low-level stability, LLWS will develop at all terminals.
Just beyond this fcst period, conditions will deteriorate as a sfc
trof settles se across the Upper Lakes.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 337 PM EDT MON APR 24 2017
Ese winds up to 25-30 kts will prevail into this evening under the
tight pres gradient between hi pres retreating to the e and a lo
pres moving into MN. Although there could be some gale force gusts
mainly in a ribbon from Isle Royale to the tip of the Keweenaw and
the ne portion of the Lake, overall hi stability over the relatively
chilly waters will limit the potential for a more widespread gale
and the need for headlines. As the gradient slowly weakens overnight
into Tue, especially over the w half, winds will diminish. Stronger
se winds up to about 25 kts will persist over the e thru Tue.
Tuesday night northeast winds will increase to gales of 35 knots
across the west and north central portions of the lake as a surface
trough pushes east across the area. A few locations may see gusts
upwards of 40 knots. Through the day Wednesday, gales to 40 knots
will persist across the west and central, with winds 20 to 30
knots across the east. A few gale force gusts will be possible
across the east. By late Wednesday night into Thursday morning
winds will begin to subside to 20 to 30 knots as winds become
northerly. Late Thursday through Friday, winds will further
decrease to 10 to 20 knots as winds become westerly. Winds of 10
to 20 knots are expected through the weekend and into early next
week.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Watch from Tuesday evening through Wednesday evening for
LSZ162-263.
Gale Watch from Tuesday evening through late Wednesday night for
LSZ264.
Lake Michigan...
None.
&&
$$
SHORT TERM...KC
LONG TERM...Ritzman
AVIATION...Rolfson
MARINE...Ritzman
Area Forecast Discussion
National Weather Service Sacramento CA
331 PM PDT Mon Apr 24 2017
.SYNOPSIS...
Weak weather systems will bring light precipitation through
Wednesday. Gusty north winds likely to develop Friday.
&&
.DISCUSSION...
A weak weather system is currently skirting across the far
northern portions of California. A few light showers have been
detected by radar through the course of the day. The HRRR model is
showing some modest instability toward the Northern/Central
Sacramento Valley this afternoon and tonight, so have included
slight chance wording for thunderstorms there. Snow levels are
projected to fluctuate between 5000 and 7000 feet through tonight,
with a few inches of snow accumulation possible over the higher
elevations.
Additional weak weather systems are forecast to move through the
region on Tuesday, and again on Wednesday. Both of these will
again bring only precipitation totals to the region. Snow levels
will also be a fair bit higher, so little to no impact expected to
the mountains.
Breezy north winds along with warming and drying conditions
commence Thursday.
Dang
$$
.EXTENDED DISCUSSION (Friday THROUGH Monday)
Dry northerly flow expected over the weekend as an upper ridge
builds inland over interior NorCal. This will lead to dry
conditions and temperatures trending upward across the forecast
area. Daytime highs could be around 5-8 degrees above normal this
weekend, with Valley temperatures reaching the lower 80s. Periods
of gusty northerly winds are expected Friday into Saturday as
pressure gradient tightens, with 35-45 mph gusts in the Valley.
&&
.AVIATION...
Local MVFR/IFR conditions possible with isolated LIFR in shower
activity this evening. Isolated thunderstorms possible through 06z
Tuesday from KRDD southward to near KOVE. Improving conditions
expected overnight as shower activity ends. Gusty winds will be
decreasing this evening, with additional gusts up to 20 kts mainly
south of KSAC after 18z Tuesday.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
834 PM MDT Mon Apr 24 2017
.UPDATE...
Issued at 828 PM MDT Mon Apr 24 2017
00z KUNR sounding showed steep lapse rates, but some dry air to
work on via lift ahead of shortwave energy spinning over southwest
WY per latest water vapour movie. Latest KUDX radar loop showed
drier air as precipitation struggling to make it east of the
Black Hills at this point, but raining nicely over the higher
terrain. Forecast updated earlier for quicker movement of
precipitation shield.
01z RAP showed upper low moving into southwest SD by Tuesday
morning with well-defined band of 850-700mb frontogenesis across
far northeast WY into the Black Hills. Forecast wet bulb zero
suggest changeover over the highest elevations by 06z and then
above 4500 feet by 09z and then on the adjacent plains between
09z-12z. Forecast snow amounts tricky, but feel current headlines
depict best potential. Will be watching snowfall rates overnight
from northern Campbell into Butte County and then south into the
northern Black Hills.
&&
.DISCUSSION...(This Evening Through Monday)
Issued at 335 PM MDT Mon Apr 24 2017
Current surface analysis shows frontal boundary remaining from
northeast WY through southern SD, with colder air across northern
and eastern portions of the forecast area. Upper level analysis
shows low pressure over the Pacific NW, with trough digging south
and east across the western US. Skies are variably cloudy across
the area. KUDX radar showing isolated showers over the southern
Black Hills area, with regional radars showing showers and
isolated storms expanding across central into eastern Wyoming now.
Current temps in the 50s and lower 60s, warmest across far
southwest SD. North-northwest winds remain brisk across portions
of northwest into central SD.
All medium range models in good agreement on an unsettled and very
cool week ahead as the large upper trough to the west digs and
settles over much of the western and central US over the next couple
of days. A series of systems will move through the trough, bringing
near daily chances for pcpn through the weekend.
For late today and this evening, the first of these systems will
approach the area, bringing increasing chances for rain showers
across northeast WY and into western SD. Upper low will develop
across northern WY tonight and slowly track east into northeast WY
by morning, before sliding slowly southeastward and weakening as it
moves into the plains. As colder air sinks south into the area to
the northeast of the low, pcpn will start to change over to snow
generally from north to south and from higher to lower elevations
across northeast WY and western SD. NAM, GFS, and EC are bulls-
eyeing the most pcpn later tonight/early Tuesday over far northeast
WY, generally near and just north of the track of the upper low. If
the low ultimately tracks this way, the Bear Lodge Mts would likely
see the most snowfall, while the Black Hills would not see as much
pcpn and somewhat lower snowfall amounts later tonight into Tuesday.
Have decided to issue winter wx advisories for most of the area
covered by the watch, except for the Wyoming Black Hills/Bear Lodge
Mts zone, where a warning has been issued. Also included Butte
County and the foothills zones from Spearfish to Sturgis and
Piedmont in the advisory. Looking for mostly 2 to 6 inch amounts
across much of the advisory area, with 1 to 4 inch amounts across
southern Campbell County, the Weston County plains, and southern
Black Hills. Over the Bear Lodge Mts, it looks like amounts to
around 8 inches are likely, especially across the higher elevations.
Any adjustments in the track and strength of this system late
tonight and Tuesday morning, or changes in timing of a switch to
snow, would alter pcpn and snowfall amounts across these areas.
Rain and snow will taper off in the afternoon, with pcpn mostly over
by late afternoon. Highs on Tuesday will mostly be in the 30s, with
some lower 40s over far eastern portions of the CWA. Skies will stay
mostly cloudy Tuesday night, with some clearing possible over
western and northern areas toward morning. Lows will be chilly,
mainly in the 20s.
Wednesday looks to be the one dry day of the week before the next
system moves into the high plains. Highs will be in the 40s. The
next system will dig south into the Central Rockies Wednesday night
and Thursday, then slowly track across the Central Plains through
Friday. Pcpn chances look rather widespread, with the better chances
and more significant pcpn likely from northeast WY through southern
SD. With some colder air being drawn in on the north side of the
system, some snowfall looks likely across at least the higher
elevations of the area during the overnight/morning hours. Latest
models, especially the EC, have trended a bit further south and west
with the system, so will see if that trend continues over the next
day or two.
The weekend looks mostly dry at this point, but still cool, as the
broad upper trough remains across the region. A stronger upper low
is progged to remain mostly south of the region as it tracks across
the plains. Highs will be in the 40s and 50s. Some unsettled weather
could return Monday as trough moves further east and northwest flow
on the back side of the trough brings additional energy across the
area.
.AVIATION...(For the 00Z TAFS Through 00Z Tuesday Evening)
Issued At 531 PM MDT Mon Apr 24 2017
A storm system will move across WY into SD tonight. It will
spread widespread rain into the area from southwest to northeast.
Precipitation will change to snow from north to south overnight as
colder air moves south, and from higher elevations to lower
elevations. Areas MVFR CIGS will transition to widespread IFR
conditions after 06z with areas LIFR conditions with the heaviest
snow bands, especially near the Black Hills. Conditions may start
to slowly improve late Tuesday afternoon.
.AVIATION...(For the 00Z TAFS Through 00Z Tuesday Evening)
Issued At 531 PM MDT Mon Apr 24 2017
A storm system will move across WY into SD tonight. It will
spread widespread rain into the area from southwest to northeast.
Precipitation will change to snow from north to south overnight as
colder air moves south, and from higher elevations to lower
elevations. Areas MVFR CIGS will transition to widespread IFR
conditions after 06z with areas LIFR conditions with the heaviest
snow bands, especially near the Black Hills. Conditions may start
to slowly improve late Tuesday afternoon.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory from midnight tonight to 3 PM MDT
Tuesday for SDZ012-024-025-028-029-072.
WY...Winter Storm Warning from midnight tonight to 3 PM MDT Tuesday
for WYZ057.
Winter Weather Advisory from midnight tonight to 3 PM MDT
Tuesday for WYZ054-056-071.
Winter Weather Advisory from 6 AM to 3 PM MDT Tuesday for WYZ055-
058.
&&
$$
Update...Helgeson
DISCUSSION...26
AVIATION...Helgeson