Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/19/19
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
301 PM AKDT Mon Mar 18 2019
.SHORT TERM...While an atmospheric river sweats moderate rainfall
across a narrow band across the northeast gulf including Yakutat,
forecasters have been sweating when this band slides east and how
much more the rivers and streams around Yakutat can handle without
swelling over banks. This rainfall event produced around 1 to 4
inches across the bulk of the Panhandle this weekend, but Yakutat
and Pelican have each recorded around 6 inches of rainfall. Late
model guidance, including the HRRR have been a little more
hopeful regarding end of the barrage of rainfall. The GFS, ECMWF,
and NAM have all been a little high estimating QPF, which makes
the HRRR that much more impressive at guiding changes. Our best
proxy of what is going on has been the Situk, and it has been
steadily rising all day around 0.1 foot per hour, sometimes
higher. We are still looking for a crest, but as of yet, the
rainfall has been too persistent. But MIMIC satellite data has
indicated that the deepest moisture has moved west of the region,
which should indicate diminishing rainfall trends here this
afternoon. But we will continue to monitor on whether minor
flooding does occur, but as of right now, we still think flooding
will be avoided. After tonight, rainfall will remain west of
Yakutat, and will not return to the Panhandle until Wednesday when
a weak front presses up against the Panhandle slowly through
Wednesday night. But other than Yakutat and the immediate coast,
most areas will see a dry Wednesday and should not look forward to
more rainfall until at least Wednesday night.
Winds are strong and gusty still in Yakutat and in Skagway (gusts
to 45 mph) and along the Klondike Highway where sustained wind
speeds have edged upwards to 40 mph. This has prompted us to
extend the gusty winds at least for Yakutat. Winds have greatly
begun to diminish across the rest of the Panhandle. This trend
continues tonight to set up potential for patchy fog development
in many areas of the Panhandle. Capping, light winds, and clear
skies, as well as saturated ground will support this.
Finally, temperatures have rocketed into the lower 60s over much
of the southern and central Panhandle. This is but a prelude to
Tuesday when skies will be clear and an offshore gradient should
help temperatures with some adiabatic boosting. But flow will not
be super strong, and so the worry is that some areas may be open
to channel breezes. With surface water temperatures around 40 to
45 degrees for much of the Inner Channels, this will tend to curb
high rises in temperature. But that said, more high temperature
records look likely Tuesday, and probably Wednesday as well.
Ensembles continue to suggest atmospheric temperatures up to 3 to
4 standard deviations above normal.
The more heavily impactful immediate short-term forecast was given
the most attention as the rest of the forecast looked very
reasonable. Although temperatures were edged upward Tuesday as
much as adjusted to current conditions for this afternoon.
Forecast confidence is good.
.LONG TERM.../Wednesday through Monday as of 10 pm Sunday/
Did not make any big changes to the longer term forecast. Still
looks like a weakening occluded front will move onshore Wed
afternoon or evening, then dissipate over the inner channels Thu.
A stronger front will move NE into the area for Thu into the
weekend, with significant model differences on when it might come
onshore.
Did nudge temps upward a little bit for Wed. Still concerned about
potential for mixing out to occur from at least the 925 mb level
downward Wed, which would result in somewhat higher temps than
current forecast has them. Could see some records fall during Wed.
A band of light precip is likely to move onshore Wed afternoon or
night as weakening occluded front moves in. This should diminish
Thu as the front dissipates over the inner channels.
With the differences on how far NE the stronger front gets, there
is potential for a much warmer/drier scenario for late week if the
more SW model solutions work out. Decided to keep a middle ground
POP forecast for Thu night into the weekend for the time being.
Overall, temps will remain above average through the period.
&&
.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind until midnight AKDT tonight for AKZ018.
Strong Wind until 10 PM AKDT this evening for AKZ017.
MARINE...Gale Warning for PKZ042-043-051-052.
Small Craft Advisory for PKZ012-041-053.
Small Craft Advisory due to Seas for PKZ022.
&&
$$
JWA/RWT
Visit us at http://www.weather.gov/Juneau
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
255 PM PDT Mon Mar 18 2019
.SYNOPSIS...Mild and dry conditions can be expected through most
of Tuesday. Light rain can be expected late Tuesday and
Wednesday, with a quick round of moderate rain expected Friday.
Rain will taper off on Saturday with a dry day on Sunday.
&&
.DISCUSSION...High pressure has started to move out of the area as
a frontal boundary has started to approach the area. This change
in flow as brought stratus back to the coast. The marine layer is
quite shallow and there has been some dense fog on the coast. Some
dense fog is possible this evening again, but after midnight
tonight southeast winds will start diminish the fog. Coastal
clouds may linger into Tuesday morning as the marine layer
deepens.
Tuesday afternoon the front will start to bring some showers to
the inland areas. These is some instability over the interior,
but it doens`t look like the lapse rates are good enough for
thunder. Tuesday night into Wednesday this front moves across the
area. Southeast flow ahead of the front may keep the Humboldt
coast fairly dry, although a few sprinkles are possible. This
front will bring showers to the area through the day on Wednesday.
Rainfall amounts will generally be light, less than a quarter in
most areas. Snow levels will be mainly above 5,000 feet with this
event.
These showers are expected to taper off Wednesday night. Thursday
mainly dry conditions are expected, although there could be a few
showers over the area interior area in the afternoon. Valley fog
is likely, especially near the coast.
Thursday night another system starts to approach the area. This is
expected to bring a period of rain to the area at some point on
Friday. Southerly winds will pick up to around 15 to 25 mph as the
front moves through. There are still some model discrepancies on
the exact timing of the front moving through, but it looks like it
will be only 3 to 6 hours of rain. Currently there is still a
chance for rain Saturday, but confidence is low on when it will
end and it could end earlier.
Sunday looks dry and warm with another system possible on Monday.
The 12Z GFS shows this moving in late in the day on Monday, but
confidence is low on the exact timing of this. MKK
&&
.AVIATION...Visible satellite imagery showed extensive stratus
clinging to the immediate shoreline this afternoon. Fog and stratus
has been meandering menacingly in and out of KACV. Even though it
was parked right along the shoreline, KCEC has surprisingly remained
clear through most of the day. With the stratus lurking about
offshore, expect highly variable conditions with fog and low clouds
in and out of the coastal airports through this evening. Also, if
the layer remains shallow, light easterly and southeasterly winds
later this evening may scour it out, with VFR prevailing through the
remainder of the night. NAM profiles suggest this drying out, while
the HRRR deepens the saturated layer through night. Forecast
confidence the coastal terminals will see significant improvement
remains low. Southerly winds may advect moist air from Sonoma county
to around KUKI early Tue if the marine layer deepens and pushes into
Sonoma county. Confidence this will occur is too low at this point
to add fog or low cloud to the forecast for UKI.
&&
.MARINE...Generally light southerlies will persist through tonight
before increasing to around 15 kt over the southern waters on Tue.
This will result in the development of steeper wind waves as another
westerly swell builds through the day on Tue. Combined seas around
10 to 12 feet are expected over the southern waters due to a
combination of westerly swell and shorter period wave groups. Winds
are forecast to become N-NW Wed and Thu. Seas may become steeper
during this time frame as westerly swell subside and N-NW wind wave
builds. However, a larger westerly swell will start to build late on
Thursday and into Friday. Combined seas will start to ramp up (above
10 ft) on Friday, due to a combination short period southerly wind
waves and longer period westerly swell. Seas will probably remain
elevated (above 10 ft) through much of Saturday.
&&
.BEACH HAZARDS...A long-period westerly moving through the
coastal waters will result in a moderate to high sneaker wave
threat on area beaches from tonight through Tuesday evening.
Beachgoers should use caution along area beaches and keep a safe
distance from the surf zone, as waves may suddenly wash much
farther up the beach than expected after several minutes of
relatively smaller waves.
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement from 11 PM PDT this evening through
Tuesday evening for CAZ101-103-104-109.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory from 9 AM to 11 PM PDT Tuesday for PZZ455-
475.
&&
$$
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For forecast zone information
see the forecast zone map online:
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Area Forecast Discussion
National Weather Service Jackson MS
930 PM CDT Mon Mar 18 2019
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
Taking a look at the latest IR Satellite and observations while
outside for the balloon launch indicate mostly thinning cirrus
clouds from a low pressure system riding the subtropical jet in the
GOM. The only real issue tonight, however, is how cold will it get
in the northeastern areas of the CWA, basically north and east of
Jackson. A few CAM models I looked at, most notably the HRRR /
ARW / NSSL / SREF plumes do show about a 30% chance of hitting 32F
north of a Kosciusko to Philadelphia to DeKalb line. The frost
point will be in the upper 20s, so skin temps could indeed reach
that level, especially in low-lying valley-type areas. With
clearing skies per trends on the satellite, mostly light winds,
cool continental air will be able sink into the region from
northeast and isolated / patchy hoar frost is possible, but for
the most part will stay isolated. Decided to add a limited threat
area to the HWO to accommodate this.
Adjusted the temp curves to account for observational and model
trends with regard to low temps. No other notable changes are needed
in the overnight into the morning period. /TP/TW/
Prior discussion below:
Tonight and Sunday:
Another quiet and cool night is expected across the region
tonight. High clouds will hang on across a good portion of the CWA
through much of the night. However, they`ll gradually lessen
towards day break as the disturbance responsible for them shifts
further east across the Gulf of Mexico. Look for lows tonight to
range from the mid 30s to lower 40s.
High pressure will remain wedged into the region from the northeast
on Tuesday. This will again result in quiet conditions across the
area under mostly sunny skies. Temperatures will be a couple of
degrees cooler Tuesday afternoon, compared to today. This is as a
result of cold advection from the northeast that`ll reside over the
region through the day. /19/
Tuesday night through next Sunday:
Tuesday night: Expect the pattern to remain quiet through most of
the extended period, other than a brief chance of rain around mid
week or so. At the start, psuedo-zonal flow with slightly northwest
winds will be situated over the area with surface ridging extending
down through the Ohio Valley to Appalachians & into the ArkLaMiss.
Due to light winds & very light gradient, we should be able to
radiate well into the mid-upper 30s, especially for areas along &
east of the I-55 corridor. Due to that, decided to at least
introduce some patchy frost in the weather grids but wanted to hold
off at least another package or so to confirm mention of it in the
HWO & graphics.
Wednesday-Wednesday night: A shortwave trough will dive down into
Wednesday night, with some increasing low-level thermal warming out
ahead Wednesday. This will lead to gradual increase in highs &
moisture late into Wednesday afternoon & through daybreak. Due to
this, some increasing isentropic rain & showers are possible,
especially north of I-20 into Wednesday evening & before midnight.
Right now, low-level southerly return flow will not be evident, so
only expect increasing clouds & light rain showers & no thunder.
Rest of week-weekend (Thursday-Sunday): In the wake of this
shortwave trough & weak cold front by mid-late week, expect low-
level ridging building into the area. Due to this, expect drier
conditions with increasing thermal warmth & highs warming up near
normal into the weekend, especially across the southern half of
the area.
As another lead shortwave trough digs into southern Plains into the
weekend, this will help gradual increasing southerly return flow.
This increasing isentropic lift will help clouds to increase from
west-east on Saturday, with the best rain & gradual storm chances
more into Sunday & after the period. Timing details remain
somewhat unclear, with some global consensus a little more
amplified & more robust into early next week. Right now, expect
rain & some storm chances to slowly increase upward, especially
late weekend & into early next week. /DC/
&&
.AVIATION...
00Z TAF discussion:
Expecting VFR conditions through the next 24 hours with high
clouds (generally based over 20kt) thinning out through tonight.
Winds at the surface will be from the north to northeast tonight
and between 5 and 10 mph. Tomorrow, expect surface winds to be
more out of the northeast through east but still mainly in a range
from 5 to 10 mph. /BB/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 41 65 37 67 / 0 0 0 2
Meridian 35 63 36 68 / 0 0 0 1
Vicksburg 41 63 39 66 / 0 0 0 3
Hattiesburg 38 66 37 70 / 0 0 0 1
Natchez 44 66 39 67 / 0 0 0 1
Greenville 38 60 39 64 / 0 0 0 17
Greenwood 36 61 38 65 / 0 0 0 13
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
Area Forecast Discussion
National Weather Service North Platte NE
745 PM CDT Mon Mar 18 2019
.SHORT TERM...(This evening through Tuesday night)
Issued at 316 PM CDT Mon Mar 18 2019
The RAP and GFS indicate a convectively enhanced area of snow
developing tonight across ncntl Nebraska. This is about 50 miles
north of the previous forecast. The rain changing to snow forecast
tonight uses a blend of the RAP, HRRR, HREF, model consensus and the
previous forecast for 1 to 2 inches of snow with 0.25-0.33 inches of
total liquid. Since the ground is still frozen across ncntl
Nebraska, this precip will produce additional runoff and overland
flooding across the region Tuesday and Wednesday. The severity of
the flooding from tonight`s rain and snow appears low given the
total liquid is generally around 1/4 inch.
Note that the HRRR, RAP and ECM show convectively induced bulls-eyes
of around 1/2 inch of QPF across ncntl Nebraska which could be
interpreted as periods of heavy rain or heavy snow. The RAP and HRRR
visibility products indicate these are brief so, unless the upper
level support stalls across ncntl Nebraska, the risk of heavy snow
or rain would appear low.
The temperature forecast tonight and Tuesday uses the consensus
model solution. The guidance blend plus bias correction is in place
Tuesday night. This strategy tries to keep temperatures warmer
tonight and cooler Tuesday than the guidance blend. The guidance
blend plus bias correction lowers temperatures Tuesday night.
.LONG TERM...(Wednesday through Monday)
Issued at 316 PM CDT Mon Mar 18 2019
The models are in excellent agreement for a major warming trend
Wednesday through Sunday with temperatures at the h850mb level
rising to between 5C and 10C. Sfc temperatures should rise into the
40s, 50s and 60s with lows in the 20s, 30s and lower 40s. This will
likely result in a period temperatures above freezing both day and
night and a partial to complete spring thaw in some areas of western
and north central Nebraska.
The upper level support for the warming trend is in the form of a
blocking upper level ridge centered over the Great Plains and an
approaching long wave trof moving through srn California and the
desert Southwest. Ultimately the long wave trof will move east and
draw heavy moisture into wrn and ncntl Nebraska with showers
possible beginning as early as Thursday night.
Rain chances continue Friday through Sunday with a slow moving upper
low drifting through the cntl Plains but the models, despite the
very high moisture across Nebraska, focus the best rainfall across
the srn Plains. We will be watching the models this week to see if
there is a northward trend in the Srn Plains rainfall. The flood
potential next weekend revolves around predicting if the heating
this week will be sufficient to remove most or all of the frost from
the ground before rain arrives. The area of concern for flooding is
generally along and north of highway 2.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 742 PM CDT Mon Mar 18 2019
A weather system is tracking southeast toward the area. This will
bring the possibility of scattered precipitation and lower
ceilings. It appears that the higher chance for MVFR or local IFR
conditions will remain across northern Nebraska late tonight into
Tuesday. Winds will become north around 10 kt with gust to 20 kt
Tuesday.
&&
.HYDROLOGY...
Issued at 316 PM CDT Mon Mar 18 2019
After consultation with our key partners in Custer County we`ve
decided to cancel the Flood Advisory for the northern and eastern
portions of the county. Rivers across the county have returned to
near normal levels while areas that are/were impacted by the
flooding have been barricaded. The Flood Advisory for Holt County
and portions of north central Nebraska was extended through
Wednesday morning. Local emergency management continues to report
widespread flooding and highway closures due to ongoing flooding.
The Flood Warning for the Elkhorn River near Ewing remains in
effect. The latest river forecast shows levels at or above minor
flood stage through at least Tuesday morning. Given the prospects
of additional light precipitation overnight and the continued
runoff, we felt that additional rises will be possible, thus the
warning was extended until mid-day Wednesday. Temperatures will
warm once again mid and late week, but an additional storm system is
looking more likely for Friday and next weekend which potentially
could produce a long period of rainfall across north central
Nebraska.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Taylor
HYDROLOGY...Jacobs
Area Forecast Discussion
National Weather Service Omaha/Valley NE
Issued by National Weather Service Hastings NE
636 PM CDT Mon Mar 18 2019
.SHORT TERM...(Tonight through Thursday)
Issued at 339 PM CDT Mon Mar 18 2019
Potent vort max is progged to sweep southward through the Dakotas
tonight and eventually into the central Plains Tuesday night. The
RAP advertises scattered precip developing early this evening
then gradually into the CWA around midnight. A precip mix of RA/SN
will be possible between midnight tonight through early Wednesday
morning. During the rest of the morning hours, the dominate
precip type will be rain. As of now models are in reasonable
agreement bulk of rainfall accumulation will occur generally
along/south of the I-80 corridor with a quarter inch or so by
events end Tuesday evening.
A noticeable warming trend is expected over the next several days
with highs going from the mid 40s on Tuesday to the mid 50s on
Wednesday and Thursday.
.LONG TERM...(Thursday night through Monday)
Issued at 339 PM CDT Mon Mar 18 2019
Well amplified ridge is progged to be over the central CONUS
Thursday night and slowly get displaced eastward on Friday in
response to upper system approaching from the west. Series of
impulses rounding the base of the system get ejected into the
central Plains and aids with inducing scattered precip Friday
afternoon over the central High Plains. Precip activity is progged
to expand into the CWA then late Friday night/Saturday morning and
increase in areal coverage through Sunday morning. Precip chances
continue Sunday afternoon through Monday as the main upper
circulation moves over the CWA, allowing upper dynamic support to
be maintained.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 623 PM CDT Mon Mar 18 2019
deteriorating conditions are expected at all terminals toward 09z
Tuesday morning. All terminals will initially see IFR with RA/SN
mix before change over to all RA between 12z-14z. RA will be the
predominate precip type then the remainder of the fcst pd.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
SHORT TERM...DEE
LONG TERM...DEE
AVIATION...DEE