Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/26/18
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
525 PM CST Sun Nov 25 2018
.Discussion...
Issued at 244 PM CST SUN NOV 25 2018
Extremely powerful storm system will continue to produce whiteout
conditions with periods of heavy snow and wind gusts up to 55 mph.
When comparing the drying on water vapor imagery with the 1.5 PV
pressure surface, broader scale models have underestimated the
intensity/ how far south the upper level features of the system
dug. The higher resolution models and CAMs seem to have done a
better job with the intensity, particularly the winds. Leading up
to today, we`ve had to adjust the winds upward above the most
aggressive model with every forecast. With the surface low
tracking along and just north of I-44, a nearly perfect scenario
for a classic winter storm for this forecast area. The surface
low, which at 20Z was near Jefferson City, will continue to deepen
and move to the northeast as the upper system pushes east of the
area, leaving a deformation band of heavy snow that will shift
east through the late afternoon and evening hours. As the whole
systems shifts east, the pressure gradient will begin to weaken
and winds will begin to decrease. But with a pressure gradient
magnitude of greater than 60 ubars/km on the northwest side of the
surface low, sustained winds in the 25 to 35 mph range will
continue for another few hours in eastern KS and western MO, and
through this evening in central and northeastern MO. The HRRR and
the RAP depict a secondary deformation band in our eastern zones
and have increased QPF to account for this. This then increased
snow amounts several inches from in our eastern zones. With this
forecast issuance, will keep the blizzard warnings going. But a
clearing of the warnings from west to east will occur through the
evening hours.
For the rest of the forecast, it looks like quiet weather can be
expected through Thursday or Friday. It looks like another active
weather pattern will develop in the area next weekend. The GFS has
several storm systems moving through with temperatures supportive
of wintry weather late in the weekend or early next week.
&&
.Aviation...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 524 PM CST SUN NOV 25 2018
Terminals along the Kansas-Missouri border will continue to bear
the brunt of a significant blizzard for another hour or two before
CIGs, VIS, and wind improve on the back side of the system. CIGs
are starting the hedge up, with upstream observations indicating
that VIS will start to follow soon. However, expect the strong
and gusty winds to persist through the night, though the gusts
should ease up a bit late tonight.
Anticipate lots of amendments at KMCI and KMKC as conditions will
be changing as the storm moves out. However, there will be no
amendments for KIXD and KSTJ terminals, due to the failure of the
ground observation equipment at those sites. It is unknown at
this time when those two sites will return to normal service.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...Blizzard Warning until 9 PM CST this evening for KSZ025-057-060-
102>105.
MO...Blizzard Warning until midnight CST tonight for MOZ007-008-016-
017-023>025-031>033-039-040-045-046.
Blizzard Warning until 9 PM CST this evening for MOZ001>006-
011>015-020>022-028>030-037-038-043-044-053-054.
&&
$$
Discussion...CDB
Aviation...Cutter
Area Forecast Discussion
National Weather Service Pendleton OR
806 PM PST Sun Nov 25 2018
.UPDATE...The upper level ridge is flattening and shifting
eastward. By sunrise on Monday, the axis of the ridge will be
along the WA/OR/ID border. The upper level flow is backing to the
southwest, allowing mid and high level clouds to spread east of
the Cascades. Precipitation is increasing on the backside of the
ridge from the Puget Sound area south to Eugene. The band of
precipitation will gradually approach the WA Cascades by early
Monday morning. Although warmer air will cause snow levels to rise
to around 4000 feet along the east slopes of the central and
southern WA Cascades, cold air will remain trapped in the valleys.
There is a potential for light freezing rain in this area late
tonight and Monday morning. NWS Spokane and Seattle have winter
weather advisories for freezing rain and understandably so based
on the amount of QPF expected overnight and Monday morning.
Looking at the HRRR for the Cascade east slopes in Kittitas,
Yakima, and Klickitat Counties, only a trace to a 0.03" of QPF are
expected before 8 AM Monday. After 8 AM, temperatures could warm
above freezing with precipitation primarily as rain. Will hold off
on any advisories, but forecasters will be keeping a close eye on
radar if precipitation spreads faster than models advertise.
Only minor updates were made to the forecast. Temperatures along
the east slopes were lowered a few degrees for tonight. Patchy
freezing fog was added to the Kittitas Valley. Wister
&&
.PREV DISCUSSION... /issued 215 PM PST Sun Nov 25 2018/
SHORT TERM...Tonight through Wednesday...A ridge of high pressure
over the region will keep a cold front positioned off the Pacific
Northwest coast overnight. The ridge will be slow to move eastward
Monday but as it does some precipitation will begin to spread into
the Washington Cascades. This means there is a slight chance of some
freezing rain early Monday from the Kittitas valley up to Snoqualmie
Pass. Temperatures will be right around freezing so the efficiency
of ice forming will not be good so decided not to issue any advisory
for this. That said, the NWS Seattle office has issued a freezing
rain advisory for the west side of the Cascades which includes the
Snoqualmie Pass region. The cold front will not make a push eastward
until late Monday night and Tuesday with a frontal passage occurring
by Tuesday afternoon and evening. The front will bring precipitation
across the forecast area mainly in the form of rain with high snow
levels then turn to showers Tuesday night and Wednesday. Snow levels
will lower Tuesday night and Wednesday to around 4000 to 5000 feet.
There will be some accumulating snow during these periods above 4000
feet but not expecting enough to warrant issuing any type of
headlines.
LONG TERM...Wednesday night through Sunday...An unsettled pattern
is expected to persist through the weekend with the best widespread
precipitation chances Thursday night into Friday morning. Wednesday
night an occluded front will move across WA and OR. While
precipitation may be heavy at times in the Cascades most of the
precipitation will remain on the west side. Model consistency
becomes rather poor beyond Thursday with significant spread in the
ensemble solutions. Another occluded front will move through
Thursday night. Models show that the second occlusions will retain
its structure better so it should produce more rain. Rain will taper
off behind the front Friday. Another occlusion will move across WA
and OR Saturday night. The GFS has the triple point over south
central OR so there may be some stronger winds mixing to the surface
over high elevations in OR. The ECMWF has the triple point over
central OR and a massive surface low with strong winds in western
WA. I leaned toward the GFS since ensemble spread does not favor
strong solution. Snow levels generally 4500 to 5000 ft slowly
trending down to 1500 to 2500 by Sunday. Coonfield
AVIATION...00Z TAFs...TAF sites expected to remain VFR for next 24
hours. Increasing mid/upper level cloudiness tonight. Light winds. 76
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 29 46 41 46 / 0 0 20 80
ALW 30 47 43 46 / 0 0 20 80
PSC 29 38 33 46 / 0 10 50 80
YKM 29 38 32 44 / 10 30 70 80
HRI 31 41 34 47 / 0 0 40 80
ELN 28 39 32 44 / 10 50 80 80
RDM 28 54 44 51 / 0 0 30 80
LGD 29 46 38 45 / 0 0 20 90
GCD 28 49 38 47 / 0 0 20 90
DLS 34 45 38 50 / 10 10 60 90
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&
$$
85/85
Area Forecast Discussion
National Weather Service Tallahassee FL
756 PM EST Sun Nov 25 2018
.UPDATE...
Made some adjustments to PoPs based on latest radar trends and
expected timing. Otherwise no major changes. A marginal risk of
severe weather remains in place for mainly the Florida panhandle
and western big bend overnight. Latest 00z KTAE sounding has
quite a bit of work to do to support surface based convection with
a low level inversion in place. However, the airmass is expected
to quickly change from west to east overnight as a more unstable
airmass to the west advects into the area.
&&
.PREV DISCUSSION [639 PM EST]...
.NEAR TERM [Through Tonight]...
A Marginal Risk for severe thunderstorms tonight from Dothan to
Tallahassee and points southwest, with the primary threats isolated
damaging wind and a brief tornado, beginning as soon as 9 PM this
evening in the far Western FL Panhandle and Southeast Alabama and
translating eastward into the Tallahassee area in the 5 AM to 8 AM
time frame.
The 18Z Surface Analysis indicated a 997 hPa low over Missouri with
a southward extending cold front entering the Mississippi Valley,
and a warm front over southeast Louisiana advancing northeastward.
Thunderstorms were developing along this warm front as of late this
afternoon with some supercells already noted on the LIX WSR-88D.
The warm front will advance northward across the area overnight,
followed quickly by a strong cold frontal passage. There is broad
agreement amongst the model guidance for a northeast-southwest
oriented line of convection along or just ahead of the cold front,
reaching the Ben Hill-Colquitt-Leon-Gulf County area in the 5 AM to
8 AM time frame.
The threat will hinge on just how much instability can work inland,
with model disagreement between the robust NAM/RAP and conservative
GFS. Nonetheless, there is broad agreement for an axis of higher
instability just ahead of the cold front, with a rather narrow area
juxtaposed with higher shear (0-1 km) in association with the warm
front, supporting the brief tornado threat. In addition, minimal
Convective Inhibition (CIN) is noted in some of the NAM and RAP
runs, especially near and south of I-10. The wind field is also
robust, with Bulk Shear in excess of 50 kt, and even 850 hPa winds
approaching 40 kt, supporting the isolated damaging wind threat.
If parcels can become surface based, e.g., weaker CIN, then the
isolated damaging wind and brief tornado threat could materialize.
The greatest chance of this would be in the marginal risk area
closer to the coast. Also, steeper lapse rates in the hail growth
zone could favor marginally severe hail, but this appears to be a
lesser of the threats.
With the warm/cold frontal passage, a mild night is in store as
temperatures will only bottom out in the mid-50s to mid-60s for
lows, in some cases warmer than Saturday`s high temperatures!
.SHORT TERM [Monday Through Tuesday Night]...
The previously mentioned cold front looks to be right down the
middle of our CWA and right over Tallahassee at 7AM Monday and it
will continue to move southeast through the day. There should be
ongoing widespread rain showers with the front which will also
overspread to the southeast. For now, we only have isolated
thunderstorms in the forecast for Monday. It looks like the line
weakens as it moves east with the bulk of the lift well to the
north and any jet influences weakening as it moves east. There
could be a brief period right before the frontal passage for
these storms but the severe threat looks low. Temperatures will be
quite tricky as the temps will generally cool with the front.
However, parts of SE AL where the front will already be through by
7AM will likely warm a few degrees. Meanwhile, other parts of the
area may see their highs overnight/before noon on Monday. This
means there will be plenty of room for temps to fall with temps
Mon night near freezing in the north and upper 30s in the south.
The base of the upper trough will still be to the west on Tuesday
and will continue to push through Tuesday night. Surface high
pressure will slowly build in from the west with dry weather
returning. Tue highs will only be in the lower to upper 50s with
lows a deg or two cooler than Mon night. This could end up being our
first freeze for SE AL and SW GA and possibly into the FL Panhandle.
Right now lows for those areas are around 31-33 deg.
.LONG TERM [Wednesday Through Sunday]...
The mid level ridge will start to build in from the west Wednesday
and continue to build through Friday. The surface high pressure will
move directly overhead Wed night into Thursday. This all leads to
dry weather continuing through Friday night. The building ridge will
lead to a slight warming trend. Highs Wed will be in the mid 50s,
rising to the mid 60s Thu, lower 70s Friday and even the mid 70s
Sat/Sun. Lows will warm from the mid 30s Wed night into mid to upper
50s by Saturday night.
A deep upper low will be digging into the midwest states on Saturday
with a strong surface low to its southeast. A cold front will be
moving east and will overspread rain across our region Saturday
and Sunday. The timing is still a bit off and the overall strength
of any storms can`t be determined at this time. Either way, it
will probably be a stormy weekend and something to keep an eye on.
.AVIATION...
[Through 00Z Tuesday]
Showers and thunderstorms are beginning to overspread the region
ahead of the next low pressure system. Started rain a little
earlier than previous TAFs but kept mostly the same after that.
TSRA will be possible later this evening as the dynamics get
closer. IFR/LIFR in TSRA appear likely in the overnight hours. A
front will swing through from west to east overnight into Monday
morning ending rainfall and flt conds improve beginning Monday
afternoon.
.MARINE...
Winds increase tonight to close to 20 knots with occasional seas
to 6 feet. For now, have held off on a Small Craft Advisory with
any 20 knot wind or 6 feet seas being too occasional to warrant
one. The winds will stay elevated for the next few days with the
far western waters having the highest chance for near advisory
criteria conditions. Widespread rain showers across the waters
are likely tonight into Monday afternoon with dry weather expected
Monday night through Friday night.
.FIRE WEATHER...
Red flag conditions are not expected for the next several days.
.HYDROLOGY...
Half an inch to an inch of rain is possible tonight but should not
cause any flash flooding or river flooding issues. Additional
rainfall is expected for the weekend but it`s too far out for
exact rainfall amounts.
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 61 68 37 55 33 / 80 70 10 0 0
Panama City 59 63 40 55 38 / 80 60 0 0 0
Dothan 52 55 33 51 32 / 60 30 0 0 0
Albany 56 61 35 52 32 / 80 50 0 0 0
Valdosta 59 67 37 54 32 / 80 80 10 0 0
Cross City 61 72 41 58 35 / 20 70 30 0 0
Apalachicola 64 68 40 57 38 / 80 70 10 0 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk until 10 PM CST this evening for South
Walton.
GA...None.
AL...None.
GM...None.
&&
$$
UPDATE...DVD
NEAR TERM...LF
SHORT TERM...LN
LONG TERM...LN
AVIATION...Scholl
MARINE...LN
FIRE WEATHER...DVD
HYDROLOGY...LN