Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/16/20
Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
543 PM CST Sat Feb 15 2020
For the 00Z TAFs, patchy fog is expected to develop late tonight
and continue into Sunday morning before dissipating late Sunday
morning across the eastern sections of the OK and TX Panhandles.
This fog development is forecast to remain well east of the
terminal sites. As a result, VFR conditions are expected to
continue at KGUY, KDHT, and KAMA through late Sunday afternoon.
.PREV DISCUSSION... /Issued 244 PM CST Sat Feb 15 2020/
SHORT TERM...Tonight and Sunday...
Dry northwesterly flow aloft across the Panhandles tonight through
Sunday will allow for generally clear skies. Subtle perturbations
in the northwesterly flow aloft will result in some high level
clouds, however skies should remain generally clear. Surface ridge
will build into the forecast area tonight while surface low
pressure develops across eastern Colorado and eastern New Mexico
tonight through Sunday. Light north and northeast winds will veer
around to the east and south tonight and then mainly westerly to
Patchy fog or areas of fog should develop or spread westward into
the eastern sections of the Panhandles late tonight through
Sunday morning. The fog is expected to affect mainly the areas
along and off the Caprock betweeen about 09Z to about 15Z to 17Z
Sunday. The HRRR and NAM are forecasting visibilities of as low as
about 1 mile to around 4 to 5 miles. The fog should lift by mid
to late morning Sunday. Highs on Sunday expected to be well above
normal. No precipitation expected tonight through Sunday.
LONG TERM...Sunday night through Friday...
The upper level pattern will be shifting to more zonal flow as
jet streak rounds broad 250mb northern stream trough across the
central plains. Split flow is evident as southern stream jet
streak moves up across the southern plains through Monday. These
two jet streaks are progged to merge across the MS Valley, with
entrance region moving over the Panhandles by Tuesday into Thurs.
Split flow is even more apparent looking at 500mb, with at least
three separate jet streaks noted in the wind fields going into
Tuesday as the main trough deepens from the Pac Northwest. The
northwestern Panhandles end up between two speed maxes Monday
night into Tuesday. Overall dynamic lift looks pretty weak, and
models will likely struggle given the complexity of the split flow
pattern. However, the mostly zonal orientation of the jets suggest
a lack of better return flow. Indeed, the model soundings for
Monday night through Tuesday do not show impressive moisture in
the DGZ. Even the NAM solution keeps most of the moisture in the
lowest 700mb. That being said, the depth of cold air behind a cold
front Monday night may still be sufficient to squeeze out some
moisture, even if it is in the lowest 700mb. A 700mb baroclinic
zone will be in the area as well, so some very localized 700mb
frontogenesis can`t be ruled out. Therefore, while max snow
amounts were reduced in the northwest, the area of very light snow
was expanded some. Outside of the northwest zones, some
drizzle/freezing drizzle will be possible if the NAM solution
pans out given the shallow moisture as the cold front moves
through. The easterly flow will likely support clouds through the
day Tuesday keeping max temperatures down (probably still room to
drop). The GEFS members are in good agreement with colder
temperatures along with NAM, with operational GFS being the warm
outlier Mon - Thurs.
The next disturbance continues to trend later and later in the
week, now favoring Wednesday night into Thursday as a minor
southern stream perturbation advances out of the Baja region and
across a cold front. This event still favors better precip
chances south of the Panhandles where the best moisture is
expected. Lift is mostly tied to jet dynamics with entrance region
of departing northern stream jet, while edge of southern stream
jet provides some ageostrophic response as well.
A warming trend is expected going into weekend ahead of more
active weather early next week.
Area Forecast Discussion
National Weather Service La Crosse WI
544 PM CST Sat Feb 15 2020
.SHORT TERM...(Tonight through Sunday)
Issued at 157 PM CST Sat Feb 15 2020
Early afternoon analysis showed a surface trough axis and
boundary sliding through the forecast area, bringing some very
light snow to parts of western and central Wisconsin. Forecast
soundings do indicate some loss of in-cloud ice, but also look to
struggle to maintain deep saturation, so not expecting much if any
drizzle or freezing drizzle to fall anymore. In other words, if
anything does fall in a given location, it should be very light
For tonight, another surface boundary looks to slide in and bring
some cooler air to the area, though not as cold as the past few
nights. Expect lows in the single digits above zero. Said boundary
then looks to retreat back northward as a warm front on Sunday.
Latest guidance has trended toward a good amount of warm air
advection, a bit of a moisture surge, and some mid-level
frontogenesis working into the area and producing some light
precipitation. Model soundings indicate no issue with saturation,
so would expect some light snow to fall by mid to late morning
across northeast Iowa and southeast Minnesota and work
east/northeastward into Wisconsin. Still questions as to how far
northeast it makes it, as RAP guidance shows diminishing
frontogenesis, but for now have introduced at least some lower-end
snow chances to the forecast across much of the area.
.LONG TERM...(Sunday Night through Saturday)
Issued at 157 PM CST Sat Feb 15 2020
A real up and down weather pattern expected for much of the coming
work week, with initial split flow regime consolidating into broad
upper troughing for the mid CONUS into midweek before the pattern
again flattens out by late week and into next weekend. Pretty solid
agreement among guidance regarding the overall upper pattern, with
confidence a bit above average for once (haven`t been able to say
that too much this winter). By far, the primary feature of interest
remains a fast-moving shortwave expected to drop into the local area
sometime later Sunday night into Monday, with still just a bit of
question about how amplified said wave will end up (NAM/GEM least
impressed, GFS the most, with others in between).
Forcing, per current trends at least, looks brief but fairly robust,
with deep layer warm advection ascent working in tandem with PWAT
values around 0.5 inches (roughly 150% of normal for mid February).
Toss in some hint of transient frontogenetic forcing and the end
result should be a swath of a few inches of snow sometime later
Sunday night into Monday. With that said, we may deal with a warm
layer at times south of I-90 for some loss of cloud ice issues as
well as a potential warmer boundary layer in some of the river
valleys, though that will be dependent on timing of precipitation.
Given the progressive nature of the system, have a hard time at the
moment buying into continued high GFS QPF values with 0.6+
inches, with the GEFS ensemble/WPC/ECMWF mean closer to 0.3-0.4
inches seemingly more reasonable, though we`ll have to watch it
closely with some hints of a much more pronounced frontogenetic
band into Monday afternoon/evening. All told, may end up needing
an advisory for parts of the area given a likely bout of heavier
snowfall rates, but we`ll refine those details over the next 24-36
As that system passes Monday night, burgeoning upper ridging through
Alaska should drive downstream troughing back across the Upper
Midwest into midweek, with mainly dry but progressively colder
temperatures by Wednesday as stronger Arctic high pressure works
through the region. Looking like another cold night on tap Wednesday
night with the low level ridge pretty much overhead, with sub-zero
lows likely before gradual moderation takes place by late week
and the first half of the weekend along with probably another bout
of breezy conditions as is so typical in retreating Arctic airmasses
this time of year.
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 541 PM CST Sat Feb 15 2020
Skies will be mainly clear through 16.08z and then a 4-8K deck of
clouds will rapidly increase ahead of a short wave trough moving
into the area from the Northern Plains. These clouds will then
linger across the area for Sunday as yet another shortwave trough
approaches the region from the Northern Plains.
Area Forecast Discussion
National Weather Service Caribou ME
1028 PM EST Sat Feb 15 2020
A warm front will cross the region overnight through early
Sunday. A cold front moves through the area later Sunday night.
High pressure builds Monday night. A frontal system approaches
from the west Tuesday and tracks across the region Tuesday
night. Cold Canadian high pressure builds Wednesday into
.NEAR TERM /THROUGH SUNDAY/...
A warm front will cross the region overnight through early
Sunday. Clouds will increase overnight, with warm advection
snow showers also developing. Any snow accumulations overnight
will be less than an inch. Low temperatures will occur late this
evening then begin to increase overnight with thickening clouds
and warm advection. Low temperatures will range from 5 to 10
north, to 10 to 15 interior Downeast with mid teens along the
Downeast coast. Have updated the forecast to adjust for current
conditions along with overnight temperatures and clouds.
A jetstreak of 45-50 kts at the 850-700mb layer will provide
good forcing ahead of a warm front. Llvl convergence along and
just ahead of the boundary w/the NAM and RAP soundings showing
the profile to moisten. This should be enough for some snow to
develop later after midnight into Sunday morning. The NAM and
RAP both show an area of decent frontogenetical forcing from
850-700 mbs setting up across northern and eastern Maine from
09-12Z which will allow for a band of snow to set up and move
across the region. Any accumulation of snow looks to be an inch
or less w/the best potential across the eastern sections of
Aroostook and Washington County. The snow should come to an end
by mid morning Sunday w/the best forcing pushing off to the
east. SW winds of 10-15 mph and some sunshine returning allowing
for temperatures to shoot into the 30s as far n as
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
The area remains in the warm sector Sunday night. Some clearing
and light winds will produce shallow inversions with lows in the
teens and lower 20s. The cold front arrives in northern zones
later in the night. Low level instability seems most likely in
northern Aroostook late Sunday night and will go with chance
pops for snow showers. Accumulations should be less than a half
inch. The front moves through quickly and weakens before
reaching southern portions of the forecast area. The colder air
will take some time to filter into the area. As a result, Monday
highs will still be in the lower 20s north and above freezing
for Bangor and Downeast. Strong radiational cooling seems
probable for Monday night as the 1034mb high settles over the
state. Have adjusted lows downward with readings approaching 20
below in northern Aroostook County and subzero readings
everywhere north of Bangor and Downeast. The steep low level
inversion will slowly break Tuesday with warming southeast
winds ahead of the occlusion. In general, models have trended
colder and slower in the past 24 hours with increased likelihood
of a secondary low developing in southern New England and
tracking towards the Gulf of Maine. Expect most of the area to
receive a quick burst of 2 to 3 inches of snow by Tuesday
evening...and this will be the bulk of precip with this system.
The exception will be the coast where onshore flow will warm the
boundary layer with a resultant changeover to rain during the
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The rain/snow line will continue to push northward towards
Bangor and through Hancock/Washington counties during Tuesday
evening, but most precip will be over by midnight. Still looks
like an advisory-level event. The passage of the warm occlusion
will leave temperatures seasonably mild Wednesday morning with
highs in the upper 20s north to mid 30s for Bangor and
Ellsworth. An Arctic cold front crosses Wednesday afternoon.
Could be some decent snow showers in the northern half of the
area but will maintain chance PoPs for now. Arctic air will
generate potential wind chill advisory conditions by later
Wednesday night and Thursday will be the coldest day of the week
by far with readings barely above zero in the Saint John Valley.
Strong radiational cooling appears likely for Thursday night
with subzero readings everywhere and some minus 20 readings
possible in Aroostook County. A dry warm front will scour out
the Arctic air later Friday. Saturday promises a return to above
normal temps with sunshine.
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
NEAR TERM: Occasional MVFR conditions are possible Downeast
through early morning. Otherwise, VFR conditions are expected
across the region into the early morning hours. MVFR/IFR
conditions will then develop late with snow showers which will
persist early Sunday. Conditions will improve to VFR levels
Sunday afternoon. Low level wind shear is also a concern across
the entire region overnight into Sunday morning with 35 to 40
knot southwest winds at 2000 feet.
Saturday night into Tuesday midday...Predominately VFR
Tuesday afternoon into Wednesday morning...IFR cigs and vis
expected with tempo LIFR in snow. Slight chance of fzra for
Bangor as well as LLWS Tuesday evening.
Wednesday afternoon into Thursday...Predominately VFR outside
snow showers and tempo MVFR cigs north of HUL.
NEAR TERM: A Small Craft Advisory remains in effect overnight
through Sunday afternoon. Wind gusts could approach gale levels
overnight. Visibilities will be reduced in snow showers later
tonight through early Sunday.
SHORT TERM: SCA conditions are expected later Tuesday into
Thursday morning. A brief gale is possible Tuesday evening for
the outer waters.
MARINE...Small Craft Advisory until 5 PM EST Sunday for ANZ050>052.
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
529 PM CST Sat Feb 15 2020
.SHORT TERM... (Through Late Sunday Night)
Issued at 324 PM CST Sat Feb 15 2020
A weak cold front will slowly move through the area tonight
progressing into southern IL and southern MO by daybreak on
Sunday. The current pre-frontal cloud band will slowly shift
southeastward with the progression of the front tonight and there
is some weak lift showing up later this evening into the overnight
period from the St. Louis region and to the southwest within the
axis of southwesterly low level flow. The RAP wants to generate
some spotty light precipitation with weak lift. I am not sure
there is deep enough moisture but its certainly worth a mention of
sprinkles. The surface temperatures with any of this appear to be
all above freezing. The front stalls to the south on Sunday as
the weak post-frontal surface high/ridge slowly retreats to the
east. There will be periods of clouds in the morning and then
again increasing from the northwest in the afternoon. I am a
little worried we may be too ambitious with high temperatures. I
made a few small downward tweaks but nothing too major.
Sunday night marks the beginning of a pattern change and large
scale amplification across NOAM. The flow aloft across our area
briefly becomes quasi-zonal ahead of the next progressive trof and
associated cold front. Low level WAA and poleward moisture
transport gets underway primarily overnight on Sunday into the
early morning hours on Monday, and this maybe sufficient to
support scattered light rain. The models suggest the most
favorable area would be across southeast MO and southern IL.
Surface temperatures are expected to be above freezing, so any
rain should be all liquid.
.LONG TERM... (Monday through Next Saturday)
Issued at 324 PM CST Sat Feb 15 2020
The coverage of rain is expected to ramp up through the day on
Monday and into Monday evening in response to continued isentropic
lift ahead of an advancing cold front, and increasing weak large
scale lift associated with the migratory short wave trof driving
the advancing cold front. Present indications are the rain will
all be pre-frontal and will end west to east on Monday night as
the cold front progresses quickly eastward with the advancing
low amplitude upper trof. Given the precipitation is expected to
be pre-frontal then there should be no threat of any wintry
precipitation unless the distribution with respect to the front
would change. Its worth mentioning the NAM wants to generate a
band of snow within the cold air in its later time ranges late
Tuesday into Tuesday night associated with a weak disturbance in
the flow aloft and attendant mid level frontogenetic forcing. At
this time its the sole deterministic model with this signal and
the ensembles largely don`t support it at this time. Something
worth watching however.
Wednesday through Thursday Night look winter cold with below
average temperatures as a large Arctic High builds southward into
the region and dominates. There are some differences amongst the
deterministic, ensembles, and MOS products on the strength of the
cold airmass. The current forecast resides on the colder side of
the overall guidance suite.
.AVIATION... (For the 00z TAFs through 00z Sunday Evening)
Issued at 509 PM CST Sat Feb 15 2020
A weak cold front will slowly push through the area overnight. Low
VFR with patches of high MVFR will remain ahead of the cold front.
These clouds shud continue to push south overnight. With areas
behind the front clearing and winds becoming light, KUIN/KCOU may
see fog developing late tonight as temps cool. Winds will
eventually become SE to ESE late Sun afternoon, but remain light.
SPECIFICS FOR KSTL/KSUS/KCPS: Low VFR with patches of high MVFR
will remain ahead of an approaching cold front. A few sprinkles
will be possible late this evening and overnight. Clouds shud
clear out Sun morning with winds eventually become SE to ESE,
Area Forecast Discussion
National Weather Service Norman OK
523 PM CST Sat Feb 15 2020
(This evening through Sunday)
Issued at 218 PM CST Sat Feb 15 2020
The lee surface trough currently stretched across northwest Oklahoma
will continue to slowly push southeastward, with the latest HRRR
having it wash out near the I-44 corridor later this evening.
Latest visible imagery showing stratus clouds across the Central
High Plains spreading into northcentral Oklahoma, and expected to
increase across much of our forecast area through this evening.
However by early into mid Sunday morning, increasing surface
moisture enhanced by light surface winds could result in fog
developing. Already, moisture advection in the southerly winds ahead
of the surface trough has increased dew point 3-5 degrees in the
last 3 hours as per the Oklahoma Mesonet, and model trends continue
the moisture advection well through Sunday. With the surface trough
washing out and a lack of dry air behind it, we could see fog
develop across our entire forecast area as our nocturnal
temperatures fall. Much of the fog across the western one third of
our forecast area would be more patchy, to more widespread and dense
across portions of central and southeast Oklahoma. Expecting the fog
to be dissipated by Sunday afternoon.
(Sunday night through next Friday)
Issued at 253 PM CST Sat Feb 15 2020
For Sunday night, will need to watch for the potential of low
clouds and fog again. With mainly light surface winds (east and
southeast) and weak moisture advection over eastern Oklahoma,
there will be some potential of fog. Above the surface, winds may
be too strong for fog (mixing) and southwest to west in direction.
North central Oklahoma may have light enough winds for some fog
by Monday morning. Other areas may experience heavy dew.
On Monday, a cold front will move across most of Oklahoma by
late afternoon. The airmass behind the front will not be overly
cold, but will keep temperatures across northern and central
Oklahoma closer to Sunday`s high temperatures. A better shot of
colder air will arrive Tuesday into Wednesday as cold high
pressure builds southward. The source region of this air is
brutally cold with temperatures around -45 to -50. The colder NAM
keeps temperatures in 30s and lower 40s on Tuesday while other
models are warmer. For now will nudge the blends cooler for
Tuesday and Wednesday. As a shortwave trough shirts the area
Wednesday into Wednesday night, some light precipitation may
develop across far southern Oklahoma and western north Texas. A
winter mix is possible. Will also keep in a chance of light snow
across mainly northwestern and west central Oklahoma during this
As cold surface high pressure builds east late Thursday into Friday,
south winds will return with warmer temperatures.
Issued at 520 PM CST Sat Feb 15 2020
A weak wind shift (roughly KPNC-KJWG-KELK at 23Z) will wash out
overnight, leaving light/variable or calm winds across most of the
region. With increased moisture in place ahead of the wind shift,
mostly clear skies, and light winds, fog is likely to occur. Some
dense fog (visibility 1/4 mile or less) is possible over central
and southeast Oklahoma. This area of fog will gradually lift and
dissipate through the day tomorrow.
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 38 61 43 63 / 0 0 10 10
Hobart OK 34 62 40 63 / 0 0 10 0
Wichita Falls TX 38 67 47 72 / 0 0 0 0
Gage OK 29 61 34 60 / 0 0 0 0
Ponca City OK 33 59 40 60 / 0 0 0 10
Durant OK 47 67 50 73 / 0 0 10 0
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
700 PM EST Sat Feb 15 2020
Latest RAP model shows nearly zonal flow aloft the Gulf region
overnight while surface high pressure along the eastern seaboard
extends into the Gulf of Mexico. Light northeasterly flow along
with adequate low level moisture will support low clouds and
patchy fog forming later tonight and continuing until mid Sun
morning when the fog and clouds begin to burn off and lift.
During Sun a short wave trough with a weak surface reflection
tracks along the northern Gulf coast and crosses northern FL in
the afternoon and evening. These feature will provide a slight
chance to a chance of showers...reaching the Nature Coast early
afternoon then spreading southward during the rest of the
afternoon and evening.
16/00Z TAFs. Light NE flow along with adequate low level moisture
will support late night CU/SC/ST with BR. Prevailing MVFR is
expected AFT 06-08Z with PSBL TEMPO IFR/LIFR. BR and low clouds
begin to mix out and lift 14-16Z with VFR through the end of the
period. Winds become easterly in the morning then S to SW in the
Prevailing northeast winds become easterly and southeasterly...but
with an afternoon onshore component along the immediate coast...at
15 knots or less. Then toward the end of the week a cold front
followed by high pressure will increase winds into the 15-20 knot
.Preliminary Point Temps/PoPs...
TPA 61 78 65 79 / 0 10 20 10
FMY 64 82 65 83 / 0 10 20 10
GIF 60 83 63 84 / 0 10 20 20
SRQ 62 79 65 81 / 0 10 20 10
BKV 55 82 59 82 / 0 20 30 20
SPG 63 76 65 78 / 0 10 20 10