Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/20/20
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
621 PM CDT Sun Apr 19 2020
.SHORT TERM...(This Evening through Monday Night)
Issued at 335 PM CDT Sun Apr 19 2020
A weak upper level short wave tracking across southwestern SD will
bring light showers to the southwestern CWA through this evening.
Dry conditions are expected elsewhere thanks to a surface high
pressure. As the surface high drifts southeast, southwest to
westerly winds will develop, keeping lows in the 30s. A weak frontal
boundary sliding southward tonight will bring partly to mostly
cloudy skies. With a dry airmass in place tonight, will not mention
light showers as the NAM suggests.
An area of low pressure will slide southeastward across the region
on Monday. Strong northwesterly to northerly winds will develop
behind the surface low with gusts around 45 mph possible. Boundary
layer dew points off the RAP drop into the teens during the
afternoon hours which would produce min RH values below 30 percent.
The combination of strong winds and low dew points will create very
high fire danger on Monday. Will issue a fire weather watch for
eastern South Dakota and western MN. An additional fire weather
headline could be needed further west. A wind advisory will probably
be need as well Monday afternoon into Monday evening. Decreasing
winds Monday night, along with low dew points and mostly clear skies
should allow temperatures to drop into the 20s by Tuesday morning.
.LONG TERM...(Tuesday through Sunday)
Issued at 335 PM CDT Sun Apr 19 2020
A relatively quiet weather pattern will kick off the extended
portion of the forecast through midweek before it becomes a bit more
unsettled toward the end of the week into the weekend. High pressure
will slide south and east out of the eastern Dakotas and western
Minnesota on Tuesday as low pressure and associated frontal
boundaries approach the region from southern Canada. This system
will then push through the region on Wednesday. Dry conditions are
expected through midweek. A more active pattern then will set up
Thursday through the end of the period as successive waves move
through the region. We`ll see increasing chances of rain along with
a few thunderstorms at times. At this point, these systems look to
move through fairly progressively so chances will be more on and
off. Temperatures are expected to remain at or above normal with the
warmest days of the period likely to be Tuesday and Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 620 PM CDT Sun Apr 19 2020
Mostly VFR skies/vsbys are expected through the tonight. The wind
will become gusty on Monday.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Fire Weather Watch from Monday morning through Monday afternoon
for SDZ271>273.
MN...Fire Weather Watch from Monday morning through Monday afternoon
for MNZ039-046.
&&
$$
SHORT TERM...SD
LONG TERM...Vipond
AVIATION...TDK
Area Forecast Discussion
National Weather Service Bismarck ND
1041 PM CDT Sun Apr 19 2020
.UPDATE...
Issued at 1032 PM CDT Sun Apr 19 2020
Light radar reflectivities were over Rolette county in response
to an embedded shortwave trough through the northwest flow aloft.
Forecast soundings in this area show a dry sub-cloud layer with
just weak saturation aloft. Due to this precipitation chances were
kept out of the forecast tonight. No changes needed to the going
forecast overall with this update.
UPDATE Issued at 819 PM CDT Sun Apr 19 2020
Red Flag Warning cancelled as winds are gradually diminishing and
relative humidity is on the rise.
UPDATE Issued at 634 PM CDT Sun Apr 19 2020
Currently fairly strong westerly surface winds, gusting to 40 mph
across the northern tier of counties, were ongoing in the pre-
frontal sector of a surface low centered over eastern Manitoba.
The attendant frontal boundary and wind shift is currently
located north of the International Border and won`t arrive in
northern North Dakota for several more hours. Surface observations
show relative humidity values in the 20-30 percent range across
our north. With the marginal RH values but still strong winds
ongoing, we opted to keep the RFW going for this update.
&&
.SHORT TERM...(This evening through Monday)
Issued at 245 PM CDT Sun Apr 19 2020
The main forecast issue in the short term period will be fire
weather and wind highlights.
Currently, surface low pressure was located over central Manitoba
with a weak pre-frontal trough into northwest ND. Currently, the
lowest humidities are over southwest North Dakota, with a 20
percent reading at Glen Ullin around 2:30 PM CDT but winds remain
relatively light compared to the stronger winds in the north.
The strongest winds are along the northern tier counties,
sustained around 25 mph but humidities are still in the 30 to 35
percent range. However, we still anticipate warmer and drier
conditions through the rest of the afternoon and early evening.
The frontal boundary has slowed and is not expected to produce a
significant wind shift this evening. However, with the low
humidities and strong winds, will keep the RFW going, and the
evening shift may be able to drop it a little early.
Otherwise breezy and mild tonight with lows only falling into the
30s, which is much milder than the teens this morning. We will
also see increasing clouds from north to south tonight, and
possibly a few showers skirting the Turtle Mountains this evening.
On Monday we see a secondary trailing cold front drop through the
forecast area, with a surface low that develops along the boundary
and drops southeast through eastern North Dakota. This will do a
few things. First, it will aid in the development of strong winds
over the forecast area with a compact pressure gradient developing
over the area from mid morning through early evening, and a decent
fall-rise pressure bubble dropping from northwest into eastern
North Dakota. Second, there looks to be enough forcing with the
front to produce some showers as it drops south through the
forecast area. Showers will be most numerous in eastern portions
of central ND, but there may be enough forcing to produce some
isolated showers over western ND as well. Finally, this cold front
will hamper what could have been another Red Flag Day across much
of western and central North Dakota.
We will see near critical fire weather conditions across most of
the area on Monday. Winds will be stronger than today over most of
the CWA, but it will also be colder over the north central, and
there will be more clouds and scattered showers elsewhere which
may keep humidities from getting as low as we need for RFW
conditions. Thus we will not issue a Fire Weather Watch at this
time, but will will again mention near critical fire weather
conditions for most of the forecast area. The most critical period
appears to be late afternoon into the early evening, behind the
secondary cold front. This is when we see the lowest humidities
dropping into the north cental portion of the state. Once again we
mixed our given guidance with the HRRR to arrive at afternoon
dewpoints for tomorrow. The RAP dewpoints Monday afternoon were
even lower. Because of the period of warm advection ahead of the
cold front, with the chance of showers, and the limited time
(right around 3 hours) when both winds and humidities will be at
or near critical values, we decided to hold off. Furthermore,
today we are slow to reach critical RH values. Think we may be
slow again tomorrow in the north central, which would limit the
time criteria even more. However, with all this said. we are still
close and thus the near critical wording. Will let the evening and
overnight shift evaluate once again. Also, we will likely need a
wind advisory for a good portion of the forecast area. Once things
clear out behind the cold front Monday night, it looks like
another cold night with overnight lows dropping into the lower 20s
across eastern portions of central North Dakota. We utilized the
MOS base guidance over the given blend.
.LONG TERM...(Monday night through Sunday)
Issued at 245 PM CDT Sun Apr 19 2020
We remain in a northwest flow pattern Tuesday/Wed though it
weakens and we will benefit from strong WAA as a broad ridge
develops across the western CONUS allowing mild Pacific air into
the Northern Plains. Sill expecting daytime highs in the 60s to
low 70s Tue/Wed along with mainly dry conditions.
Slightly cooler with increasing chances for precipitation through
the remainder of the week as a series of embedded S/WV`s move
across our region. Some thunderstorms may be in the offing late in
the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 634 PM CDT Sun Apr 19 2020
A cold front is expected to drop south tonight into Monday with a
secondary cold front to follow during the day. Winds shift to the
northwest and become gusty through the day. Increasing VFR cloud
cover will arrive with the fronts as well, with a slight potential
for MVFR cigs Monday morning. MVFR cigs would be more likely
towards the east, at KJMS or possibly KMOT, but TAFs were kept to
VFR for now due to low confidence in MVFR occurring.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AE
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...AE
Area Forecast Discussion
National Weather Service Caribou ME
1036 PM EDT Sun Apr 19 2020
.SYNOPSIS...
A cold front will cross the area overnight. High pressure will
build in from the west on Monday and crest over the area Monday
night. Low pressure will approach from the west on Tuesday and
track north of the area Wednesday with high pressure building in
for Thursday. Another low from the Mid-Atlantic states will
track well south of the region on Friday.
&&
.NEAR TERM /THROUGH MONDAY/...
1030 PM Update...
A line of showers were moving across NE Maine this evening ahead
of the cold front. Some enhanced echoes lifting up across
portions of eastern Aroostook County. This first batch looks as
though it will lift out by midnight w/a break in activity. The
dewpoint took off this evening as winds turned to the SW
allowing dewpoints in most locations to shoot into 30s. The 02z
sfc analysis showed a weak low pres moving ene w/the cold front
sitting back in Quebec. The cold front is forecast to slide
across the region w/another area of precip to push across the
region overnight. Temperatures are expected to cool off w/rain
going to period of snow by early morning across the nnw areas.
Any accumulation will be across the NW region such as Estcourt
and St. Francis region of less than an inch. Elsewhere, trace
amounts expected.
Temperatures were adjusted to back up the cooldown by a few hrs
using the latest RAP and LAV guidance through 12Z.
Previous Discussion...
Clouds and showers will rapidly work their way into the area
this evening. The strongest forcing and positive vorticity
advection from the 500mb trough will reside over northern Maine.
Raised PoPs to likely over the north this evening, with much
lower chances Downeast due to drier air and weaker forcing. The
cold front will reach western parts of the area around 0z this
evening, then pass beyond the coastal waters by 12z Monday
morning. Cold air aloft behind the front will steepen lapse
rates enough to break any nocturnal inversion in place, so wind
gusts were adjusted upward compared to the NBM late tonight into
early Monday morning.
Conditions will dry out quickly early Monday morning, with
clearing skies across the north and lingering clouds across
Downeast Maine from a separate area of low pressure passing well
to the south of the Gulf of Maine. 850mb temperatures will be
much colder around -10C across the north, suggesting that
surface temperatures may struggle to surpass 40 even with full
sunshine. Lowered high temperatures to the upper 30s across the
far north given the latest trends in guidance and observations
across western Quebec. Farther south across coastal and Downeast
Maine, 850mb temperatures will not be as cool, but clouds
should limit full warming potential.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
Weak sfc hi pres will provide fair skies, lgt and vrbl winds
with chilly ovrngt lows by Tue morn due to some radiational
cooling. Temps will recover durg the day Tue, but with
increasing cldnss, spcly durg the aftn as low pres from S Cntrl
Can apchs with increasing Srly winds.
Precip from this low will reach the Rgn by erly eve, initially
in the form of rn, but the combo of dynamic cooling from alf and
a triple point low forming ovr E cntrl/Interior Downeast ptns of
the FA durg the eve hrs will likely allow for a transition to
wet sn by the late ngt hrs despite a brisk Srly wind spcly N
and W where an inch or two is possible with lcly up to 3 inches
ovr hi trrn by Wed morn. Little or no sn accum is xpctd ovr E
Cntrl and Downeast areas with this event with event liq equiv
QPF between 0.35 to 0.50 inches. Steady sn or sn/rn mix will
taper to isold to sct sn/rn shwrs Wed morn, lingering longest
into the aftn hrs N and mtns with brisk W wind, giving more of a
wntr feel to the day Wed.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Continued Cool and Unsettled for the Late Week into the
Weekend...
Clds will break by late Wed ngt and Thu morn between systems
before cldnss increases again late Thu and Thu eve. Of all of
the long range models, only tdy`s 12z dtmnstc GFS and its
accompanying ensm mean support precip for late Thu ngt thru Fri
from new low pres tracking ENE from off the NJ coast to S of
Nova Scotia while the 12z ECMWF and CanGem models msly kept this
system S of the FA. Tdys National Blend of Models (NBM) favors
the GFS solution a little more than the other models attm, with
max PoPs ranging from low chc across the far N to low likely alg
the Downeast coast. Given the large uncertainty of impact for
our FA with this system, the same NBM gives a relatively large
diurnal-nocturnal range between fcst hi and low temps implying
msly rn dytm precip types and rn to sn ngt tm precip types. To
erly for any confidence of QPF amts attm, if any, with this
system never mind the prospect of accum sn.
Behind this system, it will cont brisk and cold Fri ngt into Sat
with dmnshg winds Sat ngt and then increasing cldnss on Sun
ahead of another low that may emerge off the Mid Atlc coast.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
NEAR TERM: VFR at all terminals to start, becoming MVFR across
northern terminals in -SHRA this evening. Brief IFR possible at
FVE with -SHSN after 6z. Winds shift NW and increase between 6z
and 12z with a period of gusts up to 25 kts possible early
Monday morning. Becoming VFR again region-wide with NW winds
gusting to around 15 kts Monday afternoon.
SHORT TO LONG TERM: Mon Ngt - Tue...all TAF sites VFR. Lgt
winds Mon Ngt and Tue morn, becmg mdt SE to S Tue aftn.
Tue Ngt - Wed Morn...all TAF sites lowering to IFR clgs/vsbys
in rn, then rn/sn mix, then all sn with more in the way of sn
for Nrn most TAF sites. Mdt S to W winds.
Wed Aftn - Wed Ngt...all TAF sites MVFR SC clgs with mdt W
winds.
Thu - Thu ngt...all TAF sites VFR with lgt winds.
Fri...All TAF sites MVFR clgs/vsbys with lgt rn. Lgt winds.
&&
.MARINE...
NEAR TERM: SCA conditions continue over the outer waters for
high seas late this afternoon, then both winds and high seas as
gusts increase ahead of a cold front passing through late
tonight. Winds decrease Monday morning, but seas will remain
around or above 5 feet through midday. Conditions subside below
SCA Monday afternoon.
SHORT TO LONG TERM: Initially no hdlns needed for our waters
Mon ngt thru erly aftn Tue, with S winds and seas increasing to
SCA ahead of low pres apchg from the W late Tue and contg Tue
ngt. Winds and seas will cont strong SCA Wed into Thu as the low
moves E into the Can Maritimes, with the direction
transitioning to Wrly. Aftwrds, wind and seas will slowly
subside to below SCA Thu ngt into Fri morn. Kept close to
blended model wv guidance for fcst wv hts with wv pds msly arnd
10 sec.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory until 2 PM EDT Monday for ANZ050-051.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service Charleston SC
856 PM EDT Sun Apr 19 2020
.SYNOPSIS...
A warm front will lift north through the area tonight ahead of
a strong storm system. A cold front will push offshore Monday
morning with high pressure prevailing through Wednesday before
another storm system impacts the area Thursday and Thursday
night. A cold front could push off the coast by the middle of
next week.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
The overall thinking of how severe weather will unfold late
tonight and Monday morning has not changed significantly in the
past few hours. The warm front is showing signs of moving north
with winds across Southeast Georgia now more solidly southeast
with rising temps reported at some stations. The latest high-
res guidance still support rapid atmospheric recovery overnight
as the warm front lifts north and instability advects in from
the south ahead of low pressure currently organizing over
southern Mississippi. The RAP depicts some impressive SigTor
numbers developing ahead of the squall line currently organizing
over portions of Mississippi Valley. Overall, it still appears
ingredients are starting to come together to support a
potentially significant severe weather event for Southeast South
Carolina and Southeast Georgia Monday morning. This will
include an elevated risk for damaging winds in excess of 70 mph
and strong tornadoes.
For the mid-evening update, adjusted hourly temperatures
slightly to take current temperature trends into account. Also
adjusted hourly pop grids to slow a slightly faster progression
of the approaching squall line per a blend of the latest RAP and
H3R.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
See the Near Term section for a discussion on the evolution of
severe weather including a QLCS/squall line, which will bleed
into the Monday morning period.
Monday: QLCS/squall line will be pushing into the coastal
counties by daybreak. There still remains some uncertainty on
how quickly the line will move offshore, but conditions will
rapidly improve behind the line as the supporting shortwave
exits off the North Carolina coast. If the line is slower to
progress east as some of the CAMs suggest, then the severe risk
will increase. An enhanced risk was coordinated with the SPC for
parts of the area due to this uncertainty. Dry weather should
prevail by afternoon for most areas which will continue into the
overnight hours. Highs will range from the lower-mid 70s with a
few lower 80s across the Georgia coastal counties. Lows Tuesday
morning will range from the lower-mid 50s, except upper
50s/lower 60s at the immediate coast.
Tuesday and Wednesday: Quiet weather will prevail as mid-level
heights slowly rise across the region. A dry cold front will
push offshore Tuesday night, but no significant issues are
expected. Highs will warm into the upper 70s/lower 80s Tuesday
then cool off the mid-upper 70s Wednesday in the wake of the
cold front. Lows will drop into the lower 50s inland to the mid-
upper 50s at the coast with lower 60 along the beaches Wednesday
morning.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Another potent storm system is likely to move through the
region with at least a small risk for some severe tstms, mainly
Thursday afternoon/evening. Drier conditions should then return
by Friday, with another storm system possibly affecting the area
over the weekend. Temperatures should mostly be near to above
normal.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
Rains will impact both terminals through the night resulting in
occasional bouts of MVFR. Cigs/vsbys should largely remain VFR.
Vsbys/cigs will lower and winds increase as a squall line
approaches the terminals. Could see gusts 35-45 kt with the
squall which is timed to impact both KCHS and KSAV roughly
11-15z.
Extended Aviation Outlook: Restrictions possible
Thursday and Thursday night as showers/tstms associated with the
next storm system impacts the area.
&&
.MARINE...
Gusty winds to 25-30 kt that are occurring along portions of the
lower South Carolina coast should not be long-lived and appear
to be largely associated with a fairly rapid isallobaric
adjustment.
Tonight: A warm front will eventually lift northward through the
waters, turning the low level flow to southerly. Until that
occurs late this evening, winds will primarily be north in the
10-15 knot range, with stronger winds expected in and around
passing thunderstorms. Once the front lifts through, speeds will
steadily increase through day break and into the 20-25 knot
range. Gale Warnings go into effect right around sunrise (except
for Charleston Harbor and the nearshore Georgia waters), but the
bulk of the gale force gusts will occur Monday morning. Seas
will steadily increase as well, averaging 3-5 feet by late
tonight. Mariners should also be aware of thunderstorms moving
into the waters through the evening hours, capable of producing
strong wind gusts.
Monday: South to southwest winds will quickly ramp up just
before daybreak Monday as a squall in approaches. Gusts to 35-40
kt will common over the South Carolina nearshore waters and the
Georgia offshore leg, so Gale Warnings will be posted with
Small Craft Advisories for the Charleston Harbor and the Georgia
nearshore waters. Winds will quickly diminish by early
afternoon as the low- level jet shifts east and the squall line
moves east into the Gulf Stream. Gusts 50 kt or greater,
waterspouts and even hail will be possible with the squall line.
Tuesday through Wednesday: There are no concerns. A dry cold
front will push south across the waters Tuesday night.
Thursday through Friday: Small Advisory are expected Thursday
into Friday as yet another potent storm system affects the area.
Gale conditions are also possible for some areas during this
time.
&&
.HYDROLOGY...
As much as 2-3 inches of rain has already fallen across
portions of far interior Southeast Georgia since early
afternoon. Rainfall rates have not been overly high so far, but
as the warm front lifts north and instability builds, convection
should deepen with time. This will result in an uptick in hourly
rainfall rates. Short term guidance suggests an additional 3-5
inches of rain could fall across interior Southeast Georgia
until a squall line pushes though Monday morning. As rainfall
rates increase and soils saturated, the risk for flash flooding
should increase, especially if convective training occurs. A
Flash Flood Watch has therefore been issued for interior
Southeast Georgia as well as Allendale and Hampton Counties in
Southeast Georgia through noon Monday. Right now, this watch
does not include the Savannah Metro Area as it appears the
corridor of heaviest rainfall will fall to the west of there.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Flash Flood Watch through Monday morning for GAZ087-088-
099>101-114>116-137-138.
SC...Flash Flood Watch through Monday morning for SCZ040-042.
MARINE...Gale Warning from 6 AM to noon EDT Monday for AMZ350-352-374.
Small Craft Advisory from 6 AM to noon EDT Monday for AMZ330-
354.
&&
$$
Area Forecast Discussion
National Weather Service Dodge City KS
657 PM CDT Sun Apr 19 2020
...updated aviation section...
.UPDATE...
Issued at 504 PM CDT Sun Apr 19 2020
The HRRR model shows eastward prorogation of new development over
southeast Colorado to reach the highway 83 corridor early this
evening, perhaps as early as 7 pm. MCS maintenance probability is
quite high across southwest Kansas which adds confidence to the
Hrrr solution. With similar CAPE around 500J/kg but weaker mid
level lapse rates, would expect less of a wind risk and more of a
small to marginally severe hail risk. The entire event should
linger to as late as 1 or 2 am with storms exiting the Barber
county area. Additionally, an area of storm development over
western Nebraska may brush the I-70 corridor near Hays around that
same time (around midnight or later).
&&
.SHORT TERM...(This evening through Monday)
Issued at 100 PM CDT Sun Apr 19 2020
Short-fuse models and CAMs continue to show another round of showers
and isolated thunderstorms possible this evening across portions of
southwest Kansas as a series of H5 vort maxima associated with a
+110kt jet core kick out of the southern Colorado Rockies into the
high plains. Despite a lack of robust instability, weak post-
frontal H7 frontogenetic banding may provide enough forcing to
allow showers and possible isolated thunderstorms to develop
during the evening hours. Otherwise, drier conditions in general
are expected to take hold later tonight through Monday afternoon.
As for temperatures tonight, little change to the general air mass
across the high plains and likely increased cloud cover will keep
lows dropping much below the 40s(F). Expect highs pushing the
lower/mid 70s(F) Monday afternoon.
.LONG TERM...(Monday night through Sunday)
Issued at 217 PM CDT Sun Apr 19 2020
Medium range models are in fair agreement indicating an open upper
level shortwave trough moving off the Pacific into the Desert
Southwest Tuesday, creating an increasingly difluent southwest
flow aloft across the Western High Plains and returning precip
chances to portions of western Kansas. Surface low pressure is
still projected to develop in eastern New Mexico late Tuesday,
then deepen while shifting east into the South Plains of northwest
Texas Tuesday night with an attendant warm front expected to
develop into western Oklahoma. With a band of increased lift
associated with the boundary and an influx of moisture into
southern Kansas, rain chances are forecast to pick up through the
day Tuesday and continue into early Wednesday. Drier conditions
are expected Thursday as the upper level shortwave moves off to
the east.
Fairly seasonal temperatures are expected Tuesday and Wednesday
with little change to the general air mass across the region. Look
for highs generally up into the 60s(F) to the lower 70s(F) Tuesday
with slightly cooler temperatures likely Wednesday due to increased
cloud cover and potential precip about as the upper level system
passes across our southern fringe.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 651 PM CDT Sun Apr 19 2020
Convective activity that earlier impacted DDC has moved off into
central Kansas early this evening. The next round could bring a
few even weaker storms though the area, mostly focused in the far
south and and north central Kansas, and it is unlikely we`d see
impacts at Gck or DDC. LBl has the best opportunity for high
based thunderstorms with brief moderate rain and very small hail
in the vicinity after 01 UTC as the models have been showing.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 42 71 44 69 / 20 10 10 30
GCK 39 70 42 67 / 20 10 10 30
EHA 41 71 45 66 / 60 10 40 60
LBL 40 71 45 67 / 50 10 30 50
HYS 40 71 41 73 / 30 10 0 10
P28 44 74 47 72 / 90 10 0 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Russell
SHORT TERM...JJohnson
LONG TERM...JJohnson
AVIATION...Russell
Area Forecast Discussion
National Weather Service Grand Forks ND
927 PM CDT Sun Apr 19 2020
.UPDATE...
Issued at 851 PM CDT Sun Apr 19 2020
Band of showers along the leading edge of the initial cold front
just moving into the northern valley, and will continue to
propagate southeast through the evening hours. Up to a tenth of
precipitation expected.
Grids, HWO, social media, and weather stories have been updated to
account for the expected 1-2 hour period of heavier snow Monday
morning. Still some uncertainty with degree of impacts from this
band of snow. Winds still not expected to be strong, and guidance
is delaying the timing a bit. Delayed timing would allow for
lower impacts (daytime heating). Main impact likely still the
brief period of significantly reduced visibility, and will wait
until we actually see the band of snow before issuing an SPS.
UPDATE Issued at 619 PM CDT Sun Apr 19 2020
Interesting weather pattern for the next 24 hours. Will attempt to
add a bit of detail to the grids and messaging (graphics). Will be
watching the trends and consider an SPS for the Monday morning
higher traffic period. Water vapor imagery indicated an upper
level wave near Lake Winnipeg with the nose of an associated
upper jet about to send a cold front/wind shift through the
region. Strongest synoptic forcing from this feature will pass
through northwest Minnesota with scattered showers likely. Most
guidance indicates winds will decouple overnight so anticipate no
impacts until after 12z Monday. At this time the nose of a 120kt
upper jet will send a secondary cold front through the region,
leading to a brief period of strong synoptic lift combined with a
strong mid- level Fgen propagating from north to south through the
region. This would lead to a brief period of heavier precip,
which at this time appears will be snow until changing to rain by
late morning as the band reaches the southern valley. CAM guidance
generally agrees with this thinking. Long story short: 12z-18z
Monday expect a band of brief but heavy snow to propagate through
the region from north to south, changing to rain as it approaches
the southern parts of the region by late morning. Wind appears
relatively light as this brief/heavy snow affects the region, with
the RAP indicating 925mb winds not increasing until after the
925mb trough. This would limit concerns for snow squall
conditions, but could lead to brief impacts with briefly
significantly reduced vsby. Into Monday afternoon, still expect
scattered showers (thunder) and near wind advisory conditions.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 316 PM CDT Sun Apr 19 2020
Shower chances, winds and fire weather concerns will all be
challenges for the period.
A strong shortwave in southern Manitoba will dig into Ontario and
the MN arrowhead tonight. Fairly deep surface low will move
eastward and a cold front will sag down into the CWA this evening.
CAMs bring a fairly vigorous band of precip into our northern
counties along this boundary, and looking at Canadian radar, it
does not seem completely out of the question. Will continue to
include some shower chances this evening across northeastern ND
and northwestern MN. With fairly warm temperatures even well into
Canada think that most of the precip will be rain although a few
flakes mixing in later are possible. Wind gusts will increase a
bit as those showers move in, up to 30 mph in some places in
comparison to the 20 to 25 gusts we have now. At this point think
that by the time the higher winds arrive the RH values will be
coming up as temperatures drop, but will continue to monitor.
Temps overnight will stay well mixed and there will be clouds, so
should stay mostly above freezing.
Another reinforcing shortwave digging down into the CWA will push
another surge of cold air into the area Monday. There will again
be some precip with this boundary, and with colder temps some snow
showers with gusty winds and lowered visibility will be possible
for a brief period tomorrow morning. The temperatures will
increase enough to change over to rain by afternoon, with most
locations getting into the 40s and even 50s in the south. With
very cold air aloft there is a small amount of MU CAPE over our
eastern counties that a few models show. Winds will also be very
strong with cold air advection behind the front, helped along by
additional mixing from the showers. Wind advisory will be possible
in portions of eastern ND but will hold off on a headline for
now. With showers, RH values will be higher than they are today,
at least in some areas. Still, far edge of our west central MN
counties could get low enough RH values as winds pick up to be a
concern, so included a fire weather watch for Grant county to go
along with neighbors to our south and east. Cold air advection and
clearing skies for Monday night should knock temps back into the
20s.
.LONG TERM...(Tuesday through Sunday)
Issued at 316 PM CDT Sun Apr 19 2020
The chance for impactful weather is low within the long term period.
A warming trend begins Tuesday lasting through the week. Significant
precipitation is not forecast within the long term period throughout
the period.
A subtle mid level shortwave trough and associated surface low is
expected to move through the area driven by northwest flow aloft.
This will promote an impressive amount of WAA on the forward flank
of the low, so much so that there could be 25 C difference in
temperatures over the CWA. This tightening temperature gradient
promotes strong fgen near the warm front of the low oriented
northwest to southeast. While fgen is strong, upper support is
meager. Additionally, dry air advected into this area from the lower
levels may hinder any potential perception from reaching the
ground. This dry air does however introduce the potential to wet
bulb down low enough for some locations to hold the chance of seeing
snow or a wintry mix. If this does happen, there is some potential
to see accumulation, although confidence is quite low given the
multiple conditions that must be met for this to happen. Thus, did
not deviate away from latest NBM guidance keeping Tuesday with
chance PoPs and very low QPF. Still it is something to keep an eye
on. This strong temperature gradient will also dictate temperatures
with those on the warm side of the warm front getting into the 60s,
and those on the cool side staying within the 40s under extensive
cloudiness. This low will also promote gusty winds on Tuesday.
Not much of an air mass change behind the low`s cold front with
upper ridging developing. While Wednesday morning may start cool, ie
below freezing, ridging aloft should allow Wednesday to warm nicely
with the entire CWA getting into the 50s and 60s. These high
temperatures are representative through the rest of week with low
temperatures staying near or just above freezing. Upper flow doesn`t
change much out of northwest to zonal flow and thus not much change
in the temperature trend. There may be one or more small waves that
move through the region bringing chances for light rain, although
these are more likely beyond Wednesday and confidence in timing is
low.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 619 PM CDT Sun Apr 19 2020
Winds will switch from southwest to northwest this evening.
Scattered showers possible, mainly for Thief River Falls and
possibly Bemidji. VFR cigs through the overnight. Monday morning,
anticipate most sites will experience a brief period of MVFR/IFR
conditions as a band of heavier precipitation (snow/rain) moves
from north to south through the region. Otherwise, VFR cigs on
Monday. Gusty afternoon winds up aoa 40 mph along and west of the
valley...along with scattered showers (maybe thunder) mainly east
of the valley.
&&
.HYDROLOGY...
Issued at 927 PM CDT Sun Apr 19 2020
Pembina and Drayton remain at major flood stage. Drayton is expected
to fall into moderate flood stage on Monday. Satellite indicated a
flood area up to as much as 8 miles wide was generally east of I-29
from Manvel northward to Pembina ND. Road closures and overland
flooding remain in and near this flooded area. Oslo fell into
moderate flood stage Sunday afternoon and was the only forecast
point at moderate flood stage. Fargo and East Grand Forks were at
minor flood stage. East Grand Forks is expected to remain at minor
flood stage for the next 7 days. Fargo is expected to fall below
flood stage next weekend. The West Fargo Diversion will fall below
flood stage this evening and so the flood warning was cancelled for
West Fargo. Hallock, Abercrombie, Kindred, Harwood, Mapleton, and
the West Fargo Diversion were at a high water stage.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...Fire Weather Watch from 8 AM CDT Monday through Monday afternoon
for MNZ040.
River point flood warnings continue across portions of
the region. Refer to the latest flood warnings and statements for
detailed information on specific locations.
&&
$$
UPDATE...TG
SHORT TERM...JR
LONG TERM...CJ
AVIATION...TG
HYDROLOGY...JH
Area Forecast Discussion
National Weather Service Glasgow MT
601 PM MDT Sun Apr 19 2020
.DISCUSSION...
Afternoon Update: Not much to update today. Dry and windy
conditions continue for the next few days, which could lead to
increased fire weather concerns through midweek. Otherwise,
quiet weather is expected to be the main story for the coming
week.
Cliff
PREVIOUS DISCUSSION:
High pressure over the area now will pull away by late this
morning. Winds are expected to increase across the CWA by this
afternoon. Model guidance over the last few days has generally
been too humid for afternoon RH values, with HRRR and RAP being
the dry ones today. The going forecast has borderline critical
fire weather conditions in our northeast (fire weather zone 120:
Daniels, Sheridan, and Roosevelt Counties, and the Fort Peck
Reservation portion of Valley County) and given that the models
have been over-humid on RH went ahead and issued a red flag
warning for that zone. The southeast zone (fire weather zone 122:
Dawson, most of McCone, Prairie, Richland, and Wibaux Counties)
may come close to critical fire weather conditions today,
especially in the eastern portion of that zone and will need to be
monitored for potential inclusion in the red flag warning.
Otherwise, the main story this week is the warming temperatures
expected under the building ridge. The ridge begins to break down
slightly around Wednesday-Thursday, and temperatures begin to
trend back down to near seasonal normals after peaking on Tuesday.
Showers begin to move in as well Wednesday, and the first chance
of widespread thunder for the season also makes its way in late in
the week.
97
&&
.AVIATION...
LLWS: Models appear to bring scattered areas of low level
windshear after 6Z until around 13-14Z with the highest likely
time beginning at 9Z. LLWS will move W to E with the more
confidence over the Yellowstone Valley. SDY will likely experience
more consistent LLWS during the 9Z-14Z period.
Expected Flight Category: VFR
Synopsis: Dry weather with partly to mostly cloudy skies is
expected over the region through Monday. Ceilings with the clouds
over the region should be low VFR through the period.
Winds: During the daylight hours the rest of today and Monday,
expect west-northwest winds of 10-20 kts with gusts as high as 30
kts at some sites. During the overnight hours tonight, winds
across the region should decrease to mostly light and variable.
Cliff/Ford
&&
.FIRE WEATHER...
Red Flag conditions are expected to continue through the afternoon
and evening for Zone 120.
For Monday and Tuesday, fire weather concerns look to remain
elevated, but not quite critical, over the region as low RH
values (mostly in the 20% range) and winds of 15-20 mph out of
the west-northwest are expected across the region over the next
several days. Fuels remain dry, with greenup not yet started for
many areas, which could lead to rapid expansion of a fire should
one start over the next couple of days.
Cliff
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening for MTZ120.
Lake Wind Advisory until 8 PM MDT this evening For Fort Peck
Lake for Central and Southeast Phillips...Central and Southern
Valley...Garfield...McCone...Petroleum.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Lake Charles LA
1015 PM CDT Sun Apr 19 2020
.DISCUSSION...
Tornado Watch #122 was canceled early as convection had all
weakened and mostly moved out of the forecast area...SPC
mesoanalysis also showed critical severe parameters weakening over
the forecast area while best lift was also pushing ewd. In the
meantime, dry air per water vapor imagery is quickly encroaching
the forecast area, basically spelling an end to just about all the
precip for tonight...thus POPs have been significantly reduced.
Newest forecast concern is fog development as a few stations have
started reporting restricted visibilities last couple of
hours...fog guidance has jumped on this trend, primarily across
the TX zones and thus patchy fog was inserted for tonight across
these areas.
Elsewhere, inherited grids/zones looked in good shape per
obs/trends. Update already issued.
25
&&
.MARINE...
The SCA for the cntl/ern waters and Atchafalaya Bay was extended
to 06z based on recent obs.
25
&&
.PREV DISCUSSION... /issued 616 PM CDT Sun Apr 19 2020/
AVIATION...
The potential for thunderstorms will continue at area TAF sites
through at least 03Z with the greatest coverage around Central LA
and KAEX. Further SE towards KLFT/KARA a chance for an isolated
thunderstorm could linger through 06Z. While ceilings may briefly
improve to VFR with the passage of the surface front this evening,
lower ceilings and fog will be possible late tonight/early
tomorrow morning. Conditions should improve to VFR across most of
the area by 15Z.
PREV DISCUSSION... /issued 334 PM CDT Sun Apr 19 2020/
DISCUSSION...
Wx map shows diffuse frontal boundary remaining over the I-20
corridor of NE TX/N LA this afternoon, and the sfc low deepening
over the Dallas/Fort Worth metroplex. Radar showing the bulk of
the severe thunderstorms remaining across the lakes region of SE
TX, and remainder of NE TX/N LA. The other area of interest is the
MCS development across SE TX from HOU to GLS. This has shown a
decreasing trend as additional cells develop to the north and
south. Expect this area, or individual cells to affect the region
within for the next several hours. Tornado Watch #122 (replacing
#120) now out until 10 PM for all of SE TX/C and S LA, although
the western areas of SE TX will likely be cleared out before 10 PM
as the convection is expected east of there by that time.
Rainfall of 1.5-2.0" inches expected over inland SE TX/C LA. This
area continues under a Marginal to Slight Risk of Excessive Rainfall
this afternoon and evening, with isolated urban and possible
localized flash flooding may occur. Further south, rainfall will
widely vary between 0.25-1.0", depending where one of these cells
tracks.
Coastal Flooding will be another concern. Tides are already
running about 1.0-1.5 feet above astronomical levels. With the LLJ
expected to pick up later this afternoon and evening, minor
coastal flooding seems likely. The other concern is some sort of
wake low developing with the MCS expected to move into SE TX/S LA
later this afternoon/evening. HRRR guidance has been consistent in
showing some sort of meso low with brief 30-40kt winds with the
20 kts southerly winds already in place. For now, will go with a
Coastal Flood Advisory with tidal levels along the immediate coast
of 1.0 to 1.5 feet above ground level for Cameron, and 1.5 to 2.0
feet above ground level for Vermilion/Iberia/St. Mary parishes.
For Monday through early Wednesday, tranquil weather expected
behind the departing storm system. Another significant storm
system likely to bring another round of rainfall and possible
severe weather late Wednesday night into early Thursday.
Preliminary indications the bulk of the severe weather threat will
be a little further northward. Tranquil weather expected behind
the departing storm system.
DML
MARINE...
Onshore flow will strengthen this afternoon and evening as low
pressure deepens across East Texas and Louisiana. This low, and
the associated significant upper level disturbance, will continue
to bring strong to severe thunderstorms this afternoon into
tonight. Offshore flow will briefly develop in the wake of the
system for Monday, with onshore flow resuming for Tuesday. The
next chance of showers and thunderstorms is expected Wednesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 57 77 56 82 / 80 0 0 0
LCH 63 82 61 84 / 80 0 0 0
LFT 64 82 61 84 / 60 0 0 0
BPT 63 82 64 83 / 50 0 0 0
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...Coastal Flood Advisory until 4 AM CDT Monday for LAZ052>055-073-
074.
TX...None.
GM...Small Craft Advisory until 1 AM CDT Monday for GMZ435-452-455-
472-475.
&&
$$
Area Forecast Discussion
National Weather Service Melbourne FL
826 PM EDT Sun Apr 19 2020
.UPDATE...
Late east coast sea breeze, old thermal gradient, and multiple
boundary interactions over the Treasure Coast allowed for some
storms to develop. One storm near Jensen beach produced wind gusts
to 44kts. Loss off solar insolation and activity moving offshore
will allow for the removal of POPs by mid evening. HRRR model
indicates convection moving back into northern areas late but not
until after 12z. Have lowered POPs for this area only keeping
very low chance very late night. Temperature forecast on track.
&&
.DISCUSSION PREV...
Monday...Atmospheric winds will increase markedly early Monday as
a potent low develops over the SE. Indications are that
convective parameters will become increasingly favorable for storm
development from mid-day and through the afternoon. Strong winds
in the lwr/mid levels of the atmosphere will lead to threat of
strong to potentially damaging gusts in any stronger storms which
develop. All of east central FL has been placed in a Marginal Risk
of severe storms. Training of cells may lead to some locally
higher rain amounts as well with the usual threats of lightning
and small hail. PoP coverage will be highest across the I-4
corridor to the Space Coast, Volusia Co. and Osceola Co. during
Mon. Persons should monitor the forecasts and remain alert to the
possibility of weather statements and or warnings on Monday.
&&
.AVIATION...
Convection in boundary interactions along Treasure coast will
dissipate within the hour (by 9 PM). Mostly VFR conditions
overnight with some lower cigs approaching north late. Mainly VFR
Monday with MVFR to briefly IFR in TS/SHRA midday over northern
areas and SHRA to the south.
&&
.MARINE...
Small Craft Advisory for offshore waters late tonight and Monday.
South to southwest winds will increase late ahead of surface
boundary/cool front moving into north FL. Winds 20 to 25 knots
with gusts to near 30 in offshore leg ahead of developing showers
and storms. Have adjusted wind/gusts to show better gradient
between nearshore and offshore waters through period.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory from 4 AM to 4 PM EDT Monday for Flagler
Beach to Volusia-Brevard County Line 20-60 nm-Sebastian
Inlet to Jupiter Inlet 20-60 nm-Volusia-Brevard County Line
to Sebastian Inlet 20-60 nm.
&&
$$
SHORT TERM/AVIATION...Blottman
DSS/Warning....Kelly
Area Forecast Discussion
National Weather Service Marquette MI
805 PM EDT Sun Apr 19 2020
.SHORT TERM...(This evening through Monday)
Issued at 341 PM EDT SUN APR 19 2020
With mid-level trough and 850 mb thermal trough axis overhead, there
will be enough diurnal instability to continue scattered snow
showers into the late afternoon hours for the central forecast area,
where low-level convergence along a lingering sfc trough will
enhance lift/focus. Expect showers to dissipate by early evening. Temps
this afternoon under mostly cloudy skies have generally ranged
from the lower 30s north to the upper 30s/around 40F south.
With sfc high pres ridge to the west quickly moving across the area
this evening the associated subsidence/clearing skies will allow
temps to drop quickly before return flow ramps up and clouds
increase ahead of a vigorous low pressure dropping se toward
northern Ontario. With PWAT values around .25 inch good radiational
cooling is expected so incorporated colder guidance of mainly bias-
corrected CMCnh into the fcst to reflect this potential. Some
locations across the interior central and e may slip into the upper
teens this evening. Lows in the mid to upper 20s will be achieved
this evening over the w. Then, temps will rise into the upper 30s
overnight west and mid 20s to lower 30s east as winds increase and
clouds thicken from the west. Winds will become gusty across the w
and n and in particular in some of the areas where downsloping under
a ssw wind is favorable for further enhancement. Some gusts to
around 35 mph will be possible late. Toward 12z, a few -shra/-shsn
may develop into the western Upper MI as cold front nears.
On Monday, a fairly vigorous sfc low will track east across northern
Ontario, pushing a weak cold front across the region late morning
into the afternoon hours, as gusty south winds become westerly with
the frontal passage. Isentropic ascent ahead of this initial weaker
cold front will bring a chance of a light mix of rain/snow in the
morning. Rain chances increase later in the day ahead of stronger
shortwave and associated stronger secondary cold front poised to
move in from the nw Mon night. Increasing low-level convergence
ahead of this stronger shortwave and associated frontal boundary
along with strengthening 850-700 mb fgen in response to increasing
upper divergence in left exit region of 130 kt 250-300 mb jet max
nosing south toward the northern Plains will help focus best shower
chances (with perhaps numerous coverage) south central and east. RAP
and NAM soundings indicate enough mixed layer CAPE of 150-300 mb to
warrant a slight mention of thunder over far southern Dickinson and
the southern half of Menominee County in the afternoon. Mixing
through inverted-V soundings to 5-6 kft will support gusty southwest
winds of 20-25 early shifting west by afternoon. Highs will range
from the lower 40s north to around 50F south central under mostly
cloudy skies.
.LONG TERM...(Monday night through Sunday)
Issued at 409 PM EDT SUN APR 19 2020
The anomalously deep upper-level trough over much of the eastern 2/3
of Canada will continue to be the driver of our weather locally for
the beginning of the long-term period. The pattern deamplifies
somewhat as the week goes on leading to a gradual warming, but still
not quite to normal for this time of year.
Picking things up Monday night, the primary mid-level short wave
will be dropping southward across Lake Superior and Upper Michigan
leading to a 990 mb surface low developing southwest of James Bay.
There should be enough fgen/Q-vector convergence for light,
scattered rain and snow showers (becoming all snow showers)
persisting into the evening before subsiding after about 03z.
Pressure rises and CAA increase behind the trough axis starting at
around 03z, then maximize around 09-12z Tuesday morning. Mixing to
11000 feet over the water will lead to high-end gales to 40-45 kts.
Even on land mixing to about 4000 feet with 35-40 kt winds in model
profiles below that level will lead to gusty winds area-wide on
Tuesday. 30-35 mph gusts will be commonplace with gusts up to 45 mph
possible over the Keweenaw, eastern U.P., and along the Lake
Superior lakeshores. Mechanical mixing with these strong winds, plus
subsidence behind the wave leading to partial clearing to the cloud
cover, should allow dew points to drop well below guidance during
the day Tuesday, especially over the west half.
Even though 850 mb temps drop to as low as -15 C Tuesday morning,
models continue show the sub-cloud layer being too dry and cloud
bases being too high to support anything more than a few very light
snow showers so have kept only slight chance POPs in the NW wind LES
belts of the east. Even if this cold air aloft won`t be enough for
LES it will be enough to make Tuesday feel pretty miserable for late
April, especially considering the gusts on top. Because the air mass
still looks to be near record cold for this time of year, went with
the 10th percentile of model guidance for highs on Tuesday which
ends up being only in the upper 20s to mid 30s.
Slight ridging builds in late Tuesday evening leading to a relaxing
of the winds, with wind slowest to calm over the east. There will be
a short window of mostly clear skies to allow temps to fall Tuesday
evening before steadying off later at night as cloud cover works
back in. This next batch of clouds is in advance of a weak short
wave tracking across the Northern Plains in northwest flow. There
will be a band of WAA precip with it somewhere, but exactly where
remains a question. The GFS is a northern outlier in bringing a
couple inches of snow to most of the U.P. whereas most other models
keep measurable precip south of us in Wisconsin. The Euro and UKMET
in particular have been consistent in keeping this a non-event for
the U.P. So there is some chance POPs in there for late Tuesday
night into Wednesday but future forecasts should be able to tighten
up the northern gradient and keep more of the U.P. dry. Beyond that,
things look pretty quiet with no significant weather systems
expected through at least the end of the week and temps trying to
climb back to near normal, though stumbling a bit again on Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 756 PM EDT SUN APR 19 2020
VFR conditions are expected through the forecast period with only
mid clouds affecting the region as a cold front moves through. LLWS
is expected at all sites late tonight into Mon morning as southwest
low level winds increase atop a cold layer near the surface. The
cold front moving through Mon morning will bring a period of light
snow showers or flurries and west winds gusting near 30 knots at
both KIWD and KCMX but should have little impact on vsby.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 432 PM EDT SUN APR 19 2020
Southerly winds will pick up overnight tonight, increasing to gales
for a brief period early Monday morning, especially north-central
and east. Then there will be a bit of a lull for the rest of the day
Monday when winds relax somewhat to 25-30 kts and veer to west
behind the cold front. But the coldest air aloft moves over the lake
after about midnight Monday night leading to a return to gales, this
time from the NNW and stronger with 40-45 kt winds expected
widespread from Isle Royale throughout the eastern half of the lake.
The previously issued Gale Warnings remain in effect with the only
modification being a slight extension of the eastern two zones into
Tuesday evening. Some freezing spray is likely as well given the
combination of these strong winds and unusually cold air for this
time of year, but it`s not expected to reach warning criteria. Winds
calm down quickly Tuesday night and then stay light (generally 20
kts or less) through the end of the week.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning from 4 AM Monday to 8 PM EDT Tuesday for LSZ249>251-
266-267.
Gale Warning from 4 AM Monday to 2 PM EDT Tuesday for LSZ244-245-
264-265.
Gale Warning from 6 AM to 2 PM EDT Tuesday for LSZ248.
Gale Warning from 4 AM to 6 PM EDT Monday for LSZ263.
Gale Warning from 6 AM to 6 PM EDT Monday for LSZ243.
Gale Warning from 8 AM to 6 PM EDT Monday for LSZ242.
Lake Michigan...
Gale Watch from late Monday night through Tuesday afternoon for
LMZ221-248-250.
&&
$$
SHORT TERM...Voss
LONG TERM...RJC
AVIATION...JLB
MARINE...RJC
Area Forecast Discussion
National Weather Service San Francisco Bay Area
857 PM PDT Sun Apr 19 2020
.SYNOPSIS...Temperatures will remain below seasonal averages through
Monday as a weak system brings the potential for isolated showers,
mainly to the southern portion of the region. Dry weather is
forecast region-wide for the remainder of the week. A gradual
warming trend is also expected through the week as high pressure
builds near the West Coast.
&&
.DISCUSSION...As of 8:55 PM PDT Sunday...Since early evening the
KMUX radar has been detecting elevated returns offshore out ahead
of the approaching Pacific weather system. Most of what the radar
is detecting is above 10K feet, so it`s unlikely any
precipitation is reaching the surface given the deep dry sub-cloud
layer evident on the 00Z Oakland Sounding. What the radar is
currently detecting are bands of mid and high level moisture
moving well ahead of the incoming system, which is still a couple
hundred miles offshore. Primary forecast concern in the short-term
is the potential for precipitation on Monday as the system moves
onshore. Models have been trending drier with this system for the
past few days and latest short-term model data from the NAM and
HRRR indicate only isolated showers developing across Monterey and
San Benito Counties tomorrow, as well as along the northern edges
of Sonoma and Napa Counties. We may also see patchy drizzle
develop in coastal areas later tonight and Monday morning.
Otherwise, dry conditions will prevail on Monday, as will cooler
than normal temperatures. Temperatures today were isothermal
across our region, with highs mostly in the lower to mid 60s.
Expect similar temperatures on Monday.
After this incoming weak system passes to our east on Monday
night, a broad upper ridge centered offshore near 130W is forecast
to be our dominant weather feature for the remainder of the week.
The ridge will gradually strengthen over California and result in
a warming trend from Tuesday through Friday. Temperatures are
expected to warm well above average during the second half of the
week as H5 heights rise past 582 dm and 850 mb temps warm to 17
deg C. The challenge will be determining just how warm temps will
get, and if warming will extend all the way to the coast. At
present, it looks as though onshore flow will prevail through the
week. Thus, coastal areas will likely see lest robust warming
compared to inland areas. 80s will be common for inland areas by
the end of the week and we may even see a few of our warmest
locations reach 90 by Friday. Warm and dry conditions are expected
to continue into next weekend.
&&
.AVIATION...As of 5:43 PM PDT Sunday...For 00z tafs. KMUX radar
is recently picking up a few isolated showers entering our coastal
waters and the offshore waters at 70 to 100 miles. At the terminals
it`s VFR with thorough diurnal mixing from the surface up through
925 mb with a coastal trough resulting in a patchy mix of land and
marine based low clouds.
Weakening 850 mb to 500 mb level ridging exits eastward then a
more vertically developed trough arrives off the eastern Pacific
early Monday as advertised. Near surface conditions favor VFR for
the evening, patchy low clouds tonight while more mid to high
level clouds move in from the west tonight and Monday with showers
arriving along the coast early Monday morning. The best chance of
showers is over the north Central Coast; the alignment or way
that this trough arrives Monday still could bring a few isolated
showers to the north over the Bay Area Monday, for now introduced
vicinity showers in the tafs for KSJC, KLVK, KSFO, KOAK.
Instability with the trough Monday is primarily an elevated type
of convection. The trough shows some amplification at both 700 mb
and 500 mb Monday. Earlier high resolution model output did show
isolated surface based convection over the North Bay Monday
afternoon, however recent output has backed off on this solution.
The 00z KSTS and KAPC tafs still advertise dry though low confidence
forecast. It`s worth keeping in mind the potential for isolated
convection well inland for flight planning Monday. Showers sweep
eastward Monday afternoon and evening, VFR probably extends into
Monday evening.
Vicinity of KSFO...VFR, west wind 15 to 20 knots until 04z lighter
west wind tonight. Low confidence, but a few showers possibly arrive
11z-18z Monday. VFR Monday and Monday evening.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR, west winds 10 to 15 knots until
early to mid evening, lighter west winds tonight. Increasing
clouds tonight and Monday morning with tempo moderate showers
resulting in MVFR. After showers move through to the east, clouds
should lift back VFR with partial clearing in the afternoon. VFR
Monday afternoon and evening.
&&
.MARINE...as of 4:47 PM PDT Sunday...Generally light northwest
winds will persist the rest of today with locally breezy
conditions possible over the San Francisco Bay and northern
Monterey Bay along the Santa Cruz coastline. Northwest winds will
gradually increase beginning tomorrow with breezy northwesterly
winds then expected to last into mid-week. Moderate period west
swell will continue to diminish over the weekend as a longer
period west to northwest swell arrives tonight. Additionally, a
longer period southerly swell will also remain throughout the
forecast period.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...NONE.
&&
$$
PUBLIC FORECAST: Dykema
AVIATION: Canepa
MARINE: AS
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Area Forecast Discussion
National Weather Service Tallahassee FL
1129 PM EDT Sun Apr 19 2020
...Severe Threat Rapidly Increasing Across The Region...
.UPDATE...
Tornado Watch is now in effect for the entire area until 7AM EDT
or 6 AM CDT. A line of strong storms is now sliding to the
northwest of Coffee County AL although the southern end may clip
the county. Latest surface analysis shows the warm front north of
Dothan and Enterprise AL, stretching east to just north of
Thomasville, GA. The atmosphere south of the warm front is
extremely unstable with the TLH 02z sounding showing 3000 J/KG of
surface CAPE which is consistent with SPC mesoanalysis. Otherwise,
the near term from below is still on track from a mesoscale
perspective. The southern end of the line is passing through
Slidell, LA and starting to move into far SW AL. This will be the
main severe threat later this evening.
&&
.PREV DISCUSSION [844 PM EDT]...
.NEAR TERM [Through Tonight]...
Clearly, the airmass over our western area remains very unstable
- while over portions of South Central, GA, it will be a little
longer before this boundary starts moving northward
The 00z TAE sounding shows the kinematic fields continue to
increase with near 60 kt of deep layer shear and the 850 mb winds
now up to 45 knots. RAP analysis of 850 mb winds in our western
counties already show the presence of winds around 50 kt at that
level. Further west, the KLIX VWP is showing 50 kt winds at 3000
ft. Clearly, the wind fields moving into the region are more than
supportive for significant severe weather. While the low level
flow is not sufficiently curved, even across Srn Alabama and the
Western Florida Panhandle, there still appears to be enough low
level shear present to maintain the tornado risk through the night.
Moreover, the presence of the surface frontal boundary across a
portion of our forecast area could be a significant factor in
tornado potential later tonight, especially if this boundary is
slow to recede northward. Storms nearing this boundary would
encounter enhanced low level shear as the winds back near the
boundary, thus increasing tornado potential. This risk is greatest
across Southeast Alabama and into extreme SW Georgia over the
next 2-4 hours.
Through 9 pm CDT, storms that are over South Central Alabama will
be moving eastward toward our northern SE AL counties as well as
approaching Quitman/Clay Counties in extreme SW Georgia. With the
boundary beginning to retreat northward, it is possible that
these storms will remain surface-based moving into the area and
present the risk of all severe hazard types as they move through.
As the storms move further east of Clay/Quitman Counties, the
storms should become increasingly elevated and present more of a
large hail threat into South Central Georgia, as long as they are
not overtaken by the frontal boundary, should this occur, the
storms would continue to present a risk for all severe hazards.
After midnight CDT - a large cluster of storms, now across
Southern Mississippi will be nearing our western CWA boundary.
This particular complex of storms a cross Southern Mississippi
is especially intense, with a relatively untouched airmass ahead
of it that is incredibly favorable for the continued maintenance
of the storms. 22z/23z HRRR output suggests this storm nears
Southeast Alabama around 1 am CT and will pose a risk for all
severe hazards. This storm and others in the main line would then
progress across the region throughout the early morning hours on
Monday.
Key Point:
1. A moderate risk for severe weather continues across the region
tonight. Storms are expected to increase in coverage and severity
later tonight in our region and pose a risk for all severe
weather hazards: destructive winds, tornadoes, and large hail.
.SHORT TERM [Monday Night Through Wednesday]...
Dry weather with high pressure at the surface and confluent flow
aloft. Cool-ish partly cloudy mornings and warm mainly sunny
afternoons expected. Little change made to previous forecast.
.LONG TERM [Thursday Through Sunday]...
Next strong system will approach Thursday with deep moisture and
decent shear in play. Severe weather possible along with an
excessive rain threat. Will have to see how the Friday-Sunday
period plays out as it looks like another system will move
through. We`ll look closer at that tmrw.
.AVIATION...
[Through 18Z Monday]
Return to VFR today outside of ABY/ECP where it will persist. Then
cigs lower to at least IFR tonight. A line of severe TSRA sweeps
across terminals overnight into Monday morning. Winds shift with
frontal passage on Monday gusting to 30 kt at times.
.MARINE...
Hazardous marine conditions are expected as a strong system moves
across the area. Winds and seas increasing this afternoon and
reaching SCA levels this evening into early Monday afternoon. A
Small Craft Advisory is now in effect. A cluster or line of
severe storms sweeps through overnight into Monday. After the
system departs, winds and seas gradually relax before ramping up
to cautionary/advisory levels again ahead of the next system on
Thurs.
.FIRE WEATHER...
Red flag conditions are not expected for the next several days.
.HYDROLOGY...
Thunderstorm outflow has reinforced the cool airmass to our north
and the warm front has come to a halt. This will focus a heavy
rain threat across much of our AL/GA counties...esply northern
sections...through tonight. Risk of flash flooding has increased in
these areas as has the potential for flooding on the Lee and
Lowndes County tributaries. River Flood warnings may be required
for these areas later today.
Thursday system still looks wet and after this system`s rain we
will be much more susceptible to flooding. We`re going to focus on
the short term for now but plan an ESF tomorrow to update
interests on our rivers about late week/weekend flood potential.
Stay tuned!
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur (while following all local, state, and CDC guidelines) by
calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 72 84 58 84 57 / 70 50 0 0 0
Panama City 72 81 62 81 61 / 70 20 0 0 0
Dothan 67 78 55 80 55 / 90 10 0 0 0
Albany 64 79 56 80 54 / 90 20 0 0 0
Valdosta 69 81 58 81 55 / 60 70 0 0 0
Cross City 73 81 60 82 57 / 40 70 0 0 0
Apalachicola 72 79 63 79 61 / 60 40 0 0 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Tuesday morning for Coastal Bay-
Coastal Franklin-Coastal Gulf-South Walton.
GA...Flash Flood Watch until 8 AM EDT Monday for Ben Hill-Lee-Quitman-
Randolph-Terrell-Turner-Worth.
AL...None.
GM...Small Craft Advisory until 2 PM EDT /1 PM CDT/ Monday for
Apalachee Bay or Coastal Waters From Keaton Beach to
Ochlockonee River FL out to 20 Nm-Coastal Waters From
Ochlockonee River to Apalachicola Fl out to 20 Nm-Coastal
waters from Suwannee River to Keaton Beach FL out 20 NM-
Coastal waters from Mexico Beach to Apalachicola FL out 20
NM-Coastal waters from Mexico Beach to Okaloosa Walton
County Line FL out 20 NM-Waters from Suwannee River to
Apalachicola FL from 20 to 60 NM-Waters from Apalachicola
to Mexico Beach FL from 20 to 60 NM-Waters from Mexico
Beach to Okaloosa Walton County Line FL from 20 to 60 NM.
&&
$$
UPDATE...LN
NEAR TERM...Godsey
SHORT TERM...Johnstone
LONG TERM...Johnstone
AVIATION...LF
MARINE...Johnstone
FIRE WEATHER...LF
HYDROLOGY...Johnstone
Area Forecast Discussion
National Weather Service Tulsa OK
920 PM CDT Sun Apr 19 2020
.DISCUSSION...
Earlier storms have long since shifted to the east, and isolated
storms that developed over northwest OK earlier continue to move
into less favorable environment. Some additional storms across
western KS will move southeast overnight but should meet the same
fate as they approach. Have thus removed all mention of precip
for the remainder of tonight. Clearing skies and light winds,
along with no discernible dry air advection in the low levels
will lead to widespread for potential, and already seeing
reduction in vis in areas along north edge of low clouds deck over
southeast OK and west central AR. For right now will not issue an
advisory but will closely monitor. Update will be out
momentarily.
&&
.PREV DISCUSSION... /Issued 629 PM CDT Sun Apr 19 2020/
AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
Ongoing VFR conditions across NE OK and far NW AR transition to
lower flight levels from SE OK through western AR where low
stratus continues. Convection currently moving into NW OK
currently is not expected to persist into NE OK. Evolution of low
clouds and/or fog overnight is uncertain. Given lack of dry air
advection and winds quickly becoming light overnight the fcst will
side with the persistent model signal of patchy dense fog with low
MVFR to IFR conditions from western AR through SE OK. Lesser
confidence through NE OK. Improving conditions after sunrise w/
isolated storms tomorrow afternoon currently too low probability
to warrant mention.
PREV DISCUSSION... /Issued 242 PM CDT Sun Apr 19 2020/
DISCUSSION...
Convection has been slowing increasing in coverage/intensity
across southeast OK into western AR, within an area of MUCAPES
around 1000 J/Kg and 0-6km bulk shear of 60-70kts. Warm front has
nudged up into far southeast OK, so not out of the question to see
a few surface based storms over the next several hours, although
large hail will continue to be the primary threat. HRRR suggests
that the severe threat will be winding down around 23-00Z as
storms shift east.
Have introduce some low PoPs for late Monday afternoon across far
northeast OK/northwest AR, with several CAM solutions showing
modest SBCAPES ahead of a weak cold front. Any isolated/scattered
activity should quickly diminish by the early evening.
12Z GFS/ECMWF have come into reasonable agreement with the next
upper system swing through the region on Wednesday. Areas of
showers/few storms may spread east into the area by Tuesday night
as a lead wave zips east, but the better chances will hold off
until Wednesday afternoon/evening as the main system approaches.
Severe storms will be possible, mainly for southeast OK. Have to
note that the 12Z NAM is considerably slower with the upper
system, so there are still some timing differences to consider.
Thursday looks to be mostly quiet and mild, with another system
bringing a chance of showers and storms for Friday going into the
weekend. Available moisture may be in question, so the severe
threat appears low at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 45 75 49 75 / 10 0 0 10
FSM 46 75 50 78 / 10 0 0 10
MLC 47 74 51 78 / 10 0 10 10
BVO 43 75 47 74 / 10 10 0 0
FYV 44 72 48 74 / 10 10 10 0
BYV 42 71 47 72 / 10 20 20 0
MKO 44 72 49 75 / 10 0 0 10
MIO 42 72 45 71 / 10 20 10 0
F10 46 74 51 76 / 10 0 10 10
HHW 51 73 53 77 / 10 0 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...14