Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/08/20
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
926 PM CDT Tue Apr 7 2020
.UPDATE...
Issued at 925 PM CDT Tue Apr 7 2020
Forecast is doing okay so no major changes for now. Did lower pops
some late tnt since latest CAMS are much less aggressive with late
night pcpn. Temperatures look okay.
&&
.SHORT TERM...(This Evening through Wednesday Night)
Issued at 321 PM CDT Tue Apr 7 2020
The forecast challenge is where/when tonight`s cold fropa wrings out
some shower potential, along with if there ends up being some
potential for "instability showers" sneaking down out of North
Dakota into northeast South Dakota/west central Minnesota Wednesday
afternoon/early evening. Also will need to re-investigate strength
of winds on Wednesday.
Currently, skies are sunny across the region, and temperatures are
warming into the 60s and 70s across the vast majority of the CWA.
Winds have come around to a westerly direction and becoming breezy
out across the Missouri River valley, while light and variable winds
continue to be noted further east. The cold front of interest for
later tonight is analyzed back over northern Montana at this time.
So, later tonight, said cold front will sweep southeastward through
the region. This will set the stage for, perhaps, some late
night/early Wednesday morning iso`d/sct`d rain showers over the CWA,
mainly south of U.S. Highway 212. Just a few hundredths of
precipitation potential, but behind the fropa, winds will switch
around to the northwest and begin a pattern of low level caa that
will likely not end before the end of the Wednesday night forecast
period. After sunrise, daytime mixing, in tandem with a decent
surface pressure gradient across the state, will work to create some
rather strong winds on Wednesday. Generally speaking, sustained
winds of 25 to 35 mph are probable, particularly the 25 to 30 mph
range, so marginal advisory strength in that respect. But, the gust
potential on Wednesday, if the NAM12 in BUFKIT is right, and the
RAP13 in BUFKIT is half right, would easily set up in the 45 to 55
mph (decent advisory strength gusts). A few locations throughout the
Missouri River valley could see gusts at or above 58 MPH
(significant non-thunderstorm wind gusts!). Also, given the set up
on Wednesday, won`t be taken by surprise to see some "heat of the
day"/steep-low-level-lapse rate-aided popcorn showers developing on
radar by mid to late afternoon across North Dakota and rotating down
across northeast South Dakota and west central Minnesota. And, the
NAM and RAP agree that much of any developing/growing CU will be
living in the -10C to -30C temperature range, so some lightning and
thunder might not be out of the question (or graupel) either.
Overall, looking at the vast majority of the CWA remaining at or
above the freezing mark overnight (lows progged into the 30s and low
40s). Much cooler conditions are in order, though, for Wednesday and
Wednesday night, with highs on Wednesday likely only topping out in
the low 40s to low 50s, and low temperatures Wednesday night
probably dropping into the 20s to around 30 degrees.
.LONG TERM...(Thursday through Tuesday)
Issued at 321 PM CDT Tue Apr 7 2020
Overall, the extended period is shaping up to be cool (at times
cold) with below normal temperatures. Surface high pressure will be
building south into the region on Thursday, with breezy/windy
conditions within the tighter pressure gradient pattern over the
northern plains. Surface high moves overhead Thursday night, setting
the stage for ideal radiational cooling and chilly temperatures.
Brief warm up returns for Friday, and to a lesser extent on Saturday
as we get back into return flow warm air advection. By Sunday and
into early next week it appears a stronger surge of cold air moves
southward across the northern plains, with high temperatures well
below normal. Highs Sunday and Monday may struggle to reach 40
degrees for most areas. The best chance for any widespread
measurable precipitation appears to be late Saturday into Saturday
night, and continuing into Sunday. This looks to be mainly across
western and central SD as an area of low pressure over the northern
Rockies slides southeast into the central plains. Would not be
surprised to see accumulating snow in these areas given the thermal
profiles and surface temperatures heading into Saturday night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 618 PM CDT Tue Apr 7 2020
VFR skies/vsbys are expected through tonight across the entire
region. Winds will also turn gusty, especially Wednesday
afternoon.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...TDK
SHORT TERM...Dorn
LONG TERM...TMT
AVIATION...TDK
Area Forecast Discussion
National Weather Service Birmingham AL
715 PM CDT Tue Apr 7 2020
.UPDATE...
For 00Z Aviation.
&&
.SHORT TERM...
/Updated at 1130 AM CDT Tue Apr 07 2020/
Today and Tonight.
Current satellite imagery & RAP mesoanalysis depict an area of
mostly elevated convection across Central MS along & north of a theta-
e boundary, which is generally sliding eastward/northeastward with
time. South of this boundary, surface-based instability can be found
to ~1,000 J/kg as dewpoints in the upper 60s to around 70 have
spread north of I-10 amidst favorable low-level warm/moist
advection. With resultant isentropic ascent over much of the area,
cloudy skies and increasing rain chances from the west remain the
general theme for much of Central Alabama this afternoon as we
climb into the mid 70s to lower 80s. Exceptions to this will be
areas remaining rain-cooled during peak heating hours across the
west.
As the boundary continues northeastward this afternoon, a limited
opportunity for a strong to severe thunderstorm may exist across
our southwest counties - quarter size hail and/or a damaging wind
gust in stronger storms cannot be ruled out. Best chances remain
along and south of a line from Pickensville to Selma, and will be
contingent on positioning of the boundary later this afternoon,
and if any more robust updrafts can take advantage. Once diurnal
heating is lost, convective trends are expected to weaken. This is
important to remember as the boundary becomes more diffuse while
continuing northward overnight, though isolated to scattered
showers and thunderstorms remain possible into tomorrow morning as
a warm/moist tropical airmass overspreads much of the Gulf Coast
Region.
Tomorrow afternoon.
A summer-like, humid airmass is forecast to take over Central
Alabama tomorrow afternoon. Dewpoints in the upper 60s to lower 70s
appear probable, with forecast soundings suggesting mid-level lapse
rates 6.5-7 C/km. This is setting the stage for 3,000-4,000
SBCAPE amidst eff. bulk shear 50-60 kts. This suggests severe
weather given we hang on to favorable deep-layer shear profiles &
good low-level moisture, though effects from ridging and lack of a
distinct lifting mechanism are big limiting factors in specific
timing and areas of higher risk. Regardless, any mesoscale
boundary left around from tonight`s rainfall could provide just
enough boost to expected low-level lapse rates ~8-9 C/km and air
just below convective temperatures such that isolated to scattered
storms may initiate. This notion will be watched closely as
recent CAMs suggest thunderstorms developing ~21 Z, though we may
not be able to pin down a specific threat area until tomorrow
morning when satellite imagery & surface obs help detect smaller-
scale boundaries/features. Chance PoPs are being maintained as a
broad theme, with an area-wide `Marginal Risk` being introduced in
the HWO for the afternoon/evening severe threat. The potential
thermodynamic environment tomorrow afternoon suggests capability
for robust updrafts containing damaging winds up to 60 mph (given
DCAPE 800-1,200 J/kg and LIs -7 to -9 C), as well as quarter size
(possibly larger) hail.
The next 36 hours will be a fluid forecast situation given a wide
range of solutions in guidance, as well as the two possible
rounds of severe weather tomorrow (one in the afternoon/evening,
another possible overnight and into Thursday morning along a
frontal boundary). Each preceding event will have impacts on
subsequent environments, boundaries, and associated thunderstorm
activity. Central AL residents should check back for upcoming
forecast updates.
40/Sizemore
.LONG TERM...
/Updated at 0231 PM CDT Tue Apr 07 2020/
Wednesday night through Monday.
Diurnal convection from Wednesday afternoon storms will linger
into the evening hours. Severe threat will also carry over into
the evening hours, but storm strength should weaken considerably
by 9 pm due to loss of daytime heating. There should be a lull in
thunderstorm activity between 9 pm Wednesday and 3 am Thursday. A
strong cold front will approach northwest Alabama late Wednesday
night and push through central Alabama Thursday morning. Models
are all over the place with respect to areal coverage and mode of
convection. There could be a broken line of strong to severe
storms or possibly more discrete cells. A wide range of instability
also noted among the models with 06z Thursday CAPE values ranging
from 500 to 2500 J/kg just ahead of the cold front. Dry air aloft
will produce DCAPE values above 1000 J/kg and steep mid level
lapse rates for the production of large hail. The northwest
counties will have a higher threat for severe storms and upgraded
these counties to a slight risk category. The storms should weaken
by 9 am Thursday as the convective cold pool outruns the better
instability. Only isolated storms expected for areas south of I-20
Thursday afternoon.
Much cooler and drier air will move in behind cold front. Lows
Friday morning will be in the middle to upper 40s across the
northern counties with lower 50s elsewhere. The cooler weather
will continue through Saturday morning with highs Friday in the
middle 60s to lower 70s, and lows Saturday morning in the upper
30s to middle 40s. Long range models have slowed down arrival on
rain ahead of weekend system, and lowered rain chances for
Saturday. A low latitude storm system will eject out of the
Southern Plains states over the weekend. There are still timing
and evolution issues with this system, but it bears watching for
severe potential.
58/rose
&&
.AVIATION...
00Z TAF Discussion.
Light rain showers have moved across Central Alabama the past few
hours. This activity will linger for a fro more hours and then
gradually lose coverage. The rain remains in the forecast
throughout in some manner. There will be a chance of thunder on
Wednesday afternoon.
Ceilings start off VFR will a trend to LIFR before 12z at all
locations. Vis looks to remain in the 4-6sm range. The lower
ceilings improve 16-18z.
75
&&
.FIRE WEATHER...
Showers and thunderstorms move into Central Alabama today as a
boundary spreads from west to east across the area. Minimum
relative humidity values are expected to remain above 40 percent
through Wednesday. This is due to a warm, humid airmass expected
tomorrow afternoon with strong to severe thunderstorms possible
into Thursday morning. Thereafter, a front will bring drier and
cooler conditions for Thursday and Friday. However, rain chances
return for the weekend as another system approaches.
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 61 82 62 73 44 / 60 40 50 20 10
Anniston 62 82 64 75 46 / 60 40 40 30 10
Birmingham 64 83 66 75 49 / 60 40 50 30 10
Tuscaloosa 66 85 66 78 49 / 50 40 40 30 10
Calera 64 82 66 76 49 / 60 50 40 30 10
Auburn 64 80 66 80 51 / 60 50 20 30 10
Montgomery 67 84 67 82 53 / 50 50 10 30 20
Troy 68 83 68 84 54 / 50 50 10 20 20
&&
.BMX WATCHES/WARNINGS/ADVISORIES/...
None.
&&
$$
Area Forecast Discussion
National Weather Service Boston/Norton MA
1007 PM EDT Tue Apr 7 2020
.SYNOPSIS...
High pressure in place will give way to a weak area of low
pressure moving in from the Great Lakes. This low pressure will
spread a period of rains later tonight into early Wednesday as
it moves into the waters south of New England. Another system
moves in Thursday, bringing more rain and scattered
thunderstorms. Scattered showers are possible Thursday night
through Friday. Drier weather for this weekend before our next
wet weather system early next week.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
1005 PM update ...
Previous forecast verifying nicely with current and upstream
observations along with radar and satellite trends. Thus no
major changes with this forecast update.
Previous Discussion...
The primary feature of interest for much of the night, however, is a
NW to SE oriented and rather well-defined warm front associated with
a low pressure area as of early this afternoon near northern
Michigan. The low and its related warm front will progress east-
southeast through the northern mid-Atlantic region into Southern New
England later tonight, with increasing clouds through midnight and
rains spreading east-northeastward especially for the overnight
hours.
Temperatures look to remain mild enough even across the terrain to
stay as rain. However worth noting the thermal contrast through the
warm front is fairly robust, and in addition to that, I did notice
on SPC`s mesoanalysis page a plume of weak mid-level instability
(700-500 mb lapse rates ~6-7 C/km) even on the north side of the
warm front. Some guidance - most notably the NAM and the RAP -
brings a sliver of this weak elevated instability into a part of
northern CT into central/southern RI and the south coastal waters
overnight tonight (roughly from a South Windsor to Putnam CT to
Coventry RI line). Though rain should predominate, I did opt to
include some isolated thunder (basically rumbles) along and south of
this line. Rains should continue into the Wednesday morning for
most. Model guidance QPF off today`s 12z guidance was a bit greater
than previous runs. Opted for rain totals thru 12z Wednesday from a
quarter to third of an inch for southern RI into the Hartford area,
then tapering to a tenth to two-tenths of an inch further north and
east.
Lows tonight mainly in the mid-upper 30s to the lower-mid 40s.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Wednesday:
Weak low pressure and attendant warm frontal-related showers pass
south of the coastal waters through the morning hours. As these
features pass to our south, likely to see a modest uptick in NE wind
speeds into the morning hrs and especially near the eastern MA coast
(indicated by the NAM 975 mb winds which tick up to around 25-kt
just offshore). Eventually these winds will lighten and shift to
easterly moving into the afternoon.
Some gradual improvement with rains coming to an end by late-
morning/early afternoon (latest towards Cape Cod and the offshore
waters), and skies trending mostly to partly cloudy. So the second
half of the day is looking somewhat better than the first half, but
with NE to E onshore flow and a shorter period of sun, I opted to
keep temperatures on the cooler side of guidance, into the upper 40s
to the mid 50s.
Wednesday Night:
Weak shortwave ridging/modest 500 mb height rises, ahead of a strong
frontal system to affect our area into Thursday, should allow for
dry conditions through the first part of the overnight. Model
guidance shows moisture levels starting to rise on SE flow into the
second half of the night, with increasing clouds spreading from west
to east. In addition, 500 mb height falls then spread into western
MA into northern CT into the early morning hrs. PoPs increasing to
chance type levels for these locations though most should stay dry.
Lows mainly into the upper 30s to mid 40s with modest SE breezes.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
* Widespread rain Thursday with scattered thunderstorms
* Lighter rain, and high elevation snow possible, on Friday with
a few rumbles of thunder also possible
* Potential for minor coastal flooding Wednesday to Friday
around high tide across the east and south coasts of MA and RI.
See the Tides and Coastal Flooding section below for more
details.
* Temperatures running near to below normal through Saturday,
then a warm up
Thursday...
This still appears to be the most active weather day during
this portion of the forecast. Potent mid level low shifts over
northern New England, with a low pressure passing through our
region. Almost certainly looking at some rain for much of
southern New England, with some wet snow possible across the
higher terrain. Drier air rushes in behind the cold front of
this system, drying our the forecast into Friday.
As for thunderstorm potential, surface-based instability is not
the best. However, mid level lapse rates are better than moist
adiabatic with a strong low-level jet from the south. These
factors are enough to warrant at least a mention of isolated
thunderstorms. Still too early to say if any of these
thunderstorms could be severe.
Friday...
Low pressure continues to rotate away from our region. Still in
the cyclonic flow, so cannot dismiss the idea of a few showers
during the day, rain for most with snow possible across the
higher terrain.
Saturday through Sunday...
The weekend looks drier as a ridge of high pressure makes its way
east across the Mid Atlantic states. This should mean a warming
trend into Sunday.
Monday into Tuesday...
Another low pressure should move across the Great Lakes, leading
to another round of showers sometime from Monday afternoon into
Tuesday morning. Timing is not yet locked down. Looking warm
enough for all rain.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
02z update ... no major changes from previous TAFs. Earlier
discussion below.
=============================================================
Tonight: High confidence in trends, moderate on timing.
Increasing/lowering clouds associated with a warm front which
will eventually spread rains across the TAFs. Initial VFR with
deterioration to MVFR ceilings (possible IFR ceilings south of
BDL to PVD to the Cape airports) after 08/05-07Z with VFR-MVFR
vsby rains spreading ESE through 08/08-12Z. Due to the dry air
around, timing is a bit uncertain but could be an hour or two
sooner than indicated in the TAFs.
Through midnight, mainly light/variable winds in the interior,
SE 5-8 kt towards the Cape and at BOS. After midnight through
08/12Z, winds to shift to NE around 5-10 kt as front slides S
of the coastal waters.
Wednesday: High confidence in trends, moderate on timing.
Initial MVFR, possible IFR with periods of rain to generally
taper off through the morning. Gradual improvement from
widespread MVFR to MVFR/VFR levels toward the afternoon. NE/ENE
winds 4-8 kt in the interior, around 7-10 kt with occasional
gusts to 20 kt coastal MA and the Cape.
Wednesday Night: Moderate to high confidence.
Increasing moisture levels on SE flow will result in VFR-MVFR
ceilings lowering to MVFR-IFR levels in the interior and across
the higher terrain. For the coastal plain into the Cape, initial
VFR to trend VFR/MVFR into the pre-dawn hrs. Rains should hold
off until the pre-dawn hrs in the CT Valley with dry conditions
elsewhere. SE winds 6-10 kt.
KBOS Terminal...High confidence in the TAF.
KBDL Terminal...High confidence in the TAF.
Outlook /Thursday through Sunday/...
Thursday: MVFR/IFR conditions possible. Windy with gusts up to
30 kt. Chance SHRA, isolated TSRA, patchy FG.
Thursday Night: VFR. Windy with gusts up to 35 kt.
Friday: VFR. Windy with gusts up to 30 kt. Slight chance SHRA.
Friday Night through Saturday: VFR. Breezy.
Saturday Night: VFR.
Sunday: VFR. Slight chance SHRA.
&&
.MARINE...
Winds and seas should remain below SCA thresholds through
Wednesday night.
A warm front will bring a period of steady rains for most of the
waters late tonight into Wednesday morning, with an outside/low
chance for a rumble or two of thunder across the southern offshore
waters overnight. Could see vsbys between 3-5 SM in rains,
likely lowest south coastal waters. Winds to become NE on Wed
AM, and could briefly reach marginal-SCA gusts with seas 3-4`
(near 5` per the SWAN guidance off the NAM) on the eastern
MA/Cape Cod waters. Wasn`t confident enough on criteria being
met to issue an SCA for these waters Wed AM, but may get close.
Winds lighten to under 20 kt and shift east later Wednesday and then
SE into Wednesday night. Seas mainly 2-3` Wednesday night, though
build to 2-4` by daybreak.
Outlook /Thursday through Sunday/...
Thursday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Chance of rain showers,
isolated thunderstorms, patchy fog. Local visibility 1 to 3 nm.
Thursday Night: Low risk for gale force winds with gusts up to
35 kt. Rough seas up to 10 ft.
Friday: Strong winds with gusts up to 30 kt. Rough seas up to
12 ft. Slight chance of rain showers.
Friday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 10 ft.
Saturday: Winds less than 25 kt. Local rough seas.
Saturday Night: Winds less than 25 kt. Seas locally approaching
5 ft.
Sunday: Winds less than 25 kt.
&&
.TIDES/COASTAL FLOODING...
418 PM Update:
Astronomical tides are on the rise over the next several days
(across multiple tidal cycles) due to the Supermoon. While the
overall threat is limited by poor wave action, due to the high astro
tides a number of tidal gages are forecast to be near flood stage or
into minor flooding categories per Stevens Institute guidance.
Appears the greater potential for minor coastal flooding later
tonight into Wednesday should exist for eastern coastal MA and Cape
Cod/Nantucket, especially around the period of high tides. By
Wednesday night into Thursday, stronger southerly winds ahead of a
strong frontal system will raise the coastal flood threat across
a larger area to include the South Coast and Narragansett Bay.
Coastal Flood Advisories have been posted thru Friday following
these general expectations.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Coastal Flood Advisory from 8 AM Wednesday to 8 AM EDT Friday
for MAZ019-022.
Coastal Flood Advisory from 8 PM Wednesday to 8 AM EDT Friday
for MAZ015-016.
Coastal Flood Advisory until 8 AM EDT Friday for MAZ007.
RI...Coastal Flood Advisory from 8 PM Wednesday to 8 AM EDT Friday
for RIZ002-004>007.
MARINE...Gale Watch from Thursday afternoon through Friday afternoon
for ANZ231-232-250-251-254-255.
&&
$$
SYNOPSIS...Belk/Loconto
NEAR TERM...Belk/Loconto
SHORT TERM...Nocera/Loconto
LONG TERM...Belk
AVIATION...Belk/Nocera/Loconto
MARINE...Belk/Loconto
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Dodge City KS
1035 PM CDT Tue Apr 7 2020
...Updated Aviation...
.SHORT TERM...(This evening through Wednesday)
Issued at 248 PM CDT Tue Apr 7 2020
Warmer today with 85 degrees already at 2 pm. The northwest winds
that are gusting now to around 25 mph should slowly being to
weaken per hourly HRRR wind fields and as the surface winds
slowly veer easterly with time into the late afternoon. Wind will
become light southeasterly this evening before flipping northwest
again by later Thursday morning. Overall a mild night again across
the forecast area with lows in the 40s and 50s, west to east.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 248 PM CDT Tue Apr 7 2020
A slowly progressive pattern is developing on the synoptic scale, as
a large 500 mb low rotating off the southern California coast moves
across the sw US and Mexican border, weakening to and open wave over
the central and southern High plains region by late this weekend.
For the timeline, initially on Wednesday we will see no impacts
from this system as a weak cold front enters Kansas with the best
cold advection coming late in the day or evening, when
temperature falls actually become more noticeable. By Thursday,
cooler highs in the 60s as the surface winds spends the day
veering northeast to south again by the Thursday evening timeframe
and the surface ridge settles into the southern Mississippi
valley by Friday. Sometime Friday into late Saturday has the best
potential for thunderstorms produced from any potential surge of
theta-e advection. Looking farther into the weekend and early next
week, we see increasing confidence in quite cold boundary layer
air returning and 850 mb temperatures as cold as -9C diving across
Kansas and points south. With the wave moving across the region
at the time, forecasting a period of rain and possible rain
changing over to snow at some point will become the mesoscale
forecast challenge Sunday into Monday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1035 PM CDT Tue Apr 7 2020
VFR/SKC expected through this TAF forecast cycle. Light and
variable winds overnight will trend northerly after sunrise/
12z Wed. After 15z Wed, north winds will increase behind an
advancing cold front. Expect north wind gusts of 25-30 kts at all
airports Wednesday midday/afternoon, with winds trending NEly and
diminishing around sunset/00z Thu.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 50 77 37 60 / 0 0 0 0
GCK 47 76 35 60 / 0 0 10 0
EHA 47 78 38 63 / 0 0 10 0
LBL 48 78 36 62 / 0 0 10 0
HYS 46 77 36 57 / 0 0 0 0
P28 52 81 40 63 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...Turner
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
635 PM CDT Tue Apr 7 2020
.AVIATION...
VFR conditions prevail across the area with some low clouds remaining
around the San Antonio sites. Models have come in a bit more
optimistic this evening regarding ceilings and visibility by
morning. Didn`t go quite as optimistic as the new guidance and went
with more of a blend between the old TAFs and the new guidance.
Think we will likely see BKN ceilings with some breaks in the clouds
possible. In addition, some visibility restrictions are possible. VFR
conditions should return by the early afternoon. For the afternoon,
scattered convection is possible with initiation first occurring in
the Hill Country. If the storms do develop, they would then move east
and potentially impact the I35 sites in the late afternoon or
evening hours.
&&
.PREV DISCUSSION... /ISSUED 253 PM CDT Tue Apr 7 2020/
SHORT TERM (Tonight through Wednesday Night)...
High dew point temperatures in the upper 60s to mid 70s are holding
back afternoon temps despite partly to mostly sunny skies. Shortwave
ridging in the mid levels of the atmosphere will keep most of the
area rain free this afternoon and evening, but the GFS is matching
recent runs of the HRRR to suggest a weak mid-level impulse will
trigger topography based convection later in the evening into the
overnight hours. This should only result in a isolated storm or two
that could briefly become strong over the Serranias del Burros, but
should move into well-capped low levels and be quick to weaken as
they reach the Rio Grande.
Low clouds and a few patches of light fog are possible tonight, but
there should be much less of the visibility restrictions after a
abundant sunshine provided deep mixing in the low levels. Dew points
in the upper 60s and low 70s overnight are expected to cover all but
perhaps NW Val Verde county tonight and possibly set the table for a
strong to severe storm environment late Wednesday.
Another hot and humid day starts of Wednesday with high dewpoints in
the low to mid 70s correlating with Pwat values of 1.5 to 1.8
inches. Westerly winds in the low to mid levels of the atmosphere
over North Central and West Central Texas are expected to develop
the focus for afternoon convection, the eastward shift of a dryline
into the Hill Country. At maximum heating, the various HREF members
suggest a potential for CAPES to approach 4000 J/Kg should the right
environment come together. Boundary layer winds in the near storm
environment should be mostly out of the SW, so this will curb shear
profiles some, making for mainly speed shear. But 3-4 KJ/Kg in March
should be good enough to favor a favor isolated supercells capable
of very large hail over 2 inches and damaging winds. SPC has
recognized the escalated threat and responded in kind with an
upgrade from marginal to slight risk in the day 2 outlook. The storm
severity could carry well into the mid-evening hours, but the lack
of heating later, should translate to weakening storms in the late
evening. Cell coverage should initially be isolated through the late
afternoon, with perhaps 30 to 50 percent coverage developing with
cell-mergers and small scale squall lines later in the evening. At
this time, we are not expecting a significant influence on the
surface weather pattern in terms of boundaries, as more rain and
storm chances arrive early in the extended periods.
LONG TERM (Thursday through Tuesday)...
The combination of a moving dry-line into the Rio Grande Plains area
and a shallow cold front pushing across South Central Texas on
Thursday is expected to bring scattered to numerous showers and
isolated thunderstorms. The frontal boundary will continue to push
away from the area into the Gulf coastal waters in the late
afternoon and evening. Some storms could be strong to severe as the
cold front moves along and to areas east of Interstate 35 during the
afternoon period. Large hail and damaging winds are the primary
threats.
With the frontal boundary well to the southeast of our area for the
Thursday night into the Friday morning, decided to go with only 20
percent chance for rain for the far east part of the region.
However, the dry weather conditions won`t last long since another
round of showers and thunderstorms is forecast for late Friday
afternoon into Saturday. A weak warm front is forecast to move into
the area while an upper level low pressure system and associated
Pacific front move across the region. Can`t rule out a few strong to
severe storm as the Pacific front moves along and to the southeast
of the I-35 corridor during the Saturday morning time frame.
Isolated pockets of 1 to 2 inches of rainfall are expected from
Friday afternoon into Saturday afternoon. Can`t rule out a few spots
getting up to 3 inches. All of this depends on how quickly the front
moves out from the area.
Dry weather is expected for Sunday with highs in the 80s for the
most parts followed by a dry and cooler Monday and Tuesday with
highs in the 60s and lower 70s as a polar front makes it down to the
area.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 71 91 68 80 59 / - 30 30 60 20
Austin Bergstrom Intl Airport 70 91 67 81 59 / - 30 30 60 20
New Braunfels Muni Airport 70 90 67 82 60 / - 20 30 60 20
Burnet Muni Airport 69 89 66 77 55 / 10 20 20 50 20
Del Rio Intl Airport 70 92 70 87 63 / 20 20 10 20 10
Georgetown Muni Airport 71 91 66 78 57 / - 20 20 50 20
Hondo Muni Airport 69 91 68 85 60 / 20 30 30 50 20
San Marcos Muni Airport 69 90 67 82 59 / - 20 30 60 20
La Grange - Fayette Regional 71 90 69 83 61 / 0 20 20 60 40
San Antonio Intl Airport 71 91 69 83 61 / 10 20 30 60 20
Stinson Muni Airport 70 91 69 85 62 / 10 20 30 50 20
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...Hampshire
Long-Term...KCW
Area Forecast Discussion
National Weather Service Goodland KS
835 PM MDT Tue Apr 7 2020
.UPDATE...
Issued at 830 PM MDT Tue Apr 7 2020
There appears to be a 3 to 4 hour window for a few showers and
possible thunderstorms to develop, generally 06-10z in the
vicinity of the Kansas Nebraska border. In this area sufficient
moisture in the 700-500mb layer coupled with 100-200 J/KG of CAPE
around 2KM and some convergence at 850mb between a weak low level
jet nosing in from the south and northwest winds approaching from
the northwest. 00z NAM and 23z/00z HRRR painting some light qpf
in this area.
Otherwise made some minor adjustments to all other parameters
through Wednesday.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 233 PM MDT Tue Apr 7 2020
The main short term forecast concern is the possibility of
elevated fire weather conditions ahead of a cold front on
Wednesday.
Warmer than normal temperatures of the past couple days turn
cooler on Wednesday and Thursday following the passage of a cold
front during the day on Wednesday. Ahead of this cold front dry
conditions remain in place over mainly far eastern Colorado where
relative humidity values between 15-20 percent persist. Winds are
expected to turn north and increase during the day with gusts of
30-35 mph, which will bring conditions to near critical fire
weather values over a small portion of the far southwest corner of
the forecast area. Do not expect to need a fire weather highlight
at this time.
No precipitation is expected with this front. Low temperatures
will be back down in the 30s Wednesday night with daytime highs
only reaching the the upper 50s to lower 60s on Thursday. The
cooler temperatures will bring minimum afternoon relative
humidity values back up into the 20-35 percent range with
overnight relative humidity values recovering into the 70-85
percent range.
.LONG TERM...(Friday through Tuesday)
Issued at 215 PM MDT Tue Apr 7 2020
Will manage one more warm and dry day on Friday under shortwave
ridging, but precipitation chances begin Friday night and
continue through the remainder of the period. Best chances for
precipitation will be Sunday, when an inch or two of light snow
will be possible, as a large trough digs into the northern and
central High Plains. Expecting windy conditions to accompany the
light snow as well, with current model projections suggesting
north winds gusting 40-50 mph by Sunday afternoon. Given the light
snowfall amounts and warm ground temperatures which will result
in considerable melting, not expecting blowing or drifting to be a
problem at this time. Beyond Sunday, will be under a northwest
flow with much below normal temperatures. Model POPs appear a bit
overdone, but cannot rule out weak disturbances in the northwest
flow resulting in rain/snow showers early next week. Low
temperatures will reach the teens Monday morning, and the teens
and 20s Tuesday morning, so agricultural and ranching interests
need to be prepared for the colder temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 500 PM MDT Tue Apr 7 2020
For KGLD and KMCK, vfr conditions through the period. Winds at
both sites will generally be variable at speeds under 6kts through
09z or so before establishing a westerly component under 10kts
through 14z or so as a cold front is about to move through the
area. This front is expected to produce north and northwest winds
gusting up to around 30kts through the late morning and afternoon
hours. KGLD may lose the gusts around 23z but remain just above
12kts. No precipitation is expected.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...99
SHORT TERM...LOCKHART
LONG TERM...024
AVIATION...99
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
946 PM EDT Tue Apr 7 2020
.SYNOPSIS...
A warm front north of the area will keep an influx of more moist
and unstable air over the Ohio Valley tonight. Thunderstorms,
some severe, are forecast to sweep through the area overnight
with the passage of a cold front. A brief period of high
pressure and dry weather on Wednesday will be followed by
another more potent cold front Wednesday night containing
additional showers and thunderstorms.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Current surface analysis indicates that low pressure is moving
ESE across southern Michigan, with widespread strong to severe
convection running south of / ahead of the low from Port Huron
MI to Chicago IL. The warm sector in place to the south of this
low is currently free of storms or any signs of convective
development, capped by quite a bit of warm air located at about
750mb. Current conditions within the warm sector (across IN/OH)
are characterized by SW winds, temperatures in the upper 60s to
lower 70s, and dewpoints in the mid 50s to around 60.
The main focus for tonight is on the potential for severe
thunderstorms, as the aforementioned convection moves southwest
through Indiana and Ohio. There appears to be a well-defined
wind shift and theta-e boundary in the lower levels that will
move southwest, crossing through the ILN forecast area between
06Z-12Z, with storms generally focused ahead of it. Upper level
support for convection is not as impressive, with generally
broad ridging aloft, and no obvious signs of large-scale
vorticity advection. Thus, the forcing part of the equation for
tonight is mixed -- favorable in the low levels, and not so much
aloft. A westerly LLJ is expected to develop across Indiana in
the 00Z-06Z time frame, providing a surge of warmth and moisture
into the boundary layer, which should keep conditions favorable
for additional thunderstorm development as the evening turns
into the overnight.
The key factor for tonight is instability, with high confidence
(now supported by the 00Z KILN sounding) in very steep lapse
rates aloft. The evening sounding indicated 700mb-500mb lapse
rates of 7.4 degrees C/km, and several models are indicating
that these mid-level lapse rates may exceed 8.0 degrees C/km in
the next few hours across the northern / northwestern sections
of the ILN forecast area. When looking at projections of CAPE,
it is interesting to note that the CAPE from a lifted parcel is
arranged a little differently on the sounding than might be
normal -- the majority of the instability (and the greatest
separation from atmospheric temperature to parcel) is focused
high in the troposphere, within a zone where hail growth is
favored. Deep-layer wind shear is also impressive enough to
allow for storm organization (supercells / clusters) which will
further enhance the threat for hail. This forecast is in
agreement with the SPC D1 outlook, which indicates the potential
for significant hail.
There are also a couple of limiting factors that should be
discussed. First off, there are some concerns with storm
coverage, especially on the western periphery of the developing
convective system. The last few runs of the HRRR have been quite
meager with the western extent of convection. However, not too
much attention is being paid to this solution -- current
upstream radar imagery and the expected theta-e surge (mentioned
above) would suggest that convective development is more likely
than not to continue across much of the CWA -- especially the
northern half. Second off, there are some concerns with
boundary layer stability, which can be assessed to some degree
by looking at surface dewpoints. Most of the model projections
(sans the NAM which is well too moist) suggest that dewpoints
in the ILN CWA will increase from the mid 50s to the lower 60s
over the next few hours. It remains to be seen if dewpoint
advection will be strong enough to do this. The expected
vertical profile ahead of the storms will likely feature only
marginal lapse rates in the lowest few thousand feet, topped (as
mentioned) by very steep lapse rates further aloft. Any
marginal lapse rates near the surface, and any remnant of the
cap that sticks around, would work to significantly limit the
threat for convective wind. If these storms congeal into more of
a cold-pool driven MCS, the wind threat would obviously
increase. As a final note -- 0-1km shear orientation and
magnitude, combined with the issues of boundary layer stability,
would suggest that the tornado threat for this event is not
particularly high.
Severe Thunderstorm Watch 84 is now in effect for the northern
three ILN counties, and additional watch issuance further south
may be needed.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Cold pool stratus trailing the storms from earlier overnight
will break up in the morning from northwest to southeast as
drier air works in with high pressure to the north. Upper level
height fields drop off slightly and the more traditional cold
front with the tiniest of recoveries on Thursday or a
steady/slow drop in readings through the day is expected with
upper level support reinforcing the cold advection beyond this
period.
Showers and possibly a few thunderstorms over the southern
portions of the CWA are possible overnight as the next front
crosses tomorrow night, beginning towards midnight in the
northwest and exiting by daybreak in the southeast.
Highs Wednesday will be in the upper 60s to lower 70s, with
overnight lows ranging from near 40 in the northwest to near 50
in the southeast.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
We could see a few lingering showers across our far southeast
Thursday morning but with the cold front moving off to our
southeast, expect mainly dry conditions through the day. In
decent CAA through the day, temperatures will likely not recover
too much with highs ranging from the mid 40s northwest to
possibly mid 50s across the southeast. The CAA and a fairly
tight pressure gradient will also lead to some gusty winds
through the day.
Surface high pressure will build east across the Ohio Valley
Thursday night through Friday night, leading to dry but
seasonably cool conditions. Lows Thursday night will be down
into the mid 30s but think winds may stay up enough to help
limit frost development. Highs on Friday will generally be in
the 40s. Lows Friday night will be in the low 30s and with
lighter winds, it looks like a better chance for some frost.
This will be somewhat dependent though on how fast clouds
possibly move in later Friday night/early Saturday morning.
Mid level short wave energy will lift out of the Southern
Plains and across the lower Ohio Valley Saturday into Sunday.
This will help carve out a broader trough across the central US
through early to mid next week. Models differ on their
timing/placement and strength of an associated surface low that
will lift northeast across the eastern US/possibly Great Lakes
region Sunday into Monday. This will lead to an increasing
chance of showers and perhaps a thunderstorm through the later
half of the weekend. Will allow for a gradual increase in pops
heading into Sunday/Sunday night, but mostly limit them to high
likely or chance given some of the uncertainty. For that same
reason, will linger some slight chance pops on into Tuesday.
Temperatures (and winds) through this time period will also be
dependent on the strength/track of the low. Have trended toward
the model blend for temps (and consall for winds).
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions will continue for the start of the TAF period,
with gusty WSW winds. Going into the overnight hours, the main
concern will be for thunderstorms to move in from the north.
Some of these storms may be severe, so strong winds and hail are
a possibility -- along with IFR conditions. The most likely
timing for storms will be in the 05Z-08Z time frame for
KDAY/KCMH/KLCK/KILN and a couple hours later for KCVG/KLUK.
After the storms depart, winds will shift to the northwest, and
a period of MVFR ceilings is expected for most locations.
However, confidence is not particularly high in the ceiling
forecast, and some areas may stay mainly VFR. At any rate, by
15Z, VFR conditions are expected again with clearing skies.
Very little weather of consequence is expected through the
daytime hours tomorrow, with NW winds at or below 10 knots, and
VFR conditions. The next chance for showers and storms will move
in after the end of the TAF period.
OUTLOOK...Thunderstorms are possible Wednesday night. MVFR
conditions are possible Wednesday night through Thursday
morning.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Franks
NEAR TERM...Hatzos
SHORT TERM...Franks
LONG TERM...Sites
AVIATION...Hatzos
Area Forecast Discussion
National Weather Service Lincoln IL
915 PM CDT Tue Apr 7 2020
.SYNOPSIS...
Issued at 905 PM CDT Tue Apr 7 2020
Widely scattered thunderstorms will be possible tonight, mainly
along and north of the I-74 corridor. Overnight lows will range
from the lower 50s from the Peoria area northward...to the lower
60s south of I-70.
&&
.UPDATE...
Issued at 915 PM CDT Tue Apr 7 2020
A broken line of convection has developed along a slow-moving cold
front extending from the Chicago metro westward into central Iowa.
CAMs have not been adequately catching the storm development on
the western end of the front across Iowa, making short-term
forecasting a bit challenging. Latest mesoanalysis continues to
show a moderately unstable airmass south of the boundary across
central Illinois, characterized by MLCAPEs of around 1500J/kg.
0-6km bulk shear values decrease further south, but are still an
appreciable 40-50kt across the area. Main mitigating factor for
storms continues to be mid-level capping in the warm sector,
although that has been gradually weakening this evening. Given
current radar trends, think the storms along the front will slowly
weaken with time as they track E/SE into the more unfavorable
airmass further south. Have adjusted PoPs to carry low chance
along/north of the I-74 corridor for the next few hours, then
continued just slight chance PoPs across the eastern KILX CWA
after midnight in case an isolated shower/storm can develop along
the front as it sinks further southward.
&&
.SHORT TERM...(This evening through Wednesday night)
ISSUED AT 325 PM CDT Tue Apr 7 2020
Clouds cleared out this afternoon amid a capping layer at 850 mb,
and limited low level moisture. The cold front will come into an
area of substantial elevated instability (2500 J/kg MLCAPE), with
potential for some strong updrafts after the warm layer aloft
erodes ahead of the cold front. However, HRRR and RAP updates are
showing very isolated showers/storms in our forecast area this
evening, most likely attributed to the lack of moisture. We have
reduced PoPs early this evening to slight chance, but ramp up to
Chance in our east-southeast counties later this evening,
lingering through 3-4 am south of I-70. The front does appear
poised to energize a bit farther to the southeast toward
Taylorville and Shelbyville later this evening, so we did continue
chance PoPs that far west. Confidence on coverage of storms
tonight is low, but the Slight Risk east of Bloomington to Decatur
indicates the potential for large hail should any storms develop
in that area this evening.
The next point of concern is the potential for severe storms again
with the stronger cold front Wed afternoon into evening. Once
again, deep layer moisture will be limited, and MLCAPE
instability will be lower, in the 800-1200 J/kg range. However,
wind shear will be in the 60-70kt range, and there appear to be
pockets of strong vorticity along the boundary. SPC`s 17z updated
expanded the Slight Risk northward all the way to I-74, for large
hail and damaging winds. It was previously limited to south of
I-70. Deterministic models are showing higher QPF potential, so
have gone with the likely/categorical PoPs ahead of the front. The
front will be moving quickly through the area, with forward
motion of 45-50 mph. That will aid in producing enhanced updrafts
as well.
.LONG TERM...(Thursday through Tuesday)
ISSUED AT 325 PM CDT Tue Apr 7 2020
Strong northwest winds will highlight Thursday, with sustained
winds in the 20-25 mph range, just below advisory criteria (30
mph). Gusts will reach over 40 mph at times, especially in the
afternoon. Mixing heights look to reach up to 5-7K FT, tapping
into 40-45 KT winds. So despite ample sunshine on Thursday, high
temps will struggle to reach the lower 50s, or 20-25 degrees
cooler than Wednesday.
Winds will not be as strong on Friday, in the 15-20 mph range,
but chilly highs in upper 40s to low 50s will continue one more
day.
Saturday will see increasing rain chances north of I-70 as a warm
front develops across NW Illinois. Southerly winds will bring
increasing moisture and slightly warmer temps. Highs will reach
into the mid to upper 50s under a showery day. Rain chances will
diminish only briefly Saturday night as a surface low pressure
center progresses from Oklahoma to Kentucky on Sunday. Rain
chances will increase to Likely Sunday south of I-72/Danville, but
thunder potential will be minimal.
An unfortunate result of that low passage will be colder air being
pulled into Illinois for Monday and Tuesday. Overnight lows will
dip below zero both nights, with a few flakes of snow not out of
the question Monday night for areas N of I-72/Danville. The models
tend to have a problem modifying sufficiently in response to the
warmer ground in place ahead of that system this time of year, so
there will likely be warming air mass temps as the models catch up
to a more likely scenario.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 644 PM CDT Tue Apr 7 2020
VFR conditions will prevail through the entire 00z TAF period. A
cold front currently extending from southern Wisconsin into
central Iowa will sag southward tonight...reaching the I-72
corridor shortly after midnight. Isolated thunderstorms will be
possible along the boundary: however, most model solutions keep
the activity N/NE of the terminals. Have included VCTS at
KPIA/KBMI/MCMI between 03z and 07z in case a few cells develop
this far W/SW along the front before diminishing overnight.
Further south, have kept the remaining TAF sites completely dry.
Winds will initially be SW with gusts of around 20kt this evening,
then will veer to W and decrease to 10kt or less as the front
approaches. Once the boundary passes, light NW winds are expected
late tonight into Wednesday morning. Winds will once again swing
around to the S/SW late Wednesday as a stronger cold front
approaches from the northwest.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Barnes
SYNOPSIS...Barnes
SHORT TERM...Shimon
LONG TERM...Shimon
AVIATION...Barnes
Area Forecast Discussion
National Weather Service Indianapolis IN
Issued by National Weather Service Bismarck ND
1043 PM EDT Tue Apr 7 2020
.UPDATE...
The NEAR TERM and AVIATION Sections have been updated below.
&&
.SYNOPSIS...
Issued at 438 PM EDT Tue Apr 7 2020
Severe thunderstorms are possible across the area tonight as a
weak cold front passes through the region. Wednesday will be warm
again ahead of another front that will arrive on Wednesday night
with a more widespread area of showers and thunderstorms. A few
severe thunderstorms are possible again Wednesday night. Breezy
and much cooler weather will arrive Thursday and Friday.
&&
.NEAR TERM /Rest of Tonight/...
Issued at 1032 PM EDT Tue Apr 7 2020
A line of strong to severe storms has made it`s way into northern
Indiana and will continue to sag south and east over the next few
hours. The last few iterations of the HRRR seem to have a pretty
good handle on the ongoing convection and would have the
strongest part of the line giving the north central and
northeastern portions of the forecast area a glancing blow.
Further development continues across western Illinois and eastern
Iowa but it is still pretty uncertain whether this activity will
be able sustain itself until it reaches our area. For this reason,
cut back on precipitation chances across much of our south, west,
and portions of the central. Otherwise, the forecast looks to be
in good shape.
&&
.SHORT TERM /Wednesday through Thursday Night/...
Issued at 438 PM EDT Tue Apr 7 2020
Low- and midlevel warm air advection will quickly resume Wednesday
as another, stronger shortwave trough amplifies in the upper Great
Lakes. Post-frontal drying behind tonight`s system is forecast to
be significant enough to stunt return-flow trajectories Wednesday
in advance of the next and stronger cold front expected to arrive
Wednesday night, so the expected instability with the next front
will be lower, with MLCAPE generally in the 500 to perhaps 1000
J/kg range. However, forcing for ascent will be stronger and the
12 UTC model suite and related NBM guidance supported PoPs in the
70-90 percent range Wednesday night, and strong wind fields are
supportive of a few severe storms, as well.
It will be warm again Wednesday ahead of the secondary cold front
with NBM-driven forecast highs in the 70s again. On Thursday, cold
air advection will rule with forecast highs falling into the 45 to
55 F range with gusty northwest winds. Low-level momentum transfer
in the cold air advection regime will likely support winds more in
line with MOS-based forecast guidance, so the official forecast
was weighted toward those numbers. Winds could remain elevated
enough on Thursday night behind another, reinforcing cold frontal
zone to prevent frost formation in most areas, but actual lows are
forecast to reach the lower and middle 30s F in many areas.
&&
.LONG TERM /Friday through Tuesday/...
Issued at 438 PM EDT Tue Apr 7 2020
A cool weather pattern will persist through the long term thanks
to initially-northwest flow that will be shifted only due to the
slow development of a mean central United States trough that will
keep below-normal temperatures in the cards. The 00 and 12 UTC
global deterministic and ensemble guidance and related NBM output
agree on the overall theme of the long term, with the primary
highlights being 1) potential widespread frost on Friday night and
Saturday morning, and 2) the increasing likelihood of widespread
rain and embedded thunderstorms centered on the Sunday and Sunday
night time frame. The NBM supported introduction of likely-level
PoPs Sunday, and lingering shower chances through early next week.
Highs through much of the period will be in the 50s F.
&&
.AVIATION /Discussion for the 080000Z TAF Issuance/...
Issued at 1038 PM EDT Tue Apr 7 2020
VFR conditions are forecast to prevail over the next few hours.
The risk of thunderstorm development increases after 03 UTC as an
approaching cold front will generate at least scattered
thunderstorms with locally sub-VFR conditions possible in any
storms. Timing of the potential storms is focused on the 03 to 10
UTC time frame, but confidence in impacts at any given terminal
still remains too low for inclusion of more than a VCTS in any
TAFs for now. At the moment, the north central and northeastern
parts of the forecast area look to have the best chance for
thunderstorms.
Moving into Wednesday morning, confidence is increasing that MVFR
ceilings in stratus will follow the cold front based on the
latest model guidance and trends upstream. It isn`t out of the
question that ceilings will dip into IFR categories with this
stratus but the latest guidance has backed off a bit so will stick
with MVFR for now. These ceilings should lift with a return to
VFR conditions by about 15 UTC Wednesday. More clouds and even a
few showers will approach KIND towards the very end of the period.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CJS
NEAR TERM...ZH
SHORT TERM...CJS
LONG TERM....CJS
AVIATION...ZH/CJS
Area Forecast Discussion
National Weather Service Marquette MI
625 PM EDT Tue Apr 7 2020
.SHORT TERM...(This evening through Wednesday)
Issued at 404 PM EDT TUE APR 7 2020
As a warm front gradually lifts eastward across Upper Michigan this
afternoon, visible satellite shows partial clearing over the western
U.P. but most area remaining socked in with low clouds. Some fog has
also developed due to high dew points advecting over what remains of
the snowpack and rain falling onto it. Over the somewhat clear area,
temps have risen into the low 50s but they remain in the low 40s
over the cloudy areas. A few small, weak thundershowers will be
moving east across Menominee County this afternoon as well but given
the cool surface temps are obviously very elevated and are expected
to stay well below severe limits given MUCAPE that`s only in the 100-
500 J/kg range per SPC Mesoanalysis. As that front continues to lift
away, surface wind will become generally WNW and that clearing will
expand to the central U.P. as well. Over the Keweenaw and east,
however, fog that was generated today over Lake Superior will be
advected onshore under this WNW flow and keep things socked in.
Model visibilities get down to as low as 1/4 mile so it`s not
impossible that a Dense Fog Advisory will be needed at some point
tonight, but will hold off and wait until that actually forms before
pulling the trigger. It should begin to diminish Wednesday morning
due to both typical diurnal mixing as well as wind backing to WSW
and thus less onshore.
Tomorrow, a mid-level short wave will be pushing eastward through
the Canadian Prairies and wrapping into a developing closed upper
low. As this happens, a new low center is expected pinch off in
northern Ontario and then deepen quickly tomorrow afternoon. The
system`s developing cold front will push across the U.P. in the
afternoon. This means temps will peak early afternoon (especially
west) before cooling in the afternoon. Over the south-central, where
skies will be clear more of the day and the front won`t arrive until
after peak diurnal heating, highs should reach the mid to upper 50s
with an isolated 60 reading not out of the question. NW winds will
also become blustery in the afternoon behind the front with
sustained winds up to 20 mph and gusts up to 30 mph expected.
Despite strong fgen with the front, it remains to be seen if any
showers will form with that forcing. The RAP is by far the most
aggressive in developing a wave of rain and lifting it north along
the front since it shows stronger low-level theta-e advection than
in other models. The other CAMs have spottier showers which makes
more sense, so have gone with just chance POPs south and east of a
line from roughly Munising to Iron Mountain. Lapse rates will not
support any thunder from these showers.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 352 PM EDT TUE APR 7 2020
Below normal temperatures look to prevail with chances for showery
precipitation through the end of the week as a slow moving cutoff
low gradually tracks south-southeast across the Great Lakes region.
Wednesday night into early Thursday morning, much colder air starts
to drop south across the region under prevailing northwest flow.
850mb temperatures look to cooling to -8 to -10C, and the depth of
this cold air advection and steeper lapse-rates aloft will allow for
some deeper mixing. This should help support mostly all snow as a p-
type, but kept snowfall amounts on the lower side given the stronger
winds aloft should help shred dendrites quite a bit. Snow should
hold on throughout the day on Thursday especially downwind of Lake
Superior, but across the far south-central any showers that make it
down that way should switch over to rain as temperatures warm just
above freezing. During this time period, the deep mixing tapping
into winds loft around 30-40 knots should allow for blustery
conditions, with some concerns for lakeshore flooding mainly east of
Marquette along the Lake Superior shoreline.
By Friday, the colder air continues to stream across the area under
northwest to north flow. However it does look like drier air and
increasing subsidence starts to move into the region as surface high
pressure arrives from the west. Therefore, did opt to leave the
drier NBM PoPs in there for now. PoPs look to be a bit aggressive
for the weekend, but opted to leave them as is for as there is some
uncertainty. By early next week, a trough becomes well organized
across the central CONUS with a system deepening as it lifts
northeast across the region. Depending on the track of the system we
find ourselves on the wrap around snowy side of the system and
would be more impactful across parts of Upper Michigan.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 625 PM EDT TUE APR 7 2020
Confidence is low with these TAFs as low level moisture will try to
clear out, but winds also get light overnight which could cause re-
emergence of fog and stratus again. IWD will be VFR until later
tonight when fog moves in and takes them down to IFR briefly. CMX
will stay VLIFR overnight with upslope westerly wind off of Lake
Superior before improving to VFR by Wed afternoon. SAW is trickier
and thinking is they will lose the low stratus early, then fog
develops and they will go MVFR overnight and then VFR by Wed
afternoon.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 404 PM EDT TUE APR 7 2020
Main story tonight will be areas of fog, possibly dense, due to rain
falling over the lake and moist air advecting over it. Models are
all aggressive in showing widespread visibilities less than 1 mile
so have issued a Dense Fog Advisory through late morning Wednesday.
Winds during this period will remain light. Wednesday afternoon, a
cold front will push across the lake with WNW winds increasing to 20-
30 kts behind it. Winds are expected to increase further Wednesday
night with gales becoming widespread east of Isle Royale and the
Keweenaw. These gales will last through the day Thursday before
diminishing Thursday night, with some periods of high-end gales to
40 kts possible, especially early Thursday morning. Winds subside
below 20 kts across the lake on Friday and are expected to stay
light through the weekend.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Dense Fog Advisory until 11 AM EDT /10 AM CDT/ Wednesday for
LSZ240>251-263>267.
Gale Watch from late Wednesday night through late Thursday night
for LSZ244-245-264-266-267.
Gale Watch from late Wednesday night through Thursday evening
for LSZ265.
Gale Watch from late Wednesday night through late Thursday night
for LSZ249>251.
Lake Michigan...
Dense Fog Advisory until 11 PM EDT this evening for LMZ221-248-
250.
&&
$$
SHORT TERM...RJC
LONG TERM...Ritzman
AVIATION...07
MARINE...RJC
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 400 PM CDT Tue Apr 7 2020
The day started with dense fog across much of the area, but a
powerful April sun and some dramatic BL mixing behind a wind
shift have since left us with blue skies. It was clear early this
morning that the same mixing would be driving dewpoints lower and
temperatures higher than previous forecasts. HRRR and RAP seemed
to have best handle on it and blended them into the forecast to
drive numbers significantly higher. Sure enough, records began to
fall already by noon.
.Tonight:
A RED FLAG WARNING was foisted over the western half of the CWA
with wind gusts over 30 mph at times and RH values as low as 15
percent. Expect improved conditions with the setting sun this
evening. It is set to expire at 7 pm.
.Wednesday and Thursday:
The cold front draped across the Dakotas will impact this area on
Wednesday. Expect the front to sweep through during Wednesday`s
mid- section, leaving a wide range of high temperatures in its
wake. Mid- 50s up north will end up falling 20 degrees shy of the
marks set along the Kansas state line. Highs in the south will be
recorded before the front`s passage during the lunch hour.
Chances of showers are minimal at best, but do have a slight
chance along the SD border and in parts of western Iowa. Kept QPF
at zippo.
Winds will peak just as quick or quicker than Tuesday with gusts
of 35 mph forecast in the afternoon. Fire danger will dip lower
than today`s categories.
Thursday will be cooler than average early April highs with
numbers maxing in the 40s and 50s. As the surface high settles in
Tuesday night, temps will slip sub-freezing across the CWA.
.Friday and beyond:
Upper low in south central Canada continues to dominate the
forecast in the long range, keeping our flow under it`s oppressive
thumb. Expect southwest flow to help drive temps quickly but only
slightly warmer for Friday and Saturday. Numbers will fall shy of
seasonal norms. A short wave will kick up a chance of showers and
a few rumbles of thunder for Friday.
Easter does not look conducive to egg hunts as a cold front will
knock temps into the 40s with brisk NW winds and the week`s best
chance of showers. Some of the showers may fall as snow if they
coincide with the diurnal dip.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 636 PM CDT Tue Apr 7 2020
VFR conditions are expected to persist through the TAF period with
a cold front moving through tomorrow that is not expected to
produce precipitation. Strong mixing this afternoon took care of
our surface moisture, therefore fog is not expected to be an issue
tomorrow morning and should be limited well into western Iowa.
Ahead of the cold front, wind speeds are expected to be very low
overnight, and may vary direction at times. Winds behind the cold
front will be gusty, with KOFK and KLNK being the most likely to
reach 30 knots. Once the cold front passes, little change in wind
speed is expected through the TAF period.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Red Flag Warning until 7 PM CDT this evening for NEZ016-017-
030>032-042>044-050-051-065-066-078-088>090-092.
IA...None.
&&
$$
DISCUSSION...Nicolaisen
AVIATION...Petersen
Area Forecast Discussion
National Weather Service Blacksburg VA
743 PM EDT Tue Apr 7 2020
.SYNOPSIS...
A nearly stationary boundary was located from Western
Pennsylvania to Eastern Virginia, while a cold front was noted
across the northern Missouri Valley. This cold front will move
into our region Wednesday ahead of a stronger cold front that
will quickly push through our area Thursday. Showers and
thunderstorms, some with locally gusty winds and hail will be
possible Wednesday and Thursday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 245 PM EDT Tuesday...
Showers and thunderstorms continue to develop along the northern
edge of of an instability axis in a zone of warm air advection.
Many of the short range and high-res models have performed very
poorly, with the 16Z HRRR and 12Z NAMNest showing no precip in
our area at 18Z. Considering CAPES are 500-1000 J/KG and
effective bulk shear values are over 35-40 knots, expect
additional thunderstorms to develop during the daytime hours
with the potential for hail and locally damaging winds.
This activity should diminish with loss of heating, but then our
attention turns to an approaching cold front from the north with
will generate a line (or MCS) of showers and storms that many
of the high res models agree push into our forecast area before
or around dawn Wednesday. Increased winds overnight, especially
in the higher elevations as a low level jet strengthens. This
also will keep temps on the warm side of guidance values,
especially at BLF.
On Wednesday, this boundary pushes south into our forecast area,
and while there is uncertainty about the amount of clearing
after morning showers/storms, we expect enough heating to again
generate scattered showers and storms. HREF output showing CAPES
in excess of 1000 J/KG where moisture (which is expected to be
deeper compared to today) will be pooling, primarily south of
Highway 460. Threat for large hail and damaging winds is
possible, and may be higher than today. Stayed close to the
previous forecast for highs on Wednesday, but confidence lower
behind the boundary in BLF/LWB where spread in the guidance is
large.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 210 PM EDT Tuesday...
After the afternoon convection from Wednesday dies off and moves to
our east, focus turns to a cold front that will arrive early
Thursday morning. Confidence is high now that there will be some
embedded convection with this line when it arrives thanks to CAPE
values up to 500j/kg. Likewise, shear/helicity will increase ahead
of the line, but guidance keeps a bulk of the greatest amounts to
out north. It`ll be worth keeping an eye on in case anything isolated
severe occurs.
After the fronts passage Thursday, our warmer weather takes leave
and allows cooler weather to return. Along with the cold air return,
gusty NW flow sets in. The western half of the CWA is highlighted by
40-50kt 850 winds aloft that could very likely mix down Thursday
night into Friday. Still not confident if we will need a headline
out for the wind or not, but certainly watching to see if something
will be needed. Obviously with stout NW flow, upslope should be
expect. Confidence is increasing in some light snow showers
overnight into Friday. Don`t get excited though. Most snow that
falls will melt on contact with the round with such warm ground
temps. Right now, only western Greenbrier should expect any
accumulating snowfall (less than .5").
Upslope tappers off midday Friday as NW wind gradually diminishes.
After that, we prep for a dry Friday night which should bring a big
shock temperature wise given the recent warm weather. Waking up
Saturday, much of the west will be waking up to below freezing
temps, with parts of the east not far from it. That said, with the
growing season started for the east, frost will be of concern.
After the cold start Saturday, the remainder of the day looks high
and dry with lots of sunshine to try and warm things up in the
afternoon.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 200 PM EDT Tuesday...
Guidance continues to get a better handle on the pressure system
that is currently sitting off the California coast. Late in the
week, this low gets kicked onshore and crosses across the southern
U.S., eventually shifting northward to the Mid-Atlantic. Timing has
come into much better agreement, with first a warm front lifting
northward across the area early to mid day Sunday. With the warm
front comes a return of warmer weather. By Sunday night, the cold
front associated with this low will then cross the region. Total
rainfall with this system looks pretty beefy compared to some of the
rain events we`ve had recently. Right now, rain amounts could range
between 1-2".
After Sunday`s system exits, we cool off again for Monday, though
not like what happens this Thursday/Friday. Guidance hints that NW
flow will establish some upslope showers Monday into Tuesday. Precip
type at the moment remains rain, but temperature profiles will need
to be watched over the coming days as new guidance arrives. Any area
that would have the potential for snowfall would again be most
likely western Greenbrier, similar to this coming Friday AM.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 735 PM EDT Tuesday...
Wind will stay mixed overnight and higher elevations may have
gusts up to 30 knots as a low level jet strengthens.
An approaching cold front from the north will bring showers and
isolated thunderstorms to southern West Virginia and northern
and central Virginia by early morning first impacting KLWB and
KBLF before moving south.
MVFR cigs will develop due to westerly upslope winds over the
mountains at KLWB, KBLF and KBCB overnight, with the potential
for IFR cigs. These MVFR cigs will continue through much of the
morning on Wednesday. Occasional showers and isolated storms
will also impact KBCB, KROA and KLYH on Wednesday, periodically
reducing cigs and vsbys to MVFR levels. Models had showers and
thunderstorms redeveloping along the front after 15Z/11AM. Any
storms will reach KDAN later in the day.
Above average confidence for the coverage and timing of showers
and thunderstorms tonight and Wednesday.
Average confidence for wind, ceilings, and visibility.
Extended Aviation Discussion...
A strong cold front crosses the area Thursday morning with
widespread MVFR conditions due to clouds and precipitation.
Winds will be strong and gusty behind the front Thursday night.
Colder high pressure builds into the area on Friday. In general
winds will be diminishing and ceilings will improve to VFR
except some lingering MVFR in the mountains.
Another system may bring rain our way later Saturday with sub-
VFR ceilings, though at the moment confidence is low.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...PH
NEAR TERM...AMS/PH
SHORT TERM...RR
LONG TERM...RR
AVIATION...AMS/PH