Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/09/21
Area Forecast Discussion
National Weather Service Cheyenne WY
513 PM MDT Tue Jun 8 2021
.SHORT TERM...(Tonight - Thursday Night)
Issued at 227 PM MDT Tue Jun 8 2021
A very strong cap remains evident across much of southeast Wyoming
and the western Nebraska Panhandle this afternoon w/ quite limited
cumulus development thus far. We should start to see an increasing
low-level cumulus field in the next couple of hours as we approach
our convective temperatures, but w/ upwards of 50 J/kg MLCIN still
present the likelihood of afternoon initiation appears low. HRRR &
other high-resolution guidance have continued to suggest some more
robust development between 00 and 02z along the lee trough/dryline
or roughly along I-25. Deep layer vertical shear is very modest at
around 20 knots over most of the area, but area forecast soundings
show appreciable low-level directional shear which would suggest a
good possibility of upscale growth into a linear system across the
western NE Panhandle during the mid/late evening. Substantial low-
level mixing has occurred today w/ dew points falling to around 50
F although some 60s still linger over our far eastern zones. CAPEs
in excess of 2000 J/kg will support a large & damaging hail threat
with any discrete storms. Otherwise, extremely steep low/mid level
lapse rates and large boundary layer T/Td spreads, along w/ DCAPEs
of 1500-2000 J/kg will support a threat for damaging straight line
winds with the eventual MCS. Lingering outflow from Mondays storms
could locally enhance low-level shear & contribute to a chance for
an isolated tornado if the quality of moisture is sufficient. This
is especially true along a Wheatland-Sidney line.
A brief period of upper-level ridging should limit chances for any
storms on Wednesday, but the next chance for strong/severe thunder
storms will arrive Thursday as a vigorous short wave ejects north-
northeast across the Great Basin. Increasingly difluent flow aloft
should overspread the area, leading to an eroding cap & initiation
by late afternoon. Timing will be crucial here w/ regard to severe
potential, but very steep mid-level lapse rates & dew points 55-65
deg F may contribute to CAPE in excess of 3000 J/kg to the east of
the lee trough/dryline while 0-6 km shear should be very strong at
35-45+ knots. All modes of severe weather would be possible. Would
not be surprised if the current Day 3 SLGT is expanded further S &
W in later updates.
.LONG TERM...(Friday through Monday)
Issued at 345 AM MDT Tue Jun 8 2021
Shortwave trough quickly exits northeast of the CWA by Friday morning,
followed by an expanding upper ridge over much of the CONUS through
early next week. Large scale subsidence and lack of moisture will
preclude convective precipitation through the long term. Near normal
temperatures Friday will warm to above normal with 80s and 90s this
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 507 PM MDT Tue Jun 8 2021
VFR conditions across all terminals this evening with chances of
thunderstorms at KCYS and all Nebraska panhandle TAF sites. Clouds
will begin building in in the next few hours with thunderstorms
beginning at KCYS around 00Z and moving eastward into the Nebraska
panhandle through the night. Conditions should clear in the
Nebraska panhandle between 8Z and 10Z, then depending on if the
skies clear and the leftover moisture from the thunderstorms
there`s a possibility for patchy fog, but confidence is currently
low for the fog.
&&
.FIRE WEATHER...
Issued at 330 AM MDT Tue Jun 8 2021
Elevated to critical humidities and winds are expected west of the
Laramie Range, with non-critical humidities and winds along and east
of the Laramie Range through the end of the week. Fuels remain green,
but may become more favorable for rapid fire growth west of the Laramie
Range by the end of the week. Widely scattered showers and thunderstorms
will develop this afternoon and evening along and east of Interstate
25, and over the Nebraska Panhandle Thursday evening.
&&
.HYDROLOGY...
Issued at 330 AM MDT Tue Jun 8 2021
Mild to warm temperatures will contribute to mountain snowmelt runoff
and elevated stream/river levels, especially across southeast Wyoming.
No sites are forecast to rise to minor flood stage, however with the
diurnal rise and fall, it is possible waters may approach action stage
later this week. With the lack of measurable precipitation west of the
Laramie Range, the risk for rain on snowmelt will be negligible.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...CLH
LONG TERM...MAJ
AVIATION...LK
FIRE WEATHER...MAJ
HYDROLOGY...MAJ
Area Forecast Discussion
National Weather Service Glasgow MT
1203 PM MDT Tue Jun 8 2021
.DISCUSSION...
1130AM UPDATE:
Morning dewpoints have begun to rise across the area but have not
reached critical mass yet for thunderstorms development. Dewpoints
also seem just underneath what some of the CAMs have been
displaying for this hour. While dewpoint rises may be delayed an
hour or so, strong east winds are already ratcheting up and 60+
dewpoints are just on the doorstep of the CWA in North Dakota. In
addition there is plenty of light to moderate strato-cirrus
flowing in from the south which is helping to keep the current
stratus from destabilizing into full convection as fast. But, a
couple morning thunderstorms around 9AM did prove that the
atmosphere at least aloft is ready to pop. For these reasons we
will be doing a 19Z upper air sounding to try to get a more
accurate feel for precipitable water, timing of cell development,
and hopeful improvement to the HRRR model as the afternoon
progresses. GAH
MORNING DISCUSSION:
A wave moving through SE Montana early this morning is bringing
some showers and thunderstorms to the SE part of the forecast
area. The rain will move to the east shortly after sunrise this
morning. SW flow aloft combined with an ESE low level flow will
bring increasing moisture into the area today. Look for a rapid
rise in dew points from 25 west to 45 east at 2 am (08Z) to 55 to
65 across the area this afternoon. A warm front lifts north
through SE Montana today with a surface low. The front is expected
to stall somewhere south of the Missouri River this afternoon and
remain stationary tonight as the low moves into North Dakota with
a cold front. An inverted surface trough to the NW of the surface
low will become the focus area of convection today and tonight.
The trough will combine with several ingredients necessary for
severe thunderstorms. CAPE will as high as 4000 J/Kg range this
afternoon and evening in the east. Lapse rates and shear values
will also be strong. SPC has maintained a slight risk for severe
thunderstorms, with an embedded hatched area for possible
tornadoes and hail that could exceed 2 inches in diameter. Locally
heavy rainfall is possible as precipitable water approaches 1.75
inches. There is a potential for 2+ inch downpours especially
north of the Missouri River that even in a severe drought could
bring flash flooding. Will issue a Flash Flood Watch for areas
north of the Missouri River for late this afternoon and tonight.
East winds will be strong enough today and this evening for a
Lake Wind Advisory for Fort Peck Lake.
Wednesday for the most part will be a break between system with a
shortwave ridge in the SW flow aloft.
A cold front in western Montana ahead of an upper trough in the
Pacific NW will bring thunderstorms to central Montana that could
move through the western zones of the forecast area Wednesday
Night.
The upper trough and cold front moves into the forecast area
Thursday afternoon and evening. Atmosphere once again will be very
unstable ahead of the cold front with CAPE exceeding 3000 j/kg in
some areas. Look for thunderstorms with heavy rain possible and another
round of severe thunderstorms as strong as today`s.
Chances for showers and thunderstorms will linger into Friday
especially in the NE as the upper trough moves into Canada.
The weekend looks dry with an upper ridge and surface high
pressure.
&&
.AVIATION...
LAST UPDATED: 1745Z
FLIGHT CAT: VFR-IFR
DISCUSSION: A mix of IFR, MVFR and VFR this afternoon and
tonight. A few showers and thunderstorms will move through the
KGDV through 14z this morning. Low pressure and warm front will
move north into SE Montana today. The low will move northeast into
NW North Dakota tonight. Showers and thunderstorms will develop
this morning in the KGGW and KOLF areas this morning and spread
into the KSDY and KGDV areas this afternoon. Some storms will be
severe with LARGE HAIL and DAMAGING WIND that could exceed 50
knots this afternoon and evening. Heavy rain will reduce
visibility to IFR levels at times. Low clouds will bring a mix of
MVFR and IFR ceilings at times tonight.
WIND: East at 15 to 30 kts today. Turning to the north and NE and
diminishing to around 10 kts tonight. Strong and erratic winds
are expected near thunderstorms and in any outflows that occurs in
thunderstorms.
/GAH
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through late tonight for Central and Southeast
Phillips...Central and Southern Valley...Daniels...Eastern
Roosevelt...Northern Phillips...Northern Valley...Sheridan...
Southwest Phillips...Western Roosevelt.
Lake Wind Advisory until 9 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 Grand Junction CO
901 PM MDT Tue Jun 8 2021
.UPDATE...
Issued at 901 PM MDT Tue Jun 8 2021
Similar to last evening relative humidity was slow to recover
though winds have significantly decreased and were, except for a
handful of exposed sites in northwest Colorado, reporting values
below criteria. Expect winds will continue to decrease, eventually
giving way to drainage flows later this evening as the atmosphere
decouples. Therefore, have allowed the Red Flag Warnings which
were in effect for much of the area to expire. However, critical
fire weather conditions will redevelop again Wednesday and
Thursday, so we`re not out of the woods just yet.
&&
.SHORT TERM...(Tonight through Wednesday night)
Issued at 217 PM MDT Tue Jun 8 2021
The latest upper-air analysis places a shortwave trough lifting
northeastward over portions of central Utah into far western
Colorado. The associated midlevel jet and dry slot extends along the
CO/UT state line. Boundary layer mixing into this layer has resulted
in Red Flag conditions across most of the valleys. One place that is
not as windy as previously thought is the highway 60 corridor. Some
of the midslopes could be fairly close to 25 mph so did not want to
cancel the warning there. The trough has also cooled the temps by a
few degrees, which might have been missed by some of the models.
Last night smoke from the Telegraph fire east of Phoenix spread into
our area. Satellite still shows some of that smoke transporting
northward and getting trapped in the higher valleys. Expected hazy
conditions in the mountains through the evening. Critical fire
weather conditions will linger through about sunset before typical
drainage winds develop as the midlevel jet lifts north of the area.
There may be a slight chance some of the smoke makes it into the low-
level inversion late this evening. If the winds can decouple at some
locations dry air should support temperatures cooling closer to
normal tonight. Tomorrow a trough will impact the West Coast, and
that jet begins to spread over the area through out the day. The
axis of higher wind speeds will be focused across the northwest half
of the forecast area, which is where Red Flag Warnings are now in
effect. Although afternoon wind gusts will not be as high as today.
The HRRR shows that more smoke from AZ might move through the
southeast half of the forecast area again tomorrow.
.LONG TERM...(Thursday through Tuesday)
Issued at 217 PM MDT Tue Jun 8 2021
We`ll start out the long term cranking up the fan a notch, thanks to
another passing shortwave embedded the prevailing southwest flow.
Upper level heights tighten in response to the system rippling
through, and its associated jet axis slides directly overhead. Dry
atmospheric conditions and anomalously warm temps will mix those
strong upper level winds down to the surface. Expect an early onset
to gusty conditions as well as widespread critical fire weather
conditions erupting where fuels are cured. Winds will be strongest
across the northwest corner of the forecast area, where gusts may
easily exceed 45 mph in the afternoon. Winds "taper off" near the
Four Corners area, traversing east toward Pagosa Springs along the
160 corridor...however this just means gusts may be confined to 25
to 30 mph. Winds eventually weaken overnight with a bit of recovery
in store for Friday. A slice of good news follows this system,
thanks to the slightly cooler air mass behind the trough that will
nudge highs down a few degrees. Sadly, this won`t last long as a
beefy ridge builds back over the Southern Rockies. Cluster analyses
show excellent agreement with anomalously higher heights building
over the Intermountain West in the 4 to 7 day time period. This
leads to high confidence in exceptionally warm and dry weather
lingering through the weekend and into next week. Temperatures rise
5 to 10 degrees on Saturday and keep climbing to record temps by
Monday. Just as an example, ensemble guidance has forecast 5 days
in a row reaching or exceed 100 degrees F for the Grand
Valley...Early season heat is not done just yet...
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 550 PM MDT Tue Jun 8 2021
Breezy southwest and west winds will decrease early this evening,
decoupling by or shortly after sunset. This will allow winds to
shift to a more normal drainage flow during the remainder of the
night. However, deep mixing is expected to result in another round
of breezy southwest winds Wednesday afternoon and early Wednesday
evening, though wind speeds aren`t expected to be quite as high.
Smoke from fires in Arizona, eastern Utah and northwest Colorado
will bring some haze, but won`t limit visibility below 10SM at TAF
sites. Clouds will remain limited and as a result, VFR conditions
will prevail through the next 24 hours.
&&
.FIRE WEATHER...
Issued at 901 PM MDT Tue Jun 8 2021
Conditions are focused across northern Utah and northwest Colorado
on Wednesday before once again spreading into most areas on
Thursday. Southerly winds will gust 30 to 40 mph on Thursday.
Zero chance of wetting rainfall until further notice but a slight
cool down and decreased winds on Friday looks to ease the critical
fire weather conditions.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Red Flag Warning from 11 AM to 8 PM MDT Wednesday for COZ200-202-
203-290.
Red Flag Warning from 9 AM Thursday to midnight MDT Thursday
night for COZ200-202-203-205-207-290-292-294-295.
UT...Red Flag Warning from 11 AM to 8 PM MDT Wednesday for UTZ486-487-
490.
Red Flag Warning from 9 AM Thursday to midnight MDT Thursday
night for UTZ486-487-490-491.
&&
$$
UPDATE...NL
SHORT TERM...KJS
LONG TERM...ERW
AVIATION...NL
FIRE WEATHER...TGJT
Area Forecast Discussion
National Weather Service Goodland KS
1000 PM MDT Tue Jun 8 2021
.SHORT TERM...(This evening through Wednesday night)
Issued at 239 PM MDT Tue Jun 8 2021
Satellite imagery and 500 mb RAP analysis showed southwest flow from
the west coast to the northern Plains this afternoon on the backside
of an upper ridge. A shortwave could be seen traveling from
Utah/Colorado northeast towards southern Wyoming. Meanwhile, a
closed low entered the Upper Midwest as high pressure tried to push
northward into Kansas from Texas. At 2:00 PM MT, sunny skies
prevailed for the western half of the region, with fields of cumulus
clouds along and east of Highway 25. Breezy southeast winds gusted
up to 35 mph, with temperatures mainly ranging in the low 80s to
low 90s.
For tonight, the aforementioned shortwave is anticipated to continue
northeast into Wyoming and the northern Plains. Initially, storms
should fire in eastern Wyoming this afternoon, congealing into a
line/MCS as they progress into western Nebraska and the Dakotas. The
southern end of this line could clip northern portions of the region
late tonight into Wednesday morning. Have inserted a slight to low
chance of thunderstorms along the Nebraska border and southward into
northwest Kansas where guidance hints at activity in the morning
hours. Whether storms will trail far enough south to make it into
our area at all is very uncertain at this time.
Shear ranging from 20-30 knots overnight/early Wednesday, moderate
lapse rates at 6C/km or so, and increasing instability suggest that
if storms make it into the region, a few strong to severe storms
could develop. However, confidence in severe weather occurring is
low due to the time of day and the likelihood that storms may be
dissipating by the time they reach our area. Otherwise, expect lows
in the upper 50s to upper 60s overnight with increasing cloud cover.
Beyond thunderstorm chances, adequate moisture will allow for
stratus to develop Wednesday morning, mainly east of the Colorado
border. At this point it appears fog should generally stay to our
southeast, but this needs to be monitored. Have included a small
area of patchy fog from Leoti to Gove for now.
Turning to Wednesday, thunderstorm chances dry up midday as cloud
cover decreases and temperatures climb into the mid 80s to low 90s.
Ridging builds over the region through the day and night, which
should result in dry weather prevailing. Temperatures fall into the
60s Wednesday night.
.LONG TERM...(Thursday through Tuesday)
Issued at 325 PM MDT Tue Jun 8 2021
The extended period begins with high pressure over the southern
Plains as the ridge continues to build. Overall very little has
changed with the forecast from the previous forecast package.
Thursday continues to look like a hot and humid day with gusty
winds. Guidance continues to lower afternoon highs, but increase
dewpoints across the area. Overall afternoon high temperatures in
the low to mid 90s look likely, but the influence of the surface
moisture will continue to make heat indices near 100 degrees
especially over the eastern counties where the highest dewpoints
reside. The strongest wind gusts look to be along and west of the
Colorado border where lower dewpoints along with lower potential low
level cloud cover reside allowing stronger afternoon mixing to
occur. Thursday night, a surface cyclone develops over the northern
Plains which as a result emits a southeastward moving cold front
over the Tri-State area. Along and behind of the cold front gusty to
potentially strong winds may occur during the early Friday morning
hours as wind gusts up to 40 mph possible. An area of showers and
storms may build southward from a MCS over central Nebraska but
capping concerns keeps from introducing higher pops in this
forecast package. The best area to see thunderstorms would be over
Hitchcock and Red Willow counties in Nebraska along with Norton
county in Kansas.
Friday, relative cooler and less humid conditions will be in place
in wake of the cold front and as the ridge breaks down. High
temperatures for Friday will be in the upper 70s across western Kit
Carson county to the upper 80s across the eastern Kansas counties.
Gusty winds will continue through the morning but will weaken during
the afternoon and evening hours.
Saturday and Sunday, high pressure again looks to build across
the southern plains as the formation of another ridge begins to
develop on Sunday. Overall the weekend looks to remain dry,
however a weak disturbance over the southern Rockies looks to
create some shower and storm chances across SW Kansas, which may
make it into southern areas of the CWA; confidence was to low at
this time to introduce precipitation chances into the forecast.
High temperatures for the weekend are forecasted in the mid 80s to
low 90s.
Into next week, guidance has another strong ridge developing over
the plains as high temperatures rise back into the 90s. Overall the
latter portion of the extended period looks to remain dry, however
guidance is hinting at a shortwave over the northern Plains which
may lead to an area of showers and storms moving over the area
confidence is low this far out in this scenario so have left the
forecast dry for now.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1000 PM MDT Tue Jun 8 2021
KGLD, VFR conditions are expected from taf issuance through about
08z before stratus and sub VFR cigs move in from the southeast
from 09z-19z. Winds during the period from the southeast around
10kts. After 20z VFR conditions return with winds continuing from
the southeast around 10kts. Its possible for sub VFR cigs to
redevelop after 03z but confidence is low and tied to the NAM
model. Some drizzle and fog are possible in the 09z-12z timeframe.
KMCK, VFR conditions are expected from taf issuance through about
11z with sub VFR cigs in stratus moving in from 12z-16z. After
18z VFR conditions return. Winds at taf issuance from the
southeast around 10kts continuing through the rest of the period.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JBH
LONG TERM...TT
AVIATION...99
Area Forecast Discussion
National Weather Service Gray ME
1108 PM EDT Tue Jun 8 2021
.SYNOPSIS...
Chances for showers and thunderstorms will continue to increase
into the evening tonight. A cold front will settle into the
region on Wednesday...with the chance for showers and storms
continuing. Much drier and cooler air arrives across the region
on Thursday before another weak disturbance brings the potential
for showers late Friday and Saturday, along with temperatures
below normal for this time of year. Drier weather and seasonable
temperatures are expected for the second half of the weekend. A
trough likely deepens across New England for the start of next
week.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
1105 PM Update...
This most recent update is only to remove the flash flood watch
for southernmost New Hampshire.
Continuing to monitor convection exiting southeastern New
Hampshire and southwesternmost Maine. Latest radar imagery is
indicating a mesolow about to cross into York County by 04Z.A
few embedded heavier showers are associated with this feature,
however most of the threat for thunder with torrential
downpours continues to diminish.
Temperatures have dropped considerably over southern New
Hampshire where the rain has fallen this afternoon. Heat
advisories expired earlier this evening.
Have introduced patchy fog to a few areas in the forecast area,
namely the Connecticut River and Merrimack Valleys.
Shifting focus to northern sections of the forecast area where
scattered showers and thunderstorms have weakened as they
entered the forecast area. However, the latest HRRR has the
precipitation regenerating and convection potentially
redeveloping at around 06Z-08Z over southern interior Maine as
the best instability shifts south across the region.
Prev Disc...
Surface observations show a boundary extending along the MA/NH
border with dewpoints near 70 to the south of the line. This
area will be the focus for convection this afternoon. Over the
next few hours, expect thunderstorm coverage to increase, with
multiple rounds of storms with rainfall rates of 1-2 inches per
hour. These storms will be supported by CAPE exceeding 2000 J/kg
and very deep warm cloud depths. Shear is minimal in this area,
which will keep the severe threat more marginal, and the storm
motion slow.
An additional area to watch will be the Quebec border.
Surface obs showed a weak trough through the St. Lawrence
valley mid day, and storms have fired along the St. Lawrence
and begun to move southeast. In this area the shear is much
stronger, and will support some severe storms north of the
border. As this shifts southwards into the western Maine
mountains, some additional thunderstorms stretching into the
northern edge of the CWA are possible.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
The surface trough continues its slow drop through our area.
Drying well behind the front up in Quebec will gradually push
into our region. This will be reflected in the decreasing
dewpoints across the north. To the south, showers may continue
to linger in the afternoon, but there is less focused forcing
than today so expect coverage to be more limited. High
temperatures will remain very warm in the south, with the 90s
continuing in portions of the coastal plain. While above
average, this is a downward trend from the past few days, and
do not expect additional heat advisories to be needed.
Wednesday night Drier air finally makes it fully into the region,
allowing a welcome respite to the overnight heat with temps dropping
back down into the 50s.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Thursday will feature much different conditions from what we
will have experienced for the previous several days. The cold
frontal boundary will be well to the south across the Mid
Atlantic states, and cool Canadian high pressure will be
building into New England during the daytime. This will be
occuring as part of a much larger pattern change, where the
ridge that has been bringing the extended period of heat and
humidity will gradually retrograde toward the west late this
week and this weekend, and a trough will deepen across Greenland
and parts of the Canadian Maritimes.
In the interaction between these two large scale features, small
ridges and shortwaves will transit through the Northeast US. This
will begin by Thursday, with the area of high pressure on Thursday
progressing through our area and moving offshore by early Friday. An
elongated shortwave will then move in from the west-northwest late
Friday, bringing an increased chance of showers and even cooler
conditions. This feature will stall across much of the area
through at least early Sunday, keeping the threat for widespread
showers across southern and central parts of the forecast area.
Sunday appears to be the best chance for a respite from the showers,
as a weak ridge crosses the Northeast, bringing increased sunshine
and warmer temperatures for Sunday. But this will be short lived,
as a slow moving low pressure and trailing cold front will
likely approach from the west late Sunday and Monday, bringing
an increased chance for widespread showers and storms again.
By early next week, the trough that deepens across the Canadian
Maritimes late this week will likely continue to retrograde westward
and be centered close to New England. The global models have some
differences in the placement of the trough by early next week. The
GFS and its ensemble suite have the trough centered over New England
and not as deep as the ECMWF and its ensemble suite, which has
the trough centered across the eastern Great Lakes and deeper.
Either way, early to middle next week is likely to feature cool
and wetter than normal conditions, it`s just a matter of how
much so that the different model solutions offer, with the ECMWF
offering the cooler scenario. The amplification of this feature
should become more clear over the coming days, but the
important part to know for now is that it will be the major
influence on our weather for much of next week.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Scattered thunderstorms are moving across southern
New Hampshire and will move through MHT and PSM this evening,
with a few as far north as CON. Moist conditions with VFR
ceilings will prevail across the rest of the area. Some
thunderstorms may also enter the northern portion of the area
from Quebec later this evening. Tomorrow VFR with a chance of
showers across the south.
Long Term...
VFR conditions will return by Thursday morning. Showers are
possible late Friday and Saturday as a trough crosses the
region. VFR conditions will return Saturday night and Sunday
before a frontal boundary brings another chance of showers
Sunday night and Monday.
&&
.MARINE...
Short Term...A few thunderstorms may move across the southern
portion of the waters this afternoon. A weak front will drop
south across the waters tomorrow shifting to northerly flow.
Long Term...
High pressure will cross the waters on Thursday and into early
Friday, then a trough of low pressure will approach from the
west Friday night and into Saturday. High pressure will then
build in again from the west for Sunday. Low pressure and a
frontal boundary will approach from the west late Sunday and
Monday, possibly bringing SCA conditions Monday with freshening
southerly winds and building seas.
&&
.HYDROLOGY...
Update...
Have ended the Flash Flood Watch for southernmost New Hampshire
after coordination with WFO Norton. The potential for flooding
rains has diminished in this region.
Prev Disc...
Very moist airmass in place across the southern portion of the
region with PWATs over 2 inches. Additionally forecast soundings
show deep layer CAPE with warm cloud depths in excess of 10kft.
The result is a very favorable environment for heavy rainfall
and already rainfall rates in excess of 2" per hour have been
observed. The focus for this convection will be on a surface
boundary draped across the MA/NH border, with the current
convection set up just north into NH have opted to go ahead and
issue a Flash Flood watch for Hillsborough and Cheshire counties
where the heavy rain will be focused. Some of the rain may also
extend east into eastern Rockingham county later this evening
but that area is flatter and less prone to flooding. With rivers
running very low, not much concern for river flooding with
this.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
Cannon
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1152 PM EDT Tue Jun 8 2021
.UPDATE...
Issued at 1152 PM EDT TUE JUN 8 2021
Convection has diminished across far eastern Kentucky. Further
west, additional activity is affecting locations west of I-75.
Have freshened up the PoPs through the night, generally keeping
the higher values across the western third of the area, which
maintains continuity with the previous forecast. The 00z model
guidance look to be a bit aggressive on the PWATs advecting into
our area overnight, as the latest SPC Mesoanalysis shows the 2.0
inch values across western Kentucky. Instability is also modest
across the area, with the latest RAP suggesting diminishing ML
CAPE through the overnight. As such, any heavy rainers should be
more short-lived across the area. Mostly cloudy skies look to
prevail through the rest of the night, which should keep fog in
check as well as hold temperatures up a bit more than last night.
Did make a few adjustments to the lows at some locations,
incorporating the latest trends in observations.
UPDATE Issued at 817 PM EDT TUE JUN 8 2021
Most of the more organized convection has weakened and shifted off
to our northeast, with the exit of a short wave trough. One more
cluster of showers and storms is currently moving across our
southeast, sustaining more from lingering instability downstream.
This should exit in the next hour, with a relative lull in
activity expected as we will be between waves. The next one is
gradually swinging into central Tennessee/Kentucky. This will
affect our area later tonight, especially the western third of
our area. PWATs upstream are greater than 2 inches, and most of
the model guidance has these higher values advecting in as the
wave approaches. So far, some of the higher resolution model
guidance is not indicating anything too heavy as far as
precipitation amounts, despite a favorable environment for
efficient rainers. Will continue to monitor trends through this
evening. For now, tried to allow for a better depicted lull in the
activity over the next 2 to 4 hours, before ramping PoPs back up
into the likely category overnight and into the pre-dawn hours,
particularly west. Forecast low temperatures look reasonable at
this time, so have mainly blended in current observations,
capturing the rain-cooled air already in place where recent
convection tracked. Updates have been sent.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 340 PM EDT TUE JUN 8 2021
We continue to see slow moving showers and thunderstorms develop
this afternoon mainly along and west of I-75 and around the I-64
corridor. The greatest concern has been heavy rainfall given the
weak northwest steering flow and ample moisture with PWATs in the
1.6 to 1.8 inch range. The lack of shear has also allowed some of
these to become more multicellular in nature and further leading
to periods of heavy rainfall. These will likely be mostly tied to
the diurnal trends and would expect this activity to decrease in
coverage through the evening.
Tonight, we will see the decrease in coverage early, with perhaps
some fog developing in areas that see rainfall and clearing.
Right now best chance is in the far southeast in terms of fog. The
upper low will meander east toward the Ohio Valley tonight and
noticing some weaker waves riding through the mid-level flow. This
could lead to increased showers and thunderstorms toward dawn
Wednesday morning particularly in the western parts of the CWA
such as the Bluegrass and Lake Cumberland regions. This will have
to be closely monitored given this convection could be quite
efficient in producing heavy rainfall, as PWAT values are expected
to increase closer to 2 inches toward dawn.
Wednesday, this weak upper level low will continue to push east
and lead to likely PoPs for most through the day, with best
chances remain in the western parts of the CWA. The peak of this
convection will be in the afternoon and evening. Opted to go with
chance for thunder given the lesser instability in place likely
owing to cloud cover potential. Also, opted to drop afternoon
highs a few degrees given the aforementioned cloud cover.
Wednesday night, the coverage of convection is expected to once
again wain, as we loose the little potential for heating we have
during the day. We could see some patchy fog, but this will be
more dependent on how the cloud cover shakes out.
.LONG TERM...(Thursday through Tuesday)
Issued at 320 PM EDT TUE JUN 8 2021
The large scale upper pattern in the extended will feature surface
ridging over the southeastern CONUS, troughing over the northwest,
and strong upper ridging building over the southwest. Over time,
the southwest ridge looks to build in quite strongly and expand
north and eastward. As this occurs, the large upper trough that
will have come onshore already, will be displaced northward, and
will migrate eastward along the northern edge of the strong upper
ridge. Meanwhile, the southeastern ridge should weaken and become
more elongated with time. Smaller scale features will include
upper level disturbances and a slow moving area of low pressure
aloft, all of which will move through the Ohio and Tennessee
Valley regions through out the extended period. It is these
smaller scale features that should provide the necessary lift
required to aid in shower and storm formation across our area.
Southerly to southwesterly flow around the western edge of the
weakening southeastern ridge will provide the fuel for shower and
storm formation, particularly during the afternoon and evening
hours. It appears that we will see very good chances for late day
shower and storm activity around eastern Kentucky through most of
the extended, especially Thursday through Saturday night. The
nighttime periods will also see decent chances for rain, as there
should still enough lift, moisture, and instability present to
support showers and storms. Locally heavy rainfall will be a
concern on Thursday and Friday, as those appear to be the days
during which we will see the highest precipitable water amounts
and maximum low level moisture flux. The upper level low mentioned
before may also be moving directly overhead by the end of the
week.
Temperatures should top out mainly in the 80s each day, with
nightly lows falling into the 60s. Winds will be generally out of
the south or southwest at around 5Kts each day and lighter at
night. Dewpoint temperatures in the 60s and lower 70s will make
for very warm and muggy conditions around the area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 817 PM EDT TUE JUN 8 2021
Mostly VFR conditions will start out across the area through this
evening. Skies look to remain partly to mostly cloudy, which
should limit any fog development to mainly MVFR, although locations
that have seen more significant precipitation could see IFR or
lower conditions at times tonight. As such, have included IFR
visibilities at SJS, with mainly MVFR elsewhere. An approaching
upper level disturbance will also bring an increase in convection
overnight from the southwest, affecting locations mainly along
and west of a line from KSYM to KLOZ. During the day on Wednesday,
convection will initiate across most areas, bringing MVFR or
lower conditions at times. Winds will average around 5 kts or less
generally out of the south and southwest through Wednesday
morning, before peaking in the 5 to 8 kt range during the
afternoon.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...DJ
LONG TERM...AR
AVIATION...GEOGERIAN
Area Forecast Discussion
National Weather Service Louisville KY
1112 PM EDT Tue Jun 8 2021
.Forecast Update...
Issued at 1110 PM EDT Tue Jun 8 2021
Some scattered KLVX returns currently ongoing across the region will
continue tonight as a 500mb closed low spins over the
Mississippi/Ohio Valley. KOHX VWP shows a marginal southerly LLJ of
30kts around 4-5k ft, which continues to help advect rich Gulf
moisture into Kentucky. Mesoanalysis shows that PWATs are in the 1.7-
1.9" range, which has resulted in brief tropical-like heavy
downpours. We`ve been watching rotating showers and mini supercell
structures this evening, which is a bit unexpected considering an
environment with only 30kts of Effective Bulk Shear and SRH values
right at 100 m2/s2. However, believe these have ended for the night.
Effective Bulk Shear will continue to diminish overnight, along with
SBCAPE. Mesoanalysis notes current SBCAPE between 500-1000 J/kg
across the region, but instability will be decreasing through the
night as temps drop into the upper 60s.
HRRR appears to have somewhat of a decent handle on current trends,
which suggests we`ll see the current isolated showers over
Breckinridge/Meade continue to lift northward and into southern IN.
Best chances for scattered showers for the overnight period will be
across the southern IN and Bluegrass zones. By sunrise tomorrow,
scattered showers and storms look possible across the entire CWA,
which will continue through the afternoon as peak heating
destabilizes our environment.
Updated near term grids from now to 12z, and will send fresh
products shortly.
&&
.Short Term...(This evening through Wednesday)
Issued at 234 PM EDT Tue Jun 8 2021
Large upper level currently centered over Missouri continues to
influence our active weather patten of showers and storms. We`ve
seen a few bands of showers and storms develop along the eastern
periphery of the low this afternoon, and this activity will
gradually push off to our north and northeast through the day.
Overall environment is not supportive of severe storms this
afternoon and evening. Deep layer shear is fairly weak (<25kts).
While instability is fairly modest (1000-2000 J/KG), it is spread
out over a "skinny" CAPE profile where lapse rates are poor. These
types of profiles tend to result in limited updraft strength, and
weaker updrafts will not be as likely to result in strong gusty
surface winds when the storm collapses... or send hydrometeors
high/long enough above the freezing level to result in any
meaningful hail. That`s not to say we won`t see an occasional strong
storm that develops in a pocket of clearing and takes advantage of a
localized area of enhanced CAPE... but think those will be quite
uncommon compared to most convection that develops today.
The "bigger" (albeit marginal risk) threat will be isolated flooding
issues from training storms. Atmosphere is very juicy (+1.8" PWATs)
and soundings show deep warm cloud layers supportive of torrential
rainfall. The good news is that most of the convection is developing
along east-west or northwest-southeast oriented bands with storm
motions generally to the north and northeast. This should greatly
limit any storm training threat and keep it isolated at best.
Overnight, we should see a decrease in coverage or perhaps even a
lull in activity before the next round of showers and occasional
thunderstorms swing on through. This will likely continue well into
tomorrow morning and afternoon, with much of the heavier showers and
thunderstorms igniting during the afternoon with peak heating. The
core of the upper level low currently in Missouri will be closer to
us tomorrow, so winds aloft will be a bit weaker. Depending on
how/where storms develop, there could be a slightly higher chance
for flash flooding given slower storm motions and the potential for
showers/storms to train. As a result, WPC has highlighted much of
the region within a slight risk for excessive rainfall.
.Long Term...(Wednesday night through Tuesday)
Issued at 240 PM EDT Tue Jun 8 2021
Wednesday Night through Friday...The upper level low (ULL) is
progged to be over the OH Valley by Wednesday evening, which will
result in continued unsettled weather across southern Indiana and
central Kentucky. The ULL will begin to deepen slightly while also
becoming absorbed into the main flow aloft by Thursday evening and
into Friday. This period will be characterized by continued moisture
rich flow due to the positioning of the ULL and ridging across the
SE US resulting in PWATs near 2.00 inches and a persistent chance of
showers and thunderstorms with greater chances being diurnally
driven. With several days of repeated rainfall and the potential for
showers and storms to drop heavy amounts of rain at any given
location, WPC has included our area within a Day 2 Slight Risk for
excessive rain. But confidence in any given location experiencing
flood concerns is low at this point. Temperatures will remain near
climatological norms with highs in the low to mid 80s and lows each
morning in the upper 60s to low 70s. Dew points will also remain
high with values in the upper 60s to low 70s.
Saturday through Tuesday...GEFS plumes show diurnal peaks in 3-hr
QPF dropping significantly by Saturday through Monday as the remnant
trough of the ULL passes SE of KY allowing for low amplitude upper
ridging to build in overhead. PWATs also take a dive with values
between 1.20 to 1.50 inches as mid level flow takes on a drier
northerly component. With that said, there will still be afternoon
chances of isolated pop up showers Saturday, but coverage will be
sparse. Otherwise, the area should remain mostly dry over the
weekend and into the beginning of the work week. With less cloud
cover, we`ll see an increase in temperatures with daily highs
reaching into the mid to upper 80s with some urban areas and typical
hot spots possibly reaching 90.
&&
.Aviation...(00Z TAF Issuance)
Issued at 800 PM EDT Tue Jun 8 2021
Current precip is ongoing near HNB and BWG, but shower activity is
expected across all TAF sites through the overnight hours. Could see
a break in precip for a while around sunrise, which could result in
some MVFR or low-end VFR vis due to BR. By late morning or early
afternoon, shower and storm chances will ramp up again due to peak
daytime heating.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...CJP
Short Term...DM
Long Term....CG
Aviation...CJP
Area Forecast Discussion
National Weather Service Memphis TN
949 PM CDT Tue Jun 8 2021
.UPDATE...
Showers and thunderstorms continue to develop along and south of
the MS/TN border. The latest HRRR shows development in that area,
but not this early. Flash flooding will be a concern through the
overnight hours. Will update to make some adjustments to POPS and
temperatures.
KRM
&&
.DISCUSSION... /issued 322 PM CDT Tue Jun 8 2021/
Ongoing showers and thunderstorms continue to track over the same
general areas from east central Arkansas across much of north
Mississippi. Precipitable water values of over 2 inches have
resulted in rainfall rates up to 2.5 inches per hour. Widespread
flooding has been reported across much of north Mississippi. Flash
flood guidance has been exceeded by over 300% in some locations.
In west Tallahatchie county MRMS guidance indicated over a 200
year return period. A Flash Flood watch and a Severe thunderstorm
watch continue through 7pm. These products may be need to be
extended.
Overnight, a weak upper low likely responsible for enhancing
storms across the area today will track east into Kentucky.
However, much of the Midsouth will remain on the east side of a
trough centered over east Arkansas. As a result, at least showers
will continue with isolated thunderstorms. Any additional storms
over north Mississippi could be problematic.
Tomorrow, showers and thunderstorms will likely become enhanced
once again during the afternoon hours. Currently the Storm
Prediction Center only has general thunderstorms in their day 2
outlook. Lingering outflow boundaries from storms today and
tonight, especially intersecting boundaries could help to
initialize storms and enhance updrafts. Once again any additional
rain where flooding occurred today and overnight could quickly
exaggerate ongoing flooding issues or lead to additional issues.
Diurnally enhanced showers and thunderstorms are likely each day
across the Midsouth for the remainder of the work week. The
weekend doesn`t look as dry anymore as it did in previous model
runs.
Temperatures should trend slightly warmer each day through the
work week with upper 80s to low 90s returning over the weekend.
30
&&
.AVIATION...
In the short term a line of TSRAs will impact KTUP through 01z
with SHRAs thereafter. Expect more SHRA/TSRA development across N
MS overnight into Wed AM. KMEM/KMKL will be on the periphery with
some SHRAs. Otrw expect cigs to lower to IFR areawide overnight
with LIFR likely at KJBR. Cigs will slowly improve to VFR by Wed
afternoon with additional SHRA/TSRA development due to heating.
South winds at 6-8 kts overnight becoming SSW at 7-10 kts with a
few higher gusts Wed aftn.
SJM
&&
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...Flash Flood Watch through Wednesday afternoon for Lee AR-
Phillips.
MO...None.
MS...Flash Flood Watch through Wednesday afternoon for Alcorn-Benton
MS-Calhoun-Chickasaw-Coahoma-DeSoto-Itawamba-Lafayette-Lee
MS-Marshall-Monroe-Panola-Pontotoc-Prentiss-Quitman-
Tallahatchie-Tate-Tippah-Tishomingo-Tunica-Union-Yalobusha.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Topeka KS
1051 PM CDT Tue Jun 8 2021
...AVIATION UPDATE...
.DISCUSSION...
Issued at 343 PM CDT Tue Jun 8 2021
The highlights of this forecast package include heat and humidity
continuing to build this week before our next front arrives on
Friday. Rain chances will increase with the approach of that next
boundary late this week.
Currently, a summer-like air mass remains dominate around the
region. Aloft, a weak and disorganized upper low is somewhat evident
on water vapor imagery approaching the lower Mississippi Valley. An
amplified trough is moving toward the west coast of the CONUS and an
upper ridge is building over Texas. The upper ridge will continue to
expand northward into the area through midweek. Temperatures at
850mb will respond by increasing into the 21 to 23C range in central
KS by Thursday afternoon, which is when surface highs are forecast
to reach the low and mid 90s area-wide. Heat index values remain a
concern Thursday afternoon with combined 90 degree temperatures and
dew points near 70 degrees. That will result in apparent temps
between about 97 and 103 degrees.
A wave of energy associated with the troughing pattern out west
will trigger convection along an associated surface boundary in
the northern High Plains as it progresses into south-central
Canada. That surface boundary will approach northeastern KS on
Friday and some models have tried to bring an MCS into the area
early in the day. The LLJ decreases Friday morning, mid level
temperatures remain warm and models are starting to back off on
that solution. Rather, the better threat for storms may be with
redevelopment along the boundary late in the day Friday. Before
rain chances arrive, however, we can expect another very hot and
humid day for locations ahead of the front Friday afternoon. Heat
indices in those locations could range from 100 to 105 degrees.
Upper ridging could then build back in this weekend, allowing for
warm but fairly dry weather.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday)
Issued at 1051 PM CDT Tue Jun 8 2021
No big changes the forecast thinking. The RAP forecast soundings
still suggest a marginal chance for ground fog around sunrise.
Confidence and potential impacts to the terminals seems to be on
the low side to include a tempo in the forecast at this time.
Otherwise think VFR conditions will continue with diurnal CU
redeveloping by the late morning.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Teefey
AVIATION...Wolters