Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/28/20
Area Forecast Discussion
National Weather Service Bismarck ND
941 PM CDT Sat Jun 27 2020
.UPDATE...
Issued at 941 PM CDT Sat Jun 27 2020
Convection from near Minot to Dickinson and Bowman is diminishing
concurrent with increasing MLCIN in RAP-based objective analyses,
albeit a bit more slowly than earlier anticipated. We`ve adjusted
the forecast slightly to accommodate those trends, and to account
for extrapolation of upstream convection in eastern MT. Trends in
radar imagery support the MT convection reaching west central and
northwestern ND close to 05 UTC, likely focused on the immediate
cool side of a frontal zone that has sharpened in northwestern ND
this evening amid a few-hour period of relatively-enhanced cold
air advection. Midlevel winds are increasing in that region, and
forecast effective shear magnitudes on the order of 45 kt will
support organized storms, predominantly of a clustered/linear mode
given a large parallel component of deep-layer wind fields to the
low- and midlevel front. Forecast soundings suggest effective
inflow layers will be elevated overnight with MUCAPE on the order
of 1000 J/kg. The primary source of uncertainty in overall severe
storm potential stems from disparate model simulations regarding
the depth of low-level moisture, which in turn has implications
for the magnitude of MUCIN that will be present. Recent HRRR runs
have minimized MUCIN in northwestern ND, whereas the 00 UTC NAM
portrays around -100 J/kg of MUCIN through the night in deference
to a restrained risk. Thus, we will continue to advertise a chance
of severe storms, but there remains some doubt in the strength of
overnight convection in the northwest.
UPDATE Issued at 628 PM CDT Sat Jun 27 2020
The forecast is on track so only minor adjustments were made with
this update based on recent trends. As of 23 UTC, a surface trough
and related wind shift extending from near Sherwood to New Town,
Killdeer, Belfield, and Marmarth continues to serve as the genesis
region for high-based thunderstorm activity. Steep lapse rates are
supporting MLCAPE on the order of 1000 J/kg, but weak wind fields
aloft are both minimizing the severe-storm risk and also making it
difficult for these cells to propagate off the boundary. Increasing
MLCIN for boundary-layer based parcels between 00 and 02 UTC will
result in quick cessation of this initial activity. An additional
risk of storms is still expected overnight in northwestern ND.
&&
.SHORT TERM...(This afternoon through Sunday night)
Issued at 231 PM CDT Sat Jun 27 2020
Increasing chances for strong to severe storms across portions of
the west highlights the most pressing short term forecast
challenge.
A broad longwave trough draped across the northwestern US will
slowly approach the region and amplify as a blocking pattern sets
up across the eastern US. As heights begin to fall tonight across
the northwest, a shortwave will rotate into northeastern Montana,
nudging briefly into northwestern North Dakota, and finally into
Saskatchewan.
Along a surface trough across the west, a few pop up showers or
storms may form late this afternoon and evening if they can break
through a bit of a cap. This activity will be diurnally driven
and weaken with the loss of heating rather quickly. However, later
tonight the aforementioned shortwave will approach the northwest
after sunset. This wave may be accompanied by a complex of strong
to marginally severe thunderstorms as it clips the far northwest
overnight, interacting with the stationary front/pressure trough.
On Sunday, a stronger shortwave will rotate around the amplifying
west coast trough as it nudges closer. Another complex of strong
to severe thunderstorms may accompany this shortwave as it
interacts with the same stationary boundary, now a bit further
east. Timing will once again be late (after 10 pm local time) but
strong elevated instability and sufficient deep layer shear will
lend the potential for some severe hail and/or damaging wind
gusts. Some of the latest guidance has this activity transitioning
into bowing structures by the time it reaches the west out of
Montana, and if this were to verify, a more significant wind
damage threat could emerge, but confidence is still very low
regarding such a scenario.
Another hot day is in store for Sunday for almost everyone except the
far northwest. Most other places will see continued highs in the
upper 80s to mid 90s.
.LONG TERM...(Monday through Saturday)
Issued at 231 PM CDT Sat Jun 27 2020
Above normal temperatures and continued active weather highlights
the long term forecast period.
A strong thermal ridge at 850mb builds in on Monday, with the
axis centered over the central part of the state by 00z Tuesday.
This will lead to another hot day Monday with widespread highs in
the mid to upper 90s. Accompanying the heat will be high humidity
with dewpoints into the upper 60s to lower 70s. This combination
may lead to a few hours of scattered apparent temperature readings
over 100 degrees, mainly in the central part of the state and the
southern James River Valley.
Multiple shortwaves, each one progressively a bit stronger than
the last, continue to rotate through portions of the state Monday
evening through Wednesday morning, making for a very active
pattern with widespread chances of thunderstorms, some possibly
severe. SPC has placed almost all of western and central North
Dakota in a marginal risk for severe weather on Monday in their
latest Day 3 Convective Outlook. Additionally they have placed
much of the same area in a 15% contour on their Day 4 Outlook on
Tuesday. While the best shear and CAPE doesn`t always appear to
lineup optimally, it seems reasonable that at least some organized
severe weather looks possible during the Monday night through
Tuesday night time frame.
The best chance for widespread rainfall looks to be on Tuesday
and Tuesday night. The favored area for the most rainfall will be
across the northern half of the state, but most everyone should
have a shot at a thunderstorm or two during this time frame.
Things start to quiet down midweek as some upper level ridging
tries to build back in, reinforcing the western US trough. As the
trough begins to try and nudge east again, we may see another
active period start up again towards the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 941 PM CDT Sat Jun 27 2020
Overnight a cluster of showers and thunderstorms will likely move
out of Montana and across west central and northwestern ND, with
potential impacts at KXWA. MVFR ceilings in stratus could also
impact northwestern ND late tonight and Sunday morning behind that
activity and near a weak frontal zone. That front could serve as
the focus for more thunderstorms late Sunday afternoon in western
ND, but most likely beyond the valid time of the 00 UTC TAF cycle.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CJS
SHORT TERM...ZH
LONG TERM...ZH
AVIATION...CJS
Area Forecast Discussion
National Weather Service Birmingham AL
556 PM CDT Sat Jun 27 2020
.UPDATE...
For 00Z Aviation.
&&
.SHORT TERM...
/Updated at 0310 PM CDT Sat Jun 27 2020/
Through Sunday.
A moist, unstable airmass has been present across the Lower MS
Valley for the majority of the morning characterized by dewpoints in
the lower to mid 70s and resultant MLCAPE ~3000 J/kg. Scattered
thunderstorms are expected to develop over Mississippi and western
portions of Alabama throughout the afternoon, downstream of a weak
mid/upper level trough embedded in the westerly flow of the low-
level ridge centered over the Florida Peninsula. Already beginning
to see thunderstorms firing across northern Alabama producing
frequent lightning, gusty winds, and pea size hail.
A layer of dry air was measured on both the latest 12Z BMX and JAN
soundings particularly from 850mb to 675mb which continues to advect
northeastward across Mississippi and mix with the sufficient
moisture present throughout the column. This has lead to DCAPE
values ~1000-1200 J/kg just to the west of the forecast area which
will continue to work eastward into Central AL. Eff. bulk shear is a
meager 15-20 kts per RAP mesoanalysis, but is enough to help provide
some organization to thunderstorm updrafts given the large amount of
instability. Based on these conditions, microbursts may occur in any
stronger storms that develop today. Will continue the Marginal Risk
of isolated severe storms through 9 PM for damaging winds up to 60
mph. A more robust storm may contain large hail up to quarter size,
but this is not the primary threat due to relatively unfavorable mid-
level lapse rates.
Any lingering thunderstorms should become primarily outflow driven
by late afternoon/early evening, eventually waning in intensity over
the eastern half of the forecast area with the loss of daytime
heating. Some clearing in the clouds may occur overnight as the mid-
level impulse moves over Georgia. At daybreak, there may also be
areas of patchy fog due to low dewpoint depressions, but this
will quickly mix out after sunrise. Rain chances are much lower
tomorrow as mid-level ridging takes control, but this means
afternoon highs will be back in the lower 90s for most of the
area.
86
.LONG TERM...
/Updated at 0310 PM CDT Sat Jun 27 2020/
Sunday night through Friday.
Next week Alabama will be transitioning through several upper
level pattern changes. The first half of the week the upper flow
pattern will be characterized by a building omega block pattern
with an upper trof over the Plains States and another upper trof
over the mid-Atlantic region. In between the two trofs will be an
upper ridge across the Lower and Middle Mississippi Valley
regions. Increasing heights over Alabama will result in warmer
afternoon temperatures with a tropical air mass trapped
underneath. The combination of heat and humidity will produce heat
indices of 100-103 degrees Monday and Tuesday. Despite the
presence of a ridge, scattered to numerous showers and storms will
develop each day Monday and Tuesday, with better coverage on
Tuesday. By Wednesday, the East Coast trof will begin to dig
southward and southwestward, back-building into Alabama. The
developing trofiness will result in cooler daytime temperatures
and high rain chances for the period Wednesday through Friday,
mainly in the afternoons.
58/rose
Previous long-term discussion:
/Updated at 0238 AM CDT Sat Jun 27 2020/
Sunday night through Friday.
An omega block will be present over the northern CONUS and Canada
for the first half of the week, with an upper high briefly closing
off over northern Ontario and troughs over the western and
northeastern CONUS. Meanwhile a subtropical ridge will retrograde
westward across the Gulf to Mexico. Ridging will strengthen over
the Plains and Rockies late in the week, allowing weak troughing
over the eastern CONUS. Several convective generated/augmented
waves will eject from the western CONUS trough through mid week,
undercutting the Great Lakes/Ontario ridge and interacting with a
moist and unstable air mass to result in an unsettled pattern
across the Deep South.
Ridging and dry air aloft should result in mainly dry conditions
Sunday night. A lead shortwave will eject across northern
Mississippi on Monday, flattening the 500mb flow across Central
Alabama, however the surface to 700mb flow will remain
anticyclonic and 850-700mb mean RH will be somewhat limited. Ample
instability and boundary layer moisture will be present for shower
and thunderstorm development, but the above factors will probably
keep activity widely scattered. The lower coverage of convection
compared to the rest of the week will cause Monday to have the
highest heat index values of the week, maxing out around 100 to
103 degrees. Ridging will weaken on Tuesday as flow becomes
westerly to southwesterly ahead of a shortwave over the Ozarks and
Mid-South. PWATs around 1.9 inches and plentiful instability will
allow scattered to numerous showers and storms to develop Tuesday
afternoon. Flow aloft will become northwesterly Tuesday night
through the rest of the week. Disturbances in the northwest flow
and PWATs around 2 inches will result in enhanced rain chances,
and keep highs mainly just below 90 degrees. Guidance is hinting
at the potential for one or more MCSs impacting portions of the
Deep South during this period, though confidence in any details is
low. Severe weather potential with these is unclear, but at
minimum expect daily risks of strong storms.
32/Davis
&&
.AVIATION...
00Z TAF Discussion.
Generally VFR conds thru the period. Diurnal isolated convection
thru 02z and then again after 20z. Low level winds will remain
high enough overnight for isentropic lift to form MVFR cigs across
the northern TAF sites between 10z and 14z. The cigs should scatter
by 15z, with sct cumulus after 15z.
58/rose
&&
.FIRE WEATHER...
Warm and humid conditions continue for the next few days, with
scattered showers and thunderstorms, especially during the
afternoon and early evening hours. Minimum relative humidity
values will mainly remain above 55 percent.
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 69 91 70 90 72 / 30 30 20 40 20
Anniston 70 90 70 90 73 / 30 20 20 40 20
Birmingham 71 91 73 92 74 / 30 20 10 40 20
Tuscaloosa 70 91 73 93 75 / 30 20 10 30 20
Calera 70 91 72 91 74 / 30 20 10 30 20
Auburn 71 90 71 90 73 / 30 20 10 30 20
Montgomery 73 93 73 93 74 / 30 30 10 30 20
Troy 72 94 72 93 75 / 30 30 10 30 20
&&
.BMX WATCHES/WARNINGS/ADVISORIES/...
None.
&&
$$
Area Forecast Discussion
National Weather Service Denver/Boulder CO
847 PM MDT Sat Jun 27 2020
.UPDATE...
Issued at 843 PM MDT Sat Jun 27 2020
Update to the forecast this evening to bring temperature trends in
line with observed, which are already very close, and to help ease
the pops out on the far eastern plains. Line of thunderstorms
have exited the forecast area and are into western Kansas. Anvil
debris from this afternoon`s showers and thunderstorms will give
way to mostly clear skies overnight.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 233 PM MDT Sat Jun 27 2020
A weak upper trough is currently pushing east across the state,
allowing for thunderstorms to form. Precipitable water values
continue to be about one third of an inch below yesterday`s
values. Therefore storms today will be more of the high based
gusty variety. Higher dewpoints out near the eastern border will
allow for a higher hail threat. A boundary over Lincoln County
along with a stream of storms moving up from the southwest should
bring most of the activity near there later this afternoon. As the
backside of the trough moves overhead later this evening,
convective activity is expected to die off quickly, with not much
around after 8pm. HRRR continues to show some echoes overnight,
but not buying it at this time with the subsidence on the
backside. Gusty winds along the foothills will again occur tonight
as a surface lee trough continues to deepen in response to a large
upper trough dropping into the Pacific Northwest. The gusty
downslope winds will keep minimum temperatures mild.
Southwesterly flow aloft will increase Sunday, bringing in warmer
and drier air at mid and upper levels. Maximum temperature
readings should be about 5 degrees warmer over today`s readings,
with some 100`s not out of the question over the eastern plains. A
deepening surface trough is expected to form into a surface low
over southeastern CO later in the afternoon however, so higher
dewpoints are expected to be pulled in over the northern plains
and urban corridor. Therefore, expecting more isolated to
scattered thunderstorms again tomorrow, again with high bases and
gusty winds. Less CAPE is expected tomorrow, so no severe strength
storms are expected.
.LONG TERM...(Sunday night through Saturday)
Issued at 233 PM MDT Sat Jun 27 2020
For Sunday night into Monday the upper level closed low will be over
the intermountain west digging southeast extending a broad trough
into the Great Basin through the day Monday. This upper level
pattern will increase southwest flow over the state. Closer to the
surface a deepening lee side low will further increase drier
southwest winds to push into the eastern plains with a general
eastern progression pulling winds westerly by the afternoon hours.
This will keep humidity levels low so will help to keep storms at
bay but on the flip side will increase fire weather concerns with
reduced RH levels. As mentioned in the previous discussion the
biggest question mark currently continues to be the winds. Timing
will be important with models bringing the upper jet around the
base of the trough and into western colorado by the late
afternoon/early evening. At this time winds in the mid and upper
levels are ranging from 15 to 35 kts which with adequate mixing
could translate to winds at the surface possibly gusting in the 20
to 25 mph range which is borderline for fire weather highlights.
Especially combined with precipitation that fell over the last 48
hours across much of the area. This will need to be monitored
along with local fuels to determine if a Red Flag will be needed
even with the marginal winds.
For Tuesday, the upper low will push north into the northern rockies
with a negatively tilted shortwave trough moving into western
Colorado during the day. At this time the models are showing the
upper trough pushing through during the late afternoon hours with a
cold front dropping down from the south during the morning. This
could help to increase some northeast to easterly flow at the
surface behind it for the afternoon albeit a tad weak. This will
help to provide some lift along the base of the foothills for storm
initiation. Timing of the trough passage will be important
because if it were to push through earlier in the day then flow
will turn more downsloping and subsident making storm initiation
difficult. Will stick with the former solution for now as models
are showing some consistency here. Overall, parameters are not
looking robust, however models do tend to over mix the lower
levels so still a possibility that CAPE will increase with model
updates and there is already good deep layer shear of 50 to 65
kts. Will maintain higher pops for the afternoon timeframe.
On Wednesday models show the upper trough pushing east and being
replaced with ridging that will bring dry conditions to the region.
Temperatures will be slightly cooler in the post frontal airmass on
Wednesday with highs in the lower 80s. Weather will be slightly
benign for the remainder of the week with a slight chance of diurnal
convection each day with warming temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 545 PM MDT Sat Jun 27 2020
VFR through the period with scattered showers and thunderstorms
after about 20z Sunday for all terminals. Tricky wind forecast at
KDEN with northerly environmental flow and thunderstorm outflow
wind coming up from the south. Appears outflow has stalled & went
with northerly flow for first couple hours of TAF period. Wind to
settle down to south to southwesterly after 02z and remain for the
rest of the night.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Hanson
SHORT TERM...Kriederman
LONG TERM...Bowen
AVIATION...Hanson
Area Forecast Discussion
National Weather Service Boston/Norton MA
1021 PM EDT Sat Jun 27 2020
.SYNOPSIS...
Low pressure over the lower Hudson Valley will move east off
the coast of Southern New England early tonight, with steady
rains coming to an end and improving conditions overnight. Warm
and humid weather ahead of an upper-level disturbance will spark
thunderstorms later in the day Sunday, and few may become
strong to severe. Slightly cooler than average temperatures along with
pop-up afternoon/early evening showers during the first half of
next week. Drier trend is expected for the second half of next
week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Mostly tweaks to the ongoing forecast for tonight. Widespread
showers have moved off the coast. Attention now turns to another
area of showers across upstate NY. These exhibited a weakening
trend as they moved southeast this evening. Not sure how much
will hold together to cross the Berkshires, just yet. Will be
monitoring the progress of this area overnight.
Brought temperatures back in line with observed trends. As of
this writing, a weak mesolow was centered around New Bedford.
This mesolow will move farther offshore after midnight, dragging
slightly less humid air farther southeast. This should not last
long with a warm front to our south poised to push north late
tonight.
Adjusted rainfall chances for the rest of tonight. An consensus
blend of a HRRR ensemble and NationalBlend best reflected
current thinking and timing.
Previous Discussion...
Latest observations indicate surface low along the CT/RI border.
This surface wave and its rain shield will continue to slowly
move east this evening with a drying trend to follow. Not much
of an airmass change behind the low so expecting seasonable
temps overnight with lows in the low to mid 60s along with dew
pts in the same range. This may yield some patchy fog. Light WNW
flow and associated subsidence behind the departing low should
be sufficient for decreasing clouds second half of the night
with at least partial clearing by sunrise Sunday.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
Sunday:
** Scattered strong to severe thunderstorms possible Sunday **
Any overnight to early morning mist or fog will burn off shortly
after sunrise. Mostly sunny conditions are then expected through
most of the morning into the mid-afternoon with a continued humid
air mass (dewpoints in the mid to upper 60s). This will help
destabilize the atmosphere, as we await the approach of a shortwave
trough seen in the Simple Water Vapor RGB product as of early-
afternoon Saturday north of Lake Superior. It`s this feature and its
associated cold frontal boundary that will interact with the
building convective instability to help fire thunderstorms
especially later in the day (mid-afternoon to mid-evening).
By early afternoon, it`s anticipated that convective temperatures
should be reached with any convective inhibition gone. Most-unstable
CAPE values are expected to range in the 1500-2500 J/kg, boosted by
mid-level lapse rates in the 6-6.5 C/km range. Outside of the
terrain and possibly on the western side of any sea-breezes, there
isn`t much to trigger thunderstorms. That changes by mid- to late-
afternoon with the approach of the shortwave trough, which most
models have digging southeastward into central/eastern NY. This
should generate scattered thunderstorms, and a few of these are
expected to become strong to severe. Areas in western and central MA
into northern CT and northern RI would appear to have the best shot
at seeing stronger thunderstorms given the late-day timing of the
cold front. Such a threat could extend all the way to the coast of
eastern MA but is more conditional on the frontal timing being
faster than currently progged or if the sea-breeze can ignite
thunderstorms during the early to mid-afternoon. The bigger limiting
factor to Sunday`s severe convective setup is that mid-level winds
are fairly weak, resulting in effective bulk shear magnitudes in the
25-35 kt range. This support pulse to loosely-organized updrafts.
The strongly heated low-levels with inverted-V profiles indicated in
model soundings support fairly sizable downdraft-CAPE values,
leading to a primary severe threat of strong to locally damaging
winds. Hail would be a secondary concern, and while sub-severe
hailstones would be more likely, a few 1" in diameter could be
possible with the lapse rates being somewhat steeper than moist-
adiabatic. Though isolated storms before this time could be possible
if sea breezes or terrain can get storms going, an approximate storm
timing looks to be between 3 and 8 PM. SPC has maintained the
Marginal Risk/5% severe probabilities, but locally I`ve also
added enhanced wording in the forecast for gusty winds and small
hail. Activity should be clearing central and western MA and
Hartford/Tolland Counties in CT by early evening, but may still
be ongoing across eastern MA.
Highs should reach the mid to upper 80s in the interior, with upper
70s to lower 80s near the coast and across the Cape.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Highlights.
* Isolated chance of diurnal showers and thunderstorms though the
middle part of next week.
* Cooler than average temperatures through Wednesday, followed by
a seasonably warm afternoon on Thursday.
Big Picture...
As previously discussed; an omega blocking pattern will develop with
a weak area of low pressure over New England Sunday night into early
next week. At the mid-levels a trough will extend down towards the
Mid Atlantic before becoming a mid-level cut-off area of low
pressure. Model guidance suggests that mid-level low will remain
stationary over New England for the majority of the upcoming week.
Expect periods of unsettled weather into late-week, after that, the
jet should kick the mid-level low out to sea.
Sunday night through Monday...
High-res models suggest a few isolated showers could linger
overnight, with an isolated thunderstorm across the Cape or Islands.
With the front left quadrant of the jet over western CT/MA, positive
vorticity advection could aid in generating pop-up showers Monday
afternoon. Additionally, PWATs values will remain in the ballpark of
1.50". Temperatures will be noticeably cooler as well. A light north
to northeasterly wind direction will limit our daytime heating. From
Cape Ann to Cape Cod and the Islands the afternoon high might not
get out of the 60s. Inland temperatures have a better shot of
reaching the middle 70s - with the highest temperatures in the low-
80s from Hartford to Springfield.
Tuesday through Friday...
Cooler than normal temperatures will prevail Tuesday and Wednesday
as easterly winds at 925mb advect cooler air from the Gulf of Maine.
A recent buoy observations show that the sea surface temperature are
between 62F-67F. Coastal communities from Cape Ann could struggle to
get out of the 60s, while the Cape and Islands reach the low 70s.
Further inland temperatures will still be cooler than normal with
highs reaching the middle and upper-70s; with the exception of the
Connecticut River Valley - there highs are expected to reach the
lower-80s. Diurnal heating will once again aid in the propagation of
afternoon showers and isolated thunderstorms. We don`t expect a
"washout", but, isolated heavy rain is possible with these isolated
thunderstorms.
Moving into Thursday, likely the warmest day of the week,
temperatures could return to the lower and middle 80s; a few upper
80s are possible across the Connecticut River Valley. And once again
afternoon showers and storms will likely develop as a result of the
daytime heating.
Friday the mid-level low begins to breakdown and move east. Higher
pressure from the west will begin to slide in from the northern
Great Lakes region. This will help to dry out Southern New England.
925mb wind is once again from the east and will help keep
temperatures cooler, for many highs only reach the low and middle-
70s.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight: Moderate confidence.
Mainly MVFR central/eastern TAFs as a weak low pressure passes
offshore. The question mark for tonight is with light progged
winds and the ground being wettened, and if that is enough to
spread patchy mist or fog to areas beyond just the favored
locations. I show some 4-6 SM mist at times, but confidence in
timing and development is low.
Winds become light northerly tonight except continued
southerlies across the Cape. By daybreak, winds should be from
the SW 4-8 kt.
Sunday: High confidence.
Any fog or mist burns off shortly after sunrise to VFR thru
mid-afternoon. Scattered thunderstorms, some potentially strong
to severe, will develop around mid-afternoon across the
Berkshires and progress eastward towards the coast through
late-afternoon/early evening. Local MVFR/IFR visibility
possible along with gusty winds and small hail. Will carry as a
period of VCSH for now but could see a need for VCTS with later
TAF issuances. Should have sea-breeze develop at BOS, but
otherwise winds SW 4-8 kt.
Sunday Night: High confidence.
SHRA/TSRA and their local restrictions may still be lingering
around until 03z especially east, but should be returning to
VFR thereafter all terminals. Winds become NW/NNW.
KBOS Terminal...High confidence in TAF trends. Moderate
confidence in timing.
KBDL Terminal...High confidence in TAF trends. Moderate
confidence in timing.
Outlook /Sunday Night through Thursday/...
Sunday Night: Mainly VFR, with areas MVFR possible. Chance
SHRA, slight chance TSRA, patchy BR.
Monday: Mainly VFR, with areas MVFR possible. Chance SHRA,
chance TSRA.
Monday Night: Mainly VFR, with areas MVFR possible. Slight
chance SHRA.
Tuesday: Mainly VFR, with areas MVFR possible. Chance SHRA,
chance TSRA.
Tuesday Night through Wednesday: Mainly MVFR, with areas VFR
possible. Chance SHRA, chance TSRA.
Wednesday Night: Mainly VFR, with areas MVFR possible. Chance
SHRA.
Thursday: VFR. Chance SHRA, chance TSRA.
&&
.MARINE...
Increasing southwest winds later tonight along with a southwest
fetch will cause winds and seas to rise to lower-end Small
Craft Advisory levels on the southern waters tonight. Low
clouds and patchy fog overnight, with fog possibly reducing
visibility to 3 NM or less. Any fog should burn off early Sunday.
Rough seas should continue on most of the southern waters early
Sunday, diminishing below 5 feet around noontime. Thunderstorms
are possible late tomorrow afternoon into early evening.
Outlook /Sunday Night through Thursday/...
Sunday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers, slight chance of thunderstorms,
patchy fog.
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers, chance of thunderstorms.
Monday Night through Tuesday: Winds less than 25 kt. Seas
locally approaching 5 ft. Slight chance of rain showers.
Tuesday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers.
Wednesday: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers, chance of thunderstorms.
Wednesday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Chance of rain showers, slight chance of
thunderstorms.
Thursday: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers, chance of thunderstorms.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until noon EDT Sunday for ANZ255.
Small Craft Advisory until 7 AM EDT Sunday for ANZ235-254.
Small Craft Advisory until 5 AM EDT Sunday for ANZ237.
Small Craft Advisory until 10 AM EDT Sunday for ANZ256.
&&
$$
SYNOPSIS...Loconto/Gaucher
NEAR TERM...Belk/Nocera/Loconto
SHORT TERM...Loconto
LONG TERM...Gaucher
AVIATION...Belk/Nocera/Loconto/Gaucher
MARINE...Belk/Loconto/Gaucher
Area Forecast Discussion
National Weather Service Buffalo NY
1032 PM EDT Sat Jun 27 2020
.SYNOPSIS...
A weak cold front will cross the area tonight and produce a few
showers and thunderstorms. High pressure will then build into the
Great Lakes region with mainly dry conditions, although a few stray
showers or a thunderstorm cannot be ruled out, especially east of
Lake Ontario. A warming trend then ensues for most of next week into
the holiday weekend.
&&
.NEAR TERM /THROUGH SUNDAY/...
Radar imagery late this evening showing a few linear clusters of
thunderstorms along a weak trough axis stretching from near Toronto
to the Tug Hill at 0230Z. This weak low level trough, and an
approaching mid level trough will cross the region overnight and
continue to support a few showers and storms. Latest 00Z NAM based
high-res CAMS guidance and HRRR continue to suggest maintenance of
this broken band of convection as the trough crosses the region.
This will bring a few showers and thunderstorms to much of the
region overnight with uneven coverage of rainfall.
Most of the updrafts have lost their intensity compared to early
this evening. A few storms may contain brief downpours, gusty winds,
and small hail but no severe weather is expected.
Most of this should be ending by daybreak, with just a few leftover
showers moving into the Finger Lakes and Central NY. Lows will drop
back into the mid 60s in most areas, and around 60 in the Southern
Tier valleys and Lewis County.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
The sprawling upper low over Quebec, around which the trough for
tonight is pinwheeling, will gradually shift southward toward
New England and off the coast of the Middle Atlantic state,
before finally ejecting beyond mid-week. It will make its
closest pass to the eastern portion of our CWA on Tuesday, which
will result in a better chance of daytime showers and
thunderstorms over the North Country that day. Otherwise, most
shower and storm activity will be driven by lake breeze
processes and terrain enhancement as riding attempts to
continually make inroads into the CWA through the first half of
the week. This will result in temperatures across WNY being a
good deal warmer than locations to the east of our CWA, with
even warmer air poised to make a triumphant return to the
entirety of the northeastern US in the long term period.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A closed low, will remain over the Northeast Wednesday before
joining back into the longwave pattern Wednesday night and Thursday.
Otherwise, a rather weak and poleward orientated omega block in
the upper levels will set up across Canada and Northern United
States/Canadian border for the remainder of the work week before
shifting towards a blocking high pattern across the CONUS.
Associated with the closed low on Wednesday there will be chances
for showers and thunderstorms across eastern NY due to a deeper
source of moisture. That being said, the best chances for shower
activity will lie east of the Finger Lakes region and span up into
the North Country. That said, the Western New York region will the
lowest chances of rain.
Weak surface high pressure will set up over the region for the
remainder of the work week which will promote a few days of dry
weather.
The start of the holiday weekend will be associated in the shift of
longwave blocking patterns which will promote the chances for
showers and storms.
Temperatures throughout the time period will range in the 80s. The
omega blocking pattern in the later half of the work week will
promote 850mb temperatures to soar into the upper teens Celsius and
near 20C, which will assist the day time highs to be in the upper
80s Thursday and Friday.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
A weak cold front and upper level trough will cross the eastern
Great Lakes tonight, continuing to support a few showers and storms.
Scattered to numerous thunderstorms will continue southeast of Lake
Ontario through the rest of the evening with local/brief MVFR to IFR
conditions. Overnight another round of scattered to numerous showers
and thunderstorms is expected to cross Western NY, also with
local/brief MVFR to IFR conditions. Most of this will taper off late
tonight, with just a few scattered showers left by daybreak across
the western Finger Lakes and Central NY.
Areas of MVFR/IFR CIGS will develop late tonight through Sunday
morning, with IFR favored across the higher terrain. The low CIGS
will scatter out by mid to late morning Sunday, leaving mainly VFR
for the remainder of the day. Cumulus fields with bases on the 4-6K
foot range will develop from midday through the afternoon. A few
scattered showers or isolated thunderstorms are also possible with
sparse coverage. The best chance of this will be east of Lake
Ontario.
Outlook...
Sunday night through Thursday...mainly VFR with a small
chance of showers at times, especially east of Lake Ontario.
&&
.MARINE...
A trough and weak cold front will cross the eastern Great Lakes
tonight with a few showers and storms with locally gusty winds.
Otherwise, light winds and lower chances of thunderstorms will
characterize most of next week on the lakes.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.
&&
$$
SYNOPSIS...Fries/Hitchcock
NEAR TERM...Hitchcock
SHORT TERM...Fries
LONG TERM...EAJ
AVIATION...Hitchcock
MARINE...Fries/Hitchcock
Area Forecast Discussion
National Weather Service Caribou ME
915 PM EDT Sat Jun 27 2020
.SYNOPSIS...
An upper low will move into New England with a series of
disturbances moving across Maine this weekend into early next
week. High pressure approaches the region late next week.
&&
.NEAR TERM /THROUGH SUNDAY/...
9:15 pm update: Area radars indicate widely scattered showers
from the Katahdin Region north. No recent lightning strikes and
GLM upstream not indicating any in cloud electrical activity.
Can`t rule out completely that there will not be a lightning
strike, but odds appear low. The main update at this time was to
the PoPs and weather for the remainder of the night based on
the latest radar trends and current observations.
Previous discussion:
Heating this afternoon has helped destabilize things for some
isolated convection to fire up, but nothing substantial. Weak
s/wv ridging shown nicely at 850mbs has aided in suppressing
organized convection. Activity appears to be diurnally driven
and should wind down w/the loss of heating this evening.
Watching upper trof back across the Ottawa and Ontario region
w/some convection firing up. This upper trof is picked up well
by the latest HRRR and RAP as well as the GFS and is shown by
the guidance to push into the region tonight. This feature will
allow for more showers and the potential for some tstms up
through midnight. The strongest storms will be this evening and
weaken overnight. Will not include any enhanced wording as
convective parameters weaken. Mdl soundings do show PWs climbing
to near 1.5" which would favor some heavy rainfall. Activity
looks like it will end sometime after midnight w/the loss of
substantial forcing. The GFS and NAM show some more shower
activity moving into wrn and nwrn areas by early morning hrs
Sunday. There does appear to be some vorticity advection which
will help trigger the showers. Rainfall amounts will be light.
At the same time, weak low pres will be passing off the srn New
England coast, w/any measurable rainfall remaining offshore.
There is the threat for some patchy fog overnight, especially
for areas that received rainfall.
Any morning fog will burn off pretty quick. The upper low in
Canada is expected to drop s into the state on Sunday. Cold
pocket aloft combined with diurnal heating will allow for
destabilization and showers to develop. Convective parameters
are not that impressive and shear is looking weak. The NAM looks
like it is overloading the dewpoints and ramping up the
moisture. Followed closer to the GFS and show the best
convective potential to be across the far w and nw. This means
CAPE of 400-700 joules w/shear < 10 kts. Activity will slowly
slide east during the afternoon moving into eastern areas by
later in the day. Again, any significant threat would be heavy
rainfall. Backed off the model QPF as it looks to be running too
high due to convective feedback. Afternoon high temps will be
dependent on cloud cover and extent. Stayed close to the
previous thinking of 70s to around 80F.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
Upper level low continues to drop south from Quebec the short
term period. This will keep an unsettled weather pattern across
the region through the period, with mainly afternoon showers
expected through the period. The cold pool aloft and diurnal
instability warrants keeping mention of slight chance of
afternoon thunderstorms each afternoon. More in the way of cloud
cover will result in afternoon high temperatures primarily
remaining in the 70s, which is near normal for this time of
year.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The aforementioned upper low will continue to dominate the
weather Tuesday night through Wednesday with continued, mainly
afternoon showers and thunderstorms. The upper low finally kicks
out to the Southeast of the area Wednesday night. A short wave
and associated cold front will cross the region on Thursday.
Somewhat cooler and drier air will follow for late next week
into next weekend. Temperatures will be above normal Wednesday
and Thursday, and then near normal late next week into next
weekend.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
NEAR TERM: Fog possible overnight for KBHB w/conditions
dropping to MVFR and then down to IFR/LIFR by Sunday morning.
Some of this could work its way up into KBGR by early Sunday
morning. Conditions should improve to VFR by midday. Elsewhere,
VFR right into Sunday outside of any patchy late night fog.
SHORT TERM: Mainly VFR, except MVFR will be possible in scattered
showers and thunderstorms, mainly during the afternoon Mon thru
Thu. For KBGR/KBHB IFR will be possible at night and early
morning in low clouds and patchy fog.
&&
.MARINE...
NEAR TERM: Fog remains the concern overnight into Sunday
morning. Some of high resolution guidance has been overdoing the
fog as of late. Decided to lean w/patchy fog overnight and keep
vsbys 1 to 3 NM. SSW winds around 10 kts tonight will shift to
the S on Sunday w/a slight increase in speed. Seas will remain
at 2-3 ft.
SHORT TERM: Winds/seas will remain below SCA levels through the period.
Visibilities will be reduced in patchy fog through mid week.
&&
.CLIMATE...
Today, June 27, 2020, marked the 12th consecutive day with a high
of 80 degrees (F) or warmer in Caribou, Maine. This breaks the
record for the most consecutive days with a high of 80 degrees or
warmer in Caribou. The old record of 11 days, was established
yesterday. Prior to yesterday, the record was 10 days from August
14-23, 2015. Weather records in Caribou date back to 1939.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...CB/Hewitt
Short Term...Duda
Long Term...Duda
Aviation...CB/Hewitt/Duda
Marine...CB/Hewitt/Duda
Climate...CB
Area Forecast Discussion
National Weather Service Cleveland OH
1008 PM EDT Sat Jun 27 2020
.SYNOPSIS...
A cold front will move across the area tonight and Sunday. It
will settle across southwest Ohio. High pressure will nudge
southward across the Upper Ohio Valley and largely remain across
the area this upcoming week.
&&
.NEAR TERM /THROUGH SUNDAY NIGHT/...
Band of thunderstorms over Lake Erie has been back building
across the western basin along the slow moving cold front.
Raised pops for our northwest tier of counties as it will likely
make it at least that far before starting to break up.
Thunderstorms are producing frequent lightning, heavy rain, and
wind gusts to around 30+ mph. HRRR has been showing at least
scattered showers holding together as the front crosses NE Ohio
during the overnight hours so will continue with chance pops.
Temperatures have also been holding up pretty warm with some
locations still in the upper 70s to near 80 degrees in Toledo.
Raised mins for tonight given the high dewpoints with cold
advection largely delayed until after 12Z. Stratus is expected
to fill in overnight and cannot rule out some patchy fog if
lower ceilings develop.
Previous discussion...
As of mid afternoon the cold front was located across lower
Michigan. Convective activity has been focused across central
Ohio with the MCV that moved out of central IN this morning.
Much of northern OH has been void of convection this afternoon
in the stabilizing wake of the central OH complex. That being
said, we still have the cold front to pass so cannot rule out a
shower/thunderstorm. Dewpoints will be slow to lower and tonight
will be muggy. Lows will only fall back to the mid/upper 60s.
High pressure begins to build southward across the eastern Great
Lakes for Sunday. Will maintain some mention of
showers/thunderstorms across the southern half of the area for
Sunday, but expect most of the area to be dry. The cold front
will likely be along the south shore of the lake early Sunday
morning and will continue to press south. Highs will still be
seasonable.
Sunday night the front pushes far enough south to push
shower/thunderstorm chances south of the area. We may even have
a couple upper 50s for lows across far eastern OH/inland nw PA.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Confidence increasing in omega block pattern setting up over
the region with an upper-level ridge over the Midwest/Great
Lakes area and an upper-level low situated over the northeast
CONUS through the week. On Monday and Tuesday, a surface front
lingers across southern Ohio and portions of Indiana.
Instability during the afternoon will result in isolated
thunderstorm during the afternoon. Otherwise, mostly to partly
sunny skies with highs in the 80s and lows in the 60s will occur
through the short term period.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Omega blocking pattern continues through the long term period
with a similar forecast as the short term period in mind:
Isolated showers and thunderstorms daily in the afternoon with
highs in the 80s and lows in the 60s. Hottest days expected to
be on Thursday/Friday where high temperatures could get into the
upper 80s with a few locations touching 90.
&&
.AVIATION /00Z Sunday THROUGH Thursday/...
At 8 PM, a cold front was located near the north shore of Lake
Erie with a line of thunderstorms sinking slowly south. These
thunderstorms may impact TOL or CLE through 04Z, but could also
weaken as they settle south across Lake Erie. Will monitor the
need to add thunderstorms to CLE TAF. Elsewhere showers and
thunderstorms are struggling to develop but could see a stray
showers at MFD/CAK/YNG/ERI overnight as the front settles south.
Have left out of the terminals for now as coverage is expected
to be low.
As the front arrives later tonight, expecting to see an
expanding stratus cloud deck. MVFR ceilings are likely with
pockets of IFR also possible in the 09-12Z window. Surface
moisture remains which will also contribute to MVFR
visibilities. Ceilings and visibilities will tend to improve
towards midday as drier air arrives behind the front. Southwest
winds ahead of the front will shift to the north or northwest
behind the front overnight into Sunday morning but will
generally be 10 knots or less.
Outlook...Non-VFR possible early Monday morning across eastern
OH.
&&
.MARINE...
Southwest winds of 10 to 15 knots continues through the evening
and early tonight before the cold front moves south across Lake
Erie tonight. Relatively quiet conditions are expected through
the remainder of the forecast as a weak pressure gradient sets
up over Lake Erie for awhile. Winds expected to be predominantly
northeast Tuesday through Wednesday, though sustained winds
should generally be 10 knots or less, so no major impacts are
expected.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...Oudeman
NEAR TERM...KEC/Oudeman
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...KEC
MARINE...Saunders
Area Forecast Discussion
National Weather Service State College PA
1137 PM EDT Sat Jun 27 2020
.SYNOPSIS...
An upper level trough will push across the region this weekend,
pushing a cold front through the state on Sunday. A drier and
less humid pattern early next week should trend more unsettled
heading into July with temperatures remaining near to above
daily climate averages.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Late evening water vapor loop shows one shortwave exiting
eastern Pa and another upstream over southern Ontario. Loss of
heating and passage of first shortwave has caused lingering
showers over southern Pa to die out late this evening. Focus is
now on the northern tier counties late tonight, where arrival
of second shortwave could produce a late night shower or storm
in spots. RAP and earlier HREF both indicate MUCAPES near 1000
j/kg over the northern tier even late tonight.
Model soundings indicate a very moist southwest flow beneath
developing inversion will lead to low clouds late tonight over
the Alleghenies. East of the mountains, expect clearing skies,
as cirrus shield exits the area this evening. Light wind and
clearing skies is likely to promote patchy late night fog into
those locations that received appreciable rainfall earlier
today, roughly along the I-80 corridor.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
Upper level trough axis and associated surface cold front are
progged to push southeast across the region Sunday. A late
afternoon fropa favors the best chance of a shower or storm
across the southeast counties, while only a slight chance of a
morning shower is currently forecast with the morning fropa over
the northwest mountains.
Moderate northwesterly flow aloft should promote some storm
organization and dcapes are quite high, yielding a local risk
for gusty/damaging winds with any storms that form over the
southeast counties during the afternoon.
For the bulk of the CWA on Sunday, dry and partly sunny
conditions with slowly lowering dewpoints and a moderate NW
breeze of 10-15 kts will provide a pleasant, warm end to the
weekend. Max temps will range from the upper 70s across the
higher terrain of the north and west, to the upper 80s in the
southeast.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Medium range guidance supports drier and somewhat less humid
conditions early next week, as northerly flow develops over
Pennsylvania on southwest periphery of upper low over New
England. Mean 850mb temps around 16C indicate temperatures are
likely to be slightly above average.
There are continued indications that upper troughing over
northeastern North America will become more pronounced and
extend southward into the Mid Atlantic region by the middle of
next week. This scenario would result in a renewed chance of
scattered, diurnal convection across central Pa Tuesday and
Wednesday. Eventually, the latest NAEFS and ECENS push this
trough east of Pa by late in the week, as anomalous upper level
ridge builds in from the midwest. This supports hotter and more
humid conditions to end the week. Scattered, ring of fire
convection will remain a possibility across Pa Friday and
Saturday on northern periphery of upper ridge.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
Some adjustments to the TAFS at times this evening.
Nothing on the radar now.
Earlier discussion below.
00Z TAFS sent.
A few showers across the area, but less than I expected last
night when I worked.
Aside from the showers, the main issue later tonight and early
Sunday morning will be low CIGS.
Expect conditions to improve by late morning. Left showers out
of the forecast for now.
Dry weather for Monday into at least Tuesday, if not early
Wednesday.
Outlook...
Sun...Still a chance of showers and storms across the SE third
of the state.
Mon...A chance of showers and storms, mainly south.
Tue...Mainly dry with VFR conditions.
Wed...Chance of showers and thunderstorms.
Thu...Still a chance of showers and thunderstorms.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Lambert/Steinbugl
NEAR TERM...Fitzgerald
SHORT TERM...Lambert/Fitzgerald
LONG TERM...Fitzgerald
AVIATION...Martin
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1042 PM CDT Sat Jun 27 2020
.Discussion...
Issued at 235 PM CDT SAT JUN 27 2020
A mid-level shortwave/ MCV is moving over the middle of the forecast
area this afternoon. Moist ascent on the southern side of this wave
and north of a warm front, was leading thick cloud cover from
eastern KS through central MO. This cloud cover is really inhibiting
destabilization as just southwest of the area, in southern KS, CAPE
is already around 4000 J/kg. Models did not initialize the cloud
cover well and are struggling with how quickly to destabilize the
area this afternoon. The RAP perhaps has the best handle on
things and as the cloud cover shifts east and the warm front moves
northward from the south, builds the instability northward. As
that front is lifting northward, isolated to perhaps scattered
showers and storms should develop. This looks most likely late
this afternoon through around midnight for the KC area southward
and after midnight for northern MO. The chances of severe storms
looks rather low at this time. Given the instability that may
build northward with the warm front, and the marginal shear, some
strong storms can`t be ruled with some hail and gusty winds.
Hot and humid conditions will move into the area Sunday. We should
see highs in the low to mid 90s with upper 60 to lower 70 degree
dewpoints during the heat of the afternoon. That combination should
lead to heat index values around 100 across the area. There is also
an outside chance that the heat and humidity will be enough to reach
convective temperatures, based on NAM forecast soundings. But am
more confident we`ll remain capped and stay dry so have no mention
of precipitation tomorrow. For the start of the work week, a weak
shortwave will lift into the area from the southwest during the
afternoon. This may lead to some showers and storms in across areas
mainly east of I-35. That wave may linger into Tuesday into
Wednesday with additional chances for precipitation. The other
story, and probably more likely to occur, is the building heat
through the middle of the week. By Wednesday, highs in the middle
90s look likely with heat indices approaching 105 in some places.
Temperatures should linger in the low to middle 90s through the end
of the week but the upper pattern isn`t as clear cut for heat as one
would like to see. The upper ridge is over the area but also
weakens on its east with weak troughing over the Southeast.
&&
.Aviation...(For the 06Z TAFS through 06Z Sunday Night)
Issued at 1042 PM CDT SAT JUN 27 2020
VFR conditions will persist through much of the next 24 hours.
Only issue may be early Sunday morning thunderstorms as a
decaying complex of storms moves through eastern Kansas into
northern Missouri. Timing for this looks to occur between 09Z and
14Z, as the nose of the low level jet reaches the Kansas Missouri
border. Otherwise, expect gusty southerly winds tomorrow.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...CDB
Aviation...Cutter
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
951 PM CDT Sat Jun 27 2020
...Short Term Update...
.UPDATE...
Issued at 951 PM CDT Sat Jun 27 2020
Various comments about the rest of tonight, mainly regarding
thunderstorm chances/possible severe:
1) Especially up until recently, haven`t had the greatest "feel"
for how things play out tonight, as if anything "geographic
confidence" in thunderstorm placement had been lacking somewhat.
That being said, now that the beginning stages of a strong to
severe linear mesoscale convective system (MCS) appears to be
underway in northwest KS and is tracking east, feel a bit better
about the Severe Thunderstorm Watch that SPC earlier coordinated
for most of our counties along/south of the state line (officially
valid until 3 AM). While this complex is currently expected to be
our "main show" overnight, perhaps with the greatest threat being
60-70 MPH winds (and to a bit lesser extent large hail), would
also not be surprised to see more "random" strong to severe
activity blossom farther north (outside the current Watch area).
Unlike last night, where the low level jet exit region was pretty
clearly focused in our south, tonight it actually is progged to
aim more into our central/northern counties as it veers after
midnight. IF storms do get going north of the current watch area,
at least sporadic severe hail (up to around half dollar size)
could easily materialize given healthy most-unstable CAPE up
around 3000 J/kg, although the damaging wind threat would probably
not be as high as in our south. Not necessarily sure that
possible severe development in our central/northern counties
would necessitate a northward expansion of the current Watch, but
it`s a possibility that cannot be discounted.
2) On a positive note, if storms are able to fire up north of the
current Watch area, some counties that have been VERY DRY of late
(such as Adams/Hall/Hamilton etc.) could finally get their shot at
a halfway decent rain, but again, this is far from a "sure thing",
and that is why rain chances/PoPs have been limited to 50 percent
or less in this portions of our coverage area (CWA) for the time
being. Actual rain amounts in our CWA should largely favor 1" or
less, with anything higher an exception, so not overly-concerned
about flooding (except will need to watch parts of north central
KS that had heavy rain last night).
IN SUMMARY: Although the official Severe Thunderstorm Watch is
currently placed along/south of the state line, there are signs
that an isolated/spotty severe threat could extend farther north
late tonight into our central and even northern counties. In
theory, southern counties should stand the greatest damaging wind
threat, while counties farther north would have more of a spotty
large hail threat, but as if often the case with these nocturnal
summer events, details are not entirely clear cut, and both
wind/hail hazards (along with possible Watch expansion) will be
monitored closely. No matter how much (or how little) ends up
happening overnight, the vast majority of thunderstorm activity
within our CWA should be on the decline by roughly 4-5 AM, and
the main severe threat over by 3-4 AM.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 225 PM CDT Sat Jun 27 2020
A warm front lifted north across the local area this morning. This
front shifted the winds to the south and brought a few more clouds
to the region than previously anticipated. Thanks to the cloud
cover...temps have been slow to climb...but expect the clouds to
thin over the next couple of hours allowing temperatures to max
out near 90 in most spots as previously thought.
While there has been a stray shower just outside the local area
associated with this front...do not expect any additional
activity locally until later this evening when convection
developing to our southwest tracks across the heart of the local
area. While instability will peak around 00Z...any diurnally
driven thunderstorm activity is expected to remain near the
aforementioned surface boundary...and just outside our area to the
north/northwest as depicted by the HRRR and RAP. Later in the
night...expect an MCS coming out of Colorado to cross northwestern
Kansas and move across the local area during the overnight hours.
Model placement is still not completely certain...but expect this
MCS to roughly cross through the center of the local area. With a
modest amount of instability remaining overnight and some
enhancement from the LLJ...expect a few strong to marginally
severe storms to be possible...with large hail and strong
thunderstorm wind gusts being the main threat.
For Sunday...expect a period of dry and hot weather to begin
across the local area with highs topping out in the mid 90s by
afternoon...with a few sporadic heat index values near 100.
.LONG TERM...(Sunday night through Saturday)
Issued at 225 PM CDT Sat Jun 27 2020
Dry weather is anticipated to start the extended periods as while
there will be no shortage of instability across the local
area...there also will likely be nothing to trigger it along with
a decent CAP in place. As a result...borderline hot weather is
expected to continue both Monday and Tuesday with heat index
values both days again approaching 100.
As we transition into the evening hours Tuesday...models are in
fair agreement swinging a negatively tilted trough across the
region which could trigger some convection Tuesday evening. With
a very unstable airmass in place...if thunderstorms do develop
late Tuesday afternoon or evening...expect them to rapidly become
severe...and not surprisingly the SPC has parts of our area
highlighted in a potential for severe weather...and we will need
to continue to monitor this period.
Beyond Tuesday...southwesterly junky flow will continue through
the end of the week...with small chances for thunderstorms and
slightly cooler...yet seasonable...weather anticipated. Beyond
Friday...however...a large ridge of high pressure is forecast to
build across the plains...which could result in a prolonged period
of hot and dry weather across the local area if it pans out.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday)
Issued at 751 PM CDT Sat Jun 27 2020
General overview/thunderstorm and ceiling expectations:
High confidence in VFR ceiling/visibility through at least the
vast majority of the period, with by far the main concern being
whether (or not) thunderstorms roll through tonight. If they do,
they could be briefly severe with a large hail/50+KT wind gust
threat, but confidence in thunderstorm coverage is still low
enough that feel it is prudent to maintain only a basic "vicinity
thunderstorm" group (VCTS) focused 4-10Z for KEAR/5-11Z at KGRI.
Obviously later forecasts can introduce a higher-confidence TEMPO
group, depending on how things evolve. Outside of the main 6-hour
"window of opportunity" for possible convection, fairly high
confidence in a dry/storm-free forecast. Ceiling should prevail
VFR the vast majority of the time, but there are hints of some
"sneaky" MVFR perhaps trying to briefly develop late tonight into
Sunday morning, so will "hint" at this with a FEW015 mention.
Winds:
Outside of any possible briefly-intense wind gusts associated with
thunderstorm outflow, winds are not expected to be a major issue,
generally prevailing from the south-southeast at sustained speeds
at-or-below 12KT and gusts largely under 18KT. Any appreciable low
level wind shear (LLWS) overnight should focus slightly south-
southeast of the terminals, so will omit any formal inclusion.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...Pfannkuch
SHORT TERM...Rossi
LONG TERM...Rossi
AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Goodland KS
540 PM MDT Sat Jun 27 2020
.SHORT TERM...(This evening through Sunday)
Issued at 1231 PM MDT Sat Jun 27 2020
18 UTC Water Vapor Imagery and RAP analysis indicate broad
westerly flow aloft over the area,with short wave trough
approaching northeastern Colorado per satellite imagery. At the
surface, seeing two areas of cumulus developing, one along trough
axis from Wray to Limon and another along a convergent area
between Burlington and St. Francis.
Main forecast concern will center around severe thunderstorm
potential late this afternoon tonight.
Expect thunderstorms to develop along trough in eastern Colorado
by 22 UTC, although secondary area of cumulus to the east of the
Colorado state line makes me think there may be 2 areas of initial
development, especially as this area is supported by persistent
forced ascent due to WAA. Despite the possibility of an isolated
cell or two in Kansas, still think forecast will play out similar
to yesterday. Storms will form along trough axis, and with high
bases and strong DCAPE will quickly form strong cold pool/gust
front. With the orientation of 0-3km wind shear, seems like a
favorable environment for MCS to develop and remain in balance
with cold pool for several hours. With potential organization into
a linear mode and strong DCAPE think wind gusts up to 70 mph
primary threat, although if isolated storms develop further east
ahead of the line hail may become more of a threat.
Storms should move across the area fairly quickly with any MCS out
of the area by 06 UTC. On Sunday very warm and dry conditions
expected. Heating may be enough to overcome any capping and with
weak dryline developing would not be out of the question to see an
isolated storm. Signal right now looks fairly weak however and
think continued dry forecast is in order.
.LONG TERM...(Monday through Saturday)
Issued at 119 PM MDT Sat Jun 27 2020
The extended starts with troughing over the western US, ridging over
the Southeastern and GREAT Lakes regions, and troughing over the New
England States. This upper level pattern will produce southwest flow
aloft over the Tri-States area and aid in dry and hot (highs are
expected to reach at or above 100) conditions through Tuesday
afternoon. Add in relative humidity values of 10 to 15 percent will
result in possible fire weather conditions.
Tuesday afternoon, the models are showing a cold front moving
through the region and producing a chance of thunderstorms during
the afternoon and evening hours, mainly the the northwestern part of
the Tri-State region.
For the rest of the week, temperatures will be in the above normal
range of the middle 90s and an upper-level ridge will build over the
High Plains and influence the area. The However, disturbances
traveling within the upper-level flow may result in afternoon
thunderstorms each day.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 540 PM MDT Sat Jun 27 2020
Adverse aviation conditions associated with thunderstorms are
possible at both terminals late this afternoon and evening, mainly
in the 00-06Z time frame. Otherwise, VFR conditions will prevail.
South winds at ~15 knots gusting to 25 knots will persist through
sunset. Winds are anticipated to become light/variable late this
evening. Note -- gusty/erratic winds (possibly gusting to 45-55
knots) will be possible invof any thunderstorms at both terminals
this evening (00-06Z).
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...BW
AVIATION...VINCENT
Area Forecast Discussion
National Weather Service Grand Rapids MI
1059 PM EDT Sat Jun 27 2020
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 238 PM EDT Sat Jun 27 2020
- Mild Weather with little chance for rain in the upcoming week
- Seasonably warm temperatures through next week
&&
.UPDATE...
Issued at 1059 PM EDT Sat Jun 27 2020
I have added low chance pops over our extreme southwest CWA (Van
Buren County) for from now till midnight for thunderstorms. There
is an area of increased surface convergence on the cold front
slipping south into that area. There is a small are of instability
that holds on in that area until the front really get south of
there. HRRR model soundings in southern Van Buren County at 11 pm
have MU cape near 1000 j/kg. This will be short lived but I would
think we should see a few thunderstorms there.
&&
.DISCUSSION...(This evening through next Saturday)
Issued at 238 PM EDT Sat Jun 27 2020
- Mild Weather with little chance for rain in the upcoming week -
As the upper levels slowly dry, skies will slowly clear today.
Patchy fog will remain along Lake Michigan coast through mid
afternoon but dissipate as winds mix down.
The long wave trough will keep a boundary along Michigan`s
southern border this evening. However the propagation of the upper
level low into the northeast will keep any precipitation south of
the region.
There is good consensus that the Upper level low will stall over
the Northeast. This will thus stall a high over the Great Lakes.
That building high will continue through most of next week.
Thus Pops have been lowered with any chance for precipitation on
Thursday being stifled by the stable atmosphere.
- Seasonably warm temperatures through next week -
Along with the high pressure will come warmer than normal
temperatures. Expect Maximum Temperature around 10 degrees above
normal. with Max Temperatures in the upper 80s to low 90s through
the upcoming week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 700 PM EDT Sat Jun 27 2020
We are expecting skies to become clear by mid evening and winds to
become light and variable (at the surface). Sunday will feature
light northeast winds with nearly clear skies, however MKG will
likely have a lake breeze turn the wind there to the northwest by
early afternoon.
One possible glitch is near I-94, fog is possible tonight. Some of
our high resolution models have dense fog at all of our I-94 TAF
sites around sunrise. Given the light winds and heavy rain
yesterday this would not be out of the question. For now I have
MVFR visibilities around sunrise for those TAF sites. The fog
would mix out quickly if it does happen.
&&
.MARINE...
Issued at 303 AM EDT Sat Jun 27 2020
High pressure will bring tranquil conditions on Lake Michigan
this weekend with waves at or below 2 feet. West winds of 10 to
15 kts are forecast today with offshore winds of around 5-10 kts
Sunday that will veer west by around midday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...WDM
SYNOPSIS...Ceru
DISCUSSION...Ceru
AVIATION...WDM
MARINE...Laurens
Area Forecast Discussion
National Weather Service Wilmington NC
1042 PM EDT Sat Jun 27 2020
.SYNOPSIS...
Weak high pressure will remain in vicinity of the area thru Sun.
A series of weak to moderate upper level disturbances will move
across the Southeast States tonight thru early next week,
resulting with increasing chances for showers and TSTMs. A cold
front will drop into the area early next week, stalling just
south of the region by the mid-week period of next week.
&&
.UPDATE...
Public:
Upped POPs and Cloudiness across the FA, mainly across the
southern portions of the FA for the remainder of this evening
and overnight to account for the convection and debris
cloudiness. The majority and worse of the convection will remain
south of the FA within the WNW to NW flow aloft. The outflow
and/or any sustainable convection may clip the southern portions
of Williamsburg and/or Georgetown Counties thru midnight. Have
lowered mins across the FA tonight by a degree or 2 with low 70s
covering it. This based on latest sfc dewpoint trends, upper 60s
across the FA, then applied to the overnight temp/dewpt regime.
Due to the Saharan Dust/Sand plume affecting the Bi-State
region tonight thru much of Sun, have included "Hazy" conditions
for most zones especially when prevailing VSBY drops to 5 miles
or lower.
Marine:
Tweaked winds overnight into daylight Sun with a solid 15 kt
applicable to the ILM NC Waters Only. Will increase the seas to
up to 4 ft for the waters from Cape Fear south to Little River
Inlet due to short period wind driven waves slightly hier input
to the overall seas. Could see VSBY drop to 5NM from Haze, which
is due to dust associated with the Saharan Dust/Sand Plume
moving across the local waters.
&&
.NEAR TERM /THROUGH SUNDAY NIGHT/...
There have been just enough reports of slightly lowered
visibility from the Saharan dust that it has been added to the
forecast through tonight for SC zones. The HRRR still shows a
few showers and perhaps thunderstorms crossing our inland NC
counties this evening so slight chance POPs have been left.
There is rather unusual model disagreement and thus forecast
uncertainty for day 2/Sunday. A disturbance is slated to cross
the area in the developing NW flow but models are having trouble
resolving the convective signal associated with its passage
Sunday eve/night. The GFS for example has rather light precip
across the area as the bulk of it passes by to our north while
the WRF clobbers us pretty good with what looks like an MCS
(currently not the favored solution). SPC has demoted the area
from Slight to Marginal but has expressed a similar low
confidence while collaborating today. The EC is even slower with
the disturbance relegating to midday Monday. Will carry slight
chance POPs through afternoon and raised Sunday night to low end
of chance range.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Shortwave exits the coast late Monday morning, setting up some post
wave subsidence. Deep northwest flow continues with 5h ridge to the
south and cutoff low over New England. A weak front will remain
draped across the area along with an abundance of moisture.
Subsidence through Mon afternoon will help limit coverage of diurnal
convection. However, the lack of subsidence Tue coupled with the
boundary and deep moisture results in an increase in diurnal showers
and thunderstorms. There will be periodic shortwaves moving in from
the northwest which could enhance convection Tue, if the timing
works out. Highs will be near climo with lows running above
climo.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Pattern aloft remains unchanged with 5h ridging to the south and
southwest and cutoff low over the Northeast shifting off the Mid-
Atlantic coast. Deep northwest flow will persist, keeping surface
boundary and associated deep moisture in the region. The boundary
will act as a focal point for daily showers and thunderstorms. A
series of shortwaves will occasionally drop south across the area,
potentially enhancing convection if the timing is right.
- Afternoon and evening storms possible each day with coverage
decreasing slightly late next week.
- High temperatures near climo with low temperatures slightly
above climo.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Mainly VFR thru the 24 hr period with the exception of the SC
terminals where haze (associated with the Saharan Dust/Sand
Plume moving across the region) could reduce vsby to 3sm-5sm
now thru 15Z Sun. The NC terminals may see an occasional 5sm-
6sm in haze HZ or dust DU, but the bulk of the HZ or DU will
pass across SC tonight thru midday Sun. Between 07-11Z, the SC
terminals may experience tempo 2sm or lower, especially if winds
drop to 3 kt or less with a secondary vsby reduction coming
from possible BR. Although temp/dewpoint spreads should remain
high enough to prevent BR, the exception will occur at CRE.
Daytime CU and the threat of an upper level s/w trof in the late
aftn has prompted PROB30 groups for TSRA toward the end of the
24 hr TAF Issuance Period. The sea breeze will again be limited
with it`s inland progression due to strong WSW-WNW winds in the
lower levels of the atm.
Extended Outlook...A disturbance aloft, ie. a s/w trof, could
bring scattered showers and storms Sunday evening with brief
MVFR/IFR conditions along with isolated wind gusts of 30-40 kt.
A mixture of lowered flight categories could occur Mon thru Wed
as a series of disturbances aloft move through the area,
creating convection possibilities when they pass thru, which
may include the overnight hrs.
&&
.MARINE...
West to southwest winds are expected now through Sunday night.
High pressure will be located over the western Atlantic while
piedmont trough stays in place as well-both conducive to SW
flow. Waves in the 2-3 ft range will be comprised of a 10 sec SE
swell and a 4-5 second wind chop.
West-southwest flow Mon will become light and variable Tue and
Wed as weak surface boundary settles south across the area. The
boundary will stall across the waters, but will not remain in
the same location, so winds may vary from southwest to northeast
depending on the location of the front. Speeds will generally
be under 10 kt from Mon night on. Seas will be a mix of a
dominant southerly wind wave and a weak southeast swell.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...DCH
UPDATE...DCH
NEAR TERM...MBB
SHORT TERM...III
LONG TERM...III
AVIATION...DCH
MARINE...DCH/III/MBB
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
957 PM CDT Sat Jun 27 2020
.UPDATE...
957 PM CDT
Convection continues to diminish in intensity and coverage across
most of the area late this evening, though a cluster of storms
had developed earlier over western Lee/Ogle counties along what
appears to be a region of low level confluent/convergent flow
along the otherwise diffuse synoptic cold frontal boundary.
Expectation is that these storms (which are diminishing) will fade
away over the next 1-2 hours, ending the localized heavy rain
threat there. Farther south, scattered storms continue to fester
across central IL, and will likely continue to persist along
residual outflow boundaries as a mid-level short wave moves slowly
east-southeast downstate. Will maintain chance pops overnight for
our southeastern counties, though hopefully this activity will
remain more scattered than earlier given substantial flooding over
portions of east central IL/northwest IN.
Ratzer
&&
.MESOSCALE DISCUSSION...
526 PM CDT
Flash flooding is ongoing across a portion of northwest Indiana,
in particular southern Newton and Jasper Counties, and likely
will be occurring soon in northern Iroquois County. Given the
hydrology metrics we are analyzing, namely amounts over 300
percent to flash flood guidance, we have upgraded the impact-
based warning (IBW) to considerable given some locations should be
seeing significant flooding.
On the mesoscale, a northwest to southeast boundary evident the
past 2-3 hours on satellite, is draped from Ottawa IL through
West Lafayette IN. It appears inflow into this (20 kt of 850 mb
flow on ILX VWP) and prorogation vectors to the southeast at a
slow speed are heavily offsetting, helping the boundary-initiated
storms to train over the same area with little cold pool-driven
movement. Individual storm cores have been nearly vertical and
have had VIL densities indicative of very heavy rain when
considering freezing levels are nearly 15,000 ft. The warm rain
process are dominant in these storms as they tap into precipitable
waters around 1.8 inches.
The growing concern is that these storms continue for another few
hours, or possibly longer, in this convergent axis. This
convective area is likely being assisted to regenerate by the
convectively-enhanced short wave moving eastward near Quincy, IL.
This is also helping to enhance moisture convergence in the
700-925 mb layer on the RAP solution. This is forecast to continue
at least in that general area through 8 pm.
We have again issued a Considerable Flash Flood Warning for this
area of northwest Indiana and will continue to highlight in
messaging.
MTF
&&
.SHORT TERM...
335 PM CDT
Through Sunday night...
The forecast concerns in this period -- similar to much of the
forecast -- are handling the many thunderstorm chances and
deciphering if and when the likelihood is higher.
The thunderstorm cluster in northwest Indiana as of 3 PM is
gradually shifting southeast, and is on the northeastern periphery
of the MCV passing eastward through central Illinois. There also
is likely a subtle boundary or two (as well as outflow induced
from this convection) that will help to trigger more storms in the
southern CWA over the next few hours. In this area, the deep layer
shear is slightly better (around 30 kt) and has resulted in a few
deeper storms capable of gustier downdrafts. The main threat
though looks to be a corridor or two of flash flooding due to
training storms with very heavy rainfall rates thanks to PWATs
above 1.75 inches.
Further north, isolated to scattered showers and some storms have
started to develop and should continue near/just north of I-80. A
couple more may generate on the lake breeze and the weak cool
front sinking slowly southward in the far northern CWA. Overall
intensity of this convection should not be robust, however
individual cores may be. The slow motions and pulsy nature will
make for some wind gusts over 35 mph and locally heavy rainfall.
Heading into the evening, some convection is likely to fester with
a gradual southeast progression. The propensity for lightning
should ease after dark and more so overnight, but could continue
some showers at least into the overnight over the southeast
forecast area. Guidance has a fair amount of cloud cover
overnight, but suspect it is overdone. With the high dew point air
and spotty areas seeing further boundary layer and ground
moistening with rain this P.M., patchy shallow fog is possible
lingering into early Sunday morning.
The remnant synoptic boundary, which has been modulated some by
convective influences, will eventually take shape as a warm front
during Sunday and start returning slowly northeastward. Heights
in the mid-levels will be building at the same time and overall
there will be less of a convective focus or especially impetus
compared to the past couple days. However, a continued moist air
mass including dew points in the upper 60s to 70 will support
potentially enough instability for scattered showers and storms
near the confluence of the gradually developing front. Further
northeast over the metro the chances appear less, even with a
lake breeze, as model soundings are fairly set on a capping
influence winning out.
As the isentropic ascent strengthens on Sunday evening into the
night, the potential for convection will increase. Also there are
indications of a weak short wave or MCV moving southeastward near
or into the northern Illinois CWA Sunday evening. Confidence on
that is low, but do have chances increasing through the night. The
shear/instability space especially during Sunday night is enough
for some potent cores to strong to severe limits, and possibly
organized convection into northern Illinois north of I-80 from
the northwest if that MCV were to come to fruition.
MTF
&&
.LONG TERM...
257 PM CDT
Monday through Saturday...
Hot and humid will be the story through the work week with the
area situated under an upper level ridge with highs mostly in the
low 90s and dewpoints in the 70s expected. Easterly flow should
keep things a bit cooler near the lake.
The extended is littered with multiple weak waves embedded
beneath the ridge resulting in multiple precip chances through the
extended thanks to the lingering moist and unstable airmass in
place. The better chances look to be Monday through Wednesday with
chances decreasing toward the end of the week.
Winds will turn northeasterly toward the end of the period which
should help temps and dewpoints ease slightly as we approach the
Fourth of July holiday weekend.
Petr
&&
.AVIATION...
For the 00Z TAFs...
Aviation forecast concerns:
* Isolated TSRA possible early this evening mainly near southern
Chicago metro terminals (MDW/GYY). Not expecting widespread
coverage, and should dissipate with sunset.
* Messy wind forecast across Chicago terminals, with lake breeze
trying to move inland, and several convective outflow boundaries
converging from the south/southwest early this evening. Wind
direction will likely be somewhat variable across the Chicago
TAF sites this evening.
* Low probability of some fog/low stratus development late
Diffuse cold frontal boundary was near the IL-WI border late this
afternoon, while a residual outflow boundary from previous
convection has become a focus for renewed thunderstorm development
this afternoon south of the I-80 corridor. A couple of smaller
outflow boundaries have spread north into the central/southern
parts of the Chicago metro area from this activity, with a few
isolated SHRA/TSRA primarily across the southern metro. Convective
SHRA/TSRA have generally struggled over the metro, and are not
expected to become widespread and should dissipate with sunset.
In addition, the lake breeze boundary had struggled to move
inland during the afternoon, remaining east of the terminals,
though has recently shown some west- southwestward push especially
north of ORD. Expectation is that the lake breeze will make it
into ORD this evening, with a wind shift to the northeast for a
time. However, presence of multiple convective outflow boundaries
across the metro makes the wind direction forecast rather
complicated in the near term. Winds should become light and
probably somewhat variable after sunset, before eventually turning
light east- southeast by Sunday morning with a bit of lake breeze
enhancement by early afternoon.
One other potential concern is with guidance depicting the
possibility of some fog/low stratus development mainly across
northern Chicago metro areas late tonight. Already some marine
haze noted in webcams along Kenosha-Racine WI shore late this
afternoon, and models indicate this may spread/develop inland late
tonight. Guidance seems to be somewhat overdone with the extent
currently based on Satellite imagery, though did indicate a tempo
for ORD of an MVFR vis/low IFR cloud layer pre-dawn. Confidence
is fairly low with this occurring and affecting ORD or other
terminals, but worth monitoring for early Sunday morning.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
603 PM CDT Sat Jun 27 2020
.SHORT TERM... (Through Late Sunday Afternoon)
Issued at 312 PM CDT Sat Jun 27 2020
Challenging convection forecast for this afternoon and tonight. An
MCV left over from last night`s convection over Kansas and Nebraska
is moving east across Missouri this afternoon. This MCV combined
with what`s left of a cold front is expected to produce another
round of thunderstorms later this afternoon and tonight...the
beginnings of which may be developing in central Missouri at this
time. Current thinking is that the showers currently forming will
continue to expand in coverage and strengthen through the afternoon.
The HREF ensemble paintball plot shows that the majority of the
members blow up convection along and about 40 miles north and
south of I-70 by late this afternoon. The area of convection
pushes south, likely due to outflow, and then starts drifting
north again as the warm front gets pushed northward by the low
level jet. If the RAP is right, there will be just enough
instability available for these storms to produce marginally
severe hail and wind, although any severe storms should be fairly
isolated and will probably weaken after sunset. Forecast
precipitable water approaching 2 inches and potential for back-
building/training storms is concerning for heavy rain and
flooding. Have decided not to issue any hydro watches at this time
as antecedent conditions are rather dry. Sunday should be quieter
than today with warming temperatures. There may be some lingering
showers/storms along the warm front as it continues moving
through Illinois...primarily during the morning.
Carney
.LONG TERM... (Sunday Night through Next Saturday)
Issued at 312 PM CDT Sat Jun 27 2020
Little has changed in the forecast for next week. Upper level
pattern becomes highly amplified with large cut off lows over the
eastern and western CONUS, and ridge extending from the deep south
north through the Mississippi Valley. This blocky pattern holds
into next weekend. Both the GFS and ECMWF ensembles show fairly
low standard deviation in the upper pattern, so confidence is high
in this forecast. This translates to a period of warm and humid
weather for the Mid Mississippi Valley with highs in the upper 80s
to low and mid 90s. Medium range guidance has been consistently
pushing a short wave into the upper ridge on Monday where it cuts
off and gets stranded over the Mid Mississippi Valley Monday night
into Tuesday. According to all of the guidance, this compact low
will be enough forcing to allow convection to develop each day
through the week despite the larger scale upper ridge. Have
therefore kept PoPs in the forecast through next Saturday.
Carney
&&
.AVIATION... (For the 00z TAFs through 00z Sunday Evening)
Issued at 553 PM CDT Sat Jun 27 2020
Storms will persist along and just south of the I-70 corridor for
the next few hours before storm chances shift into southern MO and
IL into the early morning hours. To the north and east of these
storms, guidance is showing at least a chance for cigs to drop
below 3kft, with the best chances toward UIN. Therefore have a few
hours of MVFR cigs at UIN and limited the St. Louis terminals to
SCT015 through tomorrow morning.
Around daybreak, storm chances will then shift back to the north,
moving out of the area by mid day. This will likely bring isolated
to scattered storms to the area, but confidence on these storms
impacting any of the terminals is low. For now have kept the TAFs
limited to VCTS during this period, though should a storm hit a
terminal, expect to see cigs and visbys ball below VFR criteria.
BSH
&&
.PRELIMINARY POINT TEMPS/POPS...
Saint Louis 73 95 78 95 / 70 40 10 40
Quincy 70 90 73 90 / 30 40 20 50
Columbia 71 91 73 90 / 50 20 10 40
Jefferson City 72 92 74 92 / 60 20 10 40
Salem 72 90 73 93 / 60 50 20 40
Farmington 73 91 73 91 / 60 20 10 30
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
1005 PM CDT Sat Jun 27 2020
.NEAR TERM /Now Through Sunday night/...A look at the geo-potential
height field aloft shows a short wave trof at H30 advancing eastward
across the northern border of AL/MS while in the lower levels,
high pressure over the FL Peninsula extends west into the central
Gulf coast. Even with the passing high level impulse, convection
has been spotty despite an environment that was loaded with
instability where MLCapes ranged from 2000 to 4000 J/KG. The only
item lacking was a point of surface focus. Otherwise, forecasters
expect the outcome would`ve been starkly different. Going into the
evening, the radar is quiet, but will maintain a small PoP north
of US Highway 84 where there is still potential for an evening
pop-up storm. The remainder of the night looks rain-free. Low to
mid-layer high pressure ridge over the Gulf noses northward over
the deep south Sunday. At H30 though, a trof axis aligned over the
southeast may be enough to support a chance of showers and storms
during time of max heating and atmospheric destabilization when
MUCape values swell to 2000 to 4000 J/KG. Deep layer moisture
changes little with afternoon PWAT values ranging 1.8 to 2 inches
which remains well above climatology for the end of June. Storms
Sunday afternoon could be strong at times; however, the shortwave
is not as potent and weak bulk-shear magnitudes favors a low risk
for any severe weather.
Temperatures will continue to be hot with highs in the upper 80s
along the coast to lower 90s inland. Some locations east of I-65
could see the mid 90s on Sunday as the influence of the upper
level shortwave ridge keeps cloud cover down and allows for max
solar heating before storms develop. Heat indices in these areas
possibly 100 to 105. Lows remain in the 70s. Perhaps upper reaches
of the 70s/near 80 over beach areas. /10
&&
.PREV DISCUSSION... /issued 559 PM CDT Sat Jun 27 2020/
AVIATION...
00Z issuance...The potential exists for isolated shra/tsra along
and north of US highway 84 this evening which could bring brief
lower cigs and strong gusty winds. Otherwise, mainly high based
clouds streaming eastward over the Gulf coast with VFR conditions
expected tonight. Light and variable to calm wind after sunset.
/10
PREV DISCUSSION... /issued 427 PM CDT Sat Jun 27 2020/
NEAR TERM UPDATE /Now Through Sunday/...Storms have struggled
this afternoon with dry air entrainment keeping storm development
quiet so far. Conditions are still favorable and what few showers
we have seen should help moisten up the environment to where
isolated to possibly scattered storms should still develop over
the northern half of the forecast area. Visible satellite shows
clearing over most of Mississippi with agitated cumulus across
most of the state. A weak boundary (likely seabreeze) was noted
surging northward across the area as another boundary from earlier
convection to our north drops south. What storms do develop will
likely be focused along these two boundaries and who sees rain
might be highly dependent on the location of mesoscale boundaries
this afternoon. If (starting to look like a bigger if) we can get
storms this evening, a severe thunderstorm could still be possible
with damaging winds.
PREV DISCUSSION... /issued 1256 PM CDT Sat Jun 27 2020/
Relatively zonal flow persists across the area as we are
sandwiched between a building upper ridge over the Florida
Peninsula and very subtle and weak troughing over northern
Pennsylvania and southern New York. Embedded in this flow is a
subtle but noticeable shortwave currently over south central
Louisiana. This shortwave will progress across the southern half
of our area as we head through the afternoon and evening.
Increasing ascent ahead of the shortwave coupled with increasing
low-level convergence proceeding the surging afternoon seabreeze
and a fairly deep moist profile with PWATS approaching 1.8 to 1.9
inches will be sufficient for storm development during the
afternoon. The best coverage will likely be north and west of I-65
where synoptic ascent will be maximized. Morning high res models
have depicted this; however, coverage on the models seems to be on
the lower side. This has been a common trend the last few days
and has always verified with more storms than modeled. With that
in mind, I kept pops near 50 percent over the far northwestern
locations decreasing to around 10% along the coast.
Storms this afternoon will have to watched carefully as SPC RAP
mesoanalysis shows between 2500 to 3000 J/KG of MLCape already
present. As the shortwave moves through, bulk shear values will
approach 35 knots which is supportive of at least some cold pool
maintenance and storm organization (likely multicellular
clusters/bowing segments). Looking at the 12z Jackson MS sounding,
steep 700-500 mb lapse rates approaching 9 degrees per KM with
drier air over top a very moist boundary layer would support the
production of wet microbursts capable of damaging winds. Some
small hail up to nickle and possibly quarter sized could occur in
the stronger storms given the lapse rates. The best chance for a
severe storm will likely be further northwest where the drier air
aloft is a little more prevalent. Nonetheless, conditions are
supportive across most of the area for gusty winds and the SPC has
highlighted most of the area in a marginal risk for severe
weather. Storms should subside late evening as the shortwave
progresses east and we enter the unfavorable left entrance region
of the jet streak.
Shortwave ridging will build over the area tonight before another
shortwave trough moves through the upper pattern tomorrow
afternoon. Once again another round of showers and storms will be
possible across the area. Some storms could also be strong;
however, the shortwave is not as potent and the lack of any shear
and drier air aloft will limit severe potential.
Temperatures will continue to be hot with highs in the upper 80s
along the coast to low 90s inland. Some locations east of I-65
could see the mid 90s on Sunday as the influences of the upper
level shortwave ridge keeps cloud cover down and allows for max
solar heating before storms develop. Lows will remain in the mid
70s given the high dewpoints. A low risk of rip currents will
continue through the period. BB/03
SHORT TERM /Sunday night Through Tuesday night/...An upper high
pressure area over the Gulf of Mexico will expand westward to
include northern Mexico through the short term. An upper ridge
extending northward from the north central gulf to the western
Great Lakes region will remain intact and shift slightly eastward
through noon Monday. The upper ridge will then breakdown into a
zonal flow over the southeast conus as a series of upper level
impulses and shortwaves exiting the central Great Plains passes
north of the area. Meanwhile, the local area remains on the
western periphery of a surface high in the western Atlantic, which
will maintain our general southerly to southwesterly flow.
The isolated to scattered convection late Sunday afternoon will
dissipate by sunset with the loss of daytime heating. Due to
influence of the upper ridge aloft, expect dry conditions Sunday
night through much of Monday morning, followed by scattered
afternoon showers and thunderstorms due to decreasing stability.
Again the convection late Monday afternoon will dissipate by
sunset with dry conditions overnight. Scattered afternoon showers
and thunderstorms are expected again Tuesday afternoon. A few of
the stronger thunderstorms both days could have brief gusty
strong winds.
Daytime highs Monday and Tuesday will range from 88 to 93 degrees,
and remain muggy. Expect widespread 100-105 heat index on
Monday and around 100 on Tuesday. Low temperatures will be a
carbon copy each night with temperatures only falling into the low
70s inland with upper 70s at the beaches. Rip current risk
remains LOW through the short term. /22
EXTENDED TERM /Wednesday Through Saturday/...A large upper level
ridge will build over the central conus through the remainder of
the week, while an upper low over the northeastern conus deepens.
An upper shortwave west of the low pressure will progress
southward over the Ohio River Valley on Wednesday. This upper
shortwave will continue to dive southward over the southeast conus
and stall through the remainder of the extended period, with a
possible cutoff low forming over the region on Friday. Meanwhile,
the local area remains on the western periphery of a surface high
as it migrates southward, but will still maintain a general
southwesterly to westerly flow through Friday. A cold front
approaching the region late in the week may stall across the
forecast area on Friday, and possible move as far south as the
northern gulf coast late Friday night into Saturday morning. With
a slight increase in overall moisture, the upper trough, and a
frontal boundary passing through, there will be the potential for
daytime scattered to likely showers and thunderstorms mid week,
and numerous to categorical showers and thunderstorms Thursday
through Saturday. Isolated to scattered convection is expected
during the overnight hours. /22
MARINE...A light southerly flow continues through Tuesday with
occasionally moderate onshore flow over the nearshore waters and
bays during the afternoon. Isolated showers and thunderstorms will be
possible each afternoon along the seabreeze and nearshore waters and
bays. Winds will become more westerly by Wednesday and Thursday.
BB/03
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&
$$
This product is also available on the web at:
http://weather.gov/mob
Area Forecast Discussion
National Weather Service Marquette MI
750 PM EDT Sat Jun 27 2020
.SHORT TERM...(This evening through Sunday)
Issued at 326 PM EDT SAT JUN 27 2020
Water vapor imagery and RAP analysis show mid to upper level ridge
beginning to amplify over the central CONUS in response to a trough
now digging into the Pacific NW Coast. The central CONUS ridge will
continue to amplify through the rest of the weekend into early next
week over the Western Great Lakes as the trough over the western
CONUS continues to amplify and a blocking closed low sets up over
New England. This amplifying ridge will lead to dry conditions and a
warming trend over the area. As for today, conditions have been
drier with some gustier nw winds of 15-20 knots in the wake of last
night`s cold frontal passage. Some lingering moisture and cyclonic
flow near a shortwave trough moving through eastern Ontario has led
to some stratocumulus clouds and patchy fog over eastern Lake
Superior and eastern Upper Mi this morning into early afternoon, but
expect these clouds and fog to dissipate with increased ridging from
the west later this afternoon. Onshore nw flow along with a
developing lake breeze have kept conditions cooler immediately
downwind of Lake Superior this afternoon with highs generally in the
lower to mid 70s, and it might not get out of the 60s for locations
stuck longer in lower cloud cover along the eastern Lake Superior
shoreline. Farther inland, well away from Lake Superior`s influence,
temp readings near the WI have made it into the lower 80s.
Tonight, a surface ridge moves across the Upper Peninsula tonight
as upper-level ridging starts to build into the region. This will
favor a pleasant night with light winds and clear skies. After
midnight, return flow starts to work into western parts of Upper
Michigan where overnight lows will remain milder, in the mid to
upper 50s. Across the east, where the center of surface ridging
will track, overnight lows will be locally cooler, perhaps dipping
into the upper 40s at some locations. There could be some patchy
fog that develops overnight, but given the drier air working into
the region confidence wasn`t high enough to include mention within
the forecast at this time.
Sunday, mid-level ridge will continue to amplify over the western
Great Lakes to Hudson Bay, supporting sfc high pres ridging from
Hudson Bay to MI. Meso highs will develop during the day over far
eastern Lake Superior and northern Lake MI, resulting in onshore
winds off Lake MI and onshore winds with an easterly component along
Lake Superior. Lake breeze may fail to push much onshore over far
western Upper MI. Under mostly sunny skies, expect highs in the 80s
in the interior, warmest w.
.LONG TERM...(Sunday night through Saturday)
Issued at 342 PM EDT SAT JUN 27 2020
Upper level ridge axis moving into the Mississippi River Valley
Sunday will set off an omega-like blocking pattern that will extend
through much of the extended period. As this ridge settles in and
continues to build into northern Canada, anomalous troughing will
amply in the western CONUS through the middle of next week while
an mid-upper level low remains nearly stationary over the
northeast. This will position the Upper Great Lakes on the
cyclonic side of the ridging, which will expose the region to a
few northward propagating short waves moving through the trough
into Canada. Through the week the western CONUS trough will
deamplify which will result in the some uncertainty in the ridge.
Overall, this will result in a few opportunities for precip early
in the week in the west and be accompanied by warm to hot
temperatures and high humidity.
Confidence is high that daytime surface high over the region will
erode as a shortwave lifts into the region Sunday night into Monday.
12z guidance has become more consistent, reaching more of a
consensus then previous runs on the evolution of this feature. By
Monday morning, the shortwave looks to lift into mainly the
western portion of the forecast area. This would bring a chance of
precip mainly to the west and central. Daytime instability looks
to increase so its possible there could be some thunderstorms, but
severe weather is not anticipated given the weakly shear`d
environment. As ridging over Ontario stretches west during the
day, this looks to elongate and slow/stall the feature over the
Arrowhead to just north into Canada through early Wednesday.
Elected to keep chance PoPs over mainly the western lake and
western UP through Wednesday morning. PWATS within this airmass
will be anomalously high, and moderate to heavy rain cannot be
ruled out in any showers. With 850mb temps climbing near 16-19C
Monday and Tuesday, surface temps in the mid 80s is looking likely
away from the lakeshores and near 80 by the lakeshores. Some
isolated pockets near 90 cannot be ruled out in areas prone to SE
downsloping, especially if widespread precip doesn`t take place.
With the weak synoptic flow, afternoon lakebreezes could help to
cool things off some in the late afternoon. Guidance suggested
the dewpoints climbing into the 60s is likely as well, and some
suggested near 70 in the west. Overnight lows in the 60s are
expected, but with little relief in humidity, expect the
uncomfortable days to transition into uncomfortable nights.
Beyond this, model guidance begins to diverge on how the mid-
upper level ridging will unfold. The 12z guidance suggests the
upper level ridge continuing to block any incoming shortwaves from
the south and even the north on the east side of the ridge. Given
how much the model guidance has changed between the previous 0z,
6z and now 12z runs, confidence is low on how effective the ridge
will be at keeping the region dry. Consistent signals between
model runs for the heat and some humidity to stick around during
the remaining week are there so continued the heat going into the
4th of July.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 749 PM EDT SAT JUN 27 2020
VFR conditions are expected through the forecast period with winds
under 10 knots.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 326 PM EDT SAT JUN 27 2020
Surface high pressure stationed over the area will keep winds below
20 knots this weekend into next week. Expect patchy fog over eastern
Lake Superior this afternoon into tonight.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...JP
AVIATION...JLB
MARINE...Voss
Area Forecast Discussion
National Weather Service Paducah KY
856 PM CDT Sat Jun 27 2020
.UPDATE...
Issued at 846 PM CDT Sat Jun 27 2020
We have allowed the Lake Wind Advisory to expire, and issued a
Flash Flood Watch for the Evansville Tri State area through 18Z
Sunday.
The first round of heavy rainfall that is currently exiting the
area produced 1 to 2 inches of rainfall over much of the Flash
Flood Watch area. This has basically primed the pump for the next
18 hours or so. The next round of convection is approaching from
eastern Missouri. Recent runs of the HRRR indicate that multiple
rounds of convection will traverse the northeast portions of the
forecast area through the night into Sunday morning, as
persistent 30kt 850mb southwesterly flow provides a constant
inflow of moisture to the area.
WPC QPF now has 1.5" to nearly 3" through 18Z Sunday. It had been
pretty dry recently, so much of the region will likely be able to
handle a couple of inches of rainfall, but some less fortunate
areas, could see some flash flooding. The threat will increase
with each round of convection. Extensions of the Watch may be
needed.
&&
.SHORT TERM...(Tonight through Sunday night)
Issued at 320 PM CDT Sat Jun 27 2020
The biggest concern in the short term seems to lie with the heavy
rain potential from repeating/back-building storms along/east of
the MS River tonight into early Sunday, as a trof of low pressure
aloft works its way from the MS River Valley east into the lower
OH Valley. Low level (H925 to H85) moisture transport is expected
to increase tonight ahead of the the trof as swly winds pick up.
Could also see PWs up close to the 99th percentile of normal for
late June. However, given degree of placement/timing uncertainties
and the fact that much of that region has been placed in D0
drought, decided to hold off on a flash flood watch at this time.
Should see a return to some sunshine from west to east slowly
during the day Sunday, once the trof axis shifts farther east.
However, should end up pretty darn uncomfortable Sunday afternoon,
esp over se MO/far western KY and southwest IL, with sticky dew
points in the lower half of the 70s and heat index values creeping
up close to the century mark.
.LONG TERM...(Monday through Saturday)
Issued at 320 PM CDT Sat Jun 27 2020
The start of the extended forecast will see a blocking ridge in the
middle of the country, flanked on both sides by closed lows. The
models have shifted the ridge slightly east this run, putting the
Quad State near the center of the ridge axis. The low to the
northeast will have a trailing cold front across northern Ohio to
Illinois. Precipitation Monday remains more likely in the northern
and eastern portions of the forecast area, closer to the front.
However, with the models centering the low slightly further east,
PoPs Monday are lower than in previous runs. This front will slowly
drift southward over the following days.
The GFS, Canadian, and ECMWF all place an upper-level low in
Missouri on Tuesday. Tuesday through Wednesday is when the models
are most agreeable on putting the Quad State to the east of this
system. With instability provided by the low and moisture from the
Gulf, this would be the most likely period in the extended to have
thunderstorm activity.
For the remainder of the workweek, there is ample opportunity for
precipitation to occur with the stalled out front or the upper-level
low meandering around the middle Mississippi Valley providing a
focus for developing convection. Declining model agreement at this
range is what leads to a decrease in PoPs and thunder chances.
By the end of the week the eastern closed low will head out into the
Atlantic. The closed low to the west will have moved towards Canada
along the ridge. The ridge itself will decrease in amplitude but
broaden in both directions to cover most of the contiguous United
States. This will leave the upper-level low as the primary remaining
region for development of storms.
Highs at the start of the long term will be driven by Gulf flow,
reaching the upper 80s to lower 90s Monday and Tuesday. Afterwards,
influence from the cold front to the north slowly dropping southward
through the area will result in slightly cooler highs for the
remainder of the workweek. Gulf moisture will keep dew points near
70 and lows in the lower 70s.&&
.AVIATION...
Issued at 632 PM CDT Sat Jun 27 2020
Tracking thunderstorm complexes across the taf sites is the main
forecast issue. One round of storms over the kevv/kowb areas at 23z
will pass quickly east of the area. Another round of storms over
east central Missouri at 23z will move east across southern
IL/southwest IN/northwest KY late this evening into the overnight
hours. Current indications are that kcgi/kpah will be on the
southern fringe of this activity. Once the activity sets in,
widespread mvfr cigs are likely to become entrenched at least
through midday Sunday. However, kpah and kcgi are currently expected
to remain vfr as the bulk of these storms should stay north of those
sites. Winds will remain southwest, becoming gusty during the
daytime hours.
&&
.AVIATION...
Issued at 632 PM CDT Sat Jun 27 2020
Tracking thunderstorm complexes across the taf sites is the main
forecast issue. One round of storms over the kevv/kowb areas at 23z
will pass quickly east of the area. Another round of storms over
east central Missouri at 23z will move east across southern
IL/southwest IN/northwest KY late this evening into the overnight
hours. Current indications are that kcgi/kpah will be on the
southern fringe of this activity. Once the activity sets in,
widespread mvfr cigs are likely to become entrenched at least
through midday Sunday. However, kpah and kcgi are currently expected
to remain vfr as the bulk of these storms should stay north of those
sites. Winds will remain southwest, becoming gusty during the
daytime hours.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Flash Flood Watch through Sunday afternoon for ILZ075>078-082-
083-087.
MO...None.
IN...Flash Flood Watch through Sunday afternoon for INZ081-082-
085>088.
KY...Flash Flood Watch through Sunday afternoon for KYZ014-015-
018>020.
&&
$$
UPDATE...DRS
SHORT TERM...GM
LONG TERM...ATL
AVIATION...MY
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Sunday)
Issued at 349 PM CDT Sat Jun 27 2020
Cloud cover has been slow to clear out in far eastern KS, having
only scattered out in the last hour or so as of 20Z. The rest of the
area has seen clearing skies with mesoscale subsidence behind this
morning`s storm complex. 20Z water vapor imagery shows the remaining
MCV well off to our east with a shortwave in CO ahead of a broad
trough over the Pacific Northwest. As a result of the clouds, have
trimmed highs for a small eastern part of the forecast area to the
low to mid 80s, while everyone else should still reach the upper 80s
to low 90s with more insolation occurring this afternoon. Regarding
thunderstorms late this afternoon/early this evening, have backed
down on PoPs with only low-end chances remaining through tonight.
The HRRR has been showing a decreasing trend throughout the day
likely due to less destabilization, with only a few isolated storms
popping up in east central KS after 02Z. Since CIN increases by this
time, thinking this might be a result of speed convergence with a
strengthening LLJ later this evening. In any case, any storms that
develop are expected to be isolated and short-lived. North central
KS could see storms overnight associated with the shortwave
currently in CO; however, these are expected to weaken as they move
northeast through the state.
Southwesterly flow is expected to keep plenty of moisture in the
area on Sunday with hot temperatures in the 90s area-wide. Heat
indices are forecast to reach the 98 to 105 degree range. Have held
off on issuing a Heat Advisory for now, but one may be warranted if
these trends continue and confidence in reaching criteria increases.
.LONG TERM...(Sunday night through Saturday)
Issued at 349 PM CDT Sat Jun 27 2020
The broad trough previously mentioned will slowly progress into the
western US and then weaken later this week, with embedded waves
bringing small precipitation chances on and off throughout the week.
The main story will be the persistent heat as high temperatures
reach the 90s each day this week and morning lows only fall back to
the 70s. These hot temperatures with dew points in the 70s will
combine to bring heat index values in the upper 90s to low 100s, so
we will need to monitor the potential for heat headlines.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 621 PM CDT Sat Jun 27 2020
A few isolated storms will be possible south of the terminals this
evening, but are expected to dissipate in the next 1-2 hours and
should not impact any of the TAF sites. Winds at 2-3 kft will
increase out of the southwest early Sunday morning, resulting a
period of LLWS or low-level turbulence at all sites, especially
KTOP and KFOE. Although there is a small possibility of some
storms developing around the area during the early morning hours,
uncertainty is too high to warrant a mention with this issuance.
Ceilings are expected to remain VFR, and winds will increase out
of the south by late morning, becoming gusty by 18z.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Picha
LONG TERM...Picha
AVIATION...Laflin
mentioned in the previous long term forecast discussion,
deterministic models are beginning to show increased moisture across
Arizona, perhaps enough to generate some showers and thunderstorms
for Mohave County as early as Thursday and lingering with a similar
pattern through the weekend. At the moment, a slight uptick in PoPs
were noted in the morning run of the NBM for these periods, but not
enough to produce QPF or mentionable Wx, keeping this well east of
the CWA. However, ensemble meteograms of both the EC and GEFS show
about 10% of members indicating precip as far west as Kingman
beginning Friday. Would not be surprised to see PoPs increase in
later forecasts as a result.
&&
.FIRE WEATHER...Not much change to the fire weather forecast
through the weekend. Elevated fire conditions today as increasing
winds out of the south and southwest today reach up to 30 mph but
staying below critical. The main focus is Sunday where a well
forecast wind event will take place, ramping up by late morning and
persisting through the evening hours. While critical thresholds look
to be exceeded across the Great Basin, highest wind gusts will be
higher elevations of the eastern Sierra and Spring Mountains. Gusts
over 60 mph out of the west/southwest respectively are not out of
the question, especially for the Sierra slopes south of Aspendell to
Olancha. Peak gusts are expected between 3PM and 9PM in those areas.
Winds should decrease through the overnight hours Sunday night into
Monday morning with the main system shifting east. Wind gust
potential is significantly lower Monday but still near critical for
northwest Arizona (zone 102).
&&
.AVIATION...For McCarran...Winds will favor the easterly direction
early this afternoon; becoming more southerly between 22z-00z.
Speeds during this time should remain around 10 knots or less with
intermittent gusts to around 15 knots possible. Overnight, south to
southwest winds will remain up around 9-13 knots with continued
gustiness. Winds will begin to rise around 15z on Sunday and peak
between 21z-01z Sunday afternoon at speeds of 20-30 knots gusting up
to 40 knots.
For the rest of southern Nevada, northwest Arizona and southeast
California...Breezy, south to southwesterly winds are expected for
much of the area this afternoon and into tonight. An isolated shower
or storm will be possible overnight across northern Lincoln County
but otherwise dry for the period. Southwest winds will begin to pick
up between 15z-18z on Sunday morning; peaking between 21z-03z.
Widespread wind speeds of 20-30 knots gusting 30-40 knots are
expected through tomorrow evening.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
UPDATE...Pierce
DISCUSSION...TB3
AVIATION...Guillet
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