Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/21/21
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1154 PM EDT Sun Jun 20 2021
.SYNOPSIS...
A warm front will move across the region tonight with some
isolated showers or thunderstorms. A hot and humid air mass will
open the first full day of summer. The threat of strong to
severe thunderstorms with locally heavy rainfall ahead of a cold
front will increase Monday afternoon into the evening. A much
cooler air mass will build into the region in the wake of the
cold front on Tuesday with showers ending.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
.UPDATE...Cluster of storms developed over central NY and has
moved northeastward into our forecast area. This activity is
expected to weaken as it moves away from the unstable air over
the next couple/few hours, then gradually increase pops to
isolated/scattered as the next potential cluster of showers and
a few thunderstorms develops in central NY and moves across
areas north of I-90 late overnight, as a dewpoint boundary
continues to lift northward. 00Z HRRR solution looks reasonable
depicting this. 00Z KALY sounding revealed fairly steep 700-500
mb lapse rate of 7.0 degC/Km, which could support some thunder.
Will have to watch for isolated convection farther south, but
can be added if needed in the next update. It will be warm/muggy
across much of the area through the night.
.PREVIOUS [0753]...Tranquil conditions in place early this
evening. Moderate instability in place south of Albany, although
no forcing mechanisms present for any showers or storms at this
time. Also, near term forecast soundings indicate plenty of dry
air aloft.
Nearest cluster of convective showers and thunderstorms
currently near KBGM over the southern tier of NY. This activity
should generally track NE tonight and possibly move into the
northwest half of our region overnight. CAMs have been
inconsistent in showing where this convection will track. This
activity should generally hold together, as a warm
front/dewpoint boundary lifts northward overnight resulting in
sufficient instability and moisture. For now will mention
isolated to widely scattered showers and storms for areas north
of Albany after midnight, but the timing/coverage will likely
need to be refined with the next update later this evening. Will
continue to monitor trends.
A weak surface anticyclone will move away from the region into
tonight. The mid and upper level flow becomes southwesterly
ahead of an approaching upper level trough over the Great Lake
Region and Upper Midwest.
The warm front or leading edge of humid air will move northward
across the region tonight, as the boundary layer flow increases
out of the south. Showalter values dip in the zero to -3C range.
The elevated instability, and increased low-level theta-e
advection will allow for some isolated showers or thunderstorms
to form overnight. The better elevated instability expands
northward between 06Z-12Z/MON. Slight to low chance PoPs were
kept in north and west of the Capital Region. It will become
muggy with lows in the 60s and a few upper 50s over the southern
Dacks.
Summer begins at 1132 pm EDT tonight.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
Heat Advisory posted for the Hudson River Valley including
the Glens Falls area, southern Washington and Montgomery
Counties noon to 6 pm EDT Monday...
Marginal to Slight Risk of Severe Thunderstorms Monday
Afternoon into the Evening...
Tomorrow...The first full day of summer will likely begin with a
bang! Heat and humidity surges into the forecast area in a warm
sector ahead of a pre-frontal sfc trough and a cold front. Sfc
dewpts surge into the 60s...possibly widespread mid and upper
60s with isolated 70F readings. H850 rise above normal into the
+17C to +19C range. The combination of the heat and humidity
will allow for heat indices to get into the mid and upper 90s in
the Hudson River Valley including the Capital District, Saratoga
Glens Falls area, and portions of the central Mohawk Valley, so
a Heat Advisory has been posted. An expansion of the head line may
be needed.
The instability will build across the region with SBCAPES
reaching the 1500-2500+ J/kg range. The 0-6 km bulk shear
increases to 30-40+ kts especially from the Capital Region north
and west, and the low-level jet increases from the south during
the late morning into the afternoon. The pre-frontal trough
/PFT/ likely focuses some organized deep convection with multi-
cells and some supercells in the early to mid pm. Mid level
lapse rates are marginal at 6-6.5C/km but model sounding
indicate thick CAPE between -10C and -30C. DCAPE values increase
greater than 1000 J/kg with steep low-level lapse rates. We
believe damaging winds will be the main threat, but some large
hail and isolated tornadoes are possible W/NW of Albany. The
latest 12Z HREFS have STP values 1 to 3 over the northern zones
closer to the low-level jet.
All modes of severe look possible and any discrete convection
should form into lines ahead of the PFT and then the cold front
which arrives towards nightfall. The SPC Day 2 Outlook looks
good and the greatest threat of severe weather looks like the
I-90 corridor including the Capital District and northern Berks
north and west into the eastern Catskills 18Z/2 pm MON to
04Z/Midnight. Max temps will be in the upper 80s to lower 90s in
the valleys, and upper 70s to mid 80s over the hills and mtns.
See the hydro section for the heavy rain threat.
Monday night...Convection continues into the night time period
with strong upper jet dynamics arriving, but instability will
be waning. Heavy rain will continue to be a threat with PWATS a
couple STDEVs above normal in the 1.25-1.75" range with slightly
higher amounts. We will continue to monitor for locally heavy
rainfall, but the convection should weaken after 06Z/TUE. Lows
will be in the 50s west of the Hudson River Valley, and lower to
mid 60s to the east with spotty cooler values over the higher
terrain.
Tue-Tue night...The cold front slowly moves across the region
with occasional showers through the morning, but the pcpn should
diminish to the north and west of the Capital Region by the
afternoon, and quickly moving move away to the south and east by
the mid to late pm. It will be much cooler and brisk with highs
only the 60s to lower 70s with some upper 50s over the mtns. The
chilly air mass builds in Tue night with decreasing winds
clearing skies. Lows will be 40s with some upper 30s over the
southern Dacks, and eastern Catskills.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The period starts out on Wednesday with an upper level short
wave exiting to our east in New England and surface high
pressure in place. This should result in dry conditions with
mostly sunny skies. Temperatures will be on the cool side, with
850 mb temp anomalies of -1 to -2 STDEV forecast from the NAEFS
ensemble. Highs should run about 5-10 degrees below normal
with.
High pressure will gradually shift eastward off the New England
coast on Thursday, but still providing dry conditions. Low
level flow will become southerly, allowing for temperatures to
warm closer to normal for highs after a cool start to the day.
Humidity levels will continue to be noticeably low with
dewpoints mainly in the 40s to lower 50s.
Further warming is expected on Friday, as upper level heights
rise and low level southerly flow increases. An upper level
trough will start to approach from the Midwest and upper Great
Lakes, but should remain far enough to our west for continued
dry conditions.
Next weekend looks to be rather unsettled, as the
aforementioned upper level trough upstream moves eastward with
the main trough axis remaining just to our west across the
central/lower Great Lakes. This will provide a warm/moist south-
southwest flow across the Northeast. PWAT anomalies are forecast
to rise to +1 to +2 STDEV and a surface front may stall
somewhere over the region. Too far out to pinpoint specific
details, but showers with some thunderstorms seem likely with
locally heavy rainfall at times especially late Saturday through
Sunday. ECMWF/GFS in generally decent agreement with regards to
the upper level pattern evolution. Will mention highest
probability for more widespread showers and storms on Sunday.
&&
.AVIATION /04Z MONDAY THROUGH FRIDAY/...
A warm front will lift northward across the region tonight.
Isolated to widely scattered showers and thunderstorms will be
possible late tonight at KGFL. Convective activity should
remain north of the other TAF sites. Will mention PROB30 for
possible TSRA between 09Z-13Z at KGFL, although the time frame
may have to be adjusted based on subsequent guidance.
Mainly VFR conditions expected to prevail through much of the
night. However, with increasing moisture due to low level
southerly flow some low stratus clouds may develop and get as
far north as KPOU/KPSF. Best chance for MVFR cigs between 08Z-
12Z at these sites. At this time the low stratus clouds are
expected to be south of KALB.
VFR conditions should prevail much of the day Monday once any
low level cigs scour out. There is a chance of scattered strong
to severe thunderstorms late Monday afternoon into Monday
evening. Will mention PROB30 at all TAF sites for now, with
possible IFR conditions associated with any TSRA.
Winds tonight will be variable around 5 kt or less, becoming
southerly on Monday and increasing to 10-15 kt with gusts around
20-25 kt. Strong wind gusts will be possible with any TSRA as
well.
Outlook...
Monday Night: High Operational Impact. Breezy. Likely SHRA...TSRA.
Tuesday: Moderate Operational Impact. Chance of SHRA.
Tuesday Night to Friday: Low Operational Impact. NO SIG WX.
&&
.FIRE WEATHER...
A warm front will move across the region tonight with
some isolated showers or thunderstorm. A hot and humid air mass
will open the first full day of summer. The threat of strong to
severe thunderstorms with locally heavy rainfall ahead of a cold
front will increase Monday afternoon into the evening. A much
cooler air mass will build into the region in the wake of the cold
front on Tuesday with showers ending.
The RH values will rise to 85 to 100 percent tonight. The RH
values will drop to the 45 to 60 percent range Monday afternoon with
showers and thunderstorms moving into the region. The max RH
values will be close to 100 percent Tuesday morning.
The winds will become southerly at 5 to 15 mph tonight.
Southerly winds will increase to 10 to 20 mph Monday afternoon with
some gusts 30 to 35 mph possible in the Hudson Valley. The winds
will shift to the southwest to west at 10 to 15 mph Monday
night.
Stronger wind gusts are possible with thunderstorms Monday
afternoon into the evening.
&&
.HYDROLOGY...
No significant hydro issues are expected on the main stem rivers
the next several days.
Late this pm into tonight looks to be mainly dry with isolated
showers or thunderstorms ahead of a warm front.
There is a potential for locally heavy rain Monday into
Tuesday ahead of a pre frontal trough and a cold front. Some
notable within bank rises may occur on creeks, streams, brooks
and maybe main stem rivers. Ponding of water on roadways and
standing water in low lying areas is possible in thunderstorms
Monday into Tuesday. Poor drainage flooding is also possible.
The showers should end Tuesday late morning into the afternoon
with bodies of water seeing lowering flows and levels as a dry
period of weather occurs through the mid week.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Heat Advisory from noon to 6 PM EDT Monday for NYZ040-041-049-
050-052-053-059-060-064-065-083-084.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Wasula
NEAR TERM...IAA/JPV/Wasula
SHORT TERM...Wasula
LONG TERM...JPV
AVIATION...JPV
FIRE WEATHER...Wasula
HYDROLOGY...NAS/Wasula
Area Forecast Discussion
National Weather Service Amarillo TX
713 PM CDT Sun Jun 20 2021
.AVIATION...00z TAF Cycle...
VFR conditions will prevail through 06z, with isolated storms
near KAMA through about 02z. At this time, storm activity is
south of KAMA by about 15 miles and storm motion is southeast.
Based on this, did include a VCSH to account for potential, but
at this time it appears all lightning will remain outside the 10
mile ring. A cold front will bring gusty northeast winds starting
around 06z to 09z Monday. A few gusts could approach 40 knots at
KAMA and KDHT between 10z and 15z. MVFR cigs are also expected to
fill in behind the cold front at all terminals. Some IFR can`t be
ruled out. VFR may not return until late Monday morning or even
early Monday afternoon.
Ward
&&
.PREV DISCUSSION... /Issued 224 PM CDT Sun Jun 20 2021/
DISCUSSION...
A pattern shift is ongoing across the region this afternoon as the
upper level high over the desert southwest continues to move
towards the southwest over northern Baja California. Northwesterly
flow aloft is being observed on the latest water vapor satellite
imagery and GOES satellite wind plotter data, with thunderstorms
starting to fire over the New Mexico mountains. Surface
observations show a surface trof draped southwest to northeast
across the northwestern half of the combined Panhandles, which
will potentially serve as a focal point for late afternoon and
early evening shower and thunderstorm activity. In addition, quite
a few observations show 100 to 104 degree temperatures across the
region, both ahead of and behind the surface trof, with cooler
temperatures behind a cold front presently over east central
Colorado and northwestern Kansas. Latest mesoanalysis shows that
instability is increasing across the region, with CAPE values
around 1000 to 1500 J/kg mainly along the surface trof. There is a
strong cap in place and subsidence aloft that needs to be
overcome, though a vorticity max does appear to be transiting the
region this afternoon. Given these factors, a few high resolution
models do suggest a thunderstorm or two break out mainly after 5
PM where the cap can be reached along the surface trough, with
isolated thunderstorms introduced to account for that potential.
Later this evening, a cold front will move into the area with some
disagreement among the CAMS guidance as to whether anything is
going to occur. The RAP is the least favorable of the bunch, while
the HRRR and the NAMNest are both showing showers and
thunderstorms occurring along the frontal boundary as it
progresses south late tonight into early Monday morning. The main
disturbance supporting this frontal boundary activity is presently
moving into Wyoming, and is pushing a shortwave trof across the
Colorado Rockies. It will be these features that must align with
the cold front in order to cause thunderstorms to occur, with the
Oklahoma Panhandle and northeastern Texas Panhandle favored.
Activity should exit east of the area by midday Monday, with low
and mid level clouds filtering in behind the cold front helping
to keep daytime high temperatures in the 70s (a few 80s cannot be
ruled out) Monday afternoon.
Tuesday will see a rebound in temperatures as the upper high
starts to strength once more and the main ridge axis pushes east
into New Mexico. On Wednesday and Thursday, the center of the
upper level high will be over west Texas with the ridge axis
across the combined Panhandles. High temperatures recover into the
mid 80s east and mid 90s west on Tuesday as a result of rising
heights aloft, and into near record/record territory with nearly
the entire region seeing triple digit heat return. A Heat Advisory
will become necessary for Palo Duro Canyon and Hutchinson County
once more for both Wednesday and Thursday afternoon if the
forecast trend holds, as high temperatures could reach as high as
107 to 108 degrees for both locations.
Towards the latter end of the forecast period, medium range
guidance is showing another shortwave disturbance moving
southeast out of Canada and diving down the front range of the
Rockies Friday into Saturday. This will help to bring back
northwest flow aloft late Thursday night, and better chances for
precipitation for Friday and Saturday as dynamics aloft become a
bit more favorable for activity to make it to the region from the
mountains of New Mexico and Colorado. It is a bit early to tell if
there is any severe potential with such activity, let alone where
the best chances may lie until details come into focus. However,
with that being said, this is our next window of opportunity for
precipitation in the region, as these extended dry streaks have
done us no favors in keeping up with year-to-date precipitation
averages.
Bieda
AVIATION...Previous Discussion...18Z TAFs...A surface trof is in
the Texas Panhandle this afternoon, which has made the winds
variable at KDHT and northerly at KGUY. This feature should slowly
progress south, and could help cause an isolated thunderstorm
near KAMA AFT 20/22Z. The coverage of such thunderstorms will be
sparse enough to not mention at this time. A cold front will be
moving into the Texas and Oklahoma Panhandles late this afternoon
and evening, which will increase northerly to north-northeasterly
winds to around 15 to 25 kts with gusts as high as 35 to 40 kts.
In addition, some light showers and thunderstorms could form along
and behind this front, though there is only enough certainty to
prevail such a condition at KGUY BTWN 21/10Z thru 21/16Z. Lower
CIGs are also being hinted at by some high resolution models with
this cold front, possibly as low as 1500 to 2500 feet AGL, which
will need to be monitored with the future TAF issuances.
Bieda
&&
.AMA Watches/Warnings/Advisories...
TX...Heat Advisory until 8 PM CDT this evening for the following
zones: Hutchinson...Palo Duro Canyon.
OK...None.
&&
$$
7/99
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
745 PM EDT Sun Jun 20 2021
.AVIATION...
Scattered showers and thunderstorms will work northeast into the
area this evening with another round sweeping through the region
overnight in advance of cold front. Degree of convection during the
time frame between these two periods remains in question. Coverage
will be greatest from KPTK south this evening and perhaps KPTK north
overnight although confidence remains pretty low for overnight
placement. Strong post frontal cold advection on Monday looks to
sustain MVFR clouds before lifting into low VFR later in the day,
with scattered light showers possible. West-northwest winds will be
strong throughout the day, generally 15-20 knots sustained, with
gusts of 25 to 30 knots at times.
For DTW...Thunderstorm chances increase quickly in the 00z-01z time
frame and persist until 04-05z. Another round may also occur
overnight with a cold front.
.DTW THRESHOLD PROBABILITIES...
* High for cigs aob 5000 feet this evening through Monday.
* High for thunderstorms this evening, low overnight.
&&
.PREV DISCUSSION...
Issued at 401 PM EDT Sun Jun 20 2021
DISCUSSION...
A convectively induced shortwave that has emerged out of the Central
Plains/Kansas City has been the dominant feature in driving a line
of shower and thunderstorm activity today across portions of
Missouri and Iowa. Thus far, the activity has been struggling to
become organized because of a convectively overturned and high CIN
thermodynamic environment out ahead of it across western Illinois.
The convectively induced shortwave is in a good location, just ahead
of the longer axis of stronger absolute vorticity and broader
cyclonic flow, to act as a warm advection wave and release
northeastward along a line from southern edge of Chicago toward
Detroit. For the most part, visible satellite imagery has shown a
high amount of insolation ahead of this MCV, particularly across
much of Southeast Michigan. RAP based mesoanalysis shows a tight
surface based CAPE gradient in place along a stationary front,
draped from the southern rim of Lake Michigan eastward long the
southern Michigan border to the south shore of Lake Erie. Surface
based CAPEs of 3000-4000 J/kg are in place to the south of the
gradient with mixed layer CAPE of at least 2000 J/kg immediately
south of Toledo.
Modeled parameter space shows very little change to the shear and
instability fields over the forecast area through approximately 00Z.
Quickly thereafter, models have sub 850mb wind speeds rapidly
increasing immediately south of the stationary front as it begins to
advance northward. Uncertainty exists with how progressive/how far
northward this warm front will make it but current indications
suggest as far north as I 96 or M 59. Expectations are for the
ragged line to fill in with time this afternoon as it crosses and
interacts with greater instability south of Lake Michigan and across
northern IN/OH. Combination of instability and shear suggests
scattered multicellular to possible supercellular storm mode
possible across the far southern forecast this evening. Combination
of CAM Hires consensus corroborates latest Time of Arrival time of
00-03Z as greatest threat time for severe weather. Without a forward
propagating cold pool the storm threats include: damaging wind gusts
to 60 mph, large hail in excess of 1 inch, and potential tornado.
The greatest tornado threat appears dependent on any discreet
supercell activity or interaction of bowing segments normal to the
advancing warm front.
Uncertainty does exist after this first wave, particularly with how
much lingering activity will persist in the 05-09Z time window. HRRR
runs and ARW advertises that convection and thunderstorm activity
will continue to fire over/near the southern three tiers of counties
including Metro Detroit. Despite the evening activity, cannot
discount this continuation of thunderstorm idea because of the
nature of the warm advection wave and rich low-midlevel thetae that
is forecasted to lift directly into the state ahead of the
geopotential height falls. Severe weather potential remains with
this activity during the overnight period given projected shear and
instability. The second wave of more organized shower and embedded
thunderstorms will be late tonight primarily in the 7-10Z time
window. While shear remains very high late tonight for storm
organization, the severe potential is expected to be less early
Monday morning with less CAPE density and high static stability in
the lowest 5000 ft agl.
Will need to watch for localized heavy rainfall for those areas that
receive multiple rounds of heavy rainfall tonight. Confidence is too
low for any flood products, particularly low confidence in the
morning line holding together.
Cold advection will occur for all of Southeast Michigan by 15Z
Monday as cold front sweeps across the area. Models show good bet
for clouds locked in the 3.0-4.0 kft agl layer at the base of strong
subsidence inversion with convective debris high cloud overspreading
aloft. Temperatures are expected to peak during the morning hours
and fall into the 60s for most areas during the afternoon. A
secondary cold front is then progged at 03Z Tuesday which will take
the rug out on temperatures. 850mb temperatures of 0-1C will make
for a very chilly late June night. In fact, temperatures are
expected to drop into the 40s areawide, potentially below 40 in
northern Midland County.
Models are showing that stable high pressure will hold across the
region through the middle of the week. Finding it difficult to
believe totally dry QPF solutions as cold midlevels could support
some afternoon instability showers. Will need to watch the Tuesday
and Wednesday afternoon time periods for slight chance/chance PoPs.
The extended period is advertising the potential for a tilted upper
level ridge to extend into Southeast Michigan Thursday and Friday.
Another deep trough axis is shown to track across Canada and impinge
on the western Great Lakes. d(prog)/dt has shown a westward shift to
the resultant strong baroclinic zone to now well west of Lower
Michigan. So, low confidence exists on the Friday-Sunday timeframe
as the positioning of this slow moving front will make all the
difference to the sensible weather forecasts.
MARINE...
Advancing low pressure and its attendant cold front will approach
the central Great Lakes this evening, with potential for multiple
rounds of strong to severe storms mainly during the late evening-
overnight hours. Strong winds, enhanced wave heights, and lightning
will be likely with these storms. As precipitation chances diminish
through the morning hours tomorrow, expect wind gusts to ramp up
across all marine zones as lingering low-level wind field and cooler
air mass aloft allow gusts to reach the surface in the 25-30+ kt
range by early afternoon, with Small Craft Advisories going into
effect Monday morning along the Lake Huron nearshore. Strong gusts
reach low end gales Monday as well across the open waters,
particularly across northern Lake Huron where northwesterly flow
aligns with the longer axis of the lake, in which Gale Warnings are
now in effect through Monday evening. Winds to gradually weaken by
Tuesday morning as the pressure gradient relaxes and high pressure
tracks overhead, before rain chances return to end the work week.
HYDROLOGY...
Another round of showers and thunderstorms moves into southeast
Michigan tonight into Monday morning. Warm and humid air will be in
place while storms are expected to be fast moving and limit average
rainfall to around a half inch across the region. Bands of heavier
rain are expected along a warm front that moves from the Ohio border
northward to the I-69 corridor tonight. This area has potential for
total rainfall in the 1 to 2 inch range in a short period of time.
Urban and small stream flooding is possible along with flooding of
other poor drainage areas.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory from 10 AM to 10 PM EDT Monday for LHZ421-422-
441>443.
Gale Warning from 10 AM to 10 PM EDT Monday for LHZ361-362.
Lake St Clair...Small Craft Advisory from 4 AM to 10 PM EDT Monday for LCZ460.
Michigan waters of Lake Erie...Small Craft Advisory from 4 AM to 10 PM EDT Monday for LEZ444.
&&
$$
AVIATION.....DG
DISCUSSION...CB
MARINE.......MV
HYDROLOGY....BT
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Grand Rapids MI
1150 PM EDT Sun Jun 20 2021
LATEST UPDATE...
Aviation
.SYNOPSIS...
Issued at 344 PM EDT Sun Jun 20 2021
- Severe Weather/Heavy Rain threat tonight
- Windy and colder Monday with some frost Tuesday morning
- Next major system end of week / some showers possible Wednesday
&&
.UPDATE...
Issued at 11 PM EDT Sun Jun 20 2021
The first round of severe weather has moved through with power
outages along the I-94 corridor. There remains some strong storms
with tornado risk along the southern tier of counties in
Michigan as of 11 PM. Once those storms exit the region, there
will be a lull before the next round begins to move into the
region from the west after midnight.
The major concern for the overnight storms remains to be strong
to severe storms from the polar jet and training storms that could
cause flooding overnight into Monday morning. The southern
portion of Michigan has already received around a half inch
upwards of an inch south of Jackson.
Due to the antecedent conditions, the copious amounts of PWATs
in the system moving through Southern Michigan and the training
storms, a flood advisory has been issued for the areas of concern.
&&
.DISCUSSION...(This evening through next Sunday)
Issued at 344 PM EDT Sun Jun 20 2021
- Severe Weather/Heavy Rain threat tonight
Overall it seems our severe weather threat is somewhat less than
we were thinking earlier. Even so there still remains a
significant threat for strong to severe thunderstorm tonight.
Locally heavy rain is expected near and south of I-96. The risk
for strong to severe storms is from around 6 pm tonight till
around 5 am Monday.
There will be two periods of severe storm potential. The first is
the warm advection push in front of the system. Seems the overall
threat is a little less as a result of the MCV upstream that has
pushed the warm air farther south. Even so, we have our boundary
stalled near I-94, so when the upstream MCV over MO gets into this
area I am thinking it will track along the boundary. That is
supported by most our HI-RES models. It is this first wave of
convection that has the greatest risk of tornadoes. Surface winds
will turn to the east north of the boundary this evening and that
will increase the low level shear. Surface based capes in the
2500 to 4000 j/kg range south of I-94 to I-80. The effective bulk
shear over the southern counties will be between 40 and 50 knots.
All of this supports strong to severe storms, large hail and
isolated tornadoes.
The second period of strong to severe storm is from the polar jet
on the northern stream coming into this area. We get into the
entrance region of that jet. It is at that time the low level jet
really develops, and increases to near 50 knots. The HRRR 17z run
showed 60 knot winds associated with the line of storms coming on
shore near South Haven just after midnight. It is during that
time when train echoes are possible near and south of I-96.
Locally 2 to 3 inches of rain is possible in some areas.
- Windy and colder Monday with some frost Tuesday morning
The cold front sweeps through around sunrise. This will be some
seriously cold air coming in behind the front. The 850 temps fall
to near 2c by Monday evening, from 13c in the morning. We get on
the polar ward side of the polar jet by evening too. It would not
be out of the question to get some lake enhanced rain showers. Air
temperatures will fall during the day. Temperatures could be in
the upper 50s by evening.
Skies should clear Monday night. With dew points in the 30s, it
would seem likely frost would develop over northern area. I could
see locations like Leota getting below freezing.
- Next major system end of week / some showers possible Wednesday
The next digging northern stream system stays in Canada but it
boots the trough over the Great Lakes out into the north Atlantic.
This sets up a warm advection event Wednesday, which may well
bring showers to the area again. instability is not all that high
so this would be more rain showers than thunderstorms.
Behind that we get shortwave ridging briefly so Thursday will be
quiet but seasonably warm. Finally there is another northern
stream shortwave that digs into the central North American trough.
It will significantly deepen that trough and result in another
system not to much different than what is happening tonight into
Monday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1139 PM EDT Sun Jun 20 2021
The first round of severe weather has moved through and as of
0340Z we are in a lull with VFR conditions at all TAF sites. This
will deteriorate as the next round of storms move into the region
from the west. Expect storms to enter from the south around 05Z.
The Western TAF sties will see VCTS at first after 05Z with MVFR
to IFR in TSRA at AZO and BTL and then spreading at all the TAF
sites through 08Z. The cold front will drop the ceilings to the
MVFR/IFR with gusty afternoon winds. Expect the low clouds to
persist until around 17Z Monday before lifting.
&&
.MARINE...
Issued at 344 PM EDT Sun Jun 20 2021
The push of cold air Monday will result in a rather unpleasant
beach day to say the least. Winds will be gusting to over 30 mph
and air temperatures will be falling into the 50s. The strong
winds will result in possible rip currents and 5 to 7 foot waves.
Our current hazards for tomorrow look good so no changes were
made.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through late Monday night for MIZ037-043-
050-056-064-071.
LM...Small Craft Advisory until 2 AM EDT Tuesday for LMZ844>849.
&&
$$
UPDATE...Ceru
SYNOPSIS...WDM
DISCUSSION...WDM
AVIATION...Ceru
MARINE...WDM
Area Forecast Discussion
National Weather Service Lincoln IL
806 PM CDT Sun Jun 20 2021
.SYNOPSIS...
Issued at 244 PM CDT Sun Jun 20 2021
A strong cold front will push into the region from the northwest
tonight. Strong to severe storms are possible ahead of the front,
into tonight. Scattered showers and a few storms will linger
behind the front on Monday, along with much cooler temperatures.
&&
.UPDATE...
Issued at 803 PM CDT Sun Jun 20 2021
Thunderstorms continue to increase in coverage along and ahead of
an advancing cold front in IA/MO this evening. While a special 19Z
KILX raob was overall unimpressive, the latest 00Z sounding shows
MLCIN decreasing to 54 J/kg while instability has increased, now
measuring over 2000 J/kg MLCAPE. Veered 0-3 km wind profile and
deep layer shear to around 40 kt will support organized storms
and a severe threat into portions of west central and central
Illinois this evening. Do anticipate some downward trend in storm
intensity starting around midnight as storms cross the I-55
corridor as we lose daytime heating and diurnal instability wanes.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 244 PM CDT Sun Jun 20 2021
Complex of storms has weakened as it pushed into western IL early
this afternoon. 19z ILX sounding indicated a layer of warm air
centered at 850 mb, providing a significant cap for deeper
convective development. Besides the cap, the atmosphere is
supportive of robust convection given 60 kt winds at 500 mb and
mid level lapse rates at 7C/km. Latest forecast soundings and SPC
mesoanalysis show a weaker cap over eastern IL, which could be
eroded from outflow moving in from the west. Latest hi-res
visible satellite imagery shows modest cu development east of
I-57. This will be the area to watch over the next few hours, and
the last few runs of the HRRR have shown discrete convection here
between 21-00z. All severe modes would be possible given nearly 3k
J/kg MLCAPE and strong deep layer shear near 50kt, but with the
warm front located farther north near I-80, damaging winds and
hail are primary threats.
A line of thunderstorms is expected to develop ahead of a cold
front across eastern Iowa early this evening, then push into the
northwest CWA towards mid evening. Severe storms are possible
given moderate instability and favorable deep layer shear.
Damaging winds gusts are the primary threat, with hail and an
isolated QLCS tornado possible. A localized flash flood threat
exists due to high rainfall rates when PWs peak over 1.75" this
evening. As the line shifts farther southeast into central IL near
I-55 towards midnight, conditions become less favorable for both
severe and flash flooding with decreasing instability. The
weakening trend continues overnight with diminishing storm
coverage expected near and south of I-70 late. Southwest gradient
winds gusting over 20 mph ahead of the front this evening, will
veer west northwest post frontal late tonight, also gusting over
20 mph.
The upper trof and an associated shortwave cross the region on
Monday. This could bring a band of showers as far northwest as
I-55, and scattered afternoon showers and storms to southeast IL.
Low level cold advection looks fairly impressive for early
summer, as 850 mb temps drop into the single digits C. This
combined with mostly cloudy skies should limit highs to the low
and mid 70s.
.LONG TERM...(Tuesday through Sunday)
ISSUED AT 244 PM CDT Sun Jun 20 2021
High pressure stretching across the Ohio Valley keeps quiet and
seasonably cool conditions in place for Tuesday with highs in the
mid to upper 70s. Showers and storms along an elevated warm front
should stay to our northwest Tuesday afternoon into Tuesday night,
but will need to monitor where the better warm/moist advection
lays out across the front. The warm front shifts well north of
the region on Wednesday, and southerly winds will bring a warming
trend, returning highs to the 80s. A warm and potentially active
pattern then sets up across the Midwest for Thursday and into the
weekend. This occurs as a longwave trof settles into the upper
Midwest, bringing southwest flow and several upper level waves to
the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 519 PM CDT Sun Jun 20 2021
VFR conditions and a modest S/SW breeze will be in place through
most of the evening. Late this evening and overnight, a cold front
will move across the region with a decaying line of thunderstorms.
Storms may be strong to severe as they approach PIA, but should
weaken with time overnight. Winds will turn NW behind the front
with MVFR ceilings overspreading the region. These ceilings should
lift back to VFR midday Monday.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Deubelbeiss
SYNOPSIS...25
SHORT TERM...25
LONG TERM...25
AVIATION...Deubelbeiss
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
846 PM EDT Sun Jun 20 2021
.SYNOPSIS...
High pressure will remain over the Atlantic through Monday and
Claudette will pass southeast of the area tonight into Monday.
A strong cold front will pass through the region Monday night
into Tuesday. High pressure will build overhead for the middle
portion of next week as drier and cooler weather returns.
&&
.NEAR TERM /THROUGH MONDAY/...
The showers and thunderstorms that formed along the Allegheny
front are starting dissipate as diurnal heating has shut off. A
shower or thunderstorm can`t be ruled out over the next few
hours but the threat for storms should end by midnight. The mid
and high level clouds from the storms are starting to move out
and partly cloudy skies are expected to return overnight.
An extra note for Monday will be the the increasing heat.
Afternoon temperatures will likely peak in the mid 90s with dew
points in the 70s. Heat indexes in the DC metro area could reach
close to heat advisory criteria but most 105 indexes will be
isolated and only for a hour in spots.
.Previous Discussion
A mix of sun and clouds continues this afternoon across the region.
Some CU clouds have developed across northern MD and VA as well as
along and west of the Blue Ridge. Hot and humid conditions continue
with high temperatures in the upper 80s to low 90s for most with dew
points near 70. H5 heights continue to rise this afternoon through
tonight. However given the nature of the unstable atmosphere along
with the observed CU field, do continue the risk for widely
scattered showers and thunderstorms developing late this afternoon
through early this evening mainly for the Potomac Highlands into
northern VA, eastern WV, and northern MD. However, given the
subsidence of the rising heights, think convection will be minimal.
The HRRR has continued to push back the timing of the development of
any convection with each new hourly run, very similar to its
performance yesterday. Thus, think that any shower/storm that does
develop will be quite brief in nature. Chances for convection will
decrease with the loss of daytime heating this evening.
Meanwhile, Claudette will continue to track south and east of the
region through early tomorrow morning and is not expected to impact
the region. Overnight lows will remain in the low to mid 70s,
slightly cooler across the mountains. Patchy fog expected overnight.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
Claudette will continue to shift offshore early Monday morning. Some
isolated showers pay be present during the pre-dawn hours as
residual moisture associated with the system increases the already
fairly saturated atmosphere. Any shower activity will be mainly
inside of I-95 but should cease by daybreak. Overall, expect
temperatures Monday to be similar to today, perhaps a degree or two
higher with slightly more humidity. The moisture advection should
cause dewpoints in the 70s for most locations, and with highs in the
90s, that will put heat indices around 100 degrees (especially east
of the Blue Ridge Mountains).
The heat and humidity will lead to plenty of instability, and
heights will be falling in response to an upper-level
trough to our west that will be slowly shifting eastward as an
associated cold front approaches the region. The forcing from the
front along with falling heights and plenty of instability means
that chances for showers and thunderstorms will increase,
especially during the afternoon, continuing into the evening hours.
There is still some uncertainty as to how progressive the front is.
Current thinking is that the front approaches the region from the
west, igniting showers and storms for areas mainly west of the
Blue Ridge. With the parent trough still over the Midwest, thinking
that the front is likely to linger in place overnight into Tuesday.
So while convection will relax overnight due to the loss of daytime
heating, showers and perhaps some residual thunderstorms are
expected to persist overnight.
As the parent trough swings eastward on Tuesday, will cause the
front to finally cross the region. While there is still some timing
differences in guidance, appears that this occurs during the late
morning into the early evening hours. As a result, rain that may be
heavy at times, especially in instances in embedded thunderstorms,
can be expected mainly during the mid morning through late
afternoon. Rain will then taper off from NW to SE Tuesday evening.
There is an isolated threat for flooding and severe storms during
this time as well due to plenty of moisture that will be in place
along with a shear vector nearly parallel to the cold front and
instability ahead of the front. The best chance for heavier showers
and thunderstorms will be east of Interstate 81 on Tuesday.
High pressure will build overhead Tuesday night behind the cold
front through Wednesday bringing noticeably cooler and less humid
conditions.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Long term will start with Canadian high pressure building
across the region, with dry air and highs into the lower 80s. This
won`t last however, as a weak low pressure now looks more likely to
start pushing northward up the coast Thursday night into Friday.
Should this happen, increased clouds along with a chance of showers
or some drizzle will exist, and temperatures are likely to slide
back downward a bit, though 80s remain likely. The influence of
this system appears most likely in eastern portions of the forecast
area, near the bay and Potomac, with much less influence, if any,
likely in the Allegheny Front.
By Saturday, this system is nudging northeast off the coast, with
lowering influence, but another front will start moving towards us.
Southwest flow ahead of the front should allow warming to resume if
it gets interrupted, but the shower/t-storm risk will increase.
However, it must be noted that guidance has significant differences
regarding the speed of this system, and its quite possible it holds
to the west for several days before reaching us. This would lead to
a few days of more typical summer weather, with terrain forced
storms in a warm, humid air mass.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
VFR conditions expected to continue this afternoon under a
southerly flow. A isolated shower and/or thunderstorm is possible
late this afternoon through early this evening. Highest confidence
for any TSRA remains over MRB.
Increasing moisture overnight may result in a period of low ceilings
and MVFR conditions in the pre-dawn hours Monday. Highest confidence
for this occurrence is CHO, as well as DCA, BWI, and MTN as a result
of Claudette passing offshore. VFR conditions resume by daybreak
tomorrow morning. However, a strong cold front will approach the
region from the NW which will ignite additional showers and
thunderstorms late Monday afternoon into Monday evening. The front
is then expected to push through the region on Tuesday. As a result,
increasing chances for CIG/VSBY restrictions are expected late
Monday, continuing into Tuesday. High pressure builds back into
the region Tuesday night, as VFR conditions return.
VFR Wednesday under high pressure. However, a weak low pressure
moving up the coast Thursday night into Friday could produce just
enough easterly flow to bring a few showers, some drizzle, or some
low clouds, with sub-VFR cigs possible. The influence from this
system is most likely at BWI/MTN, with lowest risk at MRB.
&&
.MARINE...
I have extended the Small Craft Advisory on Monday through the
afternoon due to southerly channeling winds along with Tropical
Depression Claudette moving off-shore.
High pressure will remain over the Atlantic through Monday while
Claudette passes offshore early Monday morning. An increased
gradient will cause a southerly flow to increase this
afternoon into tonight. An SCA is in effect for the Bay and the
middle/lower portion of the Tidal Potomac River.
Additional SCA may be needed Monday and Tuesday for portions of the
waters with an increased southerly flow ahead of a cold front, slated
to slowly cross the region by Tuesday. Additionally, gusty showers
and thunderstorms may require SMWs during this time.
Dry with sub-SCA winds under high pressure Thursday. Weak low
pressure moving up the coast Friday could nudge winds closer to SCA
levels, but probability remains low.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ530-
531-536-538-539-542.
Small Craft Advisory until 6 PM EDT Monday for ANZ532>534-537-
540-541-543.
Small Craft Advisory from 8 AM to 6 PM EDT Monday for ANZ530-
531.
&&
$$
SYNOPSIS...MSS
NEAR TERM...MSS/JMG
SHORT TERM...
LONG TERM...RCM
AVIATION...MSS/RCM
MARINE...MSS/RCM/JMG
Area Forecast Discussion
National Weather Service Marquette MI
738 PM EDT Sun Jun 20 2021
.SHORT TERM...(This evening through Monday)
Issued at 349 PM EDT SUN JUN 20 2021
...Steady rain tonight, then blustery and sharply cooler on Monday...
A potent shortwave as noted on water vapor imagery and the RAP
analysis was over the Dakotas embedded at the base of a mid/upper
level trough from northern Hudson Bay through Manitoba into the
northern Plains. The deepening sfc low associated with the shortwave
is over southern MN at present and is forecast to track across
central WI and the Straits of Mackinac tonight bringing fairly
widespread rain to the area and blustery nw winds behind the system
late tonight into Monday.
Although some light showers have worked into west half portions of
Upper Mi this afternoon, the steadier rain is expected to spread
into the area later this afternoon into this evening with increasing
isentropic ascent and mid-level fgen in response to coupled upper-
jet structure fueling the deepening sfc cyclone which will be
tracking just south through WI. Although all areas should see some
rain during this event, the most consistent model signal for the
heaviest rainfall has been over west and north central Upper Mi
where fgen forcing/deformation will be maximized in the nw quadrant
of the cyclone track. Model consensus indicates that an inch or more
of rain could fall over the nw half of the U.P. with the greatest
amounts of 1.5-1.7 inches over the Porcupine Mtns and Huron
Mtns/Michigamme Highlands where orographic lifting will aid with
amounts. Closer to the track of sfc low...rainfall amounts over
south central and eastern counties will more in the 0.25 to 0.50
inch range.
As the low pressure system deepens and moves east of the area late
tonight cold air wrapping in behind it and associated increased
mixing and 6 hr pres rises of 6-11 mb will create gusty northwest
winds of 30-40 mph late tonight into Monday, highest across the
Keweenaw and the east half of the cwa. Moist cyclonic flow and
orographic lift will maintain higher rain chances for northwest flow
favored locations late tonight into early Monday. The strong winds
will cause waves to respond and potentially build to near 11 feet on
Monday between Shot Point and Whitefish Point, which could cause
some minor lakeshore flooding concerns and obvious marine
boating/recreation hazards. Precip looks to be largely over by
midday Monday after lingering lake-induced showers over the
northwest lake effect zones end.
Expect min temps tonight ranging from the lower 40s west to lower to
mid 50s south central. Highs Monday will be much blo normal, mainly
in the 50s with coolest readings north.
.LONG TERM...(Monday night through Sunday)
Issued at 431 PM EDT SUN JUN 20 2021
Expect the precipitation associated with the cold front to be over
by Monday night. Ensembles show 850mb temperatures near the
climatological minimum for 00z Tuesday, with conditions warming back
to normal from Monday night to Tuesday night. Therefore, thinking
some frost across the interior (especially the interior west) is a
definite possibility, as lows could approach freezing.
As a shortwave moves through Tuesday, expect some cloudier
conditions, with a slight chance of showers and thunderstorms
possible. While there is abundant shear, there is hardly any energy
available for parcel uplift, and moisture is rather limited (some
ensembles have PWATs down in the 10th percentile until around
Tuesday night). Therefore, it`ll be tough for any showers and
thunderstorms to develop, although the shortwave would provide the
lift should they occur. As temperatures warm Wednesday ahead of
another cold front, expect dry conditions as a capping inversion
should prevent precipitation from developing.
Another cold front looks to slowly prog through the U.P. Thursday
and Friday. This may bring some additional thunderstorms across the
area, especially across the western U.P. Thursday afternoon as the
front acts as a forcing mechanism. Given that the front is predicted
to be slow in moving across the area, thinking that this will
hopefully bring a soaking rainfall across the area, especially
across the east (where it is greatly needed). Could see some breezy
conditions across the eastern U.P. Thursday ahead of the cold front.
Behind this second cold front, expect temperatures to cool again,
but to be warmer than what`s expected Monday night/Tuesday. Model
guidance suggests another low progging or remaining over the area
this upcoming weekend. This should bring continued rain showers over
our area next weekend. Temperatures should be close to
climatological normal by next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 737 PM EDT SUN JUN 20 2021
IFR and LIFR conditions are expected tonight at all the TAF sites as
rain continues to expand across the area. Conditions will improve to
VFR/MVFR during the morning on Monday. A cold front will move the
area during the early morning hours with winds becoming Northwest
and breezy behind the front with a few gusts to 40 knots possible at
KCMX. Winds will begin to subside in the afternoon.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 349 PM EDT SUN JUN 20 2021
Light winds across the lake today will sharply increase tonight as a
potent low pressure system tracks just south of the area.
Unseasonably cold air wrapping around the low late tonight through
the day Monday will lead to strong NW winds. Models have had a
consistent signal for a several-hour period of gales Monday morning
over the north-central and eastern portions of Lake Superior.
Therefore, Gale Warnings will continue with this forecast package.
Could see a brief period of NW winds up to 35-40 kts Monday morning.
Winds will quickly diminish Monday night to 20 kts or less and
remain that way through at least next Thursday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Beach Hazards Statement from 6 AM EDT Monday through Monday
evening for MIZ005-006.
Lake Superior...
Gale Warning from 10 AM to 6 PM EDT Monday for LSZ251-267.
Gale Warning from 8 AM to 4 PM EDT Monday for LSZ249-250-266.
Gale Warning from 8 AM to 2 PM EDT Monday for LSZ248-265.
Gale Warning from 5 AM to noon EDT Monday for LSZ244-245-264.
Lake Michigan...
Gale Warning from 8 AM to 2 PM EDT Monday for LMZ248-250.
&&
$$
SHORT TERM...Voss
LONG TERM...TAP
AVIATION...NL
MARINE...Voss
Area Forecast Discussion
National Weather Service San Francisco Bay Area
537 PM PDT Sun Jun 20 2021
.SYNOPSIS...Though warmer temperatures can still be expected
farther inland, pleasant conditions are forecast for Father`s Day
2021 as temperatures continue their cooling trend. As the marine
layer has reestablished and lower pressure develops just west of
the coast, these cool temperatures will continue for much of the
week and possibly drop below average by midweek. The next chance
for warmer temperatures looks to be next weekend with inland
areas returning to the 90s.
&&
.DISCUSSION...as of 01:48 PM PDT Sunday...Seems appropriate that
sunny skies accompany the Summer Solstice. Most of the Bay Area is
experiencing sunny skies this afternoon, but coastal areas on the
other hand are hanging onto some clouds. Despite the inland
sunshine temperatures are actually running a few degrees cool
across the interior. 5-10 degrees cooler in fact.
As for the Willow Fire - conditions have improved a little this
afternoon with less smoke production, but satellite still shows
some heat. Nearby weather stations are still relatively hot and
dry with temps in the low 90s and RH dropping into the teens. HRRR
smoke appears to be a little over done for this afternoon, but
some smoke/haze is still possible N and E and of the Willow Fire.
For tonight...low clouds along the coast will move inland again.
Some patchy fog/drizzle will also be possible.
The upper level low pressure lurking off the CA coast will
continue to slowly drift eastward. This low will help to deepen
the night/morning marine layer and cause further
cooling/moistening of the region. Temperatures will cool a few
degrees each day through Wednesday with more widespread 60s/70s at
the coast and 70s/low 90s inland. A few of the models spit out
some precip as the low approaches over the waters and coast. This
is most likely drizzle. Therefore patchy drizzle has been added to
the forecast. Wouldn`t be surprised to see a few bucket tips
Tuesday and Wednesday mornings. The previous discussion mentioned
the possibility of thunderstorms over NorCal. Lastest guidance
stills shows some lift and moisture Monday and Tuesday, but
primarily north of the Bay Area.
The upper low meanders slowly to the NE Wednesday through Friday
keeping relatively quiet and cooler weather in places. What
happens there after is lower confidence as medium range models
shows are almost out of phase. The EC keeps the low/trough in
place and the GFS shows a robust ridge with more of a heat signal.
Ensembles fall somewhere in the middle. Given the uncertainty will
allow for a slight warming trend next weekend, but not increase
too much yet. Far interior locations have a shot at triple digit
heat once again. Stay tuned...
&&
.AVIATION...As of 15:30 PM PDT Sunday...For the 00z TAFs. VFR
conditions through this evening before low clouds are expected
move inland once again. The marine layer will be around 1000 to
1500ft tonight. MVFR/IFR cigs will be seen at most sites except
KLVK/KSJC. Hazy or smoky conditions aloft have been increasing
this evening due to the Willow Fire, however smoke concentration
aloft will start to decrease after 06Z. The latest HRRR smoke
model forecast still transports smoke to the N/NE as winds aloft
remain in a general southwesterly pattern. This may occasionally
reduce slant range visibilities in some areas. Southwest to
westerly winds expected at the surface for most locations with the
typical afternoon sea breeze along the coast.
Vicinity of KSFO...VFR conditions through this evening. The marine
layer will return tonight around 08Z. MVFR/IFR conditions
expected through mid to late tomorrow morning. Onshore winds
tomorrow afternoon around 15kts.
SFO Bridge Approach...Wildfire smoke may occasionally reduce
slant range visibility, otherwise similar to KSFO.
Monterey Bay Terminals....VFR conditions this evening before
IFR/LIFR cigs return by 02Z. Patchy fog and drizzle possible
tomorrow morning. W/NW winds through most of the period becoming
10-15 kt tomorrow afternoon.
&&
.MARINE...as of 04:46 PM PDT Sunday...A developing weak low
pressure system over the outer to offshore waters as well as an
approaching upper level low will allow south to southwest winds to
persist through early this week. Locally breezy west to southwest
winds are expected north of the Bay Bridge in the afternoons and
evenings the next couple of days. Winds will gradually shift back
out of west to northwest mid to late week as the low drifts
slightly southward. Seas remain northwest at 9 to 11 seconds
along with a marginal southerly swell.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...SF Bay until 9 PM
&&
$$
PUBLIC FORECAST: MM
AVIATION: Dhuyvetter
MARINE: AS
Visit us at www.weather.gov/sanfrancisco
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 310 PM CDT Sun Jun 20 2021
Forecast Summary:
Cold front passing through the area this evening will bring cooler
and drier air to the region to start the workweek. Ahead of the
front, there is a small chance a few thunderstorms could pop in far
southwest Iowa and southeast Nebraska through early evening. Behind
the front, below-normal temperatures are forecast for Monday.
However a rebound to warmer temperatures begins Tuesday and
continues into Wednesday. Thunderstorm chances the rest of the week
will favor Thursday into Friday when another cold front disrupts the
warmer weather.
Tonight through Wednesday:
Cold front was moving southeast through eastern Nebraska this
afternoon, in wake of thunderstorm complex that brought some much-
needed rain to the area overnight. Front was moving through
Interstate 80 corridor as of 3 PM, with gusty northwest winds behind
it. Dew points had dropped into the 50s in northeast Nebraska, and
farther northwest, temperatures were in the lower 70s. Ahead of the
front, dew points in the low to mid 70s were pooling in southwest
Iowa where southwest winds continued. RAP objective analysis
indicated 3000 J/kg of MLCAPE in that area with eroding cap. Weak
surface convergence was also noted. Given these parameters, there
appears to be a window of opportunity for thunderstorms to fire in
far southwest Iowa and far southeast Nebraska before front sweeps
southeast of there early this evening. And there`s an even narrower
window for severe to occur given relatively short residence time of
cells in our CWA.
Much cooler air will continue to drop through the region overnight
and Monday as reinforcing shortwave deepens trough in the central
CONUS. Forcing with shortwave will cause showers and isolated
thunderstorms across western Nebraska into Kansas, and northern
periphery of precipitation potential will skirt southeast Nebraska
later tonight. Otherwise 850 temperatures drop into the single
digits C on Monday, translating to surface temperatures in the 70s.
Mid level heights quickly begin to rise by Tuesday and continue into
Wednesday. 850 temps rebound to over 20C by Wednesday as favorable
south to southwest low level flow develops. Thus warming
temperatures back into the 80s Tuesday and 90s Wednesday appear
likely. Also, mid level warm advection where low level jet
convergence is maximized may trigger showers or storms later Tuesday
night in our northern CWA.
Thursday through Sunday:
Models are in better agreement this afternoon in evolution of mid
level pattern later this week. Upper ridge trying to build into the
region by Wednesday gets suppressed south Thursday as strong trough
in Canada ejects energy south into the Plains. Initial shortwave
enters our area Thursday with attendant chance for thunderstorms,
then cooler air spills in behind for late week. Reinforcement of
cooler air follows for Friday through Sunday when highs should
average the 80s. Thursday`s highs are still in question given chance
for precipitation. Currently our forecast in the lower 90s
represents the 75th percentile of model output.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 621 PM CDT Sun Jun 20 2021
Gusty northwest wind 18 to 28 knots will diminish by 02-04z. And
while there will be a chance of rain in southeast NE overnight,
believe it would stay south of KLNK. Otherwise, VFR conditions
expected.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Dergan
AVIATION...DeWald
Area Forecast Discussion
National Weather Service Pueblo CO
253 PM MDT Sun Jun 20 2021
.SHORT TERM...(This evening through Monday)
Issued at 240 PM MDT Sun Jun 20 2021
Currently...satellite imagery shows widespread cumulus development
across southern Colorado. A surface boundary is currently backing
westward across the Plains, having reached the I-25 corridor as of 2
PM this afternoon. Surface flow behind this boundary is east-
northeast, with gusts near 25 mph across much of the Plains. This
is helping to bring moisture back west, with KPUB in the mid 40s,
and areas east the east seeing lower 50s dewpoints. Temperatures
are also quite warm, with mostly mid 90s across the region.
Rest of today...the main concern will be the thunderstorm potential
for strong to severe weather across El Paso, Pueblo, Otero and
Crowley Counties. CAM solutions are a bit all over the place, and
have discounted the HRRR for this afternoon with a very dry bias.
The consensus has moisture working back behind the boundary, with
dewpoints in the upper 40s, helping to produce MLCAPE values around
1000 j/kg. 0-6 km shear values are modest at 30 kts. An embedded
upper wave in the northwesterly flow is currently moving into the
Pikes Peak region and the boundary itself all point to a continued
severe threat through the afternoon. If a severe storm does
develop, hail to 1.5 inches and wind gusts to 60 mph may be
possible. In addition, shear along the surface boundary could lead
to an isolated landspout this afternoon, especially from Pueblo to
Kim. Storms that form should push southeast this afternoon,
dissipating this evening.
Tonight...a re-enforcing cold front is forecast to drop south into
the Plains overnight, ushering in moist upslope flow across the
Plains. This will likely lead to widespread showers and
thunderstorms, banked along the Eastern Mountains and I-25 corridor.
Much cooler air will filter in behind the frontal boundary as well.
Overnight lows will be cooler, with 50s across the area. The main
time frame for precipitation will be after 2 AM for much of the
Plains, prevailing into the morning hours.
Monday...showers and embedded thunderstorms will be continuing for
the morning hours, shifting south along the Eastern Mountains into
the Raton Mesa region. This shower activity should dissipate with
clearing conditions expected by the early afternoon. The main thing
people will notice for Monday will be temperatures. Areas across
the Plains will be significantly cooler, with highs int he 60s to
lower 70s. The warm spot is expected to be the San Luis Valley with
upper 70s to lower 80s. Enjoy the cooler weather, because a return
to hot conditions expected by Tuesday. Mozley
.LONG TERM...(Monday night through Sunday)
Issued at 240 PM MDT Sun Jun 20 2021
Monday night-Wednesday...
The cooldown from the passing front and the cloud cover from the
moist upslope flow expected Monday will slowly dissipate into Monday
evening, with clearing skies and low temperatures expected
to only get down into the 50s over the plains. Starting on Tuesday,
models still show an upper ridge building into the area, resulting
in warm and drier conditions for the middle of the week. A few
isolated showers and thunderstorms will be possible on Tuesday and
Wednesday afternoon, but with the weak forcing any showers
would stay over the mountains. High temperatures will increase again
to above-average under the ridge, with the eastern plains expected
to reach back into the low 100s, with high 80s possible over the
higher terrain.
Thursday-Sunday...
The upper-ridge will flatten over the area somewhat as a broad
trough begins building in from the west, delivering some additional
moisture and synoptic-scale lift to the region. More widespread
showers and thunderstorms will be possible, likely originating over
the mountains before the westerly flow aloft pushes it off and east
towards the plains. As the trough axis swings through Friday-
Saturday, a cold front will push south across the area, bringing a
decent temperature cooldown over the plains as well as a higher
chance of precipitation through the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 240 PM MDT Sun Jun 20 2021
KALS...VFR conditions through the next 24 hours. A few
thunderstorms may be possible across the San Luis Valley this
afternoon with gusty outflow winds possible at the terminal. There
could be a few low stratus clouds late tonight into Monday morning
at around 2 kft. These should quickly clear once the sun comes up,
with VFR conditions into the afternoon.
KCOS and KPUB...a few thunderstorms are expected this afternoon with
gusty outflow winds and briefly reduced CIGS and VIS as they pass
the terminals. Increasing northeasterly flow will lead to
widespread stratus and rain potential overnight into Monday morning.
Generally MVFR conditions are expected to prevail, which may reduce
to IFR late tonight into the morning. Expect clearing and a return
VFR conditions by Monday afternoon across both terminals. Mozley
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MOZLEY
LONG TERM...GARBEROGLIO
AVIATION...MOZLEY