Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/16/21
Area Forecast Discussion
National Weather Service Bismarck ND
956 PM CDT Thu Jul 15 2021
.UPDATE...
Issued at 955 PM CDT Thu Jul 15 2021
Minimal updates needed to the forecast late this evening. Hi-Res
models still indicating thunderstorms possible later tonight
across the northwest. Around or shortly after midnight, the nose
of a low level jet looks to set up across northwestern ND where MU
Cape of 1000 to 2000 j/kg and somewhat steep mid level lapse
rates will be found. Modest shear looks to be the limiting factor
with these storms. That said, high amounts of dcape and an
inverted-v sounding will support perhaps a gusty wind threat from
these storms. Perhaps some small hail is also possible, although
dry air near the surface should limit this threat. Overall made
some minor adjustments to the pops in the northwest for the
potential for thunderstorms tonight, with severe weather not
expected at this time. Lingering isolated storms will diminish
Friday morning. More warm temperatures in the 90s are expected,
with perhaps another round of thunderstorms possible late Friday
afternoon through Friday night mainly in the north and west.
Expect haze and smoke to continue across the region as the latest
HRRR Smoke Model projects smoke starting to filter in from the
west Friday into Saturday.
UPDATE Issued at 645 PM CDT Thu Jul 15 2021
Limited changes needed early this evening. Thunderstorms in the
eastern part of the CWA have diminished or move eastward, thus
pops have been reduced or removed. Mainly dry conditions are
expected through the evening hours. A low level jet and weak
elevated instability could still bring some thunderstorms across
the northwest overnight tonight. Satellite showing some elevated
smoke entering the area from the northwest, although should bring
limited impacts through the night. More smoke may return tomorrow
from western US fires, especially across the west. Friday overall
remains on track to be continued warm with perhaps an isolated
afternoon/evening thunderstorm in the west.
&&
.SHORT TERM...(This evening through Friday)
Issued at 348 PM CDT Thu Jul 15 2021
A chance of thunderstorms in the west Friday and warming
temperatures highlights the short term forecast period.
At 20Z water vapor imagery shows a relatively low amplitude mid-
level ridge over the Northern Rockies, shifting east. An embedded
circulation was centered over north central Montana, with a
surface low under this wave. Southerly winds in the eastern
periphery of the low were observed across western and central
North Dakota. Isolated thunderstorms were located over eastern
North Dakota this afternoon in a region of steep low level lapse
rates and a subtle open mid-level northwest flow wave.
This evening, convective activity in the east should decrease as
insolation is lost. A modest low level jet should develop tonight
as the aforementioned upstream arrives in the west. A few elevated
showers and thunderstorms will be possible, more likely northwest.
Best high-res guidance agreement is in the placement of this
activity in the northwest on the nose of the southerly low level
jet, then with varying degrees of eastern progression between
models. POPs may need to be adjusted tonight as predictability is
low. With steep mid-level lapse rates arriving as well, a few
stronger thunderstorms can`t be ruled out.
Convective activity may linger in the early Friday morning hours
before diminishing after sunrise. Then convection in the west will
be possible again late Friday afternoon and evening, as shortwaves
continue to push through the eastward progressing ridge. With
continued southerly flow, surface dew points may reach 60 degrees
in the central (though GFS/RAP keeps dew points in the 50s
compared to higher values from NAM/ECMWF), producing MLCAPE of
1500-2500 J/kg. Bulk shear of 20 to 30 kts will be on the lower
side for severe thunderstorms, but with the steep mid level lapse
rates in place several strong to marginally severe thunderstorms
are possible.
.LONG TERM...(Friday night through Thursday)
Issued at 348 PM CDT Thu Jul 15 2021
Above normal temperatures continue through the long term forecast
period.
In the long term period, the upper level pattern becomes more
amplified as a ridge builds and becomes centered over eastern
Montana and the western Dakotas. This will feature a prolonged
period of above normal temperatures with daily highs in the 90s
with some areas of the west likely hitting 100 at times. At this
point surface dew points look low enough to keep heat index values
below the advisory threshold, with forecast max apparent
temperatures remaining below 100 F each day.
This pattern will also feature weak embedded impulses which will
provide low-predictability chances for convection periodically
through the period. Current consensus gives the best opportunity
Saturday evening, with inherent uncertainty during the period of
building mid-level heights.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 645 PM CDT Thu Jul 15 2021
Overall VFR conditions are expected through the forecast period,
with perhaps an isolated thunderstorm at times. Look for southerly
winds to diminish somewhat tonight, while mainly clear and VFR
conditions remain. An isolated thunderstorm is possible overnight
tonight, mainly in the northwest. This could impact KXWA, although
confidence is not high enough to include at this time. Friday then
sees a light breeze from the south, continued warm temperatures,
and mainly VFR conditions. An isolated thunderstorm is also
possible Friday afternoon/evening, although confidence remains to
low to include at this time. Haze due to smoke from
wildfires continues, but so far visibility has remained generally
around 10 miles. Some increased haze and smoke is possible for
Friday, although will refrain from adding to TAFs unless
visibility becomes further impacted.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Anglin
SHORT TERM...AE
LONG TERM...AE
AVIATION...Anglin
Area Forecast Discussion
National Weather Service Boise ID
838 PM MDT Thu Jul 15 2021
.DISCUSSION...Isolated showers and thunderstorms which formed over
eastern Valley County and south central Idaho earlier today have
dissipated. On Friday, southwest flow aloft will continue to
bring elevated moisture to these same areas with additional
afternoon and early evening shower and thunderstorm development
possible. An upper trough along the Pacific coast will shift
slightly east tomorrow, resulting in temperatures a couple degrees
lower than today but still 3 to 5 degrees above normal. Smoke
from area fires will continue to move through the area, although
the HRRR near-surface smoke indicates some improvement over today
is possible. No changes to the current forecast.
&&
.AVIATION...VFR with areas of low VFR and local MVFR
visibilities due to smoke from wildfires. Significant visibility
restrictions aloft due to smoke layers. Surface winds: mainly west-
northwest 5-15 kt. Winds aloft at 10kft MSL: variable 5-15 kt.
Density altitudes will remain high due to hot temperatures.
Weekend outlook...Generally low VFR with areas of MVFR due to smoke.
Significant visibility reductions aloft due to smoke layers from
wildfires. Light winds.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Saturday night...A few showers
popping up across south-central Idaho this afternoon, with
thunderstorms possible. Forecast includes some mention of showers
into the evening as a result of current radar trends. Similar
conditions expected tomorrow, with a few afternoon showers and
thunderstorms possible in continued southwest flow. Gusty winds
possible, with the strongest wind south of the Snake Plain. A
building ridge over the Four Corners Region will continue warm and
mostly dry conditions this weekend, though smoke will continue to
influence area temperatures. Temperatures currently forecast to
be 5 to 10 degrees above normal through the forecast period.
LONG TERM...Sunday through Thursday...Hot dry and smoky conditions
to continue through the long term. Record high temperatures possible
on Sunday afternoon, although smoke will likely keep temperatures
just below records. Otherwise temperatures will be around 10 degrees
above normal through the period. Monsoon moisture will move
northward over the region on Monday through Thursday, which will
increase the threat of thunderstorms during this period.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Red Flag Warning until 11 PM MDT Saturday IDZ402-403-421.
OR...None.
&&
$$
www.weather.gov/Boise
www.facebook.com/NWSBoise
www.twitter.com/NWSBoise
DISCUSSION...ST
AVIATION.....BW
PREV SHORT TERM...KB
PREV LONG TERM....KA
Area Forecast Discussion
National Weather Service Caribou ME
915 PM EDT Thu Jul 15 2021
.SYNOPSIS...
High pressure southeast of the region will maintain warm and
humid air across the region tonight. A cold front is expected
to approach tomorrow and slowly cross the area tomorrow
afternoon and evening before stalling to the south this weekend.
A broad trough will linger across the region into early next
week.
&&
.NEAR TERM /THROUGH FRIDAY/...
9:15 PM Update... A few convective showers have popped up over
the western North Woods this evening. Thus, kept the precip
forecast as is. Fog has started to creep northward as the night
has progressed. Visibilities have continued to decrease in Bar
Harbor while the stratus layer has continued to lower over
Bangor. Recent satellite images show patchy fog developing to
our east in NB. Adjusted the weather forecast to show fog
development in the north. In addition, a Dense Fog Advisory has
been issue for Hancock and Washington counties, per current
observations and the RAP and NAM soundings.
Previous Discussion...
Any lingering isolated shower activity will diminish early this
evening with loss of daytime heating and a continuation of very
dry air aloft. Low stratus and fog will return, mainly south and
east of the mountains as a 500mb shortwave and area of surface
low pressure passes to the north, pulling subtropical moisture
northward once again. Overnight lows will be very mild, ranging
from the upper 50s along the coast to mid 60s for the rest of
the forecast area.
A cold front will rapidly approach from the northwest around
daybreak Friday, increasing chances for showers and
thunderstorms. An initial band of weakening showers is possible
along a pre-frontal trough across northern Maine, followed by a
line of convection along the cold front itself forecast to
enter western Maine from Quebec around 12z. Timing of the front
will preclude any severe weather threat across the northwest.
However, to the southeast daytime heating may contribute to a
band of around 1000-1500 j/kg of MLCAPE from roughly Houlton to
Bangor and down to the coast if the marine layer erodes quickly
enough and convective debris from nighttime and early morning activity
along the front is not as significant. While the instability is
uncertain, other factors are not; There will be around 35 to 40
kts of effective bulk shear and strong surface convergence
along the front leading to linear structures capable of
producing strong, gusty winds. Surface delta theta-e values will
also be as high as 25 to 30K based on forecast soundings. High
precipitable water values around 1.5 to 2 inches and a deep warm
cloud layer will support potential for heavy rainfall. However,
with the front forecast to move faster than previously
expected, the risk of training cells and flash flooding is
lower. Hail is also possible but should not be the dominant
threat given high freezing levels and linear storm structures.
Conditions will dry out quickly from northwest to southeast
during the evening as the front moves over the coastal waters.
Highs are generally expected to be similar to today in the low
to mid 80s except along the coast and across northwestern Maine
and the Saint John Valley where the front will cross before peak
daytime heating can occur.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
Cdfnt wl be approaching the coast by Fri evening with showers and
thunderstorms remaining over far sern portions of the area for
several more hours. By the start of the period, strong storm threat
wl likely be waning as it runs into marine layer with storms
becoming elevated over time. Latest 12z guidance is fairly insistent
on mvg frontal bndry over the waters overnight with dry air
encroaching in fm the north to lessen chcs for showers drg the day
Saturday. Due to discrepancies in models hv introduced slgt chc
showers into the far southwest late on Saturday though confidence
continues to rmn low in potential for rain chcs Sat afternoon.
Confidence becomes even murkier for Sat night and how far north rain
wl overspread the region as guidance becomes even more out of
agreement with track of sfc low up through the northeast. For now
have gone with chc pops mvg to near Baxter by daybreak Sunday with
northern Aroostook remaining dry throughout the end of the period.
Due to showers and cldy skies being confined to southern half of the
area, expect that temps on Sunday wl be warmest across the St. John
Vly.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
The long term wl start off as it has most of this summer, with an
upr lvl high sitting acrs the west and a trof in the east. With
little reason to move anywhere this wl likely be the same pattern
throughout the course of the week. Thus continued chcs for showers,
and possibly storms in the afternoon, can be expected. Temps wl be
near normal drg the first half of the week but lkly dropping aft mid-
week due to showery conditions expected to persist. Looking further
ahead deterministic models are indicating an upr lvl low dropping
thru the northeast over the weekend, including the GFS and EC
ensemble means. CMC meanwhile keeps it further north into the
Maritimes but time will tell.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: Tonight...Deteriorating from VFR to IFR/LIFR this
evening with low clouds and fog. The greatest impacts will be
from KHUL south where ceilings and visibility are forecast to
drop below airfield minimums. Light S/SW winds are expected.
Friday...Improving to MVFR/VFR during the day with tempo IFR in
a line of showers/t-storms. VFR at all sites by the evening. SW
winds 5 to 10 kts with gusts to 15 to 20 kts, shifting NW.
SHORT TERM:
Fri night-Sat...Mainly VFR, but cannot rule out IFR vsbys in early
morning fog at all terminals. Light WNW winds.
Sat night-Sun...MVFR/IFR at BGR and BHB in showers and possible
fog. Light winds.
Sun night-Tue...MVFR in showers and possible storms each
afternoon with low MVFR/IFR fog possible each morning. Light S
Sun night-Mon night, then WSW around 5 kts.
&&
.MARINE...
NEAR TERM: Areas of fog and patchy drizzle will continue to
reduce visibility tonight into tomorrow. Some breaks in the fog
are possible Friday afternoon and evening. Winds and seas will
remain below SCA levels with gusts to around 20 kts and seas of
2 to 4 feet.
SHORT TERM: Seas likely to remain below 3 feet through the
period with wind gusts below 20kts. Fog will reduce visibilities
over the water at times into early next week.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Dense Fog Advisory until 8 AM EDT Friday for MEZ016-017-029-
030.
MARINE...None.
&&
$$
Near Term...LaFlash/MStrauser
Short Term...Farrar
Long Term...Farrar
Aviation...LaFlash/MStrauser/Farrar
Marine...LaFlash/MStrauser/Farrar
Area Forecast Discussion
National Weather Service Duluth MN
751 PM CDT Thu Jul 15 2021
.DISCUSSION...(This evening through Wednesday)
Issued at 333 PM CDT Thu Jul 15 2021
Dry conditions will continue into early next week for most of the
Northland and highs will be increasing to the lower eighties to
lower nineties Friday into next week.
Tonight will feature clearing skies for most areas with some
fog/haze expected. The visibility may drop to a half mile or so in
a few spots later tonight, similar to last night. Friday will be
warmer with highs in the eighties, except a bit cooler along the
North Shore. A weak upper trough may lead to a few showers/thunderstorms
Friday afternoon, mainly over western areas. Forecast soundings
show deep mixing and dry lower layers, so we expect isolated
coverage. The HRRR forecasts some improvement in the smoke aloft,
mainly over Minnesota with some increase over northern Wisconsin.
Dry conditions will continue into the weekend as high pressure
remains near/over the region. Temperatures will climb into the
mid eighties to lower nineties Saturday into Monday. The pressure
gradient will be relatively weak or not very conducive to stronger
lake breezes. 850MB temperatures will remain from 16-19C for most
of the period.
A series of upper waves and a low level boundary will affect
mainly northern portions of the Northland Monday into much of next
week bringing periodic, mainly low chances for showers and
storms. The models are not in the best agreement with the details
but they do agree that widespread rain is looking unlikely. Temperatures
will remain above normal through the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 748 PM CDT Thu Jul 15 2021
A ridge of high pressure to keep predominantly VFR conditions and
light winds. Smoke and haze from fires is expected to reduce
visibilities at several terminals overnight, and have gone mostly
with a persistence forecast as guidance is not picking up on this
very well. KHIB and KBRD are most likely to be affected by this,
and have LIFR visibilities for both sites generally between 06z
and 11z. Have included MVFR visibility for the other sites as
well, and we will see how things develop this evening. VFR cumulus
are expected to develop once again during the late morning, and
there may be some SHRA/TSRA near KINL after 18z, but given the low
probability have left these out for now.
&&
.MARINE...
Issued at 333 PM CDT Thu Jul 15 2021
Due to high pressure over or near the Northland, the gradient
will remain relatively week for the next few days leading to winds
less than 15 knots and waves less than 3 feet.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 58 84 59 86 / 0 10 0 0
INL 54 88 59 90 / 0 20 0 10
BRD 58 85 59 88 / 0 10 0 0
HYR 51 85 55 87 / 0 0 0 0
ASX 54 86 57 86 / 0 0 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
DISCUSSION...Melde
AVIATION...LE
MARINE...Melde
Area Forecast Discussion
National Weather Service Quad Cities IA IL
948 PM CDT Thu Jul 15 2021
.UPDATE...
Issued at 947 PM CDT Thu Jul 15 2021
With the clearing skies, light winds and moist ground from the recent
heavy rainfall, it is looking like a setup for fog tonight. This
looks especially the case initially for areas north of the
current area of slow moving showers over southeast Iowa into west
central Illinois. These showers are occurring along and north of
a stalled low level boundary, with some forcing from a passing
shortwave.
The forecast has been updated to focus showers along this boundary
over the next several hours and also to add patchy fog for
roughly the southern 2/3rds of the forecast area for after
midnight. Fog could potentially get much thicker or more
widespread, depending on cloud trends the next several hours and
will be monitoring closely for possible updates.
&&
.SYNOPSIS...
Issued at 259 PM CDT Thu Jul 15 2021
18Z surface data has a weak low east northeast of KUGN, over Lake
Michigan. A front runs west southwest from the low across northern
Illinois and into southern Iowa. Dew points were in the 70s south of
the front with 50s and 60s north of the front.
&&
.SHORT TERM...(This Evening through Friday)
ISSUED AT 259 PM CDT Thu Jul 15 2021
Trends with satellite and radar data along with the very short term
models indicate the rain chances should remain south of a Sterling,
IL to Ottumwa, IA line through sunset. Cloud cover has helped
stabilize the atmosphere so most of the precipitation will be in the
form of showers/rain with some embedded thunderstorms. Localized
heavy rainfall will be possible especially across the southern
halves of Hancock and McDonough counties.
After sunset another upper level disturbance will move through
Missouri and into Illinois generating an additional round of showers
and some thunderstorms. The current forecast has rain spreading back
across the area with only areas north of a Dubuque to Vinton, IA
line remaining dry. However if very recent trends with the HRRR and
RAP are correct there is a potential for most of the area to remain
dry after sunset.
For Friday the current forecast has a risk of isolated to scattered
showers and some thunderstorms for most of the area. However if no
organized rain occurs prior to sunrise then there is a very good
chance that Friday will be dry, especially during the morning.
If Friday morning turns out to be dry then differential heating may
allow isolated showers and possibly some thunderstorms to develop
during the afternoon.
Friday night any showers or storms that develop during the day will
dissipate with sunset leaving the remainder of Friday night dry.
.LONG TERM...(Friday Night through Thursday)
ISSUED AT 259 PM CDT Thu Jul 15 2021
The flow aloft will change and push the active storm track well
south of the area.
Saturday through Thursday
Assessment...medium to high confidence
The model consensus has dry conditions for the area as high pressure
slowly moves through the Midwest during the weekend and first part
of next week.
However there will be weak upper level disturbances moving through
in the flow aloft, especially toward the middle of next week. Thus I
cannot rule out the possibility of isolated rogue diurnal convection
occurring from Tuesday through Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
ISSUED AT 619 PM CDT Thu Jul 15 2021
Low clouds and showers lingering along a slow moving front will
impact the BRL site tonight. The showers are most likely early
this evening, but MVFR conditions due to low ceilings and
developing fog are expected through the night. Conditions may drop
to IFR or even LIFR there around sunrise. MLI, CID and DBQ will
see prevailing VFR conditions tonight with light fog producing a
period of MVFR conditions roughly from 09Z to 14z Friday morning.
All sites are expected to improve to VFR by Friday afternoon with
light easterly winds.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...Sheets
SYNOPSIS...08
SHORT TERM...08
LONG TERM...08
AVIATION...Sheets
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
248 PM PDT Thu Jul 15 2021
.SYNOPSIS...Seasonable temperatures are forecast to occur across
the region through Saturday, followed by a warming trend over
interior portions of northwest California Sunday into early next
week. Otherwise, conditions will mainly be dry during the next
seven days, though a threat for thunderstorms can`t be ruled out
on Monday.
&&
.DISCUSSION...Broad and weak upper troughing was occurring over
the NERN PAC and adjacent coastline this afternoon, and was aiding
in seasonable temperatures over NWRN CA. Meanwhile along the
coast, periods of marine stratus will continue to be probable
during the next several days, and drizzle can`t be ruled out along
and in the vicinity of the windward facing north slopes of the
King Range. After Saturday, model guidance indicates an upper-
level anticyclone centered over the Intermountain West will expand
slightly westward and northward Sunday into early next week. That
process will favor slightly warmer temperatures across interior
portions of NWRN CA, with valley highs ranging from around 90 to
100F. In addition, an upper-level disturbance emanating from the
sub-tropics offshore from Mexico may migrate northward across
California during Monday. Various deterministic model runs show
that feature ingesting midlevel monsoonal moisture resulting in
sufficient MUCAPE values for elevated thunderstorm development.
This low probability evolution will continue to be monitored
during future shifts.
Garner
&&
.AVIATION...Skies across the interior are mostly clear this
afternoon, with just a few cumulus clouds developing over the far
interior mountains. Stratus has persisted once again along the
North Coast and extending well inland from E of Patrick`s Point to
the Eel River Valley. Drier air is once again infiltrating S over
the coastal waters W of the North Coast this afternoon, and this
may act to scatter out clouds briefly again at KCEC. It appears
that only a few peeks of sun are possible at KACV before evening,
if that.
Clouds are expected to fill back in and spread inland overnight.
Present marine layer depth is running around 2500 ft at the
McKinleyville profiler, while the Bodega Bay profiler indicates
the marine layer remaining closer to 2000 ft deep, if not a bit
shallower. Stratus is expected to expand back inland overnight,
particularly near and N of Cape Mendocino. Visibilities are
expected to drop into the MVFR to occasionally IFR range, but the
deep marine layer and weaker inversion should keep most
visibilities from going much lower. Patchy drizzle is again
possible overnight, but it is not expected to be as persistent or
heavy as last night. It doesn`t appear that the marine layer is
deep enough for stratus to make it to KUKI from the W, and the
HRRR doesn`t indicate much in the way of upvalley flow in the
Russian River Valley. Winds will be generally light, with some
late afternoon and early evening gustiness at KCEC. /SEC
&&
.MARINE...Northerly winds will increase a bit overnight, with the
strongest winds across the S outer waters. Have also extended the
Small Craft Advisory in that area as well, as advisory-level
winds look to continue through the weekend. A generally small NW
mid- period swell will continue through the next 5 days, and a
periodic S long period swell will persist into the first half of
the weekend. /SEC
&&
.FIRE WEATHER...An upper trough located over the northeast
Pacific will aid in seasonable temperatures across northwest
California through Saturday. Thereafter, a westward expanding dome
of high pressure over the Intermountain West is forecast to occur
Sunday into early next week, and will support a warming trend
across interior areas. In addition, an upper disturbance may move
from south to north across the region during Monday. That feature
may yield a threat for dry thunderstorms, though the exact timing
and magnitude of the threat is uncertain at this time.
Garner
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until
3 PM PDT this afternoon for PZZ450.
Small Craft Advisory until 3 PM PDT Friday for PZZ470.
Small Craft Advisory until 9 PM PDT Friday for PZZ455.
Small Craft Advisory until noon PDT Sunday for PZZ475.
&&
$$
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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png
Area Forecast Discussion
National Weather Service Grand Forks ND
1003 PM CDT Thu Jul 15 2021
.UPDATE...
Issued at 1003 PM CDT Thu Jul 15 2021
Thunderstorms have ended with sunset as expected with a few
locations still reporting visibilities around 6 miles in smoke.
Forecast is currently on track, and only minor adjustments to near
term trends were necessary.
UPDATE Issued at 713 PM CDT Thu Jul 15 2021
Very isolated thunderstorms are ongoing over eastern ND and
northwest MN, but intensity/coverage is actively diminishing.
This trend should continue through sunset. Impacts will tend to
include lighting and locally heavy rain (due to slow motion and
PWATS in excess of 1"), though the current storms are unlikely to
produce rates/amounts like activity earlier based on weakening
trends. Adjustments were made to reflect location/coverage.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 226 PM CDT Thu Jul 15 2021
Decreasing impacts are expected tonight as southwesterly winds
increase and help scour out the low-level smoke across eastern ND
and west central MN. A few weak cells may develop west of the
valley this afternoon but will be short-lived and erode after sunset.
High pressure now over the top of Lake Superior is resulting in
increasing return flow into central ND. The increase in WAA is
resulting in widely isold showers/possible a clap of thunder from
the upper James Valley into the northern Red River Valley, where
MLCAPE values are around 500 to 750 J/Kg. Shear values continue to
remain nil so any cells that develop will be rather slow moving
and short lived. More likely to see some spits of rain with this
activity, although some small hail with the strongest storms is
possible.
The SW winds are improving visibilities across eastern ND and smoke
smell is not as noticeable, however some reports or irritated eyes
remain. Will keep FU in on the east side of the river where winds
will be lighter and persist through mid-morning Friday. South winds
increase more in velocity tomorrow, resulting in highs in the upper
80s and lower 90s. There is potential for elevated smoke from fires
over the PAC NW to move into eastern ND late in the period, which
could impact afternoon highs. This episode should not be as
noticeable at the surface. Overall, a dry and breezy next couple of
days as a hotter airmass returns to the area.
.LONG TERM...(Saturday through Thursday)
Issued at 226 PM CDT Thu Jul 15 2021
Overall dry and warm conditions are expected across the region in
the extended time frame. Ensemble guidance brings the strong upper
ridge to the area this weekend and through the first part of the
week with the heat wave having a high confidence of occurrence.
Short term impacts will primarily be tied to above normal summer
temperatures with highs in the mid to upper 90s most likely with
some guidance suggesting triple digits are possible on the warmest
days of Tuesday and Wednesday when the thermal ridge axis settles
over the area. Long term impacts would be to enhance the ongoing
drought conditions and deteriorating crop conditions. As the upper
ridge weakens, weak short wave activity and weak surface wind shifts
or boundaries will eventually bring the chance for thunderstorms by
Tuesday night or Wednesday to the northern half of the area. This
will bring cooler temps however still above normal temps to the
area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 713 PM CDT Thu Jul 15 2021
Isolated showers/thunderstorms developed near some terminals in
the afternoon and have lingered into the early evening. The
activity is very slow in nature and should quickly weaken/fall
apart through sunset, so possible impacts at terminals are
diminishing. Smoke continues to complicate visibility forecast
across eastern ND and northwest MN, with pockets of MVFR
conditions possibly lingering into the night (especially in MN).
HRRR smoke model indicates a more pronounced clearing trend at the
surface by Friday morning (especially in ND).
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
UPDATE...DJR
SHORT TERM...Speicher
LONG TERM...JK
AVIATION...DJR
Area Forecast Discussion
National Weather Service Gray ME
949 PM EDT Thu Jul 15 2021
.SYNOPSIS...
Very warm and humid weather will continue through Friday. Showers
and thunderstorms will be possible Friday through Sunday as a
frontal boundary slowly sinks south of our area this weekend.
Coastal and river valley fog remains likely tonight into Friday
night. A broad trough will linger across New England early next
week, with additional shower chances and seasonable
temperatures.
&&
.NEAR TERM /THROUGH FRIDAY/...
945PM Update... Issued a Dense Fog Advisory for the Mid-Coast of
Maine through the Capitol Region and coastal Cumberland
County. Visibility continues to decrease in these regions and
satellite imagery indicates this will continue through the
overnight. There is lower confidence further inland where the
increasing LLJ should keep visibility above a quarter of mile in
most locations. Across the north, some patchy fog will be
possible along with increasing chances for a scattered shower
towards dawn ahead of an approaching frontal boundary. Other
than some minor adjustments to temperatures and dew points, the
rest of the forecast remains on track.
Previously...
615PM Update... Made some minor adjustments to temperatures, dew
points, and winds to better align with surface observations.
PoPs were adjusted across the north, where high resolution
forecast guidance such as the HRRR indicates that a stray shower
will be possible through around 02Z. There is currently a shower
located to the north of Berlin, NH and the latest run of the
HRRR did a decent job at capturing this. The only real weather
concern overnight will be for areas of dense fog, which
continues to lurk just offshore. Trends will be watched
throughout the evening and a Dense Fog Advisory may eventually
be needed for portions of the area.
Previously...
Pretty quiet around the region as of this Thursday
afternoon with little forcing for ascent for robust showers and
thunderstorms. A few small showers have popped up in the
mountains and the hills of Waldo County but capped environment
will keep them at bay. Otherwise, low clouds have exited most of
the coastline except portions of the Midcoast. There`s some
sort of weak wave moving through at this time and the descending
motion associated with this feature is aiding in the low clouds
and fog dissipating or accelerating out to sea, especially
across southern zones. With a southwesterly low level jet
increasing tonight, I am currently unsure how widespread low
cloud and fog coverage will be tonight. Current thinking it will
be less widespread than last night, with the best chances for a
few-hour period of dense fog on the Maine Midcoast
northwestward to around Augusta. No dense fog advisory at this
time. Otherwise, some valley fog once again possible tonight in
the CT Valley, but not likely as extensive as late last night.
&&
.SHORT TERM /FRIDAY NIGHT/...
A short wave trough will approach from the west early Friday and
aid in the approach of a surface cold front. A hot and humid air
mass will be in place ahead of the front which will aid in an
environment conducive to thunderstorms. The path of best forcing
for ascent as well as frontal timing will favor central ME to
Midcoast ME for best chance of storms, a couple of which could
be strong to severe. Can`t rule out a couple of storms in the
rest of the region, but coverage should be much more isolated.
Heat indices may reach 95 degrees for a few hours in portions of
the Merrimack Valley on Friday afternoon. A small heat advisory
may be required.
Aside from a low probability of a few showers across southern
zones Friday night, the weather should be quiet a more
comfortable in terms of humidity in the post-frontal air mass.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Long wave pattern presents with a trough over the central US and
ridging over the east and west coast. The overall flow remains
progressive and expect the trough to move eastwards into our region
through the weekend.
Saturday the surface boundary that has been lingering across
Massachusetts will remain in place as yet another wave moves along
it. With a warm and moist airmass in place, heavy rain will be
possible as showers move through this area. Excessive Rainfall
outlook continues to highlight the southern portion of NH, which
remains appropriate. As we`ve seen the past few cases MA and
southern NH remain the focus of the convection with training storms
being the main threat for heavy rain rates. Still quite a bit of
north south spread amongst the deterministic guidance for the
location of the highest precip totals during the day Saturday,
however with this package I have leaned somewhat south which is
favored by persistence, climatology and topography. Thus Pop has
been lowered across the northern portion of the area for Saturday.
Saturday night sees the front move east of the area, expect some low
level moisture to remain, especially in the valley bottoms and bring
fog through morning. By Sunday the fropa is complete and skies will
slowly clear. Have kept temperatures on the lower side for this
day,with the residual cloud cover but still pushing comfortably into
the low 70s.
A brief break as high pressure moves in with drier northwesterly
flow for Sunday night into Monday.
By the start of next week the upper level trough axis has shifted
east over our region, leading to more unsettled weather. Tuesday
late into Wednesday looks to be the focus for the next most likely
round of precipitation but in general the forcing is weak and
scattered showers may occur throughout the mid week.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Short Term...Fog should reform over the coast tonight, but
unsure of the coverage. Right now, the best bet is northeast of
PWM to the Midcoast where LIFR conditions move on in once again.
However, there is a chance that these conditions are shorter-
lived and less widespread than early this morning as a
southwesterly LLJ kicks up tonight. VFR on Friday and likely
Friday night with a few thunderstorms possible Friday afternoon.
Long Term...Showers with heavy rainfall across the southern
portion of the area on Saturday may briefly bring IFR
conditions. Overnight Saturday into Sunday expect IFR in fog for
the Connecticut and Merrimack river valley. Conditions will
clear on Sunday and remain VFR through the start of next week.
&&
.MARINE...
Short Term...Winds and seas likely remain below small craft
thresholds (5 ft seas, 25 kt) tonight through Tuesday. However,
fog will be dense over the waters tonight, primarily off the
Midcoast of Maine. A cold front will drop across the waters
Friday evening and this will result in winds switching to
northerly.
Long Term... A front will remain draped across the waters on
Saturday with showers, front will clear through on Sunday with
northwesterly flow. Winds and seas will remain below SCA.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Dense Fog Advisory until 8 AM EDT Friday for MEZ021-022-
024>028.
NH...None.
MARINE...None.
&&
$$
NEAR TERM...Tubbs
Area Forecast Discussion
National Weather Service Tucson AZ
847 PM MST Thu Jul 15 2021
.SYNOPSIS...An active monsoon period of daily scattered showers
and thunderstorms will continue during the next seven days. High
temperatures will remain below normal into next week as well.
&&
.DISCUSSION...Pretty wild afternoon and evening for Graham County. A
series of severe storms from Safford to northwest of the town of Pima
had several bouts of severe winds and heavy rains that resulted in
Flash Flooding with washouts and debris over area roads. Further
north in Graham County another group of storms dumped at least 4
inches of rain just south of Point of Pines in the Bonita Creek
watershed. At least some of this water (what the dry ground doesn`t
suck up) should make it down the creek toward the Gila. We are
watching the gauge in the area to see how much of any increase there
may be. At this time flooding is not expected on the Bonita Creek.
All that is left is a group of storms that are holding together
surprisingly well and appear to have Tucson in their sights. It will
be interesting to see if they hold together that far although they
are already providing a good light show.
Going forward it appears that it will be a fairly quiet night
overall. Some of the CAM solutions are again pointing to a flare up
of convection just before or around dawn tomorrow for areas west of
Tucson. This is likely helped along by the nightly SW moisture surge
that we get in the lower deserts from the gulf. I tweaked pops just a
bit in the pre-dawn, to several hours after dawn period to account
for this. Other than that, I only needed to adjust the temperatures
and dewpoints through Friday morning. Grids and updated forecast
already sent and looking forward to another active day Friday.
&&
.AVIATION...Valid through 17/00Z.
SCT-BKN clouds at 8k-12k ft MSL and BKN-OVC clouds AOA 20k ft MSL
over most of the period. There could be some isolated storms
overnight potentially affecting KTUS after 16/05Z but confidence is
somewhat low. Wind gusts to 40 kts possible near any TSRA along
brief MVFR conditions. Otherwise, SFC wind generally less than 12
kts. Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...There will be a good chance of showers and
thunderstorms across southeast Arizona the next week. Gusty outflow
winds will be the primary concern with the daily storms along with
heavy rainfall. Min RH values will be in the 25-35 percent range at
the lower elevations, with higher values in the mountains. Outside
of some stronger NWLY winds at 15-20 mph in the Gila River valley
this afternoon, 20-foot winds will generally be less than 15 mph and
follow normal diurnal trends when not influenced by thunderstorms.
&&
.PREV DISCUSSION... /issued 126 PM MST Thu Jul 15 2021/
After morning convection from Tucson westward, considerable
debris cloudiness remains with temperatures very slow to warm.
We`re starting to see some breaks in the overcast in these areas
and expect that trend to continue through the afternoon.
Meanwhile, for locales east of Tucson, there has been plenty of
solar insolation resulting in increased instability. Latest RAP
analyses shows MLCAPE values of 1000-2000 J/KG with little to no
CIN across Cochise/Graham/Greenlee Counties. We`re already
starting to see shower and thunderstorm activity develop on the
higher terrain to the east of Tucson. Given the favorable
environment, expect scattered to numerous showers and
thunderstorms to continue through the afternoon. The larger scale
northerly flow will tend to push the thunderstorms from north to
south into the early evening hours. Main concerns will continue to
be heavy rain and gusty winds with the stronger storms.
Starting tonight and through Friday there are some apparent
differences in the CAMs with how convection will evolve. In the
bigger picture, there is a mid level disturbance across
north/central Arizona that is progged to move to the south, then
southwest tonight and become fairly stationary as an inverted trough
on Friday over southeast Arizona. One possible scenario is that the
thunderstorm activity building across eastern areas this afternoon
diminishes this evening, but then as that aforementioned disturbance
moves to the south and west, some new convection develops late at
night or in the early morning hours Friday. If that occurs, some
areas could be worked over and have more limited chances for renewed
thunderstorm development Friday afternoon and evening. On the other
hand, if we see little in the way of thunderstorm activity late
tonight or Friday morning, that will likely set the stage for more
widespread showers and thunderstorms Friday afternoon into Friday
evening. In either scenario, given the deep moisture in place along
with fairly slow storm movement, we felt it was prudent to extend
the Flash Flood Watch through 11 PM Friday.
For this weekend and continuing through the middle of next week, we
are in a solid continuous active monsoon pattern. With the mid level
high to our north, easterly flow with ample moisture will continue.
Certainly there will be some up and down days relatively speaking
which we`ll try to hone in on in the shorter term. Given this
pattern, temperatures will remain below normal.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Friday evening for AZZ503>515.
&&
$$
Public...Cerniglia/Lader
Aviation...Hardin
Fire Weather....Hardin
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