Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/17/19
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1153 PM EDT Mon Sep 16 2019
.AVIATION...
A region of stratus (based mainly between 800 ft and 1200 feet) will
advance across metro Detroit, including PTK, during the course of
the night as a deepening low level inversion and persistent northeast
flow allows these clouds to continue to push in from the northeast.
At FNT and MBS, the gradient will weaken during the course of the
early morning. This will likely result in either IFR stratus or fog
or a combination of both. Daytime heating will result in a rather
rapid erosion of the clouds and fog between 14Z and 16Z.
For DTW...Regional satellite data suggest intervals of low end MVFR
or IFR based stratus will affect metro during the early morning
hours, likely past daybreak, as the low level flow slowly backs
toward the east-northeast.
DTW THRESHOLD PROBABILITIES...
* Moderate in ceilings below 5000 ft overnight and Tuesday morning.
&&
.PREV DISCUSSION...
Issued at 904 PM EDT Mon Sep 16 2019
UPDATE...
The 00Z DTX sounding features a deep inversion based near 800MB and
is relatively moist below the inversion base. The inversion will
lower through the night under ongoing mid level subsidence and subtle
cooling below the inversion base. There is already some stratus
streaming into portions of Se Mi off southern Lake Huron underneath
the inversion, a trend that will likely persist into the overnight.
The gradient will also weaken during the night, especially across the
Saginaw Valley region. This weakening gradient along with current
sfc observations suggest that any areas that do not see stratus or
regions were stratus breaks apart will be conducive to fog formation.
So regions of fog and/or low stratus look likely tonight. The
current forecast looks reasonable attm.
PREV DISCUSSION...
Issued at 315 PM EDT Mon Sep 16 2019
DISCUSSION...
Amplified upper level ridge over Central North America slowly
building east will lead to an extended period of dry weather.
Morning fog/low stratus is about the only potential impactful
weather over the next several days.
Surface dew pts still in the 60s this afternoon, as mostly cloudy
skies today preventing this moist airmass from mixing out. 12z DTX
sounding indicated a higher based inversion at 760 MB. However, with
heights rising tonight and ridge axis sliding into the Western Great
Lakes, subsidence inversion should push down well below 5000 feet,
and looking at fog and/or low stratus development tonight. Winds
will become very light, but may keep just enough of a north/east
component off Lake Huron to support low stratus (see Regional Gem).
However, the RAP soundings and surface CPD`s suggest more in the way
of dense fog, which was the case underneath the high over Wisconsin
this morning. As usual, the answer probably lies in between, and will
at least be adding areas of fog to the zones, along with maintaining
the higher sky grids for stratus. Probably take much of tomorrow
morning to increase mixing depths enough to dissipate the low clouds,
but airmass will be supportive of a warm day (80+ degrees
potential), as 850 MB temps reach 15 C. However, with surface flow
still out off the southeast, mixing depths likely coming up short of
850 MB level, and will keep maxes in the upper 70s.
The upper level ridge moves directly overhead of the Central Great
Lakes on Wednesday, 587 DAM at 500 MB/320 DAM at 700 MB. 850 MB
temps increase to between 16-17 C, but still enough off a southeast
component not to fully reach this level, but around 80 (78-82)
degrees per MAV/NAM/EURO mos certainly looks doable.
Even warmer as we end the work week, as surface winds come around to
the south, and then southwest by first half of the weekend. The
strong upper wave/trough currently the west coast will be moving off
to the northeast, tracking along the Manitoba/Ontario border on
Wednesday. Thus, tracking too far north to breakdown the upper level
ridge in place over southern Lower Michigan, with the summer-like
ridge center (590 DAM at 500 MB) holding strong close to/just to the east
of the central Mississippi River Valley. The ridge will slide east
over the Weekend, with next chance of rain showers arriving on
Sunday with decent cold front tracking through (per 12z Euro).
Weak instability axis with the front worthy of a slight chance of
thunderstorms. Cooler post frontal airmass sending temps back to
normal values for Monday, lower 70s.
MARINE...
High pressure will drift across the northern Great Lakes through mid
week resulting in light winds and waves. Winds will veer from
northeasterly today to southeast by Tuesday. An approaching trough
will then bring a slight increase to southerly winds to around 20
knots.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....SC
UPDATE.......SC
DISCUSSION...SF
MARINE.......DRK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Grand Rapids MI
1013 PM EDT Mon Sep 16 2019
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 330 PM EDT Mon Sep 16 2019
- Fog potential again tonight
- Very small chances for rain mid week in the northwest CWA
- Mainly dry and mild this week
- Next decent chance for rain comes next weekend
&&
.UPDATE...
Issued at 1013 PM EDT Mon Sep 16 2019
So the issue tonight is dense fog. It`s clear there is dense fog
over Lake Michigan and the nighttime microphysics satellite loops
show the fog coming on shore south of South Haven and expanding
from north of Saginaw. Give the otherwise clear skies, light winds
and overall easterly winds it would make sense to see a more
extensive fog tonight than last night. I through about the dense
fog advisory but I have to admit I am just not confident enough
at this point to do that. Lately I have been using with
considerable success the visibility forecast from the NAMNEST and
RAP model. I have noted over the past year when both say dense
fog you can bet there will be. It is true the NAMNEST has most of
the area from MBS to I-94 to I-96 across the state down in dense
fog by morning but none of the other models do that. So at this
point I will live with our fog in the grids and zones and call it
good but we will continue to monitor how quickly it expands.
&&
.DISCUSSION...(This evening through next Monday)
Issued at 330 PM EDT Mon Sep 16 2019
First order of business is the fog. We already have dense fog out on
Lake Michigan and will be hoisting a Marine Dense Fog Advisory
there. Grand Haven beach has near zero visibility at this time. The
question is what will land areas do tonight. Model suggest we will
see a push of fog and stratus tonight from the northeast off of Lake
Huron. Confidence is not high enough at this point to issue a Dense
Fog Advisory on the land with some areas remaining VFR per the
guidance and other areas dropping to low stratus and fog. We will
have areas of fog in the forecast. We will be watching how
conditions develop tonight for a possible advisory.
There are small chances for rain in the forecast for late Wednesday
night into Thursday as models are indicating some very light
precipitation trying to work in the far northwest CWA. A weak
shortwave passes through with a low level jet on the order of 25
knots. Could see us needing to remove these pops with time but for
now will remain continuity with neighboring offices.
Overall the forecast looks mild and dry this week with temperatures
warming into the 80s. 850mb temps remain in the teens C this week
will should yield a lot of upper 70s to lower 80s highs. Ridging
aloft should prevent much if any rainfall.
The next good chance for rain comes out over the weekend as the
pattern becomes more progressive. A trough will push through the
northern plains and into our area over the weekend. Saturday night
and Sunday look to be the best chances for showers and storms along
and ahead of a cold frontal passage. Dry weather tries to settle
back in for Monday. Overall a pretty quiet next 7 days with the
precipitation out on day 5 and 6 of the forecast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 751 PM EDT Mon Sep 16 2019
Currently (2330z) skies are nearly clear across our TAF sites.
There are some upstream mid and high clouds from a weak system
that will cross our area tonight. However the more significant
issue is the fog potential tonight into mid morning Tuesday.
With high pressures building in both surface and through a deep
layer into the atmosphere above us, winds will be light to calm
overnight. Model sounding and the visibility forecast for many
high resolution models agree an area of fog is expected to plum
southwest from Lake Huron (Saginaw Bay) over the I-69 area during
the early morning hours of Tuesday. We already had this in our
TAF forecast so, that being so I did not change much from the 18z
version of our TAFs actually.
Skies should clear up by mid to late afternoon. The HREF cloud
forecast actually shows clear skies of most of Lower Michigan
Tuesday by late afternoon.
So, solid VFR through 06z or so, then IFR/LIFR in fog at many of
our TAF sites, becoming VFR again by early afternoon Tuesday.
&&
.MARINE...
Issued at 330 PM EDT Mon Sep 16 2019
Will be hoisting a Marine Dense Fog Advisory which will be valid
from this afternoon through 11am on Tuesday. Webcams and satellite
imagery confirm dense fog across Lake Michigan. The fog is sliding
down the shoreline at this time in light northerly winds. Given the
potential for the fog to expand tonight have decided to cover the
whole marine area in the advisory.
Light winds due to high pressure will keep waves at a minimum this
week. Waves look to be 2 feet or less through Wednesday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Dense Fog Advisory until 11 AM EDT Tuesday for LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...Duke
DISCUSSION...Duke
AVIATION...WDM
MARINE...Duke
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
947 PM EDT Mon Sep 16 2019
.SYNOPSIS...
Hurricane Humberto is forecast to move east-northeast well
southeast of the area the next several days. Although no direct
impacts are expected with Humberto, rough marine conditions and
strong rip currents are expected this week. A cold front will
cross the area Tuesday followed by strong high pressure building
in from the north and northeast though the end of the week
bringing the first touch of fall weather to the area.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 955 PM Monday...High pressure will remain over the area
tonight. Daytime fair weather cumulus clouds have mostly
dissipated with the loss of heating this evening, leaving mostly
clear skies with outflow Cirrus from Humberto which will
prevail into the late night hours, especially along the coast.
After midnight, conditions will once again become favorable for
low stratus clouds, especially inland, however hourly LAMP
aviation guidance and HRRR aviation fields are backing away from
a widespread low cloud event like last night, so confidence is
decreased somewhat from earlier today.
High-resolution models continue to show little in the way of
precipitation in the near term and will continue to leave the
forecast dry. Lows tonight will be in the upper 60s to lower 70s
over most land areas with mid 70s Outer Banks.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
As of 330 PM Tuesday...Tuesday should be the last really warm
and humid day for a few days. Morning stratus and patchy fog may
again be stubborn to dissipate until late morning, but once it
does, should lead to mostly sunny skies with only scattered
fair-weather cumulus. The 3 km NAM and WRF indicate minimal
precipitation coverage once again, and will keep the forecast
dry. High temperatures should be in the mid/upper 80s with
lower 80s Outer Banks.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
As of 330 PM Mon...TC Humberto will bring indirect coastal
impacts to E NC through the end of the week, though high
pressure will build in bringing pleasant sensible weather to the
region with below climo temps for a change. By the weekend the
upper ridge will shift directly over the eastern seaboard with
longwave troughing setting up over the central plains, and temps
moderating back to near normal.
Wednesday through Friday...Strong high pressure builds in from
the north through the end of the week while Humberto continues
to track ENE across the western Atlantic with unusually strong
CAA behind the backdoor front. Tight pressure gradient between
these systems will bring breezy northeast winds and a cooler and
drier airmass that will give us a first hint of fall. Windiest
conditions are expected on the OBX where gusts of 35-45 mph are
expected. Will have to watch for beach erosion and perhaps some
minor coastal flood issues for prone areas of the OBX due to the
prolonged gusty NE winds and high surf - see the tides and
coastal flooding section for more info.Highs expected in the 70s
area wide. Lows drop into the low/mid 50s interior zones to the
low/mid 60s on the beaches.
Saturday...Nerly gradient begin to relax by Sat as the high
becomes centered over the area bringing lighter winds and a
moderating airmass with dry conditions continuing across the
region. High temps moderate back to near climo in the low 80s,
though with the continued very dry airmass (TDs in the 50s),
lows will still be cool in the 50s inland to 60s beaches.
Sunday through Monday...Return swrly flow continue to moderate
temps back to climo and above, with highs in the mid 80s
possible by Sun or Mon, and lows moderating back into the 60s.
It will continue to be dry however with upr ridge holding strong
over the SE CONUS.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Short Term /through Tuesday/...
As of 625 PM Monday...Shallow diurnal Cumulus clouds will
dissipate after sunset with outflow Cirrus prevailing overnight.
With little change in the temperature and moisture profiles
over the last few days, we are once again expecting a period of
LIFR/IFR Stratus clouds after midnight along with patches of
fog. Think the sub VFR conditions will improve to VFR by mid
morning with better mixing anticipated. Could see isolated
showers or storms develop late in the afternoon as a back door
cold front passes through with better chances for this activity
expected west of the TAF sites.
Long Term /Tue night through Sat/...
As of 330 PM Mon...Strong high pressure builds in late Tue
through the end of the week with Humberto passing well offshore
bringing tightening pressure gradients and gusty north to
northeast winds, mainly during the day when mixing is maximized.
Otherwise, good flying conditions with mainly sunny skies and
lower humidities and continued breezes resulting in fog free
nights.
&&
.MARINE...
Short Term /Tonight and Tuesday/...
As of 945 PM Monday...No changes to previous thinking. Marine
conditions will continue to slowly deteriorate as increased SE
swells from distant Hurricane Humberto along our southern coast
work north overnight and Tuesday. Already picking up 6-7 ft seas
south of Oregon Inlet with a few and gusts to 25 knots at the
buoy 30 miles southeast of New River Inlet. While the seas
increase tonight, the winds should really ramp up on Tuesday, as
the gradient between Humberto and strong high pressure to the
north increases. Gusts to 30 knots are likely in the SCA areas
by Tuesday afternoon.
Long Term /Tue night through Sat/...
As of 330 PM Mon...SCA conditions expected through much of the
long term with gusty nerly winds, dangerously large seas as
combined swells from TC Humberto and pressure gradient between
building high pressure and Humberto well offshore impact the
waters.
NE winds continue to strengthen Tue evening and continue through
Wed into Thu. Solid SCA winds in the 20-30 kt range with ocnl
gusts to 35 kt expected through Thur, then gradient lesses by
Thu night into Fri with winds decrease to the 10-20 kt range.
Swell from Humberto will peak around 12-14 ft Wednesday night
into Thursday, then begin to slowly subside on Friday, though
remain above 6 ft into at least the first half of the weekend.
&&
.TIDES/COASTAL FLOODING...
As of 330 PM Mon...Longer period swells from TC Humberto will
lead to a high threat of rip currents this week. In addition to
the swells, strong NE winds will develop Tue night into Thu as
strong high pres builds in from the NE. These winds combined
with the swells will produce large seas likely aoa 10 feet over
portions of the coastal wtrs. High surf and ocean overwash are
expected in vulnerable locations especially around the times of
high tide.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Beach Hazards Statement through Tuesday evening for NCZ195-196-
199-203>205.
MARINE...Small Craft Advisory from 3 PM Tuesday to 11 PM EDT Thursday
for AMZ131-137-230-231.
Small Craft Advisory from 3 PM Tuesday to 2 AM EDT Friday for
AMZ135.
Small Craft Advisory until 8 AM EDT Sunday for AMZ152-154-156-
158.
Small Craft Advisory from noon Tuesday to 8 AM EDT Sunday for
AMZ150.
&&
$$
SYNOPSIS...MHX
NEAR TERM...JME/CTC
SHORT TERM...CTC
LONG TERM...TL/MS
AVIATION...JME/CTC/TL
MARINE...JME/CTC/TL
TIDES/COASTAL FLOODING...MHX
Area Forecast Discussion
National Weather Service San Diego CA
Issued by National Weather Service Los Angeles/Oxnard CA
206 PM PDT Mon Sep 16 2019
.SYNOPSIS...
A trough of low pressure moving inland today and a second for
Wednesday will spread cooling inland with a return of night and
morning coastal low clouds and fog. There is also a slight chance
of thunderstorms into early this evening with little or no
rainfall expected. For Friday into next weekend, that second
trough of low pressure will weaken with warming trend.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SYNOPSIS...
A broad trough of low pressure aloft will generally remain over
the area through Thursday to keep temperatures below normal while
bringing a return of night and morning coastal low clouds and
fog. The trough moves east of the area by the end of the week with
a slight warming trend for the weekend.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
The upper level trough axis has made its way onshore this
afternoon over northern California. This trough has cooled
temperatures over the forecast area as expected with current
temps 5 to 10 degrees cooler than this time yesterday. The
increasing onshore flow with this trough should also bring areas
of gusty winds to the mountains and deserts this afternoon and
evening. The other impact from this trough has been the increasing
onshore flow and mid level moisture that`s brought some mid level
instability and a slight chance of thunder. Still some stratocu
moving across the area this afternoon per area web cams and
visible satellite imagery, but the lightning activity that was
west of the area this morning has been absent so far today. High
res models show any remaining instability fading away through the
day. Latest HRRR model still shows an area of very weak
instability making its way across the area later this afternoon
and evening. Confidence in any activity developing, even isolated,
is low. However am reluctant to remove the chances of
thunderstorms from the forecast. Emphasis is more on the very
slight side and primarily over the mountains and deserts this
evening. Any thunderstorms that do happen to develop will produce
little if any rain, rather will bring a threat of a dry lightning
strike or two and possible gusty winds.
The trough axis will be east of the area tonight and heights rise
ever so slightly on Tuesday, but thickness values hold steady to
bring little if any change in temperatures. Another upper trough
drops into northern California on Wednesday to cool high temps
another few degrees over southwest California on Thursday and
make it the coolest day of the 7 day forecast. Should also see a
return of the overnight coastal stratus and fog each night
starting tonight and really through most of the week.
Long range models agree on lifting Wednesday`s trough into the
northern Great Plains on Friday or Saturday, at the same time a
tail of that trough hangs back to the southwest and extending to
the southwest of California. Heights still rise a bit even under
this extension and as a result Friday should start a weak warming
trend that will last into Sunday. Some differences in model
solutions out in day 7 whereby the EC drops another much deeper
upper trough over the Great Basin, but much less energy on the
GFS solution. EC has jumped around a little bit from run to run
on this, so favor the GFS solution for little change from day 6 to
day 7 as opposed to the cooler and windier solution from the EC.
.AVIATION...
161800Z...Coast/Valleys...SCT-BKN mid and high clouds above 12000
feet MSL. Isolated -SHRA possible until 00Z. MVFR CIGS return after
04Z tonight coastal terminals with SCT-BKN MVFR CIGS for valleys.
Mountains/Deserts...Mostly BKN high clouds at/above 15000 feet MSL
with a slight chance of TS and CB bases above 10000 feet MSL through
00Z. After sunset SCT high clouds.
&&
.MARINE...
There is a slight chance of cloud to water lightning this evening.
Otherwise, no marine weather hazards are expected through Saturday.
&&
.FIRE WEATHER...
The upper level trough that has moved into northern California
will continue to move east tonight and Tuesday before a second
trough moves into the west coast on Wednesday. This will
strengthen the onshore flow with stronger and gusty southwest to
west winds in the mountains and deserts during the remainder of
this afternoon and evening. These gusty winds combined with lower
inland humidity will elevate fire weather conditions from the
desert slopes of the mountains into the deserts from mid afternoon
through early this evening and again Wednesday.
Some weak mid level instability moving through the area this
afternoon and this evening will bring a very slight chance of
thunderstorms to the mountains and deserts. Little or no rainfall
is expected. Any thunderstorms could produce gusty winds and a
few dry lightning strikes.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC/FIRE WEATHER...MJ
AVIATION/MARINE...EB
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