Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/06/18
Area Forecast Discussion
National Weather Service Bismarck ND
944 PM CDT Sat May 5 2018
.UPDATE...
Issued at 944 PM CDT Sat May 5 2018
Only minor changes were made with this update. Convection across
southwestern ND is dwindling as a likely response to increasing
CIN and reduced CAPE for boundary-layer-based parcels per both
objective analysis data and modified regional 00 UTC RAOBS. We
modified PoPs for the next few hours based on radar trends, but
we still expect remaining convection to end by about 05 UTC per
upstream trends and recent HRRR output, which has been verifying
well this evening.
UPDATE Issued at 610 PM CDT Sat May 5 2018
We refreshed hourly forecast fields through the evening using the
consensus of recent rapid-refresh and 18 UTC global model output,
and weighted the evening PoP forecast toward the time-lagged HRRR
with this update, with no dramatic changes to the going thoughts.
As of 23 UTC, satellite and regional radar imagery reveals weak,
high-based convection most focused near a surface wind shift from
eastern MT, across southwestern ND and into SD. Steep low- and
mid-level lapse rates are largely driving MLCAPE on the order of
200-400 J/kg, locally highest in far southwest ND, per recent SPC
objective analysis data. Thus, occasional lightning will continue
with the strongest updrafts the next few hours, and the presence
of a well-mixed boundary layer with large temperature-dewpoint
spreads may support locally gusty winds, too. CAMs, in particular
the HRRR through its 22 UTC iteration, support the observational
trends in favoring the highest concentration of scattered activity
over southwestern ND the next few hours, with a downward trend in
convection in the mid to late evening as the boundary layer begins
to stabilize.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 123 PM CDT Sat May 5 2018
Surface low pressure over northeast South Dakota with a trailing
cold front into southwest North Dakota Saturday afternoon will be
the focus for widely scattered afternoon and evening thunderstorms
over western and southern North Dakota through this evening.
Pretty modest instability from the model soundings so do not
expect much organized convection.
Tonight skies will clear from the scattered cumulus convection
and Sunday will see a region of surface high pressure bring sunny
skies to the region with high temperatures a few degrees cooler
than today.
.LONG TERM...(Sunday night through Saturday)
Issued at 123 PM CDT Sat May 5 2018
This time frame will be more active with two periods of convection to
focus on. First, the global models agree in tracking a closed
upper low across the Northern Plains Monday night into Tuesday.
This will bring likely chances for showers and scattered
thunderstorms over western and southern North Dakota. In central
North Dakota, GFS forecast soundings at Bismarck have a healthy
CAP with over 120 CIN to overcome Monday afternoon/evening, but
western North Dakota looks like the cap will break. So best
chances for thunderstorms will be southwest with decreasing
chances as you go north and east. Forecast QPF shows up to three
quarters of an inch southwest to a quarter possible central and
less east.
A second short wave will move through Thursday bringing another
good chance for showers and thunderstorms. Taken together, these
two precipitation events will help the greenup but will probably
not be sufficient to soak the ground. But it will be a start.
Cooler guidance temperatures show up in the extended by Friday
through Saturday with a longwave trough that will end up pushing
the storm track further south of the state for the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 944 PM CDT Sat May 5 2018
VFR conditions are forecast to prevail for the 00 UTC TAF cycle.
Lingering showers and isolated thunderstorms in southwestern ND
will diminish by about 05 UTC. High pressure will then build in
across the entire area for Sunday, resulting in light winds and
a mostly sunny day.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CJS
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...CJS
Area Forecast Discussion
National Weather Service Denver/Boulder CO
744 PM MDT Sat May 5 2018
.UPDATE...
Issued at 735 PM MDT Sat May 5 2018
High level moisture continues to spin down for the northwest over
the top of the shortwave upper ridge to our west. A few weak
showers attempted to form over the Front Range and move off over
the adjacent plains past few hours, only to produce gusty outflow
winds of 15-28 mph. The few remaining high based cumulus clouds
generating virga should see their demise within the next hour or
so. Otherwise, varying amounts of cirrus cover and slight warming
aloft should result in slightly warmer overnight temperatures at
the ground. Current forecast already reflects this trend.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 306 PM MDT Sat May 5 2018
Some light showers developing about as predicted, mainly north of
Fort Collins moving southeastward. Can`t rule out a few lightning
strikes, but expect mostly light rain and maybe a little wind with
this as they move southeast this afternoon. HRRR showed this all
ending by 00z...presumably with some drying and subsidence. That
may be a bit too aggressive, but we`re showing not much this
evening which looks fine.
Sunday`s environment will be similar, though there should be just
a little more moisture on the plains. Low PoPs from mid afternoon
through early evening for weak convection looks good.
.LONG TERM...(Sunday night through Saturday)
Issued at 306 PM MDT Sat May 5 2018
Warmer and drier air aloft moves into Colorado on Monday, but
there should be some increase in moisture on southerly flow over
the plains as well. At this point, it looks like the plains should
be pretty well capped, otherwise it could be a severe storm setup
with CAPES of up to 1000 J/kg on the eastern border by evening.
We`ll continue to carry low PoPs for drier convection along the
east slopes of the mountains, and then along the eastern border in
the evening.
A cold front will move through Monday night, bringing a little
cooling and stabilization. Tuesday should be mostly sunny, though
there could still be some weak convection over the central
mountains and near the eastern border.
For Wednesday through Friday, Colorado will be in generally dry
westerly flow aloft with modest moisture over the plains. There is
a weak shortwave that will move across the northern Rockies
through the ridge. This could be enough for some low grade
convection, or a little bit more wind. Westerlies behind this
trough is probably the only fire weather threat of the period if
everything is a bit more amplified than what we are expecting now.
Probably a marginal situation at worst, plus most of our area will
have green fuels.
Reasonable model agreement through Thursday goes haywire by
Saturday as upstream amplification proceeds. There continue to be
serious disagreements about the latitude of strong lows over the
eastern Pacific and the location of resultant downstream
ridge/trough combinations. About two-thirds of the models we`ve
seen have some kind of trough digging down the east side of a west
coast ridge about Saturday, but these range from a moderately
strong shortwave over the northern plains to a strong low closing
off over California. The other third of the models have continued
westerly flow, some with a strong low progressing gradually
onshore. In short, a model blend solution helps set the
probabilities here so we will stick with that. Whatever happens
will likely not be in a strong or moist environment aloft, so the
closed low solutions may not be as weathery as they might look at
first. However, there will be some plains moisture and the
seasonal instability, so it might not take much dynamics to
produce a good area of rainfall. For now, a little increase in
PoPs on Friday, and then a bit more with some cooling Saturday
looks good. Probably at least 50/50 that those things will happen.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 735 PM MDT Sat May 5 2018
Until 03z, it`s still possible (maybe no more than a 10 percent
chance) that a high based virga shower drifting off the foothills
could produce a few wind gusts of 14-18kts. But, as temperatures
cool, chances of this happening will quickly dim. Otherwise,
light east-northeast winds are expected to gradually become
south-southeasterly over the next few hours at speeds under
12kts. However, there is a low chance that KDEN and KAPA could
see a southerly wind of 12-16kts for a hour or so late this
evening before assuming a south-southwesterly direction at speeds
under 10 kts.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Baker
SHORT TERM...Gimmestad
LONG TERM...Gimmestad
AVIATION...Baker
Area Forecast Discussion
National Weather Service Billings MT
802 PM MDT Sat May 5 2018
.UPDATE...
An area of light showers has recently pushed off the Beartooth
front and has tracked eastward into southern Yellowstone and
western Big Horn Counties. Though we are seeing height rises w/
ridging over central MT, moist flow and a weak shortwave moving
through the northern Great Basin will keep the potential for some
mainly light showers in our west overnight. Further east, there is
an axis of instability (slightly negative showalters) from Miles
City to Baker and Ekalaka, with PV sliding through eastern MT.
As a result we could see additional showers pop up across eastern
MT over the next few hours, as latest HRRR is suggesting. Have
adjusted pops accordingly tonight. Otherwise, have removed any
mention of thunderstorms as cirrus earlier today helped to
suppress instability. Have also made minor tweaks to temps and
winds. JKL
&&
.SHORT TERM...valid for Sun and Mon...
Upper ridge was building over the northern Rockies, but plenty of
moisture was streaming in over the top of the ridge from the
south Pacific. Southwest flow over the Great Basin will send a
series of weak waves into the forecast area tonight and Sunday.
Instability will be limited with dewpoints in the 30s and 40s and
cloud cover somewhat limiting potential peak instability. That
being said, enough moisture and shortwave influx to paint isolated
to scattered PoPs across the area.
A deep upper trough, currently off the California coast, will
shift into Idaho Sunday afternoon and evening. The majority of
forcing with the wave will stay to the north and west of the
forecast area, but increasing diffluence along with a back door
cold front sliding in, should trigger scattered convection.
Increasing mid level downslope flow will be counteracted by cloud
cover to keep high temperatures similar to that of today.
The upper low slowly slides across the area Monday. A pacific
front will move through the area and enter the Dakotas by early
afternoon. There is a chance of strong thunderstorms developing
along and east of the boundary. At this time, models keep this
over the western Dakotas, with our southeast zones just west of
the stronger dynamics. TWH
.LONG TERM...valid for Tue...Wed...Thu...Fri...Sat...
The extended continues to be consistent. The trough from Monday
will continue to move into the northern Plains Tuesday. Some
showers will linger across the eastern zones during the day.
Things will generally be dry as a ridge builds in Wednesday, but
this will be short-lived. By Thursday a trough to the north will
flatten the ridge out, putting the area in zonal flow. This will
result in chances for showers into the weekend. Any wave of energy
that comes across could produce at least a chance for some
showers, and with afternoon heating some thunderstorms are also
possible. Temperatures still look to the above normal. Reimer
&&
.AVIATION...
Scattered showers are possible through tonight and early Sunday
morning as a weak disturbance slides across the area. Outside of
occasional mountain obscurations, VFR conditions will prevail.
Winds turn SE by late Sunday morning with another round of
scattered showers and thunderstorms possible west of KSHR/KMLS on
Sunday afternoon. Dobbs
&&
.PRELIMINARY POINT TEMP/POPS...
Sun Mon Tue Wed Thu Fri Sat
-----------------------------------------------------------
BIL 051/079 053/079 052/078 051/076 052/073 049/070 047/069
21/E 33/T 42/T 12/W 33/W 33/W 33/T
LVM 045/075 047/072 044/074 044/074 045/068 042/066 041/065
33/T 34/T 32/W 13/T 44/T 33/W 33/W
HDN 049/082 053/081 053/079 051/079 052/075 049/072 048/070
31/B 23/T 53/T 11/B 32/W 23/W 33/T
MLS 052/080 055/080 055/076 053/075 052/072 047/068 047/067
20/B 22/T 43/T 21/U 32/W 23/W 33/W
4BQ 050/076 055/077 053/074 051/075 052/073 048/069 047/066
30/B 24/T 43/T 21/U 22/T 23/W 35/W
BHK 048/074 051/077 051/072 050/071 048/066 043/065 044/065
20/U 22/T 55/T 21/U 33/W 23/W 33/W
SHR 048/078 049/076 049/074 048/075 050/073 044/069 043/066
32/T 34/T 42/T 11/B 32/T 33/W 44/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Columbia SC
745 PM EDT Sat May 5 2018
.SYNOPSIS...
Dry weather still expected through tonight ahead of an
approaching frontal system. The front will cross the region
Sunday with a slight chance of thunderstorms Sunday and Monday.
Dry weather will be over the area through the middle of the week
with another frontal system approaching for Thursday night and
Friday
&&
.NEAR TERM /UNTIL 7 AM SUNDAY MORNING/...
An upper level trough currently extending through the Tennessee
Valley will approach the region from the west overnight. This
system will bring a weak cold front from eastern Alabama into
the forecast area. Regional radar early this evening shows a
broken line of convection along the front that appears to be
weakening some as it moves east. Although models do show
moisture increasing across the area tonight, the limiting factor
for any showers will be moisture given maximum PWAT values of
around 1.2 inches. The HRRR does bring shower activity into the
far western portion of the area around 09Z before it peters out.
This appears reasonable so added just a slight chance to the
far western FA toward daybreak Sunday morning. Expect most of
the area will remain dry. Patchy fog and stratus may be possible
overnight, but widespread development not expected due to
mixing and clouds. Overnight low temperatures are forecast in
the lower 60s.
&&
.SHORT TERM /7 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Upper level trough will be just west of the forecast area Sunday
as the surface front moves through during the late morning and
early afternoon hours. Models continue to indicate instability
will be lacking and the timing of the front moving through
before max heating will also limit potential. As such have a
slight chance of thunderstorms during the afternoon in the Pee
Dee and far eastern Midlands closer to the front.
Monday and Monday night the upper trough will swing into the
area with instability increasing on Monday. Moisture may be a
limiting factor as pwat values differ between models with one to
one and a quarter inches through the period. With slightly
better upper level support have remained with chance pops for
most of the forecast area. With moderate instability will
expect thunderstorms during the afternoon and evening hours.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Models continue in good agreement with differences in timing and
intensity later in the period. The upper level trough will
slowly cross the region Tuesday and Wednesday with weak ridging
moving in Thursday through Saturday. Main issue Will be
Thursday and Friday as the next frontal boundary passes to the
northwest of the area. Confidence in models remains low due to
timing and intensity differences so have made minor adjustments
to current forecast. This will keep a dry forecast over the area
through Thursday night with a slight chance of rain on Friday.
Temperatures will be near normal Tuesday and Wednesday then warm
to above normal for Thursday through Saturday.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Extensive high level clouds across the area early this evening
with winds becoming light and variable. Some potential noted for
stratus development late tonight with advection from the south
coastal plain into the eastern Midlands. This is supported by
the HRRR and lamp guidance. The mav/met mos suggest lower
threat. Based on persistence there may be a period of patchy
fog at AGS/OGB but stratus favored due to relatively strong low
level jet. So period of IFR/MVFR conditions during the period
from 09z to 14z with the greatest threat near the OGB terminal.
Low clouds should scatter out after 14z with approaching cold
front from the west. Winds shifting to west-northwest during the
afternoon with drier air advecting into the area. Expect gusty
winds in the afternoon to near 20 knots.
.EXTENDED AVIATION OUTLOOK...
Upper level trough moving through the region Monday. Restrictions
possible Monday afternoon and evening associated with scattered
showers/possible thunderstorms. Low ceilings possible early
Tuesday morning.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Caribou ME
1024 PM EDT Sat May 5 2018
.SYNOPSIS...
A cold front will slowly sag southward across the area overnight
into Sunday night. High pressure builds Monday and Tuesday.
Another cold front will cross the region Tuesday night followed
by high pressure on Wednesday.
&&
.NEAR TERM /THROUGH SUNDAY/...
1025 PM Update...
Hrly temps needed adjustments to bring readings up some as
clouds continue to spread east in advance of a weak front.
Decided to raise overnight lows a few degrees based on more
clouds. The radar did show some light returns apchg the western
border. The latest HRRR and RAP looked to be close matching up
w/the radar show a small area of showers moving across the
northern areas overnight into early Sunday morning. Followed the
daycrew`s assessment of carrying 20-30% pops to cover this
small area of showers. Any rainfall will be trace amounts to
perhaps 0.01". No other changes attm.
Previous Discussion...
A surface cdfnt wl mv out of Canada tonight and thru CWA drg
the ovrngt hrs. Expect an area of clds along bndry with perhaps
a brief shower acrs nrn and cntrl sxns. Mins expected to dip to
nr freezing acrs the St. John Vly and the lwr 40s along the
Downeast coast.
High pressure briefly impacts the CWA tomorrow bfr next wv mvs
up along the ern seaboard along stalled frontal bndry. This wl
spread rain fm south to north drg the aftn hrs.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
A dynamic situation occurs Monday night as a cold front remains
over the southern half of the forecast area with some rain.
Meanwhile, a cold upper level shortwave in the northern stream
interacts with low pressure arriving in the southern stream from
S. New England. A resultant baroclinic zone over the region will
result in steadier rain developing over the entire area during
the night. Further complicating the scenario is the addition of
enough cold air advection late in the night to contemplate a
changeover to snow in northern zones well after midnight. The
late night timing boosts the case for some unusual May snow.
However, with lows around 34F and a lack of any heavier
intensity, it`s hard to make the case for much more that a few
tenths of an inch...mostly in higher terrain. The system is
expected to exit east quickly Monday morning with skies clearing
and temperatures recovering to the mid 50s north and lower 60s
towards Bangor and the coast. Offshore winds could mean lower
60s right to the coastline. Light winds and the cool air mass
will ensure lows in the 30s on Monday night with frost possible
for most of the area. Warming southwest winds on Tuesday ahead
of a cold front will propel Tuesday`s highs well into the upper
60s to near 70F...except on the coast where the sea breeze will
keep highs in the 50s. The gusty southwest winds and low
relative humidity will increase fire weather concerns on
Tuesday.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The weak and dry cold front crosses Tuesday evening and ushers
in slightly cooler temperatures in northern zones, but it`ll
actually be warmer in coastal zones. Nonetheless, the sea breeze
will return by afternoon. High pressure will maintain dry
conditions Wednesday night into Thursday. Expect another
pleasant day in the upper 60s on Thursdays...except on the coast
where onshore winds return. A frontal system is expected to
arrive Thursday night and move out of the area Friday morning.
However, some uncertainties remain on the timing of this system
and maintained some slight chance or chance pops beyond Friday
into the weekend.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
NEAR TERM: VFR next 24 hours.
SHORT TERM: Expect VFR conditions except Sunday night into early
Monday morning when MVFR tempo IFR conditions are expected due
to cigs...and possibly a brief period of snow north of PQI.
Gusty SW winds towards 25kts are expected Tues afternoon.
&&
.MARINE...
NEAR TERM: Will continue SCA through 06z tonight, mainly for
seas ovr 5ft. Winds may gust to aoa 25kts tonight.
SHORT TERM: Fog is possible Sunday night...followed by a
potentially brief period of SCA winds on Monday morning.
&&
.HYDROLOGY...
A flood warning remains in effect for the Fish River at Fort
Kent. The river is holding steady around 11.8 ft and then
expected to begin to recede late in the weekend and into early
next week as dry weather takes hold.
An areal flood warning also remains in effect for north central
Aroostook County, and has been extended into early Sunday
morning. Flooding continues at many homes and camps along the
Fish River chain of lakes, including Portage Lake, Saint Froid
Lake, Eagle Lake, Square Lake, Cross Lake, and Long Lake. The
causeway on Long Lake to Pelletier Island remains closed w/ice
moving onto the roadway.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service Duluth MN
713 PM CDT Sat May 5 2018
.UPDATE...
Issued at 713 PM CDT Sat May 5 2018
Scattered showers or sprinkles continue to affect the forecast
area this evening. This activity is thanks to a large area of FGEN
from 1000-850mb moving across the region. Opportunity for thunder
has decreased with the loss of CAPE over the last few hours.
Still expecting the showers to subside yet early this evening.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 314 PM CDT Sat May 5 2018
Clouds and showers will continue passing through the Northland
through this evening due to a passing weak shortwave trough and
weak cold front. Leaned on the latest HRRR and RAP for timing and
placement of rain chances. There could be enough most unstable
CAPE, about 100 to 200 J/kg, to see a rumble of thunder. These
showers are high based, with a lot of dry air below, so there will
be quite of evaporation with the falling rain. These showers will
look more impressive for rainfall than what actually accumulates.
Weak high pressure will build into the region tonight and Sunday,
leading to clearing skies and light wind speeds. Temperatures
should drop into the 30s and low 40s by early Sunday morning, but
recover well into the 60s thanks to sunshine. Although, it will be
cooler by Lake Superior in the 50s because of a lake breeze.
.LONG TERM...(Sunday night through Saturday)
Issued at 314 PM CDT Sat May 5 2018
A ridge will be centered across eastern portions of the
Intermountain West. At the surface high pressure will build into
the Upper Mississippi River Valley and Ontario. The ridge will
build southeastward into the Central Great Lakes on Monday while
the surface high slides into the Eastern Great Lakes. In addition,
a trough will lift from the Pacific Northwest into the
Intermountain West. This will result in falling heights and
lowering pressures across the Northern Plains which will tighten
the pressure gradient over the Northland. Kept similar sustained
winds to the previous forecast. However, opted to increase wind
gusts as a deep mixed layer develops. If the NAM/GFS Bufkit
soundings are correct and we fully tap into the mixed layer then
gusts of 15 to 20 knots are not out of the question. In addition,
lowered relative humidity values. It will be mild with high
temperatures generally in the 70s.
The trough will dig into the Northern Plains and Upper
Mississippi River Valley on Tuesday. At the surface a broad low
will develop over the Northern Plains and a warm front will lift
into the region. There are still some differences between the
GFS/ECMWF and GEM on where the precipitation shield develops due
to the front, but kept chances of precipitation. The low will
gradually move eastward on Wednesday into early Thursday. This
will continue bringing chances of rain to northeast Minnesota and
northwest Wisconsin. Readings will be mild on Tuesday as warm
advect into the region as the front lifts through. Highs will
generally be in the upper 60s and low 70s. Expect cooler readings
on Wednesday as flow becomes northerly/northwesterly as the low
moves through. Highs range from the upper 50s to the mid 60s.
Dry weather returns on Thursday as a ridge quickly builds in.
Precipitation chances return Friday and Saturday, but guidance is
all over the place with the next trough moving in from the Pacific
Northwest. Timing, amplitude and intensity of the wave are all
over the place between the GFS/ECMWF and GEM. So, have kept a
general blend of guidance at this point. Will need to refine
things as models come into better agreement.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 634 PM CDT Sat May 5 2018
An area of low pressure was located over southern Minnesota with
an array of fronts associated with it. Meanwhile, a quasi-
stationary front was located just north of the Canadian border.
Between these features, abundant mid and high clouds were near the
terminals. Scattered showers were also moving nearby. Will
maintain a VCSH mention as the showers are of the popcorn
variety. Expect these showers to diminish around sunset and the
sky should clear. Some BR is possible late tonight, but confidence
is low and will leave out for now.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 38 64 40 75 / 20 0 0 0
INL 33 66 38 79 / 0 0 0 0
BRD 40 70 43 78 / 10 0 0 0
HYR 41 68 39 76 / 30 0 0 0
ASX 35 60 35 76 / 30 0 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
UPDATE...GSF
SHORT TERM...Grochocinski
LONG TERM...WL
AVIATION...GSF
Area Forecast Discussion
National Weather Service Green Bay WI
1009 PM CDT Sat May 5 2018
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Sunday
Issued at 228 PM CDT Sat May 5 2018
The latest RAP analysis and satellite/radar imagery show a weak
area of low pressure centered over west-central MN and an equally
weak cold front sagging south across central WI. In close
proximity to the surface low and shortwave energy digging over
south-central Canada, scattered high-based showers are pushing
across central and northern MN. Meanwhile, scattered alto-cu are
moving across western WI ahead of the showers, and into a very
dry airmass where humidities are generally in the 20s to 30s.
Forecast concerns mainly revolve around shower chances as the low
arrives tonight, followed by humidity levels for fire weather.
Tonight...The area of low pressure will slowly move southeast
across far southwest WI and northern IL by late tonight. A weak
low level trough will accompany the low, to go along with steep
mid-level lapse rates which will help support scattered showers
moving across the forecast area from late evening into the
overnight. Timing continues to slow down, and pushed backed precip
chances until 02-04z. Cannot rule out a rumble of thunder,
particularly over central WI into the southern Fox Valley, where
MU capes reach up to around 400 j/kg. Showers are due to exit
central and north-central WI late tonight, while a few showers may
hang on along the 850mb trough over northeast WI through 12z.
Lows ranging from near 40 degrees over Vilas County to the mid
40s over central WI.
Sunday...Showers will be ending over northeast WI during the early
morning hours. Broken to overcast conditions will hang around
longer, and should not see clearing take place until late morning
into early afternoon from northwest to southeast. With north or
northeast winds, temps will be significantly cooler than todays
readings. Highs should range from the low to mid 60s at most
locations away from Lake Michigan. With these highs, humidity
levels will fall again into the lower 20s over the northwoods.
Therefore elevated fire weather conditions will continue across
the north.
.LONG TERM...Sunday Night Through Saturday
Issued at 228 PM CDT Sat May 5 2018
Fire weather concerns on Monday and precipitation chances during
the midweek period are the main forecast concerns.
Canadian high pressure will bring dry and chilly conditions on
Sunday night, with lows in the 30s to around 40. Southwest winds
will gradually increase on the northwest periphery of the
departing high on Monday, with gusts to 15 to 20 mph possible
during the mid to late afternoon. Deep mixing through 800-750 mb
should push high temperatures into the upper 60s and lower 70s,
and cause relative humidity to drop into the 20 to 30 percent
range in the sandy soil areas. Elevated fire weather conditions
are anticipated, especially over northern WI, where RHs will be
lowest and winds will be strongest.
Generally dry weather will persist through Tuesday night, but
rain chances will increase Wednesday into Wednesday night as a
low pressure system and associated upper level trough move
through. Given precipitable water values increasing to 1.2 to 1.4
inches and the strength of the upper trough, we should see at
least moderate rainfall with this system.
Forecast confidence remains low for the rest of the forecast
period due to differences among the 12Z models. The GFS keeps most
of the precipitation to our south late in the week, while the
Canadian brings heavy rainfall to northern WI late Thursday night
into Friday, and the ECMWF brings heavy rain Friday night into
Saturday. Given the uncertainty, will stick with the blended model
pops, which indicate slight chance/chance from Thursday night through
Saturday. More definition of the timing and rainfall amounts will
be made during this period as models converge on a solution.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1009 PM CDT Sat May 5 2018
Scattered showers and isolated t-storms will move across the
southern part of the forecast area over the next few hours. Brief
reductions in vsbys are possible in heavier showers, although
cigs will remain above 5000 ft at most locations. Skies becoming
mainly clear on Sunday.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......Kieckbusch
AVIATION.......JKL
HYDROLOGY......MPC
Area Forecast Discussion
National Weather Service Wilmington NC
952 PM EDT Sat May 5 2018
.SYNOPSIS...
A warm weekend will prevail ahead of a cold front approaching
from the west. Tropical moisture skirting the coastal Carolinas
will bring a chance of showers or a thunderstorm late tonight
through Sunday. The front will cross the coast Sunday night
then stall just offshore. High pressure will follow much of the
upcoming week with a warming trend. The next best chance of
rain looks to be next weekend, as a front stalls near the area,
and moisture increases.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 1000 PM Saturday...Radar trends suggest yet another
westward shift in precipitation/QPF fields is needed overnight.
A large area of convection is developing south of Cape Fear with
its sights set on Brunswick, New Hanover, and Pender counties
where forecast PoPs are now a solid 100 percent. Up to an inch
of rain remains possible along the Cape Fear coast overnight.
The latest HRRR and HRRRX models appear to have initialized
poorly with precipitation a good 40 miles too far to the west
when compared to current radar imagery. For this reason I have
not increased PoPs substantially along the I-95 corridor, but
did raise them by 20-30 percent across Georgetown and Conway
north through Whiteville and Elizabethtown where even the 18Z
GFS painted small precip amounts overnight. Discussion from 600
PM follows...
A very difficult forecast is shaping up over the next 12 hours
where there will likely be a very pronounced gradient in
rainfall totals near the coast.
A slug of subtropical moisture lifted northward out of the
Caribbean by an upper level low over Cuba will graze the
Carolina coast tonight. While this by itself would produce
mainly light showers across the coast and offshore, a region of
pronounced upper level divergence preceding an upper level
disturbance passing through TN/KY should reach the eastern
Carolinas after midnight. As this rather impressive divergence
aloft intersects the subtropical moisture stream after midnight,
convective showers should blossom with embedded thunderstorms
becoming possible as elevated CAPE values rise to 300-600 J/kg.
The western edge of the subtropical moisture stream will largely
determine where substantial rainfall occurs. While model
solutions vary from just off the beaches of Cape Fear all the
way west to Whiteville, GOES-16 mid-level water vapor imagery
plus current radar activity suggests a slight westward nudge of
the more significant rainfall is necessary relative to our
previous forecast. PoPs in Wilmington have been bumped up to 80
percent with half of inch of QPF expected. It`s possible a few
spots between Bald Head Island and Surf City could pick up
an inch of rain, mainly between 2-8 AM Sunday morning.
Farther inland, the good upper divergence will still move
overhead tonight, but lifting a much drier atmosphere should
yield little if any rainfall. PoPs along the I-95 corridor are
10 percent or less, mainly due to a thick layer of dry air
between 850-500 mb. In between, my 50 percent PoP line runs from
Myrtle Beach to Lake Waccamaw to White Lake. No significant
changes are needed to temperatures, winds, or sky cover
forecasts.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 300 PM Saturday...Mid level trough axis remains just to
our west through the period. It presentation is quite ragged
however, with most of its vorticity packets weak and quite
sheared out. Additionally the deep layer moisture will have
shifted offshore with early period FROPA. End result is other
than some light rain along the coast a good bet early on
rainfall will be quite isolated and short-lived for the rest of
the short term. Picking out any area being favored over another
difficult as there will be randomness caused by mid level lapse
rates being elevated and possible mesoscale processes or
differential heating boundaries providing ascent (by day at
least, Monday night likely rain-free). However if future
forecast soundings remain as dry as those of the 12Z WRF then
measurable rainfall will likely be removed from the forecast
altogether through most of the period.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 300 PM Friday...`Seasonable With a Gradual Warming Trend
Much of Next Week` might describe the extended period. An upper
cool pool will slowly traverse overhead Tuesday and Wednesday,
but dry mid-levels should keep a cap on convection despite nice
lapse rates aloft. Warming to commence ahead of a short-wave
Thursday and Friday, when max-Ts should begin to rise above
normal by several degrees. Short-wave to bring a chance of
showers Thursday night over SE NC, while its associated surface
front stalls near the coast and dissipates slowly. The boundary
may act as a catalyst for convection next weekend as moisture
deepens.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 00Z...Numerous showers have developed an have been approaching
the coast early this evening. Areal coverage of showers should
remain high through tonight with a high confidence of MVFR
CIGs/VSBYs developing this evening. Moderate confidence in IFR CIGs
developing overnight when the extent of convection will be greatest.
CIGs begin to improve during Sunday morning generally after 13-15Z
time frame.
Extended Outlook...VFR except MVFR/IFR early Sunday due to fog.
&&
.MARINE...
NEAR TERM /THROUGH SUNDAY/...
As of 1000 PM Saturday...Seas have not responded yet to inferred
increasing wind speeds 50-150 miles offshore, analyzed in latest
model guidance. It may take a few hours for these larger seas to
push west of the Gulf Stream and into the nearshore waters.
Rainfall rates near Cape Fear are likely to become quite
substantial overnight with visibility reductions expected. No
changes to winds or seas have been made with this latest
forecast update. Discussion from 600 PM follows...
No significant changes are needed to the marine forecast
overnight. Showers developing now just outside of 20 miles from
shore should sweep across the area this evening, with heavier
showers and potentially thunderstorms developing overnight
mainly in the Cape Fear vicinity. Although winds across the
coastal waters shouldn`t increase significantly tonight, a
stronger jet of southerly winds 50-150 miles off the coast will
begin to add to local sea heights, expected to increase to 3-5
feet near Cape Fear, and 3-4 feet off the SC coast overnight.
SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 300 PM Saturday...Frontal passage Sunday night to
initiate veering of wind fields while not yielding much an
increase in wind speed. This is due to the weak nature of the
front itself and the high that builds in behind it. As such NE
flow will set up for the remainder of the period. Choppy short
period seas will build gradually and may approach SCEC late in
the period.
LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 300 PM Saturday...`Advisory Flags` still flying Tuesday
and may need extending into Wednesday, or a `Caution` headline,
because of moderately strong NE winds. Wednesday afternoon
through Thursday will become much improved, as veering onshore
wind flow eases up. A few showers are possible late Thursday.
The sea spectrum will be in varying wave heights, primarily a
mix of NE wind-seas every 4-6 seconds, and longer period SE
waves every 7-9 seconds.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...MJC
NEAR TERM...TRA
SHORT TERM...MBB
LONG TERM...MJC
AVIATION...SRP
Area Forecast Discussion
National Weather Service Lincoln IL
913 PM CDT Sat May 5 2018
.UPDATE...
Issued at 912 PM CDT Sat May 5 2018
The clouds and showers from the stationary front in the Ohio
Valley are remaining just to the southeast of Lawrence County in
southeast Illinois, and that trend should continue. A weak trough
of low pressure extending across Champaign and Vermilion counties
is producing some cloud cover, and the HRRR shows a band of
showers developing by 11 pm and shifting south. Confidence is low
on any of those showers reaching the ground, based on the dry air
below the cloud layer. Sprinkles may occur, but no measurable rain
is expected with that feature.
Farther to the northwest in Iowa, a cold front is approaching
Illinois. Showers and storms across Iowa have been diminishing as
they push into the dry airmass across eastern Iowa. That area of
forcing for precip will arrive in our NW county shortly after
sunrise on Sunday. The latest HRRR shows a more prominent band of
precip progressing from NW to SE Sunday morning, but the dry air
will erode the potential for measurable rain. Will continue with
low chances of rain and storms, with expanding coverage Sunday
afternoon as surface temps/dewpoints and instability reach their
peak.
No major changes to the going forecast, with just some minor
adjustments to temps/sky to cover expected trends.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 230 PM CDT Sat May 5 2018
After a dry and seasonable day on Saturday, the next system
topping the western north american long-wave ridge will spill over
into the Midwest on Sunday. Boundary layer moisture remains
limited and models having been backing off on amounts and coverage
of precip associated with this system despite the decent
dynamics. Boundary associated with the wave is rather diffuse and
will likely not provide much of a focus for convergence. Best
thunder chances will during the afternoon when instability is
most enhanced by axis of cooler air associated with wave. CAPE
values around 1000 J/Kg and dry levels may provide environment
capable of producing some significant wind gusts.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 230 PM CDT Sat May 5 2018
After a bit cooler temps on Monday, short-wave ridging ahead of
the next system expected midweek will allow temps to rebound
Tuesday. Midweek system will begin to impact the area late Tuesday
night. Despite larger differences than yesterday in solutions
between the GFS and ECMWF with respect to timing and strength of
wave, sensible weather not that different with a wet day expected.
Although low-levels should be more moist than tomorrow`s system,
high pressure ridging along the Gulf coast should keep that
moisture source generally cut off which should limit instability
and precipitation amounts somewhat.
Still big differences between the two major models with respect to
the evolution of the pattern after the midweek wave. 12z ECMWF
continues to indicate ridging over Illinois for the end of the
week as a strong trough digs into the inter-mountain west. The
GFS is not as zonal as yesterday suggesting it may be coming
around to a pattern change as well, but it still much less
amplified. This makes the forecasts based on the GFS wetter and
cooler than the ECMWF. GEFS output shows two clusters of solutions
at this point with one cluster closer to the ECMWF and the other
closer to the operational GFS. Given the uncertainty at this
point, will go with a blend and close to the GEFS mean.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 701 PM CDT Sat May 5 2018
High pressure will provide VFR and dry conditions for most of the
night tonight. A weak surface low and cold front approaching from
the NW will trigger some scattered showers late tonight near PIA
and BMI. Shower chances will expand to the southeast after
sunrise, with a few rumbles of thunder possible for the I-72 TAF
sites during the afternoon. Very dry air in place across central
IL should help to minimize the coverage of showers and diminish
storm potential. Have not included thunder with this TAF
issuance, but am analyzing the afternoon instability params for
possible inclusion with the 06z update.
Winds are generally light from the N-NW at the start of the 00z
TAF period. However, winds will shift to the SW this evening, as
the low and cold front approaches. Speeds will remain less than
10kt. The cold front will pass from NW to SE from around 18z near
PIA to around 21z near CMI/DEC. Winds will become W-NW after
FROPA, with some gusts to 15-18KT possible late in the afternoon.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SHORT TERM...Barker
LONG TERM...Barker
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
855 PM EDT Sat May 5 2018
.SYNOPSIS...
A frontal boundary will remain stalled over southern Virginia
through the weekend. Low pressure over the Tennessee Valley
will move northeastward into the central Appalachians overnight,
then redevelop across southeastern Virginia and depart
northeastward toward coastal New England Sunday. A secondary
cold front will approach from the eastern Great Lakes and drop
southward through the region Sunday night, followed by building
high pressure through the middle of next week. Another frontal
system may approach by late next week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Low pressure remains over the Tennessee Valley this evening
along with upper-level low pressure associated with it. A
boundary is stalled to our south and surface high pressure
resides to our north. An onshore flow along with plenty of
clouds has allowed for much cooler conditions compared to
recent days.
Plenty of moisture has streamed into the area ahead of the low
due to a southwest flow aloft. Latest mesoanalysis shows an axis
of PWATS around 1.25 inches. The shortwave energy and low-level
jet has caused a band of moderate rain across northern and
western areas (northern Maryland into the Potomac
Highlands/eastern West Virgina). Farther south and east, shower
coverage has been isolated to widely scattered farther away from
the shortwave energy and frontogenetical forcing in the low-
levels.
The upper-level low and its surface low will slowly move
northeast into Kentucky overnight. The mid-level and low-level
forcing will gradually shift north and west, and this will cause
the steadiest precipitation to shift toward the Allegheny and
Potomac Highlands overnight. Across the rest of the area, did
allow for isolated/scattered showers but much of the time will
likely be dry overnight. Plenty of clouds will hang around and
continue to lower as moisture gets trapped underneath a weak
subsidence inversion. Min temps tonight will be in the 50s for
most areas with 40s in the Allegheny Highlands. Localized
flooding of small streams cannot be completely ruled out in
the Potomac Highlands, but confidence is low at this time due to
recent dry conditions. Rainfall amounts around 1 to 2 inches
are expected across these areas.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Low pressure over the Appalachians will transfer off the
southeastern VA coast Sunday, maintaining shower chances over
much of the CWA into Sunday afternoon. This will be coupled with
support from a shortwave trough moving overhead and WAA ongoing
at 850mb. Could be a bit of a lull in shower activity Sunday
morning, with a better chance of showers in the afternoon and
early evening for our eastern zones as the trough moves through
and low pressure moves off the VA coast. Highs on Sunday will
top out in the mid to upper 60s across northern MD and west of
the Blue Ridge, with lower 70s likely D.C. southward.
Shower chances wane overnight Sunday as the primary shortwave
moves off the coast and drier air filters in to the region.
Lingering shower activity will remain a possibility Monday as
the upper level trough continues to encompass much of the Mid
Atlantic and northeast. This activity will be diurnally driven
with the lack of synoptic forcing, favoring our mountainous
areas that preside near the trough axis. Highs and lows Monday
will be near normal.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
On Tuesday, a weakening upper level trough axis will be oriented
from Upstate New York to the Carolinas. Underneath this upper level
trough, some showers will be possible over higher elevations along
and west of the Blue Ridge. However, most locations will stay dry
with a ridge of high pressure in place to the east of the
Appalachians. The upper trough will continue to weaken as it shifts
off the East Coast on Wednesday. Conditions should remain dry as the
wedge of surface high pressure remains intact at the surface.
Model guidance is in fairly good agreement that the next chance for
rain will come late Thursday through Thursday night as a weak cold
front extending south from a low over the Great Lakes approaches our
area. The greatest chances for appreciable rain with this system
will be west of the Blue Ridge. A weak ridge of high pressure builds
in Friday (assuming the cold front has already passed), reducing
chances of precipitation.
Temperatures are expected to moderate gradually throughout the long
term period with highs around 70 and lows around 50 on Tuesday,
increasing to highs around 80 and lows around 60 by Friday.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Mainly VFR conditions through late this evening for all the
terminals. Low clouds will get trapped underneath the subsidence
inversion overnight and MVFR conditions are most likely late
tonight and Sunday. However, IFR conditions cannot be ruled
out. Latest Lamp guidance does show IFR late tonight and Sunday,
but HRRR Time Lag still shows a greater probability for MVFR
conditions. Did lean toward MVFR for now due to a northerly flow
expected in the low-levels but confidence is low. A few showers
are likely, especially for KMRB this evening, and then across
the rest of the terminals Sunday afternoon/evening.
Low clouds should dissipate later Sunday night as a northwest
flow develops behind a departing low. However, the flow will be
light and radiational fog is possible overnight into Monday
morning. High pressure will bring drier conditions later Monday.
Mainly VFR Tue-Wed but can`t rule out patchy sub-VFR given
likelihood of onshore flow between high pressure to the north over
New England and low pressure to the southeast over the western
Atlantic. Precip chances appear minimal. Flow will likely be NE AOB
10 kts.
&&
.MARINE...
Sub-SCA conditions expected through Sunday across all waters,
with winds remaining light as low pressure approaches from the
west, reemerging off the VA coast on Sunday. SCA conditions
will be possible Sunday night into Monday night as drier air
filters south on the back side of the low.
A surface wedge of high pressure will build down the east side of
the Appalachians Tuesday into Wednesday as low pressure develops
over the western Atlantic. This will result in northeasterly flow,
which should be generally light during the middle of next week,
though guidance tends to underdo easterly flow at longer time
ranges. Winds should stay generally below SCA criteria but open
waters of the middle Chesapeake could be susceptible to higher
gusts.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.
&&
$$
SYNOPSIS...BKF
NEAR TERM...BJL/BKF
SHORT TERM...BJL/BKF
LONG TERM...KJP
AVIATION...BJL/BKF/DHOF
MARINE...BJL/BKF/DHOF
Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
1050 PM CDT Sat May 5 2018
.DISCUSSION...See updated information for land areas below.
&&
.UPDATE...With the upper trof axis having moved east, positioned
from the TN River Valley to the central Gulf coast, forecasters
beginning to see darkening (drying) in the water vapor imagery
expanding eastward over the central Gulf coast as frontal boundary
continues to progress east. Forecast soundings also drying out,
supporting the removal of small PoPs we had going. There are some
lingering, light returns on radar over the eastern zones which may
result in a passing brief sprinkle, but measurable rain is looking
slim for the remainder of the night. /10
&&
.PREV DISCUSSION... /issued 627 PM CDT Sat May 5 2018/
DISCUSSION...See updated information for land areas and aviation
discussion below.
UPDATE...Axis of upper level trof was moving eastward across
the Mid-South this evening. This has allowed a continued eastward
movement of a weak surface front as well, analyzed from the TN
River Valley to across the MS Sound at 05.22Z. Overall, radar
trends show that the precipitation coverage pattern has waned
ahead of the front and is generally isolated. The latest RAP and
high resolution NAM continue to reflect these trends going
forward into the evening, with the HRRR showing some re-
development, eastward across the western FL Panhandle this
evening. Given radar trends, PoPs have been lowered to 20% into
the evening and this should cover any potential redevelopment over
the southeast zones until front clears the area. /10
AVIATION...
00Z issuance...CIGs are forecast to be at mid and high levels this
evening. Shra in the vicinity of PNS by around 06.02Z. Some
potential of late night mist potentially lowering vsby to MVFR
categories after 06.09Z at MOB and BFM. Winds light from the
northwest. /10
PREV DISCUSSION... /issued 346 PM CDT Sat May 5 2018/
NEAR TERM /Now Through Sunday/...A weak cold front located roughly
along a Thomasville, AL to Lucedale, MS line as of 2 PM CDT will
continue to move east across the forecast area through the rest of
the afternoon and into early this evening. Scattered to numerous
rain showers have developed as expected across southeast MS and
interior southwest AL along this boundary, with occasional isolated
stronger thunderstorm cells also embedded within the line. Expect
mainly scattered convection to continue developing eastward across
southwest AL and portions of south central AL through the rest of
the afternoon, before a gradual weakening/decreasing trend in
coverage occurs late this afternoon into early this evening. Enough
residual moisture and lift along the boundary will support keeping a
slight chance of rain showers in the forecast this evening over our
eastern zones. Dry weather is then expected overnight as a much
drier deep layer airmass arrives into our region in the wake of a
passing shortwave trough and the surface cold front. A very shallow
moist layer near the surface may support patchy fog development late
tonight into early Sunday morning across southeast MS, much of
southwest and south central AL, and possibly a small portion of
interior northwest FL.
Our forecast area will remain on the base of an upper level trough
Sunday. Little in the way of moisture is indicated underneath this
feature, so expect mostly sunny and dry conditions through Sunday
afternoon. Northerly surface flow otherwise prevails with warm
afternoon temperatures and low relative humidity. /21
SHORT TERM /Sunday night Through Tuesday night/...A well defined
mid and upper trough axis will be draped across the area to start
the short term. Surface low pressure associated with this trough
will continue to move away from the east coast and toward the
Canadian Maritimes. Dry northerly flow on the back side of the
upper trough will remain in place through the short term period.
A well defined shortwave is forecast to translate southeast through
the northwest flow around the mean upper trough on Monday and into
early Monday evening. While the low levels will be relatively
dry, cool temperatures aloft associated with the passage of the
shortwave combined with robust surface heating will lead to modest
levels of instability and the chance for isolated showers and
thunderstorms Monday afternoon and evening. The area with the
greatest chance to see a shower or storm looks to be confined to
areas north and west of I-65. Dry and warm weather is forecast for
Tuesday as the upper trough is shunted eastward and flow aloft becomes
more zonal. Highs on Monday and Tuesday will be in the mid to
upper 80s for inland locations, a little cooler along the coast.
05/RR
LONG TERM /Wednesday Through Saturday/...The remainder of the week
looks to stay dry as zonal mid level flow is replaced by upper
ridging ahead of the next storm system taking shape across the
middle part of the country. Surface high pressure across the
northern Gulf Coast will migrate slowly to the east late Wednesday
into Thursday, allowing our winds to become southerly, increasing
low level moisture across the area. General subsidence as the
upper ridge builds into the region combined with intense May
sunshine will lead to a string of warm days to close out the work
week. Temperatures will approach or exceed 90 degrees in a few
locations each day with upper 80s prevalent elsewhere for all be
the immediate coast. Overnight lows will be in the low to mid 60s
with upper 60s along the coast. A slight chance of showers looks
to return to the area for the upcoming weekend. 05/RR
MARINE...A cold front will move across the marine area this
evening. Moderate offshore flow prevails tonight, especially over
the open Gulf waters, where we will highlight exercise caution
headlines. Light to moderate offshore flow will persist over the
marine area through Monday. An onshore flow returns late Tuesday and
continues through the end of the week as high pressure moves east of
the region. /21
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&
$$
This product is also available on the web at:
http://weather.gov/mob
Area Forecast Discussion
National Weather Service Marquette MI
646 PM EDT Sat May 5 2018
.SHORT TERM...(This evening through Sunday)
Issued at 402 PM EDT SAT MAY 5 2018
WV imagery and RAP analysis indicated cyclonic wnw mid/upper level
through the nrn Great Lakes on the srn flank of a trough from Hudson
Bay into nrn Ontario. A shortwave trough located nw of Lake Superior
supported upstream sct -shra over the MN arrowhead and increasing
clouds into nw Upper Michigan. At the surface, a cold front extended
from James Bay to near Thunder Bay. Otherwise, weak high pressure
prevailed over the area with lake breeze boundaries moving well
inland over the north.
Tonight, upstream radar trends models fcst 850-700mb fgen suggest
that the area of showers will continue to spread to the ese with the
greater coverage and amounts through the north. Since there is still
uncertainty with the pcpn development and evolution, only chance
POPs or sct coverage was mentioned. Even with the moderate to
strong forcing, moisture availability should limits rainfall
amounts to a tenth of an inch or less. Thunder chances also should
remain to the south over WI in proximity to more favorable MUCAPE
and slightly steeper mid level lapse rates.
Sunday, Some showers may still linger early over the far south or
southeast. High pressure will build into the area with nrly winds
keeping areas in the north in the upper 40s or lower 50s. Inland
areas will see readings in the mid 60s. With some gusts to around 15
mph and min RH values dropping into the 20-25 percent range inland
west, the wildfire risk will remain elevated.
.LONG TERM...(Sunday night through Saturday)
Issued at 320 PM EDT SAT MAY 5 2018
Monday is the main focus due to dry and breezy conditions
potentially leading to near critical fire weather conditions. SW
winds won`t be all that strong, but gusts to 15-20mph are expected.
Min RH values will be around 25% over the interior W half, and
generally 30-40% elsewhere. Lowered Td values and increased winds
from the blended initialization.
Beyond that, a more active pattern is expected with greater moisture
and precip chances, especially mid-late week next week. Blended
initialization handled everything quite well during this time frame,
so didn`t make any changes.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 644 PM EDT SAT MAY 5 2018
VFR conditions are expected at IWD and CMX through the TAF period.
There may be some light rain showers tonight, but there should be no
major reductions in visbility or ceilings at both sites. Could be
some MVFR cigs later tonight at SAW due to north upslope flow off
Lake Superior.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 402 PM EDT SAT MAY 5 2018
Mainly light winds can be expected through much of the week,
generally below 20 kts, as the pressure gradient remains weak. Late
in the week, Thursday into Friday a low pressure system may cross
the Upper Great Lakes, bringing a chance of increased wind speeds,
closer to the 20 to 25 kt range.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Titus
AVIATION...07
MARINE...JLB
Area Forecast Discussion
National Weather Service Mount Holly NJ
931 PM EDT Sat May 5 2018
.SYNOPSIS...
High pressure will remain centered east of the Mid-Atlantic coast
through tonight. Low pressure will organize south and west of the
area later tonight and affect our weather into early Monday. High
pressure will move in for early next week, then low pressure and a
cold front moves towards our area Thursday into Friday.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
An upper air analysis this evening placed a well defined through in
the Ohio and Tennessee valley`s. This feature shows up well on the
water vapor imagery, and there are several short waves embedded
within the flow associated with it. Meanwhile, another trough exists
across south-central and eastern Canada with a ridge across the
Intermountain West. There is an area of 850 mb warm air advection
across portions of the Mid-Atlantic. At the surface, weak low
pressure was located near eastern Tennessee with a frontal zone
eastward near the Virginia/North Carolina border which then is
draped east-northeastward and out to sea.
Low-level warm air advection from the south in addition to the
southern half of our area near the right entrance region of a 500 mb
jet streak is helping to produce some showers and sprinkles. This
activity is slowly lifting northward however there is lingering
drier air as one goes northward across the area and therefore the
showers have been weakening. The airmass will eventually moisten up
more as isentropic lift increases some through the night. Based on
radar trends, adjusted the PoPs some and the HRRR might be catching
on. Interestingly enough, some lightning has occurred northwest and
west of Washington DC. The 00z Sterling, VA raob showed pretty much
no instability, however an axis of higher precipitable water and the
presence of a low-level jet and frontogenetic forcing looks to be
aiding in advecting just enough MUCAPE northward. There is sharp
northward gradient and the latest thinking is any lightning remains
removed from our area tonight. Temperatures and dew points were
tweaked based on the latest observations, then the LAMP guidance was
blended in to assist.
While the guidance does vary some with how the showers will play out
through tonight, the consensus is for more of a focus across our
western zones where isentropic lift is a bit more maximized near a
850 mb thermal gradient. Some additional showers should develop
especially later tonight farther south and east within weak warm air
advection and near a weak inverted surface trough as weak low
pressure develops near coastal North Carolina. Overall, some showers
will be around through the night although the coverage is still
somewhat uncertain.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
Low pressure will lift northeastward from eastern Virginia and North
Carolina through Sunday. An associated warm front will try and lift
northward into parts of our region but it does not look like it will
make it very far (possibly into Delmarva). With the warm front
staying to the south of much of the region, we will see more of a
northeast to east low-level flow through Sunday. This combined with
low clouds and some showers, surface heating will be limited across
the region and therefore a cooler day is expected.
An upper-level trough will arrive toward late in the day, which
should help with some uptick in the large scale ascent. Showers are
expected at times with this feature and also with a surface low to
our south and east. The coverage of the showers is a little less
certain, however several of the model guidance looks to be focusing
on shower development near or within the I-95 corridor in the
afternoon. This may be near an inverted surface trough and thus a
low-level convergence area. The instability looks limited given the
onshore flow and the expectation of low clouds. Some warmer air
though may arrive into portions of Delmarva, with some forecast
soundings showing a small amount of surface-based instability by
late afternoon. Farther north, some rather weak elevated instability
is shown in some of the forecast soundings however this is not
enough for thunder. As a result, we only have a slight chance of
thunderstorms mentioned in the far southern areas during the
afternoon to early evening hours.
Temperatures will be near or below the normals for early May. Highs
will reach into the 60s through much of the area, with upper 50s
along parts of the NJ coast and southern Poconos. Highs across
Delmarva will range from the mid 60s to lower 70s.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
The slow moving low pressure system and its associated fronts will
be crossing the area Sunday night. We will continue with the high
chance and low likely pops across the area with a chc for thunder
N/E. The pops will trend downward through the night with the system
pulling off the coast. The 12Z CMC is much slower with the system
evening keeping chcs for showers and clouds into Monday. This is
somewhat at odds with the 12Z GFS and both the 12Z and 00Z ECMWF,
so we will not consider it attm and keep Monday dry across the
area. These dry days will continue into Wednesday ad high
pressure settles across the region. Temperatures through the
period will be close to normal with low/mid 70s for highs in
most areas, cooler up in the Poconos and close to the shore. The
warmers of the three days will be Wednesday.
Low pressure will move out of the Western states this week and
deepen across the northern Plains region Wednesday. The low will
cross the Great Lakes and then begin to move down the St. Lawrence
Valley Thu/Fri. This system will bring warmer temperatures,
increasing humidity and chc for showers and tstms for Thu/Fri. We`ll
likely see some high temperatures back into the mid/upper 70s again
later this week, so perhaps a little above normal by then.
Next weekend, could end up being much like this one with some of the
models showing a stalled front across the area and some weak short
waves moving along it. We will keep low chc or slgt chc pops for
those time periods for now. Temperatures again will be close to
normal.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Tonight...VFR ceilings lowering, then MVFR ceilings developing
mainly after 08z. Some light showers are not expected to restrict
the local visibility initially, however some MVFR visibilities
should develop at times overnight mostly at RDG/ABE. Southerly winds
10 knots or less becoming light and variable, then east-northeast
near 5 knots overnight. Lower confidence regarding the onset of MVFR
ceilings.
Sunday...MVFR ceilings, with IFR ceilings probable at times
especially at MIV and ACY. MVFR visibilities are anticipated with
showers, and the showers may become more widespread for a time in
the afternoon. East-northeast winds 10 knots or less.
Outlook...
Sunday night...MVFR/IFR conditions may be slow to improve. Showers
ending with Local fog possible.
Monday through Wednesday night...Mostly VFR.
Thursday...Mostly VFR, but scattered afternoon showers possible.
&&
.MARINE...
Conditions are expected to remain below Small Craft Advisory
criteria through Sunday.
Outlook...
Mostly sub-SCA however some low-end SCA swells possible Sun
night thru Monday night. Not enough confid to raise SCA flag
attm. Sct showers Sunday night then Fair thru Wed night. Sct
showers psbl Thursday.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.
&&
$$
Synopsis...O`Hara
Near Term...Gorse
Short Term...Gorse/Meola
Long Term...O`Hara
Aviation...Gorse/O`Hara
Marine...Meola/O`Hara
Area Forecast Discussion
National Weather Service Blacksburg VA
1149 PM EDT Sat May 5 2018
.SYNOPSIS...
A stalled frontal boundary draped over the area will lift north
overnight as a low pressure system tracks into the Ohio Valley.
A weak cold front will pass over the region Sunday morning,
followed by another on Monday. A stronger front is possible on
Thursday.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 1135 PM EDT Saturday...
Loss of heating has stabilized the airmass enough to limit
thunderstorms, but still enough elevated instability with the
upper trough west of the mountains to keep a few strikes going
across the mountains.
Appears showers will linger at times over the WV
mountains/adjacent VA mountains into dawn, so kept higher pops
here similar to previous forecast, with less coverage to the
east of the Blue Ridge.
Previous discussion from early evening...
Very active from WV to TN this evening with heavy showers and
storms, some which produced large hail along the KY/VA border
counties into WV. A few stronger storms made it into our WV
counties with quarter sized hail this afternoon in Mercer
County.
Early this evening, line of storms moving into Southern WV to
far SW VA north of a frontal boundary should move slowly east to
northeast into the New River Valley to Alleghanys. HRRR appears
to have some handle on it but may be too slow. As the low moves
into the southwest VA mountains by midnight the area with better
lift to shift northward into the Southern Shenandoah Valley to
Alleghanys. Still should only see isolated to low chance
coverage east of the foothills, and south of the NC/VA border.
Airmass will stabilized with limited severe potential but will
still have to watch for heavier downpours leading to localized
flooding.
Previous discussion from early afternoon...
An upper level trough will drive a surface low northeastward
across central Tennessee and Kentucky this evening. This low
pressure system is expected to stay west of the Appalachians as
a weak insitu wedge hovers over the Mid Atlantic region.
Moisture from the low to the west will overrun the wedge in the
east, bringing rain to area north of HWY 460 with the heavier
rain occuring north of I64. This low will also help erode the
wedge overnight, which could give way for scattered storms
persisting into Sunday morning. Also this evening and as the
wedge erodes across the mountains and eventually in the east,
scattered storms are possible and could bring localize heavy
downpours as PWATS are running around an inch. Rainfall amounts
over the next 24 hours will range from 1-2 inches in
southeastern West Virginia and up to an inch in the mountains of
southwest Virginia. Across the piedmont and foothills counties
and NW North Carolina mountains, upwards to a half of an inch is
possible.
By rise Sunday, the surface low should be near Pittsburgh and
the trailing cold front tracks across West Virginia. The front
moves quickly crosses the area Sunday morning. Only light
rainfall is expected with the frontal passage as bulk of the
heavier rain and deeper moisture tracks north with the low. As
the front moves east Sunday, temperatures will be slightly
cooler than normal.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 215 PM EDT Saturday...
Easterly moving upper low fills and becomes part of long wave
high amplitude trough over the eastern United States by Monday.
Nearly closed 500 MB low develops over the Carolinas by Tuesday
morning.
Surface wedge develops for Monday and Tuesday with abundant
cloud cover. Clouds and precipitation will hold back daytime
temperature rise. Will trend toward cooler guidance for highs on
Monday and Tuesday. Have slightly increased probability of rain
on Monday and Tuesday. Best chance will be in the mountains and
foothills.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 115 PM EDT Saturday...
Upper low move northeast by Wednesday night with pattern
becoming more zonal but still with some weak troughing as short
waves track through the northern stream Thursday and Friday.
Large differences in the models after Thursday, especially in
western United States. 06Z GFS and 00Z ECMWF/CMC were completely
out of phase. WPC is leaning toward trough in the western
United States but not to the extent of the CMC/ECMWF.
Surface wedge breaks on Wednesday with increasing southwest
wind ahead of the low pressure system approaching from the Ohio
Valley. This low crosses the areas pushing a cold front through
the Mid Atlantic region on Thursday. At this time models
indicate enough forcing and instability for thunderstorms on
Thursday afternoon and evening. Will keep the forecast dry for
Friday and Saturday behind this system. Temperatures will be
near normal through the period with a warming trend at the end
of the week.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
As of 720 PM EDT Saturday...
Timing showers and storms to impact BLF/LWB in the 00z to 02z
time frame, with more tempo groups for ROA/BCB around 01-03z.
Through the night expect better coverage of showers to stay over
the Alleghanys and into LWB, while further east coverage will be
more scattered to none at all.
Low pressure shifts east to the piedmont by 12z Sunday and
mainly concerned about low cigs and vsbys with fog overnight as
airmass moistens up.
Will see most of the forecast area with sub-VFR through 12z
Sunday, with at times IFR or LIFR with cigs in the mountains.
.Extended Aviation Discussion...
Another cold front could arrive on Monday to spark added
showers. By Tuesday, high pressure will build over the New
England, which will start a period of east winds ushering marine
air from the Atlantic Ocean that should provide lower ceilings
and visibilities espcly southern and southwest sections. Drier
air as winds turn more southerly and the weak wedge breaks down
should allow for improvement to VFR on Wednesday.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...RCS
NEAR TERM...RCS/WP
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...RCS/WP