Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/05/18
Area Forecast Discussion
National Weather Service Binghamton NY
1051 PM EDT Fri May 4 2018
.SYNOPSIS...
A strong cold front, will bring late day showers and
thunderstorms. Some storms could be severe. Later tonight and
Saturday, high pressure will bring dry weather, and seasonable
temperatures. A weak disturbance, could bring some showers back
into the area, by Sunday afternoon.
&&
.NEAR TERM /THROUGH SATURDAY/...
11 pm update...
Synoptic winds have dropped below Wind Advisory criteria and
should continue to diminish across the region tonight. Therefore
have ended the Wind Advisory early.
9 pm update...
Line of showers and thunderstorms producing gusty winds has
moved through the area...leaving lingering light rain which will
transition to mainly high clouds later tonight. A tight pressure
gradient on the back side of the departing sfc trough has
allowed non-convective gusty w/sw winds to persist. Winds will
be sustained around 20 mph with gusts 30 to 45 mph across the
Finger Lakes and into the nrn Catskills the rest of this
evening. Winds are expected to veer to the w/nw and diminish in
intensity to around 10 mph with gusts 15 to 20 mph later
tonight. Wind Advisory currently in effect remains the
same...ending at 2 am early Sat morning.
1 pm update... Still focused on potentially severe storms later
this afternoon. All details on such are still relevant from the
previous discussion below.
Once the front goes by, a drier and cooler air mass will follow
later tonight and Saturday.
Strong environmental flow should persist for a while behind the
front this evening, hence the continuation of the wind advisory.
Winds should slacken in the pre-dawn period, as the pressure
gradient relaxes.
1030 am update... Factors appear to be coming together for an
enhanced severe weather threat later this afternoon across
mainly our northern zones (northern Finger Lakes, Mohawk Valley,
and southern Tug Hill areas).
As of late morning, plenty of clouds remained over CNY/NEPA,
along with some residual showers. Warm advection generated
showers should continue to push eastward, and be largely out of
our forecast area by midday. As for the clouds, a look upstream
shows clearing working from OH/Lake Erie into western
NY/northwestern PA at this time, at the leading edge of a large
dry slot aloft rotating out of the Upper Midwest/OH Valley
regions (well seen on the various GOES-East Water Vapor channels
and the Air Mass RGB product). All indications are that this
drier air aloft will work across much of the forecast area this
afternoon, resulting in a thinning of the current cloud cover,
and eventual breaks of sunshine. As a result, we felt
comfortable accepting the HRRR model temperature forecast for
this afternoon, indicating highs near 80 across the
northern/far western portions of the region (Finger Lakes,
Mohawk Valley, and southern Tug Hill zones), generally 80-85
down in the Wyoming/Lackawanna Valleys of NEPA, and mostly mid-
upper 70s elsewhere.
The above mentioned temperatures, along with probable cooling
aloft from the northwest later in the afternoon, should be able
to generate ML CAPE in the 500-800 j/kg range, and perhaps near,
or just over 1000 j/kg across the Mohawk Valley. Model
agreement remains quite good that environmental winds will
increase significantly this afternoon, as the main upper trough
axis approaches, and the atmosphere becomes fairly well mixed.
This combination of shear and instability produces an enhanced
threat for convective wind damage later today, along any squall
lines that come through. The best chance of such is again over
northern areas, although it can`t ruled out anywhere in
CNY/NEPA. High resolution model guidance shows the likelihood of
linear storm mode, although any more discrete cells would have
to be closely watched after 3-4 pm. The expected time window
for strong/severe storms is generally 3-8 pm. Our latest
hazardous weather briefing has recently been issued.
Please monitor for possible watches and warnings later today.
The forecast from later tonight into the weekend is addressed in
the discussion below.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
1205 PM update...
A wave moving through the upper atmosphere will push a few rain
showers into the Twin Tiers of New York and Pennsylvania
Saturday night, before a cold front drops down from Canada and
brings a higher chance for rain across the entire forecast area
on Sunday.
Rain showers will taper off Sunday night as high pressure
expands toward our region.
Temperatures will fall into the middle and upper-40s Saturday
night, rise into the 60s on Sunday, then fall into the lower-40s
Sunday night.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
An extended period of quiet, dry weather is expected from Monday
through at least Wednesday evening, as Canadian high pressure
drops into NY and controls our weather.
After a cool start on Monday, with highs around 60 degrees along
the NY/PA border, temperatures will rise into the lower-70s for
Tuesday and Wednesday along the Twin Tiers.
A frontal system will approach the region early Thursday and
bring another chance for showers.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Line of severe thunderstorms moving through the area at this
time. Thunderstorms with very strong winds will hit AVP in the
next hour or so, otherwise the line will be clear of the area
soon. This will leave VFR conditions all stations with gusty
west winds. Overnight and into Saturday, VFR will remain as the
winds die off.
Outlook...
Saturday night through Wednesday...VFR. Risk of some
restrictions in occasional rain on Sunday.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...BJT/MLJ
SHORT TERM...DJP
LONG TERM...DJP
AVIATION...DGM/DJP
Area Forecast Discussion
National Weather Service Bismarck ND
949 PM CDT Fri May 4 2018
.UPDATE...
Issued at 945 PM CDT Fri May 4 2018
No significant change outside of observed trends through 02 UTC.
The CAMs through the 01 UTC HRRR have backed off on the already
minimal elevated shower and thunderstorm potential overnight given
the dry air in place.
UPDATE Issued at 709 PM CDT Fri May 4 2018
Allowed the Red Flag Warning to expire on time at 00 UTC.
UPDATE Issued at 623 PM CDT Fri May 4 2018
Little change with this update. The CAM suite through the 22 UTC
HRRR suggests isolated to scattered elevated convection tonight
with multiple impulses embedded in northwest flow aloft and steep
mid level lapse rates. However, given minimal moisture, do not
believe the shower and thunderstorm potential will be as great as
the CAMs suggest.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 235 PM CDT Fri May 4 2018
Current surface analysis places low over Ontario, with frontal
boundary draped across the central Provinces. Over our area, gusty
west to northwesterly winds have developed along and ahead of a
weaker boundary passing through the region. Lower atmosphere is
quite dry, but some moisture aloft has developed into a few light
showers as a weak short wave passes through northwest flow, but
little if anything is reaching the ground.
For the rest of today into tonight, low shower chances will
continue over various portions of the area as a few weak waves
pass on through. Otherwise, winds will be diminishing this evening
leading to a quiet evening.
On Saturday, frontal boundary to the north will pass through
early, with winds becoming northerly. Temperatures will be a bit
cooler, but still above average. Again, a weak short wave passing
through could lead to some more afternoon showers.
.LONG TERM...(Sunday through Friday)
Issued at 235 PM CDT Fri May 4 2018
Quiet and warm conditions expected on Sunday as high pressure
settles into the area.
Upper ridge slides to the east early Monday with flow shifting to
the west-southwest. This will result in an active pattern with
chances for rain showers Monday afternoon through Tuesday as a
compact low meanders through the region.
From Wednesday onward, occasional weak disturbances will move
through the area from time to time bringing chances for showers
and thunderstorms. Temperatures will be near to a bit above
average.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 945 PM CDT Fri May 4 2018
VFR conditions across western and central North Dakota for the 00
UTC TAF cycle. The one exception is KDIK this evening where smoke
downstream of a controlled burn may result in MVFR visibility at
times. An isolated shower or thunderstorm is possible across
southern North Dakota Saturday afternoon. However, impacts and
timing to any single terminal is very uncertain.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...PA
SHORT TERM...JJS
LONG TERM...JJS
AVIATION...PA
Area Forecast Discussion
National Weather Service Billings MT
801 PM MDT Fri May 4 2018
.UPDATE...
Weak shortwave moving through north central and eastern Montana
will produce a few light showers across our cwa, mainly this
evening and in our east. Boundary layer is fairly dry and
instability is minimal, so we have not seen any lightning. Have
removed any mention of thunderstorms through the remainder of the
evening. More upstream energy in ID will keep the potential for
some mainly higher elevation showers across our west through the
night. Front backdooring into our cwa may be a focus for shower/
t-storm development on Saturday. Something to keep in mind if you
have outdoor plans tomorrow. Have also tweaked forecast low temps
up a bit tonight per mostly cloudy skies and some weak downslope
gradients. JKL
&&
.SHORT TERM...valid for Sat and Sun...
Weak energy and moisture was streaming into the forecast area
from the west, generating a few showers over the western zones
this afternoon. Other showers developing over northern Montana
too, and these were progged to drop toward southeast Montana in
northwest flow. High resolution models keep the majority of the
PoPs in the mountains tonight, but the GFS and HRRR do put some
returns over central and southeast zones this evening and tonight
based on above. Added PoPs for these locations.
Heights build Saturday. Energy tries to break through the ridge
and generate a few more showers Saturday afternoon, mainly over
western zones. These showers should spread out onto the plains
during the evening as heights fall and a back door cold front
drops in, turing the low levels upslope.
The flow opens up to the southwest on Sunday. Southeast winds
will try to pull some low level moisture in for a better chance of
convection. Stronger energy moves through, so PoPs will be higher
on Sunday comparatively. Temperatures will be warm over the
weekend with highs in the mid to upper 70s both days. Low to mid
range snow melt will be on the increase and allow river levels to
rise into early next week. TWH
.LONG TERM...valid for Mon...Tue...Wed...Thu...Fri...
Models still paint a consistent solution, so no major changes in
the long term. A low will move through the area bringing some more
widespread showers and thunderstorms to the area Monday. There
continues to be some instability, so some isolated to scattered
thunderstorms are still possible. Ridging will build in Tuesday,
but the flow will remain unsettled. As weak waves of energy move
around the ridge, more scattered showers, mainly during the
afternoons and over the mountains, are possible through mid week.
Another through moves in late in the week with a little better
chance for some more widely spread showers and thunderstorms.
Temperatures through the period still look to be above normal.
Reimer
&&
.AVIATION...
There will be isolated showers this evening over the area with a
few showers possible E of KMLS overnight. While a localized MVFR
condition cannot be ruled out in a shower, expect VFR through the
night. Localized to areas of mountain obscuration will occur
tonight. An isolated shower is possible over KLVM and the
foothills Saturday morning. Expect isolated to scattered showers
and thunderstorms Sat. afternoon with possible MVFR conditions.
Gusty winds will occur with any thunderstorms. There will be areas
of mountain obscuration, increasing in the afternoon. Arthur
&&
.PRELIMINARY POINT TEMP/POPS...
Sat Sun Mon Tue Wed Thu Fri
-----------------------------------------------------------
BIL 051/076 049/078 051/079 052/076 051/076 051/072 048/072
22/T 22/T 33/T 43/W 12/W 22/W 22/W
LVM 043/071 042/073 045/072 044/072 045/073 044/066 040/067
24/T 44/T 44/T 32/W 12/T 33/W 32/W
HDN 048/078 050/080 052/082 052/077 051/077 052/074 049/073
12/T 12/T 33/T 53/W 22/W 22/W 22/W
MLS 048/076 049/077 053/080 055/074 053/074 052/073 050/070
22/T 11/B 23/T 43/T 21/U 21/B 22/W
4BQ 048/075 048/075 051/080 053/072 050/074 052/073 049/070
22/T 11/B 23/T 43/T 21/B 21/B 22/W
BHK 047/072 044/072 049/076 052/069 050/071 049/069 049/066
23/T 10/B 22/T 54/T 21/B 21/B 22/W
SHR 045/073 046/075 049/077 049/072 048/074 049/072 047/072
22/T 32/T 33/T 43/W 22/W 22/W 22/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Columbia SC
1035 PM EDT Fri May 4 2018
.SYNOPSIS...
High pressure will continue to prevail over the region through
Saturday providing dry and warm conditions. A frontal system
will move into the area this weekend bringing a chance of
showers and a slight chance of thunderstorms. The possibility of
showers will linger into early next week as a series of
shortwave troughs move over the forecast area.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
High pressure will continue to dominate tonight with dry weather and
relatively warm temperatures expected. Satellite imagery as of
0230Z indicates increasing high clouds from the west ahead of a
slowly approaching upper trough moving in from the northwest.
Patchy fog and stratus will be possible once again mainly in fog
prone locations given a slight increase in low level moisture
in southerly flow and nocturnal cooling. Widespread dense fog
not expected due to a 20 to 25 knot low level jet which will
support mixing. Overnight lows are forecast above normal, in the
lower 60s.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
On Saturday the upper level trough will continue digging into
the central Gulf States as the surface low and associated cold
front move through the Gulf States and toward the forecast area.
As this occurs an upper level disturbance offshore of FL will be
moving northeastward along with substantial cloudiness. This
will leave the forecast area between these two features through
the day with the remains of the cold front moving into the
Midlands and CSRA Saturday night. On Sunday the upper level
trough will remain just west of the forecast area with the
frontal remains offshore and the Atlantic disturbance continuing
to move northward. Rain chances for the forecast area remain low
due to some downward motion on Saturday and Saturday night as
the forecast area remains between the two disturbances and on
Sunday as moisture lessens behind the front. A few showers and
possibly a thunderstorms are expected Sunday as the upper level
trough will provide some support. Temperatures through the short
term will be in the mid 80s for afternoon highs with overnight
lows in the low to mid 60s.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
Models agree the pattern will remain active however there are
some timing and intensity issues with features. Monday the upper
level trough will move into the region and be centered over the
area on Tuesday. Weak high pressure will overtake the region for
Wednesday with another frontal boundary moving northwest of the
region for Thursday and Friday. Have remained with low pops
through much of the period due to uncertainty and low confidence
in models. Temperatures will be near or slightly above normal
during the period.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Generally VFR conditions expected except for some fog/stratus
at AGS and OGB towards Saturday morning.
High pressure ridging into the region from offshore although
weak surface trough across the Piedmont and CSRA. Winds becoming
light and variable this evening with some high level clouds
increasing across the area. Upper level trough in the southern
Plains will be moving east toward the lower Mississippi Valley
region. Surface front and deeper moisture appears to remain west
of the region through the period. The high resolution HRRR and
Lamp guidance have backed off somewhat on fog threat toward
morning with support mainly in the coastal plain. Diurnal
cooling may be more limited with increasing high clouds and
possible strato-cu development. Kept MVFR fog at AGS and OGB
with possibility of IFR conditions. At other sites will
continue VFR forecast with scattered to broken strato-cu
possible around daybreak. VFR conditions developing after 14z
with light south- southwest winds.
.EXTENDED AVIATION OUTLOOK...
There is a chance of showers or possibly thunderstorms with
associated restrictions Sunday through Monday as a slow moving
frontal boundary crosses the region.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Caribou ME
1026 PM EDT Fri May 4 2018
.SYNOPSIS...
A surface cold front will push through the region tonight
bringing with it heavy rain showers and isolated thunderstorms.
It will be gusty and seasonable to begin the weekend with
afternoon showers possible by Sunday. The work week will start
off cool before warming back up by midweek with high pressure in
control.
&&
.NEAR TERM /THROUGH SATURDAY/...
1020 PM Update...
Tstms have kicked off w/some heavy rainfall. A line of storms
w/heavy rainfall was situated front Central Piscataquis County
eastward through Baxter State Park into the Millinocket and
Houlton area. Adjusted the wording this update to push storms
further n ad the axis has shifted northward. The latest NAM and
HRRR picked up on this potential. Radar rainfall estimates
showing over one inch per hr. This closing in on FFG of 1.3
inches/1 hr. Training of cells will leading to some minor
flooding issues where the heaviest echoes were situated. The
activity appears to have picked up some forward speed over the
last hr. Will be monitoring this potential for flash flood
potential. Some wind was noted by the radar w/even some weak
rotation in the stronger cells. An Airport Weather Warning was
issued for Bangor Airport due to cloud to ground lightning
nearby. Adjusted the QPF to bring the heavier amounts further
south into the Baxter State Park and Houlton area. Further north
toward the St. John River basin including the Fish River, the
rainfall has been less which is a good thing w/the ongoing
flooding of the lakes along the Fish River.
Previous Discussion...
An occluded frontal system will move through Maine overnight
into tomorrow morning. The associated low will exit northern
Maine tomorrow by mid morning. Higher pressure will build in
behind the low and will remain through the end of the period. A
wind advisory Central High Lands and Aroostook has been issued
tonight, winds will increase to 25 to 30 mph with gusts as high
as 45 mph behind the front. Winds will be elevated for the Upper
Penobscot Valley and Downeast but not as high. Winds will begin
to subside tomorrow morning.
Used a blend of GFS/ECMWF/NAM/GEM for max/min skycon, wind, and
hrly temps. Used a SREF/WPC Blend for QPF. Used GYX wind gust
tool for gusts.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
Quiet weather expected Saturday night into Sunday morning before
a southern stream 500mb shortwave and a northern stream
shortwave begin to interact over New England. Some model spread
on how these waves interact at this time, but looks like showers
will break out by afternoon and continue to increase in areal
coverage by evening. Cold air from Quebec will advect in
Northern Maine through Sunday night with a north to northeast
wind developing. This could allow for a brief period of
rain/snow mix across the north after midnight, with some of the
higher hills receiving a light coating. Cloudy and lingering
rain/snow showers expected at day break with showers ending
before noon and partial clearing expected during the afternoon
as surface ridging builds into from the Ohio river valley.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
Mostly quiet weather is expected in the extended forecast with
near normal temperatures expected. The possibility exist for
another round of rain towards the end of the workweek, but still
large spread in model solutions at this time in regards to this
wave. Over all no high impact weather expected in the Long term
forecast at this time. The dry weather is much needed for
Northern Maine which needs a dry spell to lower water levels.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
NEAR TERM: MVFR conditions decreasing to IFR in precipitation as
a front moves through the state. Shower and thunderstorms are
expected. Scatter TSTMs Interior Downeast and Upper Penobscot
Valley, isolated TSTMs North and central. Improving conditions
tomorrow morning south to north. VFR by late morning all sites.
SHORT TERM: VFR conditions expected through Sunday mid-
afternoon, with lowering ceilings and MVFR conditions possible
by Sunday evening. Rain showers and and the possibility does
exist for a some fog on the coast which could impact BHB.
Clearing expected by Monday afternoon and VFR conditions will
return.
&&
.MARINE...
NEAR TERM: Winds and seas will build this evening a low move
east across Downeast Maine. Gale force winds are expected by
around 11pm tonight. Winds and seas will begin to subside early
tomorrow morning falling below Gale by 11am. A Small Craft for
Seas will likely be required through the end of the period.
SHORT TERM: Coastal waters will begin to improve Saturday night
as winds continue to subside to below SCA conditions. Winds
could turn southerly during the day on Sunday but they will
remain light. A weak cold front will push across the waters
Monday morning with high pressure building over the coastal
waters by Monday night.
&&
.HYDROLOGY...
The Mattawamkeag River has fallen just below flood stage. The
river will continue to fall tonight, but may see some modest
rises Saturday in response to rainfall later tonight. The river
is expected to finally fall below flood stage Sunday.
A flood warning remains in effect for the Fish River at Fort Kent.
The river has fallen from its peak at 12.05 ft to its current
11.8 ft. Modest rises are possible again tonight into Saturday.
At this time we are expecting around 7 to 8 tenths an inch
across the basin. The current forecast has some modest rises
Saturday in response to expected rainfall tonight. The river is
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 Saturday
morning due to the anticipated rainfall tonight, and will likely
need to be extended through the day Saturday. 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 is under six to eight inches of water
and is closed at this time. Flooding issues may get exacerbated
Saturday, but this will be highly dependent on how much rain
falls tonight.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Wind Advisory from 6 AM to 2 PM EDT Saturday for MEZ001>006-
010-011-015-031-032.
Beach Hazards Statement from 8 AM EDT Saturday through
Saturday evening for MEZ029-030.
MARINE...Gale Warning until 11 AM EDT Saturday for ANZ050>052.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service Charleston SC
1000 PM EDT Fri May 4 2018
.SYNOPSIS...
High pressure across the area tonight will weaken Saturday, and
give way to a cold front on Sunday. The front will stall over
the nearby Atlantic into the middle of next week, as waves of
low pressure lift along the front. High pressure should return
late next week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
The region remains under mid level ridging, although a low level
inverted trough continues to move northwest toward the Florida
coast overnight. Periods of high thin clouds will persist with a
difluent flow aloft, otherwise skies overnight. We maintained
patchy fog mentions inland areas late on this update, however
surface condensation pressure deficits still do not look impressive
for widespread significant vsby reductions. Forecast soundings
and 18Z Bufr data suggest ribbons of stratus could develop along
the I-95 corridor toward daybreak, this region may see some lower
vsbys at times. It appears that forecast temps are on track, only
minor initialization tweaks for the mid evening update.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
Saturday and Saturday night: The deep ridging of the past week will
be replaced by a SW flow aloft in advance of a strong short wave
trough progressing east through the lower and middle Mississippi
valley. Meanwhile, a TUTT low will be situated over southern Florida
and Cuba, with the sub-tropical ridge shunted east near Bermuda. At
the surface a cold front will ease E-SE into the South Carolina
upstate and central Georgia, while a non-tropical wave of low
pressure associated with the TUTT drifts west through the Straits of
Florida. Tropical-like moisture will be drawn northward in
association with the TUTT and surface wave. But the vast majority of
it stays offshore through the daylight hours, with the lack forcing,
plenty of mid level dry air and still somewhat of a cap in place.
During Saturday night though there is a little better upward motion
as the front inches into the area, the nose of the upper jet edges
in from the W-SW and the short wave trough approaches. We limited
PoP to just 20-30% and mainly east of I-95 in South Carolina, where
the PWat is higher than elsewhere. Since there is a definite
increase in high level cloudiness during Saturday we have leaned
toward the slightly "cooler" MET and ECS MOS numbers. Saturday night
will be warmer than of late with more cloud cover and a SE
to S synoptic flow.
Sunday through Monday: The cold front struggles to advance E-SE
through the local area, as it is generally aligned parallel to the
flow aloft. It does however get a nudge from short wave energy that
progresses through the SE states, and this should push the front
into the nearby Atlantic by Monday as it stalls out near the Gulf
Stream. It also causes the deeper tropical moisture to shift further
offshore and away from the local region. The proximity to the cold
front and forcing from approaching mid and upper trough and the
upper level jet will be enough to produce at least a 20-30% chance
of showers. Not convinced on the potential for any t-storms, but
since it was already in the forecast and there is some instability,
we did maintain its mention. Although the upper jet pulls out on
Monday, the mid and upper trough persists in the area, and there is
better moisture in place. These conditions should support isolated
to scattered convection, mainly along the sea breeze. The overall
thermodynamics are a little more sufficient for t-storms, but any
severe risk is close to zero. Temps will be above average through
the early part of next week.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Monday Night through Wednesday: Global models begin to differ
during this period with respect to the upper trough Monday night
through Wednesday. The ECMWF keeps the upper trough weaker and
a bit more progressive, while the GFS is stronger and closes the
low off of the SC coast. The stronger GFS also produces a
stronger surface low over the Atlantic waters, which creates
more rap around moisture/precip. over the northern forecast
area, along with stronger north- northwest low level winds by
Wednesday. Give the uncertainty, have kept slight chance to low
end chance PoPs through Wednesday, with a lower trend Wednesday
as the upper low tries to depart to the northeast. Temperatures
near normal through Wednesday.
Wednesday night through Friday: A return to drier/more zonal upper
flow as the area becomes positioned along the southern edge of a
broad upper low over northeast Canada. Models hint that a weak cold
front could approach the area and stall across the region by Friday.
Deep layer moisture should increase with the front, and therefore
have added a slight chance for precip. on Friday. Temperatures near
to slightly above normal are expected.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
VFR will prevail. Low chance for restrictions, mainly MVFR,
closer to daybreak due to low clouds/fog. The potential remained
too low to introduce any MVFR restrictions on the 00Z cycle.
Extended Aviation Outlook: Much of the time will be VFR, except for
possible flight temporary flight restrictions as isolated to
scattered SHRA and possible TSRA develop early next week.
&&
.MARINE...
Overnight: Surface high pressure will prevail with southerly winds
10 kt or less and seas 2-4 ft, highest beyond 20 NM and mainly due
to the southeast swell.
Saturday through Thursday: Atlantic high pressure will weaken across
the waters as we begin the weekend, as a slow moving cold front
moves into the area late Sunday into Monday. The front is expected
to stall nearby into the middle of next week, as waves of low
pressure ride along the front and a high pressure wedge eventually
develops inland. There isn`t much in regards to winds into early
Monday, generally at or below 10-12 kt. But a tighter gradient
develops late Monday into Wednesday or early Thursday, allowing for
onshore winds to peak around 15 or 20 kt with possible higher gusts.
Wave energy is mainly the result of swells initially, but as the
stronger winds develop the wind waves will increase on top of the
already pre-existing swells. This will likely allow for combined
seas of 6 feet or greater beginning Monday night, and the likely
initiation of Small Craft Advisories.
Rip Currents: We could be looking at an enhanced risk of rip
currents early next week due to a strengthening onshore flow and
swell energy impacting the beaches.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
554 PM MDT Fri May 4 2018
.SHORT TERM...(Tonight - Sunday)
Issued at 236 PM MDT Fri May 4 2018
Upper-level ridging will promote warm and generally dry conditions
across southeast WY and the western NE Panhandle this weekend. The
potential does exist for an isolated shower/thunderstorm after 21z
this afternoon as pressure falls continue along the Laramie Range,
but limited moisture & warm temperatures aloft will be significant
limiting factors. The latest HRRR continues to suggest a couple of
weak showers developing over southeast Wyoming by 22-23z, but over
all confidence is very low given substantial capping. Some mid-lvl
energy traversing the flow along the edge of the ridge could yield
some convective development over northern areas on Sat afternoon &
evening, but this activity should be weak in nature. Quite warm w/
H7 temperatures climbing to +4 to +6 deg C on Saturday. Subsidence
aloft should support widespread highs in the 70s. More wide-spread
convection is possible on Sunday as the upper ridge flattens. Some
stronger storms will be possible w/CAPE approaching 1000-1500 J/kg
during the afternoon as dew points climb into the 40s. 35-45 knots
of deep layer vertical shear suggests some potential for organized
storms. The main limiting factor could be that the main short wave
will still be well upstream over the Pacific Northwest at 00z Mon,
which could mean fairly limited forcing for ascent.
.LONG TERM...(Sunday night through Thursday)
Issued at 300 AM MDT Fri May 4 2018
Upper ridge overhead Sunday evening with surface boundary laying
along the east slopes of the Laramie Range. Could see some evening
convection east of the Laramie Range as GFS has some light QPF in
the southeast low level flow across the Nebraska Panhandle into
the eastern plains of southeast Wyoming.
Westerly winds return Monday as ridge axis moves east. An upper
level low pressure system tracks into Montana Monday afternoon.
Surface boundary pushed east into central Nebraska. Looking pretty
warm Monday as 700mb temperatures climb to +10C. Warmest
temperatures of the year expected with 80s forecast at Wheatland,
Torrington and a few locations in the Panhandle.
Not a lot of chances for showers expected after Sunday night. One
timeframe that may see some convection would be Wednesday evening
into Thursday as backdoor boundary moves into the northern
Panhandle. Does not quite make it into southeast Wyoming though,
so warm and dry conditions continue for the most part.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 527 PM MDT Fri May 4 2018
VFR conditions are expected for the next 24 hours across the
region as the current FEW/SCT080-100 altocumulus deck shifts
overhead from northwest to southeast. A few radar returns are
occurring in north Colorado along the Front Range along with an
isolated SHRA in far north Carbon County. As temperatures start to
cool late this afternoon, probability for SHRA/TSRA development
should decrease. Have removed VCTS given the inhibiting dry air
and slowly stabilizing conditions. A similar pattern is again
expected tomorrow with SCT080-100 ceilings by early afternoon but
stronger NW winds aloft could aid in isolated SHRA/TSRA for NE
sites into the CYS vicinity. Confidence is too low at this
juncture for weather inclusion but future TAF cycles might include
VCTS/VCSH for Saturday afternoon period from 20-01Z.
&&
.FIRE WEATHER...
Issued at 236 PM MDT Fri May 4 2018
No fire weather concerns. Fuels are likely non-critical w/ recent
significant rainfall. In addition, RH and wind should remain well
outside of critical thresholds over the next few days, despite an
anticipated warming trend this weekend. A few thunderstorms could
occur on Saturday and Sunday afternoon/evening.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...CLH
LONG TERM...GCC
AVIATION...JSA
FIRE WEATHER...CLH
Area Forecast Discussion
National Weather Service Fort Worth TX
956 PM CDT Fri May 4 2018
.UPDATE...
Precipitation has all but exited to the south and east of the
forecast area this evening as the shortwave responsible for
earlier convection begins to shift east of the Plains and a weak
cold front approaches the Gulf Coast. Slight chance POPs will be
kept for a few more hours across the far south with all POPs
ending after midnight. The main concern will be fog potential as
clearing skies and light winds affect the region on the heels of
a departing shortwave. All counties will have at least patchy fog
in the forecast for the overnight hours, and some dense fog will
be a possibility by daybreak Saturday. Visibility trends will
need to be monitored during the overnight and early Saturday
morning hours to assess the potential for a Dense Fog Advisory.
Will likely allow the midnight crew to make this determination
unless visibilities start to tank earlier than expected.
Otherwise, the rest of the forecast is in good shape with nice
weather in store for the weekend.
30
&&
.SHORT TERM... /Issued 315 PM CDT Fri May 4 2018/
/Tonight/
Widespread moderate to heavy rain continues to shift towards the
east and southeast this afternoon as low level dry advection
slowly slides southward along a diffuse cold front. This feature
is now seeping towards a Paris to D/FW to Comanche line and will
continue its slow trek southward towards Central Texas this
evening. A potent outflow boundary has essentially shunted all
surface based instability south into the the Texas Coastal Plain
and Piney Woods with RAP mesoanalysis indicating diminishing
MUCAPE. As such, I`ll just mention showers in the forecast and
this is supported by total lightning observations over the last
1-2 hours.
While the areal coverage of rain is on the decrease, southwest
flow aloft is still resulting in some gradual ascent. This is
manifest in an increase in radar echoes across the Big Country and
some hi-res guidance appears to be handling this well. Rain
chances will be highest across the Brazos River Valley of Central
Texas tonight with perhaps a few showers near and north of I-20.
There shouldn`t be a ton of widespread measurable rain and for
now, I`ll advertise a 15 PoP with a few showers. After about 03
UTC Saturday (this evening), just about all precipitation should
have diminished/exited the region, but if ascent is a bit stronger
than currently thought, it`s possible that this activity could
linger a little later into the night. Thunder chances look low as
well given the decreasing instability.
The fog potential tonight is the next challenge. Recent rainfall
coupled with what should be clearing skies should set the stage
for radiation fog. Winds just above the surface, however, look to
remain elevated in the 15 to 20 knot range which may keep the
visibility from falling too far. At this time, it looks like the
most probable area for fog will be across the Big Country and
across western North Texas where 925mb winds are forecast to be
the lightest. Across Central Texas, there may be an enhanced fog
potential where the low level airmass remains a bit more moist.
Visibility could fall down to 1 mile in spots with possible a few
low/sheltered spots seeing visibility close to 1/2 mile. Will not
issue any advisories with this package and let the evening and
overnight shift monitor trends.
24
&&
.LONG TERM... /Issued 315 PM CDT Fri May 4 2018/
/Saturday Through Thursday/
The upper trough continues to pull away from North and Central
Texas on Saturday. A few sprinkles will linger in the morning
across the far southeast counties, along with a few areas of
radiation fog areawide through mid-late morning where skies have
clear out and wet soils exist. Otherwise, look for mostly sunny
skies with surface high pressure moving into the area and dry
northwest flow aloft. Despite the abundant sunshine, much of the
energy from insolation will be used to evaporate moisture from
recent rainfall. With this in mind, we have kept highs in the
upper 70s and lower 80s Saturday afternoon. The broad high
pressure at the surface will be slow to shift east with light
winds continuing under mostly clear skies Saturday night. With
uncertainty on how much moisture evaporates out during the day and
clear skies overhead I have added patchy fog to the forecast
early Sunday morning as well. The surface ridge slowly sinks
southeast toward Western Louisiana and the Texas coastline on
Sunday. There are signs of low level warm advection increasing
above the surface and by then would think most evaporation will be
over with with continued light winds. Highs should warm up into
the 80s areawide, with even a reading or two around 90 degrees
across the far western counties where surface winds and low level
flow will be more veered to the southwest.
North and Central Texas will remain sandwiched between the upper
trough over the Eastern CONUS and the Upper Ridge over the Rockies
this coming week. A weak surface cold front tries to push into
areas just south of the Red River Sunday night into Monday,
however, increasing ridging aloft and weakening support will
combine with strong early May heating to stall the weak cold front
near the Red River Valley. Regardless of where the front lands
up, highs behind the front generally will be between 80-85
degrees, with values 85-90 degrees to the south as better cold
advection remains northeast of the area. Moisture depth within the
atmospheric column does not look sufficient at this time for any
rain or convective development. This is likely due to the lack of
large-scale ascent aloft, increasing subsidence, and only weak
surface convergence along the surface front. Nevertheless, this
area bears watching on Monday.
Otherwise, surface lee cyclogenesis off to our west beginning
Tuesday will result in increasing southerly breezes and more May-
like temperatures for the mid-late week period. Beyond mid week,
dry north flow should continue our seasonably warm and humid
conditions. Lows in the 60s will warm into the 80s and even lower
90s out west with gusty south winds at times. A disturbance does
appear to arrive Tuesday night and Wednesday across the Southern
Plains into the Ozarks and Ark-La-Tex, but the best forcing and
moisture remain northeast of our CWA and will hold on to a dry
forecast for now.
05/
&&
.AVIATION... /Issued 103 PM CDT Fri May 4 2018/
18 UTC TAF Cycle
Concerns---Cessation of rain/brief MVFR visibility this
afternoon. Overnight BR/FG potential at all TAF sites.
A large swath of rain will continue to push eastward this
afternoon with light to occasionally moderate RA and reduced
visibility ending at all Metroplex terminals by 21 UTC. Waco will
remain entrenched in periods of RA through at least 00 UTC
Saturday. Upstream observations noted some occasional MVFR cigs
along the Red River, but given that dry air should work its way
south and east, I`ve opted for a more optimistic TAF. If MVFR cigs
become more widespread along the Red River, a quick AMD for
Metroplex TAFs will be needed. At Waco, mostly VFR cigs will
prevail with MVFR to even IFR cigs possible at times. Will monitor
trends and update if necessary. The potential for TS should
remain south of the TAF. Visibility will fall to near MVFR at
times, especially within heavier batches of rain.
Winds this afternoon are chaotic with east winds occasionally
becoming northerly. At this time, I`ll go with variable winds with
a slightly more preferred north wind this afternoon as a diffuse
frontal boundary (just north of the Metroplex) slides southward.
At Waco, more sustained north winds appear to be in place given
strong outflow from morning convection.
Generally lowered confidence in visibility trends overnight into
Saturday morning, but given recent rainfall and clearing skies,
there should be a decent potential for BR. At this time, I am not
entirely confident with an overly pessimistic TAF as winds just
above the surface may be the fly-in-the-ointment for a more
widespread FG event. The current TAFs advertise vis reductions
down to 3 SM, though there`s a chance that some periods of near 1
SM or less vis are possible if winds above the surface subside.
24
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 59 82 59 87 62 / 20 0 0 0 0
Waco 59 80 56 85 59 / 30 5 0 0 0
Paris 56 80 57 84 60 / 20 5 0 0 5
Denton 54 81 56 86 60 / 20 0 0 0 0
McKinney 56 80 56 85 60 / 20 0 0 0 0
Dallas 60 82 60 88 64 / 20 0 0 0 0
Terrell 58 81 56 86 59 / 20 5 0 0 0
Corsicana 59 79 56 84 60 / 30 5 0 0 0
Temple 59 80 56 85 59 / 50 5 0 0 0
Mineral Wells 55 82 54 88 57 / 20 0 0 0 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Green Bay WI
1036 PM CDT Fri May 4 2018
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Saturday
Issued at 235 PM CDT Fri May 4 2018
The latest RAP analysis and satellite/radar imagery show low
pressure exiting the region to the east over Lake Huron early this
afternoon. Meanwhile, skies cleared behind the low by 1 pm across
most of the region, but only for scattered/broken high based cu
to pop across the northwoods. A few showers have also popped up
over Marinette county. Mostly clear conditions prevail over the
Dakotas and Minnesota, with only some alto-cu up there as well.
With quiet conditions expected tonight, forecast concerns shift to
low humidities and shower chances on Saturday.
Tonight...Northern WI will remain on the southern edge of the
northern branch of the jet stream. Cu will likely diminish with
loss of daytime heating, but additional high based clouds may
push into the region at times through the night. But otherwise,
mostly clear conditions are expected once clouds across the north
dissipate. There looks to be just enough wind to prevent fog
across areas that were hard hit with rainfall lately. Low
temperatures ranging from the low 40s over Vilas county to the
upper 40s over the southern Fox Valley.
Saturday...A shortwave will be digging across south-central
Canada and pushing a cold front into northern WI in the afternoon.
Skies are expected to be mostly clear until then, before see
clouds push from northwest to southeast in the afternoon. A dry
airmass will be in place ahead of the front, with humidities
falling into the 20 to 35 pct range at most locations by midday.
Consequently, models struggle to produce instability until very
late in the day. Have therefore backed off on the chance of precip
until after 21z. Chances will be highest over northern WI where
convergence is maximized. Cannot rule out a thunderstorm,
particularly over central WI very late in the day. Highs remaining
warm in the low to mid 70s away from Lake Michigan.
.LONG TERM...Saturday Night Through Friday
Issued at 235 PM CDT Fri May 4 2018
An upper level disturbance will move across the region Saturday
night. The models today are more bullish in rainfall totals
compared to the morning run. Although there is no distinct vort
max with this system, the weak disturbance combined with the right
entrance region of a 300 mb jet streak north of Wisconsin could
trigger scattered thunderstorms well into the evening and early
morning hours across the east. Low wet bulb heights and steep mid
level lapse rates would support scattered thunderstorms with small
hail. Bufkit soundings indicated high based convection with an
invert v signature. Some of the stronger storms could also produce
gusty winds to 40 mph. A perusal of some of the severe weather
parameters indicated total totals from 45 to 55, and 0-6 km shear
values around 40 knots, thus could not totally rule out an
isolated severe storm, especially during the evening hours.
High pressure will dominate the weather pattern on Sunday with
low relative humidity readings during the afternoon. High pressure
will dominate the weather pattern Monday and Tuesday, bringing a
chance for the area to dry from last nights rains. Did lower
dewpoint values each day to account for the sandy soil biases.
The next weather make arrives late Tuesday night, if not
Wednesday. This system if the ECMWF is correct would bring another
round of heavy rain to much of the area. Model differences for now
preclude adding heavy rain to the Hazardous Weather Outlook (HWO).
Only minor changes made to max/min temperatures during the period
to account for our cold bias sites at night, and the warmer bias
sites during the day.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1032 PM CDT Fri May 4 2018
VFR conditions expected through much of the day Saturday. A cold
front may produce scattered showers and thunderstorms late
Saturday afternoon into the evening. Isolated storms could produce
small hail and gusty surface winds.
&&
.HYDROLOGY...
Issued at 1032 PM CDT Fri May 4 2018
A Flood Warning will continue for portions of Calumet and
Manitowoc counties until late tonight. A narrow stripe of 2 to 5
inches of rainfall caused washed out and flooded roads. Runoff
from the rain over the last 18 hours will continue to lead to
lowland flooding, basement flooding, and fast flows on rivers and
creeks.
Flood Watch for Manitowoc County is for interests on the West
Twin River downstream from Shoto Dam.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Saturday afternoon for WIZ050.
&&
$$
SHORT TERM.....MPC
LONG TERM......Eckberg
AVIATION.......JKL
HYDROLOGY......JKL
Area Forecast Discussion
National Weather Service Gray ME
1041 PM EDT Fri May 4 2018
.SYNOPSIS...
Low pressure over the Great Lakes will move north and east
through tonight...with an attendant cold front passing through
northern New England. This will bring the threat for showers and
strong to severe thunderstorms this evening before strong
westerly winds bring cooler and much drier air to the region for
the day on Saturday. The dry weather will be short-lived however
as low pressure over the Mid Atlantic region moves north and
east towards New England on Sunday spreading rain back into the
area through Monday before high pressure returns for the middle
of next week with dry weather and seasonably mild temperatures.
&&
.NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...
1035 pm Update: Have dropped the severe tstorm watch as the
line of storms have moved east of the watch area and now into
central Maine and slowly weakening as the line moves east. Made
adjustments to POPs to be reflect the line of storms for the
next few hours.
845PM UPDATE...
Have locally expanded the Severe Thunderstorm Watch for all of
northern and western New Hampshire as much of the state may
eventually be under a Severe Thunderstorm Warning. Line of
convection is approaching the area now, though it is expected to
weaken as it moves eastward into a more stable air mass. Heavy
rain from thunderstorms may combine with snow melt to produce
flash flooding a little more easily than normal, so we will be
alert for this threat as well. Further forecast updates this
evening will be more sporadic than usual due to greater focus on
immediate severe thunderstorm and flash flooding threats.
645PM UPDATE...
Have updated the forecast after the Severe Thunderstorm Watch
has been issued. The best chance of thunderstorms tonight looks
like it will be with the frontal passage as a line of storms has
developed over in New York state and is moving east. There could
be a few supercells developing ahead of the line in southwest
New Hampshire where instability is better, but for the moment,
the rest of Maine is being dominated by a cold onshore flow with
some fog. Temperatures already dropping into the low 50s and
upper 40s along the coast, and have lowered temperatures here.
Will see a wind shift later tonight as the front goes through
which will clear out the fog and warm temperatures here just a
bit.
ORIGINAL DISCUSSION...
Isolated Severe Storms Possible this Evening...then Strong
Winds Likely after Midnight...
Challenging forecast in the near term with 996 mb surface low
over Lake Huron pulling to the north and east. Ahead of this
feature...a warm front is draped across the northeastern United
States with warm southwesterly winds bringing temperatures into
the lower 80s across southern NH...while backed low level flow
and cooler readings exist to the north...with even a few 50s
holding on over far northern areas. Concerns through tonight are
multi-faceted with first concern surrounding severe weather
potential through this evening as impressive mid and upper
level jet streaks arrive from the west...but QG forcing for
ascent building dramatically in a gradually destabilizing
airmass. Examining recent HRRR runs...the HREF and 3km NAM and
High Res window runs suggest that our thunderstorm potential
continues to be delayed...focusing more on convection now over
the eastern Great Lakes that is racing east. This line is not
only near the surface cold front...but also...cooling in the mid
levels...allowing for much more favorable low and mid level
lapse rates. Do expect some showers and possibly a thunderstorm
ahead of this area...but expect this activity to be isolated
and...given limited instability...not severe. Best window for
convective activity is now looking to be between 6 and
11pm...immediately ahead of the cold front...as upstream
convection begins to decay given weakening instability...with
this decay compensated for to some degree by the improving
forcing. Given the synoptic setup...enough instability would
really allow for any severe weather threat /TORs included/ given
good hodograph turning and impressive 0-3km and 0-6km shear.
However...do have significant concerns about the destabilization
potential...so at this time see only an isolated severe
threat...particularly over NH.
The next threat is wind...as low pressure tracks just north of
the region overnight. H9 flow increases to 50kts...with
impressive cold air advection and some isallobaric assistance
compensating to some degree the stabilizing influence of the
time of night. Statistical guidance points to near advisory
level wind gusts with model profiles indicating that we will
maintain a mixed layer reaching near 50kts aloft. Thus...expect
over the terrain of NH and western Maine that gusts over 45 mph
will be likely for a 3-6 hour period after midnight and have
issued a wind advisory as a result.
Temperatures fall into the 40s and 50s from north to south under
robust cold advection after midnight.
&&
.SHORT TERM /7 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Dry northwesterly flow aloft bring PWATs back to seasonably dry
readings with dewpoints falling through the 30s during the day.
While the gradient will be weakening...westerly winds will
still likely be in the 15-25 mph range...which will likely bring
us near red flag conditions over portions of the area. Will
have to keep an eye on this depending on how much rain we
receive tonight. T8s remain in the +3 to +6C range which...with
some downslope assistance should allow highs south of the
mountains into the lower 70s with 60s to the north.
Saturday night...mid level flow begins to back ahead of next
shortwave over the southeastern United States...with top down
saturation bringing and increase in upper and mid-level
cloudiness during the overnight. Despite the drier airmass...the
increase in clouds should keep temperatures from falling much
further than the night previous with lower 50s expected over
southern NH and extreme SW ME with lows in the 40s elsewhere.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
The deterministic model solutions are in decent agreement on the
long wave pattern through late next week. We begin the period
with northern stream shortwave energy over the upper Great Lakes
and a southern stream impulse over the Tennessee
Valley...sliding eastward. At the surface...low pressure will
pass southeast of Cape Cod late Sunday and Sunday Night and will
brush the area with clouds and perhaps a few showers.
Meanwhile...the northern stream impulse will shear out into the
Maritimes by early Monday and drive a cold front south across
New england Sunday Night and early Monday accompanied by clouds
and a few showers. Behind the departing northern stream
disturbance...high pressure and dry air will build into the
region for Monday and Tuesday. By early Wednesday... a moisture
starved backdoor front will briefly sag south and west into the
forecast area with a few clouds. This boundary washes out as it
meanders back north on Wednesday. For the remainder of the work
week...we become increasingly unsettled as both northern and
southern stream disturbances traverse the northeast CONUS.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Short Term...
Summary: A strong cold front will bring showers and
thunderstorms this evening with strong winds in its wake and
improving conditions as high pressure pushes towards the region
on Saturday.
Restrictions: Expect IFR stratus to impact PWM/RKD/AUG...with
VFR dominating elsewhere. Area of showers and thunderstorms in
the 21-05Z timeframe could bring local MVFR and IFR
restrictions...particularly to LEB/HIE. VFR expected for the day
Saturday.
Winds: Southerly winds 10kts this afternoon become southwesterly
and strengthen 10g18kts this evening ahead of the front before
shifting west and sharply increasing to 20-25g30-35kt with gusts
over 40kts not out of the question. Winds diminish Saturday
morning generally 12g20kts.
Thunder: Isolated thunder possible particularly NH terminals
with a severe storm not out of the question. Primary threat from
any severe storms will be damaging winds.
LLWS: 1.5kft winds increase to 40kts this evening ahead of
potent cold front with LLWS expected until the frontal passage
which occurs towards midnight.
Long Term...
Sun PM - Mon AM...areas of MVFR in -shra.
&&
.MARINE...
Short Term...Have issued gale warnings for the outer waters as
westerly winds rapidly strengthen behind the departing cold
front late tonight with winds gradually subsiding during the day
on Saturday. SCAs in the bays with a few gusts near gale force
possible.
Long Term...
Mon - Tue...SCA`s are psb...especially outside the bays.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Wind Advisory until 8 AM EDT Saturday for MEZ007>009-012>014.
Beach Hazards Statement from 8 AM EDT Saturday through
Saturday evening for MEZ023>028.
NH...Wind Advisory until 8 AM EDT Saturday for NHZ001>009-011-015.
Beach Hazards Statement from 8 AM EDT Saturday through
Saturday evening for NHZ014.
MARINE...Small Craft Advisory until 8 PM EDT Saturday for ANZ151-153.
Gale Warning until 10 AM EDT Saturday for ANZ150-152-154.
&&
$$
Area Forecast Discussion
National Weather Service Jacksonville FL
756 PM EDT Fri May 4 2018
.UPDATE...Satellite imagery shows just some high thin clouds that
will pass overhead Tonight. With mostly clear skies and diminishing
wind, should see low temps near current forecast lows. Latest
HRRR continues to suggest potential for areas of fog well after
midnight.
Current forecast looks fine...no significant changes planned
in update.
&&
.AVIATION...VFR next 24 hrs, except areas of low clouds/fog during
08z-12z period that could affect TAF sites, with best chance
being KVQQ/KGNV.
&&
.MARINE...No changes planned for next CWF issuance. A ridge of
high pressure over the region will move to the East Tonight, as
an area of low pressure gathers over the Bahamas. The low will
move West over Southern Florida Saturday. A cold front will slide
Southeast into the region Saturday night, and linger into Sunday
night, before moving to the South on Monday. An inverted trough
will be over area waters Tuesday into Wednesday, with high
pressure building to the Northwest.
Rip Currents: Moderate risk Saturday.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 59 88 64 86 / 0 10 0 10
SSI 68 78 68 80 / 0 20 10 10
JAX 60 84 66 86 / 0 20 10 10
SGJ 66 78 67 83 / 0 20 20 20
GNV 59 86 66 87 / 0 10 10 10
OCF 60 86 66 87 / 0 20 10 30
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$
Wolf/Zibura/Peterson
Area Forecast Discussion
National Weather Service Lake Charles LA
900 PM CDT Fri May 4 2018
.DISCUSSION...
Wx map shows weak frontal boundary across E TX and N LA this evening.
The scattered showers along and ahead of the front from this afternoon
to earlier this evening has for the most part dissipated. Latest
HRRR continues to show additional showers and isolated thunderstorms
developing and/or moving in from the southwest during the overnight
hours, thus will leave inherited current precip chances. Other
forecast parameters on track as well, no updates needed at this
time.
DML
&&
.PREV DISCUSSION... /issued 403 PM CDT Fri May 4 2018/
DISCUSSION...
A few isolated showers have managed to pop up across interior
East TX into Central LA thus far this afternoon, with the bulk of
the convection nearby associated with the slow moving front over
E TX into NW LA and an outflow boundary over N LA. Under
considerable cloud cover, temperatures across the area have been
held mostly in the lower 80s, though there are enough breaks and
there is enough time for the SE half or so of the forecast area to
warm another few degrees before all is said and done.
Have seen little reason through the day to deviate much from the
forecast reasoning given in the morning update discussion. High-
resolution guidance continues to depict the front and associated
convection out west nosing into the NW part of the forecast area,
with a weakening trend taking hold by late afternoon/early
evening leading to something of a lull for the rest of the
evening. The front itself is expected to slow if not outright
stall, though not sure I buy the idea that convection will
dissipate altogether as shown by some guidance. A decrease does
make sense given waning instability/forcing within an already so-
so convective environment.
Approach of main upper trof axis later tonight is expected to aid
in both a resumed frontal movement and a resurgence of convection
during the overnight hours, with activity continuing to progress
through the area from W to E through SAT morning. Most of the area
is expected to be dry by afternoon, with any lingering activity
over Acadiana to push out by SAT evening.
Rains along with slightly cooler/drier air pushing in behind the
front will lead to cooler temperatures tonight for the western
half of the area, while eastern areas will actually be a bit
warmer. Another afternoon of lower 80s expected tomorrow as the
rains come to an end, with areawide cooler readings expected by
SAT night.
NW flow aloft and high pressure at the SFC are expected to
prevail SUN and MON yielding sunny and dry weather along with
moderating temperatures. Shallow return flow will become
established by mid week, but the flow aloft will remain generally
from the NW. Maintained a dry forecast with temperatures above
seasonal normals.
13
MARINE...
With high pressure remaining to our east, a generally light
onshore flow will continue into tonight. A weak cold front will
bring a chance for a few showers and thunderstorms to the
northwest Gulf late tonight into Saturday as it approaches and
moves over the coastal waters. A dry weather pattern will then
follow in its wake, with an offshore flow being maintained through
Tuesday.
13
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 64 79 59 85 / 60 40 10 0
LCH 67 81 63 85 / 40 50 10 0
LFT 68 81 64 85 / 30 50 10 0
BPT 67 81 63 85 / 40 40 10 0
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...None.
&&
$$
PUBLIC...08
Area Forecast Discussion
National Weather Service Melbourne FL
931 PM EDT Fri May 4 2018
.UPDATE...
...High Rain Chances This Weekend With A Few Storms...
Tonight-Sat...There has been little change in model guidance
depicting a large mid-upper level low moving slowly west/northwest
across the eastern half of Cuba. This cold core low has a lot of mid
level dry air within its circulation and doesn`t have any convection
near the center, so the Hurricane Center is not giving it any
chances for developing into a tropical system. The models do
indicate a weak surface low forming or becoming embedded in an
inverted trough that will move into the peninsula on Saturday. This
will cause high moisture to advect into the area, starting along the
Treasure Coast late tonight, then across the entire area on Sat. The
resulting moist east flow pattern will favor the greatest chance for
showers along the coast through morning or early afternoon, then
shifting to along/west of I-4 from mid-late afternoon. Those
interior sections will also have the greatest chance for lightning
storms.
Recent runs of the HRRR model show showers holding off along the
Treasure Coast until just before sunrise, so will make a slight
adjustment to the timing of showers.
&&
.AVIATION...
Evening soundings show a strong capping inversion around 3-4kft, so
even as northeast-east flow increases overnight, moisture depth will
remain shallow. MVFR ceilings with isolated showers are expected
KVRB-KSUA after midnight, probably closer to sunrise. Elsewhere, VFR
conditions should prevail into Sat morning. However, moisture will
spread quickly northwest on Sat along with shower chances. Timing
of this activity should be early in the morning along the south
coast (KVRB-KSUA) and then reach to near I-4 (KISM/KMCO-KSFB-KDAB)
by around 18z and KLEE towards 21z. The greatest chance for
lightning storms and IFR conditions should be at the interior
terminals late in the period.
&&
.MARINE...
Tonight-Saturday...The pressure gradient will tighten as an inverted
surface trough lifts northwest from the Bahamas tonight. This will
cause northeast-east winds to increase to around 20 knots and create
hazardous boating conditions, especially in the southern waters, but
also extending up to around Cape Canaveral. No changes to the
current Small Craft Advisory that will commence at 02z. The trough
axis is forecast to move into the peninsula on Sat, which will cause
winds to become southeast and decrease to 10-15 knots from about the
Cape southward. A period of scattered-numerous showers will occur as
the trough axis approaches, starting before sunrise offshore St.
Lucie Inlet then advancing northwest across most of the remaining
waters through the day.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory from 10 PM this evening to 10 AM EDT
Saturday for Sebastian Inlet to Jupiter Inlet 0-20 nm-
Sebastian Inlet to Jupiter Inlet 20-60 nm-Volusia-Brevard
County Line to Sebastian Inlet 20-60 nm.
&&
$$
SHORT TERM...Lascody
IMPACT WX....Combs
Area Forecast Discussion
National Weather Service Paducah KY
620 PM CDT Fri May 4 2018
.UPDATE...
Updated aviation section for 00z taf issuance
&&
.SHORT TERM...(Tonight and Saturday)
Issued at 320 PM CDT Fri May 4 2018
A narrow line of showers and thunderstorms has developed near the
cold front just to the north of Highway 13. So far they have not
been organized at all, although a few cores have briefly pulsed up
to near 20kft. This convection is likely to continue with the
front as it moves southeast through the forecast area into the
evening hours, mainly east of the Mississippi River.
Unfortunately, the airmass ahead of it is not any better and the
low-level shear is not great, so the storms should remain rather
disorganized. We will continue to monitor for rogue cores that may
briefly pulse up to near severe levels.
There is some evidence in recent HRRR output that a minor wave may
develop along the front and briefly enhanced coverage of
convection over west Kentucky this evening. Not sure if the
convection will ever exit or come to an end over west Kentucky
tonight, but as the upper-level trough pivots toward the area
after 06Z, showers will spread back to the north over west
Kentucky and the Bootheel. Cannot rule out some of the showers
reaching portions of southern Illinois or southwest Indiana.
The upper trough will keep at least scattered showers going over
west Kentucky through the day as it finally moves overhead. The
main focus on Saturday will be the Lakes and Pennyrile regions of
Kentucky. The instability will be used up by 06Z tonight so
thunder is not expected overnight or Saturday morning, but some
destabilization may lead to a few thunderstorms in the afternoon.
.LONG TERM...(Saturday Night through Friday)
Issued at 320 PM CDT Fri May 4 2018
The medium range model solutions were in reasonable agreement for
the longer range forecast. The mid level flow pattern over the CONUS
will start out as an amplified western ridge/eastern trof
arrangement for the weekend. The ridge out west is progged to
temporarily expand eastward into the Midwest early next week as it
is impinged upon by a substantial shortwave trof crossing into the
Dakotas. Further out in time, the Midwest part of the ridge aloft
will be replaced by the shortwave trof as it moves eastward across
the Great Lakes. Toward Day 7, more northern stream energy should
tend to damp the amplitude of the wavy flow aloft across the CONUS.
As a result, Sat night and Sun morning are forecast to be mostly
clear and dry under northwesterly flow aloft and weak high pressure.
Some patchy fog is possible around daybreak, mainly in western KY. A
minor, fast-moving shortwave in the flow aloft and a surface cold
front are progged to sweep through the PAH forecast area Sun
afternoon and evening. This system is expected to generate scattered
showers and isolated tstms for our region during that time frame. A
wind shear maximum (0-3km) may arrive after peak heating of the day,
limiting severe weather potential. On the other hand, highs Sun are
expected to be in the lower 80s, with dewpoints in the middle 50s,
providing possible 2000+ MUCAPEs for a brief period. As a result, a
strong tstm or two may pop up here and there, but will probably
remain sub-severe.
As the flow aloft slackens and goes anti-cyclonic over our region, a
cooler and drier air mass will move in behind the cold front,
allowing pleasant, rain-free conditions and mostly clear skies for
the first half of the week. Northerly surface winds will gradually
give way to light easterly winds.
By Wed afternoon, scattered showers and isolated to scattered,
diurnally-driven tstms are expected to develop in the warm sector of
the aforementioned system, complete with a surface low, moving
across the northern tier of states. At this time frame, there were
some differences in the areal extent and timing of the convective
activity associated with the system for us, so chance PoPs were left
in the forecast for mainly the Wed afternoon through Thu time frame.
Most of the dynamics will be well to the north of us, so the system
should have minimal impact for our region.
As southwesterly to westerly low level flow continues during the
latter half of the week, a modest warming trend is expected.
&&
.AVIATION...
Issued at 620 PM CDT Fri May 4 2018
A broken line of showers and thunderstorms was located along a cold
front that was just north of a line from kowb to kcgi at 23z. The
front and its associated line of convection will make very slow
southward progress this evening. A weakening trend is expected as
the atmosphere cools and stabilizes after dark. North and west of
the Ohio River, vfr conditions are expected from late evening
through the remainder of the taf period.
South and east of the Ohio River including kpah/kowb, areas of light
rain will spread northward overnight. The northern edge of this rain
shield could result in periods of mvfr conditions at kpah/kowb
overnight into Saturday morning. The rain and its associated upper-
level low will move east Saturday, bringing partial clearing by
afternoon. Winds will be light through the taf period, mainly north.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
SHORT TERM...DRS
LONG TERM...DB
AVIATION...MY
Area Forecast Discussion
National Weather Service Pueblo CO
323 PM MDT Fri May 4 2018
.SHORT TERM...(This evening through Saturday)
Issued at 323 PM MDT Fri May 4 2018
An upper level ridge will continue building over the are tonight and
Sat. As expected, some light showers have developed over some of
the southern mtn areas this afternoon. The HRRR also shows a few
areas of light precip over the far southeast plains later this
afternoon and early this evening, and over the Pikes Peak area. Will
keep some isold POPs over the mtns areas this evening, mainly over
the southern mtns, but will probably not mention any over the
southeast plains. Saw a few lightning strikes south of the CO
border, and there will be the potential for a few strikes over
southern CO. These showers/tstms should end fairly quickly with the
loss of heating this evening.
On Sat, there could again be some isolated showers/tstms over the
higher elevations, so will keep that in the forecast. Otherwise dry
conditions can be expected, with above average high temps, and
relatively light winds.
.LONG TERM...(Saturday night through Friday)
Issued at 323 PM MDT Fri May 4 2018
Saturday night-Sunday...Upper level ridging continues to build
across the Rockies through the day Sunday, as a shortwave digs down
the back side of the ridge across the Northern High Plains. Models
continue to suggest the potential for isolated afternoon and early
evening thunderstorms across the higher terrain with steep lapse
rates and some mid level moisture moving across the area on Sunday,
and will keep current slight chance pops in tact. Passing Northern
High Plains wave sends a weak back door cold front across Eastern
Colorado late Saturday night with upslope flow deepening across the
Southeast Plains through Sunday afternoon. Models, however, are
lagging with low level moisture return, with dew pts only in the mid
to upper 30s and capes of only a few hundred joules progged across
the Plains by Sunday afternoon. With that said, can`t rule out a
isolated to scattered pops over and near the Eastern Mountains
Sunday afternoon and evening. Temperatures look to be at and above
seasonal levels with highs on Sunday in the 70s to lower 80s across
the lower elevations, and mainly in the 50s and 60s across the
higher terrain.
Sunday night-Tuesday...Upper level ridging across area Sunday night
flattens across the state Monday and Tuesday, as a series of
embedded short waves translates across the Great Basin and out
across the High Plains. Models continue to deepen upslope flow
across the Plains Sunday night, with stratus and possible patchy fog
develops through the overnight hours and diminishes through Monday
morning. Models differ on strength and location of these passing
waves, though with some uvv and moisture in place, should see
isolated to scattered afternoon and evening showers and storms
across the higher terrain through the period. Also, there could be a
few strong to severe storms across Eastern Colorado Monday afternoon
and evening, as lee trough/dryline mixes out across the Plains.
Temperatures again to be at and above seasonal levels through the
period.
Wednesday-Friday...Upper level ridging rebuilds across the area
through Wednesday and then is progged to flatten across the state
again as a series of waves translates across the Rockies into the
end of the work week. Late week pattern suggests the return of
isolated to scattered afternoon and evening thunderstorms, with
temperatures remaining at and above seasonal levels through the
period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 323 PM MDT Fri May 4 2018
VFR conditions are expected the next 24 hrs at KCOS, KALS and KPUB
as an upper level ridge builds over the area.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...28
LONG TERM...MW
AVIATION...28
Area Forecast Discussion
National Weather Service Blacksburg VA
930 PM EDT Fri May 4 2018
.SYNOPSIS...
High pressure off the southeast Atlantic Coast will weaken and
give way to a weak cold front approaching from the northwest
late tonight. The front should stall across the region Saturday
allowing a wave of low pressure to track northeast along the
boundary Saturday into Saturday night before exiting offshore
Sunday. Another weak cold front will swing through the region
by early Monday followed by high pressure for early next week.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 925 PM EDT Friday...
A few shower may make it east of the Blue Ridge late this
evening but overall trend in radar is weakening/dissipating of
the showers. The latest RAP also shows this and to some extend
the HRRR. Will keep a low/slight chance going on the VA
foothills/piedmont into early overnight with better threat
arriving toward dawn across our WV counties.
Previous discussion from late afternoon...
Have increased POPs in the near term across the western third of
the region. Small area of light to moderate showers will impact
this part of the forecast hour of about a two to three hour
period, perhaps reaching as far east as the I-81 corridor by 900
PM with some dissipation expected by that time. A few isolated
thunderstroms will be possible with this first round of showers,
especially in the Richlands, Tazewell, Bluefield, Marion
sections of the area.
A second round of precipitation is still expected to arrive
across the northwest section of the region towards midnight and
work its way southeast through the region during the overnight
hours in association with an approaching cold front.
As of 230 PM EDT Friday...
Majority of the deeper moisture/instability remains west of the
region attm with dry air continuing to hold showers along a
lead weak outflow west of the ridges per latest regional radar
loops. However moisture advection progged to slowly increase
into this evening with several Hi-Res models showing a band of
shallow convection pushing east into far northwest sections
early this evening, and perhaps out toward the Blue Ridge
before weakening under residual ridging around sunset. Since
seeing some development off to the west, appears at least a few
showers possible west/north so kept in some pops early on.
This forcing then quickly fades after loss of heating and within
a deepening westerly flow aloft ahead of the actual cold front
to the northwest. This suggests that could see a lull in pops
overnight with timing of the surface front late across the north
where moisture will be less. Since appears best westerly
convergence to remain out west will maintain some low pops
mainly west of the Blue Ridge overnight. Lows to remain mild
under clouds in spots and moistening dewpoints with most in the
50s to lower 60s.
Front across parts of the area will become more of a focus for
rainfall espcly by Saturday afternoon as an upper level trough
and associated shortwave energy swing northeast toward the
region. Models continue to struggle early on with the track of
this feature given the baroclinic zone aloft farther northwest
and a weak surface wave to the south. Overall trend has been to
shift best convergence within developing southeast flow aloft to
the northwest, while increasing instability across the
south/east where could see more insolation into Saturday
afternoon.
Latest guidance giving a swath of an inch or more QPF
far northwest counties with much less southeast sections, where
could end up in between this system and developing coastal
front convection. Latest Nam also a bit more pronounced with
thunder chances over the southwest espcly along the gradient of
clouds/showers to perhaps more sunshine to the east. Therefore
beefed up thunder/heavier rain chances along the southern
corridor espcly where should be south of the weak surface front.
However think dry enough given lack of rain in over a week to
handle most heavy rain per higher FFG values so appears only a
small far western flood threat in order for now. Otherwise kept
the trend of increasing pops to likely/categorical espcly
west/north Saturday with mainly chance southeast including a
sharp gradient in between. Highs quite tricky since likely quite
mild to start before winds turn more northeast eastern sections
and ahead of heavier showers out west. Since the latest Euro
seems to handle the front and showers better, leaned toward its
Mos a bit more in having a range from 60s northwest to 80
southeast, and 70-75 in between.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 300 PM EDT Friday...
Unsettled weather expected Saturday night into Sunday with
periods of rain, heavy at times. A quasi-stationary frontal
boundary with a couple of waves of low pressure will remain situated
across our region Saturday night into early Sunday. The highest
chances of rain Saturday night into early Sunday will be west of the
Blue Ridge. SPC Day 2 outlook supports general thunder, with any
convective instability appears elevated in nature. Low temperatures
Saturday night will range from around 50 degrees in the northwest
mountains to the lower 60s in the piedmont.
The axis for the best chance of rain Sunday will try to shift to
eastern areas as the upper trough shifts eastward across our region.
A secondary shortwave diving down the Northwest flow may provide
additional support for convection Sunday afternoon. However, on
Sunday afternoon into Sunday evening, the low pressure center off
the coast may try to focus the more significant rain off to our
east. High temperatures on Sunday will vary from the mid 60s in the
west to the mid 70s in the east.
High pressure to our northwest in the Ohio Valley will build in for
Sunday night with drier weather. Low temperatures will generally be
from the upper 40s in the mountains to the mid 50s in the piedmont.
Deep longwave troughing sets up across the East Monday. Another
reinforcing shot of cold air, single-digit 850 mb air drops
southeast from the Ohio Valley. A shortwave will rotate east across
the region. This should result in clouds and scattered showers
mainly in the west. The timing of this feature and the qpf are
different depending on model choice. High temperatures Monday will
feature readings from around 60 degrees in the northwest to the mid
70s in the southeast.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 300 PM EDT Friday...
Will keep some light pops in the southwest mountains Monday night
with the weak surface trough. Surface high pressure will wedge down
the east side of the Appalachians Tuesday and Wednesday. With no
organized forcing, we will continue the low probability of rain
Tuesday and Wednesday. We will trend temperatures toward cooler
guidance based on the expected wedge and cloud cover. A warm front
will lift north across the west Wednesday night into Thursday
morning. On Thursday, a cold front approaches and brings a chance of
more widespread precipitation. On Friday, the upper trough axis will
reach the East Coast. Scattered showers and perhaps a thunderstorm
are possible in the west.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
As of 735 PM EDT Friday...
Areas east of the crest of the Blue Ridge are experiencing VFR
conditions, and are expected to continue to do so through
through approximately 16Z/noon on Saturday. Across the
mountains, a mix of VFR and MVFR is expected tonight as band of
showers moves through the area this evening. Then after
approximately 05Z/1AM Saturday, MVFR will be the dominate
flight category for ceilings with areas of MVFR for heavier rain
and some patchy fog for visibilities. During the day Saturday,
IFR/MVFR will prevail for ceilings with MVFR common for
visibilities.
This weather scenario will transpire in response to a cold front
that will move through the region starting late tonight and
continue through the day on Saturday. Thunderstorms, not yet
reflected at any TAF location, will be isolated to scattered in
association with the front on Saturday, especially in areas
along and east of the crest of the Blue Ridge.
Confidence in the above conditions is moderate to high.
.Extended Aviation Discussion...
The cold front should push east of the region Saturday night
into Sunday while leaving behind upper level energy that could
result in continuing sub-VFR along with more showers overnight
into Sunday. Some improvement may occur during Sunday night as
the upper level trough gets booted east, but another cold front
could arrive on Monday to spark added showers. By Tuesday, high
pressure will build over the Northeast, 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.
&&
.FIRE WEATHER...
As of 250 PM EDT Friday...
Another very warm and rather dry afternoon under gusty southwest
winds will transition into a more moist environment overnight
as moisture ahead of a cold front pushes east.
This along with clockwise wind flow around high pressure
offshore will also bring moisture northward from the Gulf of
Mexico and the southeast Atlantic coast. This will result in
increasing dewpoints with humidity minimums trending up
overnight into Saturday. Fuel moisture response will lag and
will likely not respond until the arrival of clouds and showers
tonight and Saturday associated with the cold front.
A better chance for widespread shower activity is expected this
weekend as the front stalls across the region and low pressure
tracks up from the southwest. Rain amounts of a half inch to an
inch or more are expected along and west of the Blue Ridge this
weekend, with a quarter inch or less across the Piedmont.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JH
NEAR TERM...DS/JH/WP
SHORT TERM...KK
LONG TERM...KK
AVIATION...DS/JH/PW
FIRE WEATHER...JH/PM
Area Forecast Discussion
National Weather Service Shreveport LA
1014 PM CDT Fri May 4 2018
.SHORT TERM...
The earlier convection has reinforced an outflow bndry SE across
the remainder of E TX and N LA this evening, with the 02Z sfc
theta-e analysis depicting the bndry extending from just S of a
JAS, to DRI, to AEX, to TVR line. Much of the more organized
convection has diminished as well, as drier air has begun to
entrain ENE into the region ahead of the upper trough axis
extending SE KS into Cntrl OK and NW TX. While a lull in the
convection can be currently seen attm, this looks to change after
06Z Saturday as deep lyr forcing increases late as the trough
swings E across the region. The HRRR has initialized with more
-SHRA than what is currently depicted, and is slower to shunt the
-SHRA E across the area overnight than the 00Z NAM. Did compromise
though with and increased pops farther W after 06Z, extending chance
pops farther W into NE TX/SW AR, but maintained likely pops for
portions of Deep E TX into much of N LA. Also toned down mention of
thunder to isolated, although this may be a stretch given the very
limited instability in place. Also added patchy FG to the forecast
across much of NE TX/SE OK/SW AR as the cigs gradually diminish
late, and temp/dewpoint depressions remain low until drier air is
able to advect SE into the region by mid to late morning Saturday in
wake of a weak cold fropa. Did make a few minor tweaks to min temps
tonight as well based on the current trends.
With the front quickly exiting the region by midday Saturday, drier
air advecting in its way should limit the extent of any post-frontal
development, and thus reduced pops to slight chance for the far Ern
sections of the region Saturday afternoon along the H850 trough as
it swings through. But even this may be a stretch although post-frontal
cigs are a good bet across much of the region.
Zone update already out...grids will be available shortly.
15
&&
.PREV DISCUSSION... /issued 720 PM CDT Fri May 4 2018/
AVIATION...
For the ArkLaTex, VFR in the wake of aftn convection w/ a weak
fropa struggling through the area as well w/ lingering -ra. SFC
winds bcmg NW 5KT overnight. Models all looking for IFR/MVFR to
set in soon. Also, the upper pattern shows a jet streak on
approach with some SVR turbulence reported over KACT. More shra
expected to dvlp over the front tonight. Our climb winds are light
N and back to W/SW by 6kft with increasing speed SW/W20-100KT by
high alt FL. Outlook is NW10KT deepening w/ VFR 15Z W to 21Z E.
/24/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 63 81 59 86 / 50 20 0 0
MLU 64 81 59 86 / 60 40 10 0
DEQ 55 82 54 86 / 20 10 0 10
TXK 59 79 57 84 / 30 10 0 0
ELD 61 79 56 86 / 60 20 10 0
TYR 60 80 58 85 / 30 10 0 0
GGG 60 79 58 85 / 40 10 0 0
LFK 63 81 59 85 / 50 20 10 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
15/24
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
842 PM EDT Fri May 4 2018
.UPDATE (Overnight and Saturday)...
00Z water vapor and H4 RAP analysis showing our region in-
between a longwave trough and associated strong shortwave
lobe to our NW over the central Plains/MS valley...and an
upper level TUTT low feature migrating westward from the
Bahamas toward the Florida straits. The very dry atmospheric
column that has existed over our heads for the better part
of the week and helped keep our forecast rain free is still
in place this evening. 00Z KTBW sounding (still in progress)
is showing that our boundary layer efficiently mixed up to
around 800mb today, and that above that layer, the column is
extremely dry...with common dewpoint depressions over 30C.
Any cumulus updrafts along the sea-breeze had no chance
today fighting that kind of hostile thermodynamic
environment. However, things are going to change on
Saturday in a big hurry in terms of column moisture. More on
that further down in the discussion.
At the surface...The strong ridge of high pressure off the
SE Conus coast that has provided a synoptic easterly flow to
our region the past several days is still in place, but
beginning to be nudged northward in response to the approach
of a surface low/inverted trough toward the Florida
peninsula from the east. This feature is the surface
reflection of the parent upper TUTT/Low mentioned above. As
this trough pushes over the FL peninsula during Saturday,
large scale surface winds will shift to the NE and then
north. There has been some activity on social media during
the past 24 hours about this disturbance and potential
tropical development. Simply stated...this is NOT a tropical
cyclone...and it is NOT expected to develop into a tropical
cyclone. These types of systems can look ominous on a
satellite loop, but the ingredients for further development
are just not present. The National Hurricane Center gives
this system a near 0% chance of tropical formation. As you
will read further down, the impacts that this disturbance
will have on our region will not be that dissimilar to what
we experience with our typical summer diurnal thunderstorms.
After what we experienced last year...we should all refuse
to invite hurricane season into our lives any earlier than
we have too.
For the rest of tonight...the fair and dry weather will
continue across west-central and southwest Florida. The
strong diurnal heating over land was enough to overpower the
synoptic gradient and shift winds onshore near the coast
during the past several hours. Now that the sun is setting
and terrestrial heating is fading, this circulation will
decay and allow winds to again shift offshore along the
coast before midnight. Skies will remain mostly clear for
the majority of night across the region...but clouds will
begin to increase toward dawn to the south of the I-4
corridor. This increasing cloudiness will be the telling
signs of the rapid surge of atmospheric moisture that will
be pivoting westward ahead of the approaching disturbance.
This moisture will overspread areas south of the I-4
corridor before midday and then begin to slow down in its
progress over the Nature Coast during the afternoon. This
slowing northward expansion...shown by most guidance...will
have a big impact on how far north the higher rain chances
in the forecast expand.
Even for our southern zones, expect the morning hours to be
basically dry. You will likely notice an uptick in the
humidity by tomorrow morning compared to what we have
experienced much of this past week. That morning run/walk
may be a bit more uncomfortable.
The ingredients for the expected developing showers and
storms on Saturday will be similar to those that bring our
normal summer storms. The moisture will be moving into
place through the day, but still expecting decent diurnal
warming during the morning/midday hours. This warming will
eventually cause a shifting of winds to the NW near the
coast/I-75 corridor. The enhanced convergence caused by this
wind shift should be enough to force the afternoon/eve
shower development. Showers that form will then migrate to
the W/SW with the prevailing large scale flow.
So...looking at the all available guidance from the HREF, it
certainly appears as through the best rain chances will be
from the I-4 corridor and southward. We are likely to see
some showers further north, but coverage should decrease
rather quickly as one heads northward from the I-4 corridor.
The main threat from any storms will be scattered lightning
strikes and locally heavy rainfall. Overall instability is
not impressive, and neither are mid-level lapse rates, which
should temper overall updraft strength potential. The heavy
rainfall threat looks to come from the fact that the main
convergence zone is unlikely to move much during the later
afternoon/early evening hours. That being said, predicting
just where along this extended band of convergence training
storms might be favored is simply not possible. These are
forced by mesoscale type influences, nearly impossible to
pin down this far in the future.
Once the sun sets Saturday evening, the overall coverage of
storms should decrease, but given the moisture in place and
the fact that we will then be shifting attention to the
approach of the large scale troughing from the west...a few
showers are likely to persist around the region throughout
the overnight hours.
&&
AVIATION (05/00Z through 06/00Z)...
VFR conditions through the evening with a few-sct cumulus
field dissipating with sunset. Winds that have shifted
NW near the coast will shift back to the NE by 03Z as sea-
breeze decays. VFR conditions generally persist through the
morning hours of Saturday with slowly building cumulus
field and increasing mid-level clouds. Passing showers and
storms look likely for all terminals by mid/late afternoon
and into the evening hours...but will wait till future TAF
packages to try and get detailed with timing at any one
terminal. Allow a switch in winds to NW at KTPA/PIE/KSRQ in
the later afternoon. If clouds come in later and sea-
breeze gets more defined, some potential to see a switch
further south at KPGD/KFMY, but staying closer to
statistical guidance and holding E/NE direction for this
forecast issuance.
&&
Prev Discussion... /issued 226 PM EDT Fri May 4 2018/
SHORT TERM (Tonight through Saturday)...
Upper troughs rotating eastward from the Great Lakes
southwestward into the S Plains while strong early season
upper TUTT low continues to spin over Cuba/Bahamas this
afternoon and tonight with dampening upper ridging over the
area. W Atlantic surface high pressure continues to stretch
into the Deep South but is weakening as a cold front moves
through the MS River Valley and tropical wave approaches
from the N Carib. Warm and dry tonight with benign sensible
weather conditions.
Saturday, TUTT low slows it eastward movement and stalls over
Cuba and into the FL Straits as southern tier upper trough
deepens from the OH River Valley into the N Gulf Coast
region, which is expected to weaken and absorbs/merge with
TUTT in time. At the surface, frontal boundary dips into N
FL Panhandle while weakening easterly wave moves over the
central to south FL Peninsula with rapidly increasing
moisture to combine with diurnal heating and seabreeze
interactions to produce numerous showers and isolated storms
with highest POPs over mainly interior and southern areas
Saturday afternoon. Increased cloud cover to keep temps near
seasonal averages.
LONG TERM (Saturday Night - Friday)...
There are several upper level features influencing the
weather to start out the long term period. First of all, the
upper ridge has pushed farther eastward and will be located
east of Bermuda. Closer to Florida, an upper trough (TUTT)
located over Cuba extends northward. Moisture associated
with this trough and return flow on the west side of the
upper ridge will produce a significant increase in
atmospheric moisture over the Florida peninsula. PWAT values
will be on the increase beginning Saturday evening with
PWAT ranging from 1.5-2.0 inches and will continue until
late Sunday into early Monday morning when the trough moves
northeast of the area.
Farther north, another trough of low pressure extends through the
Ohio River Valley southwestward to eastern Texas. This trough will
move slowly eastward toward the eastern seaboard by the beginning of
next week. The upper trough (TUTT) that was over Cuba will move
northward and be absorbed into this trough as it moves
northeastward away from the area. A series of short wave troughs
will move through the axis of the main trough through next week.
On the surface, increasing moisture associated with an upper trough
over the area will produce increasing rain and storm chances on
Sunday. A weak surface front moves off the eastern seaboard by early
Monday morning and will pull most of the moisture and rain chances
to the east of Florida allowing for drier conditions over Florida.
High pressure builds in from the north and will keep most of the
area rain-free, with the exception of a slight chance over the
Nature Coast and northern counties. Temperatures will remain around
average or a couple degrees above through the period.
AVIATION...
VFR conditions to continue with afternoon FEW-SCT 040-050 Cu field
to dissipate after 00Z and E-NE wind surge this evening lightening
overnight. VC SHRA and TSRA possible Saturday afternoon for
flight restrictions.
MARINE...
Weak tropical wave continues to slowly move eastward from the
Bahamas tonight towards the Florida Peninsula then over the south
central FL Peninsula Saturday before stalling in the SE Gulf Sunday
morning as a cold front sinking into the N Gulf waters. The cold
front to sweep over the area pushing trough east of the state
Mon/Tue. Expect times of easterly surges with scattered afternoon
into evening showers and isolated storms mainly across the central
and southern waters through this weekend as these features move
through. ATTM, expect winds 15 kts of less and seas 2-3 ft or less
this weekend but will continue to monitor conditions.
FIRE WEATHER...
Abundant low level moisture to remain over the area this weekend
with good rain chances to prevent fire weather concerns. Drier air
will filter into the region next week with lower RHs expected.
&&
.Preliminary Point Temps/PoPs...
TPA 67 84 73 85 / 0 30 30 30
FMY 68 86 73 87 / 10 60 50 40
GIF 65 84 71 89 / 0 50 30 60
SRQ 68 81 72 82 / 0 40 30 20
BKV 61 85 69 86 / 0 20 20 30
SPG 68 85 73 85 / 0 20 30 30
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION...Mroczka
Previous Discussion...Wynn/Davis