Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/08/18
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
820 PM CDT Mon May 7 2018
.UPDATE...
Issued at 818 PM CDT Mon May 7 2018
No major changes anticipated. LLJ will probably serve to keep at
least some of the convection organized overnight into eastern
South Dakota. Once storms get east of the Missouri valley, they`ll
likely become elevated with a lesser chance of hail/gusty winds.
Latest HRRR keeps a broken line of storms moving across overnight.
&&
.SHORT TERM...(This Evening through Tuesday Afternoon)
Issued at 344 PM CDT Mon May 7 2018
Two main rounds of thunderstorms will be possible through Tuesday
afternoon, both in response to an incoming shortwave which is
currently positioned across southern Montana. The first round may
develop this evening across western South Dakota by 23z and head
east through the overnight. Several CAMs are picking up on this
idea, as a combination of 1000+ J/kg of CAPE, steep low level lapse
rates and around 20 knots of deep layer shear provide a favorable
environment. By sunset, a multicell cluster of storms may be
underway across central SD. MLCAPE will have taken a nosedive, but
this cluster may be sustained due to a strengthening LLJ of 45+
knots across central/northeastern SD. A few storms may reach severe
limits at times across portions of western and even central South
Dakota, but generic to strong thunderstorms will be most likely
across the majority of the CWA with gusty winds and some small hail
being the main threats. The second main round of thunderstorms are
expected to develop near and southeast of the surface low Tuesday
afternoon/evening once the atmosphere has a chance to destabilize.
Dewpoints into the 50s, CAPE in the 1000-2000 J/kg range, and low-
level shear may once again provide a marginal environment for a few
strong to severe thunderstorms. The area of greatest concern will be
focused along a surface trough extending from the low, in central
South Dakota, southeastward into southeastern South Dakota.
.LONG TERM...(Tuesday Evening through Monday)
Issued at 344 PM CDT Mon May 7 2018
When the period opens, a low pressure system is departing the
region, resulting in decreasing precipitation chances Tuesday night
into Wednesday. Dry conditions should be in place for most of
Wednesday through Thursday before the next low pressure system moves
in, bringing more precipitation chances mainly anchored on Thursday
night into Friday. Beyond that, forecast confidence really dwindles
with an upper level rex-block pattern of sorts developing. Models
tend to mishandle system track/timing in blocky patterns. At the
moment, not all that confident that this forecast areas sees much in
the way of precipitation chances beyond Friday.
The 12Z deterministic GSM models continue to trend cooler with low
level thermal advection progs beyond Wednesday. Temperatures could
be running near to a few degrees below climo normal during the
second half of the week into the weekend. Still not seeing a lot of
support for that scenario in the NAEFS Ensemble S.A. table. 850hpa
standardized anomaly output suggests temperatures could still be one
or more standard deviations above normal beyond Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 659 PM CDT Mon May 7 2018
Outside any thunderstorms, conditions will be mostly VFR through
the night. Lower visibility and cigs can be expected with
thunderstorms.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...TDK
SHORT TERM...Lueck
LONG TERM...Dorn
AVIATION...TDK
Area Forecast Discussion
National Weather Service Glasgow MT
925 PM MDT Mon May 7 2018
.DISCUSSION...
930PM UPDATE:
Changes to the near-term forecast was to adapt PoPs for the next
couple hours to current radar trends and blend that into newer
model data going forward. RAP and SREF appeared to have the best
representation of the current observations and radar spatial
coverage. Most other things in the forecast look to be on track.
GAH
AFTERNOON DISCUSSION:
Generally updated the precipitation forecast for the forecast
period. With ongoing stronger thunderstorms to the south, small
hail and gusty winds were included in the forecast through
midnight for areas along and south of Hwy 200. These storms seem
to be driven mainly by diurnal heating. With no shear support
present, the storms seem fairly vertically stacked, and therefore
generally are lasting approximately an hour or so. Otherwise, the
forecast was relatively unchanged from this morning. Bigelbach
MORNING DISCUSSION:
Upper ridging over the area will move off to the east today,
closely followed by a shortwave trough moving in from the west.
The ridge is expected to move out slowly enough that high
temperatures across areas from Valley and Garfield counties and
east are anticipated to once again make it to the low to mid 80s.
Phillips and Petroleum counties may not get quite as warm as the
influence of the shortwave should limit the amount of solar
insolation across those areas today. The shortwave will bring with
it a chance of showers and thunderstorms. Thunderstorm chances
will be greater over areas that receive the most surface heating
during the day.
Northwest flow aloft returns to the area Tuesday, and another
shortwave trough will move across the region, bringing another
chance of showers and thunderstorms to northeast Montana.
Another ridge will briefly set up over the area Wednesday, leading
to dry weather for most of the day. This will quickly flatten out
as yet another shortwave approaches, so temperatures will not get
much warmer than they were on the previous day. Showers return
Wednesday evening into Thursday morning yet again with this
disturbance.
Beyond this, model consensus shows a pretty strong area of low
pressure diving from the Pacific Northwest into the Great Basin
region Friday and then potentially across the Rockies on Saturday,
but guidance diverges regarding how far northward the moisture
makes it. The ECMWF and Canadian models have at least our southern
zones receiving more rain, while the GFS misses northeast Montana
almost entirely. Assuming the latest forecast pattern pans out,
would not be surprised if the wetter pattern is closer to what
eventually occurs. For now, went with the latest model blends.
Hickford
&&
.AVIATION...
FLIGHT CAT: VFR-MVFR
SYNOPSIS: Low pressure system across the areas may continue to
bring a few scattered showers, but these should diminish in
coverage overnight. Ceilings will generally remain at VFR. However
some MVFR ceilings could sneak into KGDV mid morning.
WIND: north to northeast at 5 to 10 kts overnight... becoming
light and variable Tuesday afternoon... then gaining a western
component Tuesday night.
Bigelbach/GAH
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Green Bay WI
618 PM CDT Mon May 7 2018
Updated aviation portion for 00Z TAF issuance
.SHORT TERM...Tonight and Tuesday
Issued at 231 PM CDT Mon May 7 2018
The latest RAP analysis and satellite/radar imagery show high
pressure centered from the mid-Mississippi Valley to the central
Great Lakes early this afternoon. Mostly sunny skies are
prevailing across the region, with only a little cu popping over
western WI and the Upper Peninsula. Meanwhile, humidities are
falling into the low to mid 20s over parts of the northwoods,
where temps are in the mid to upper 70s and winds are gusting up
to 20 kts. Looking upstream, mid clouds are on the increase
across the Dakotas ahead of the next low pressure system. Forecast
concerns revolve around lingering low humidities into Tuesday and
precip chances on Tuesday afternoon.
Tonight...High pressure will continue to shift to the east into
New England and the Ohio Valley. Increasing mid-level moisture
will lead to 10 kft clouds pushing across northwest and north-
central WI late in the night. Until then, should see mostly clear
skies with a light southwest wind. Warmer lows ranging from the
mid 40s near the U.P. border to the mid 50s over the southern Fox
Valley.
Tuesday...Low pressure will continue to move east across the
eastern Dakotas and into the northern Mississippi Valley. As the
low draws closer to the state, clouds will be on the increase from
west to east through the day. The clouds will be running into a
very dry airmass, which should keep the morning dry. However, as
pwats climb above 1.00 inches, will see a chance of showers climb
in the afternoon, particularly over far northern WI where a weak
front will drop south over the Upper Peninsula. Perhaps could see
up to 200 j/kg of cape around Iron Mountain, though with the dry
air, will keep chances of showers low, and thunder out of the
forecast. Perhaps a few other showers could drift into north-
central WI late in the day within the mid-level theta-e advection
zone. With the clouds arriving from the west, north-central WI
should see slightly cooler temps, while eastern WI will likely
reach the upper 70s.
.LONG TERM...Tuesday Night Through Monday
Issued at 231 PM CDT Mon May 7 2018
Precipitation trends for Wednesday/Wednesday night, and Thursday
night through Saturday night periods, are the main forecast
concerns.
A lingering frontal boundary and increasing low-level jet should
generate scattered showers over our western and northern counties
Tuesday night. Rain chances will increase Wednesday into Wednesday
night as a low pressure system and associated upper level trough
move through. Given precipitable water values increasing to 1.0 to
1.4 inches and the amplitude of the upper trough, we should see
a quarter to a half inch of rain with this system. Some elevated
instability will support a small chance of thunderstorms,
especially over central and east central WI.
Generally dry conditions are anticipated on Thursday into Thursday
evening as Canadian high pressure passes through.
Forecast confidence remains low for the rest of the forecast
period due to differences among the medium-range models. A strong
frontal boundary will set up just south of the region, with
periods of moderate to strong overunning occurring at times due to
a 30 to 40 knot low-level jet. Though there is no true concensus,
the blended model data supports the highest precipitation chances
late Thursday night into Friday, and again on Saturday, mainly
across central and east central WI. Thunder will also be possible
over our southern counties during this period. The bottom line is
that a round or two of significant rainfall is possible later in
the week, which could cause flooding concerns to flare up again.
Temperatures will start off near normal, then drop to much below
normal by Friday and Saturday. Cannot rule out a rain/snow mix
over far northern WI late Thursday night, though confidence is
low.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 618 PM CDT Mon May 7 2018
A stable layer of air coming off of Lake Michigan on south-
southeast winds have kept any mid-clouds away from eastern
Wisconsin early this evening. Upon sunset, most of these initial
clouds should dissipate before more mid/high clouds arrive late
tonight into Tuesday morning. VFR conditions to prevail tonight
and Tuesday before cigs/vsbys drop Tuesday night as our next
weather system moves into the region.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......Kieckbusch
AVIATION.......AK
Area Forecast Discussion
National Weather Service Huntsville AL
831 PM CDT Mon May 7 2018
.NEAR TERM...(Tonight)
Issued at 830 PM CDT Mon May 7 2018
The storms earlier this afternoon developed as a result of a weak
frontal boundary and weak upper shortwave dropping south across the
area. Much of the stronger activity is now out of the area. However,
a few lingering showers continue to form off of remnant outflow
boundary interactions. A rumble or two is possible as latest RAP
analysis puts about 500 J/kg of MUCAPE over the area but this
activity will be very isolated. Expecting all precip to end with in
the next hour or two and have don`t have any PoPs in past 10 pm.
Debris cloudiness from these showers/storms remains over the area and
has help temps up by a few degrees compared to sites to our N/NW. But
as a surface high continues to build into the OH Valley and the upper
level wave shifts south expect clouds to dissipate. Drier air over
KY/N TN begins to move south overnight lowering dewpoints into the
lower 50s (if not there already). Temps tonight should bottom out in
the low to mid 50s, which is slightly below normal for this time of
year.
.SHORT TERM...(Tuesday through Wednesday night)
Issued at 230 PM CDT Mon May 7 2018
The sfc high looks to become better established across the region
starting Tue, as additional weak sfc ridging moves into the Gulf
Coastal areas out of the srn Plains. This should translate into quiet
and warm conditions for the mid TN Valley, as drier mid level air
above H85 filters into the region from the N/NW. Weak upper ridging
out of the srn/mid Plains also looks to briefly move into the region
in the Tue/early Wed time frame, aiding with the dry/warm pattern.
Afternoon temps both days look to climb again into the near 80F/lower
80s range, which is perhaps near/just above normal values for this
time of the yr. Lows Tue night look to again trend predom in the
mid/upper 50s.
The overall wx pattern may then begin to change heading into late Wed
afternoon/Wed night, as both the sfc/upper ridge over the region
weaken in response to an upper trough pattern digging ewd across the
nrn/mid Plains states. Another frontal system is also expected to
lift newd out of the mid Plains on Wed, with the trailing cold front
perhaps stretching into the Lower MS Valley. Some discrepancies exist
between the 12Z GFS and ECMWF/NAM whether the front will move ewd
into the area by Wed night, with the GFS the more aggressive and
showing some convective activity developing along/ahead of this next
front. Given the inconsistencies between the latest model runs, will
maintain low chances of showers/tstms developing Wed afternoon into
Wed night, if some semblance of the boundary can move into the area.
.LONG TERM...(Thursday through Sunday)
Issued at 230 PM CDT Mon May 7 2018
An upper-trough over the Northern Plains will shift into the Great
Lakes and upper-Ohio Valley late Wednesday night into Thursday,
dragging a cold front south into the Tennessee Valley. Based on the
latest model guidance, the remnants of a MCS will move south into
Tennessee during the early morning hours on Thursday. This activity
will continue to weaken as it moves into a more unstable air mass
across the Tennessee Valley. However, additional redevelopment of
showers and storms is expected along/near this boundary again
Thursday afternoon and evening -- especially if some destabilization
occurs during the day. Given the weak shear, most of this activity
will be fairly disorganized and outflow driven. However, a strong
storm or two may be possible before sunset. Models disagree with
coverage somewhat, with the GFS being more aggressive with
redevelopment than the NAM/ECMWF (which keeps the best coverage over
NE AL and E. TN -- closer to the better frontal forcing). Still,
think that scattered convection is plausible both Thursday afternoon
and evening, and have stuck close to SuperBlend for these periods.
Convection should wane quickly with the loss of heating by late
Thursday evening, though a rogue storm or two could linger overnight.
Another weak disturbance will shift from the Mid South into the
Southern Appalachians on Friday, resulting in another shot for
isolated to widely scattered showers and storms on Friday. However,
most areas on Friday should remain dry and pronounced warming trend
will begin thanks to a building subtropical ridge to the southwest.
Highs on Friday are progged to climb into the mid to upper 80s. As
mentioned, this ridge will continue to build into the region this
weekend, promoting mostly sunny and dry conditions. A noted increase
in thickness values and temperatures aloft will help highs reach the
upper 80s to perhaps the lower 90s both days. Have forecasted 90
degrees at KHSV and KMSL on Saturday, the first of the year so far at
each site.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 620 PM CDT Mon May 7 2018
Weak frontal boundary that generated isolated shra/tsra is moving
south of the terminals and any lingering activity should stay away
from TAF sites. SCT/BKN cigs around 7,000 feet may continue for a
few hours but then clear skies expected overnight. Drier air should
prevent any storms from developing Tuesday afternoon. Winds remain
light and variable through the period but tend to favor a N/NW
direction.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&
$$
NEAR TERM...Stumpf
SHORT TERM...09
LONG TERM...AMP.24
AVIATION...Stumpf
For more information please visit our website
at weather.gov/huntsville.
Area Forecast Discussion
National Weather Service Wilmington NC
943 PM EDT Mon May 7 2018
.SYNOPSIS...
Considerable clouds and an isolated shower will linger into
Tuesday as a weak upper level disturbance moves slowly across
the eastern Carolinas. Dry high pressure will dominate midweek.
Deeper moisture will begin to flow northward late week and
during the weekend with isolated showers and thunderstorms
popping up in the summerlike heat and humidity. Showers and
thunderstorms should increase ahead of a cold front early next
week.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 930 PM Monday...The leading edge of the low clouds has
slid across the state line and is now approaching North Myrtle
Beach. Interestingly, farther north and "deeper" into what
should be the heart of the area of low-level moisture, clouds
appear to be fragmenting according to airport observations and
GOES-16 10.3-3.9 micron difference imagery. The latest HRRR has
a decent initialization and shows the low clouds sliding
through all of Horry County in the next 2 hours, but also shows a
continued erosion of clouds across the Cape Fear region and
farther north into eastern North Carolina. Based on the rich
moisture observed in the 950-900 mb layer (roughly 1500-3000 ft
AGL) on the 00Z MHX sounding I am not convinced I need to
reduce overnight sky cover forecasts too much. Changes near the
coast include adjustments to sky cover based on current
observations and the 18Z GFS and latest HRRR, and an small upward
adjustment to wind speeds.
Very few changes are needed back across the Pee Dee region
where it appears the moisture will have trouble reaching due to
950-850 mb winds veered with just enough westerly component of
motion to keep dry air in place. The western edge of the low
clouds will probably end up reaching a line from Lumberton to
Dillon to just west of Georgetown around midnight.
Low temperatures should generally reach the upper 50s, perhaps a
little warmer along the beaches and a little cooler from
Lumberton to Bennettsville.
Discussion from 300 PM follows...
Much of the stratus has broken up into an extensive stratocu
field leaving partly to mostly cloudy skies, except from eastern
half of Brunswick, Columbus and Pender counties eastward to the
coast. This is where a blanket of stratus continued to cutoff
most of the sunshine. Expect to see some brightening in this
northeast corner of the forecast area, but overall, this low
level moisture will persist through tonight along the coast,
where elsewhere will see a mix of sun and clouds. Temps were
into the mid 70s over the eastern half of the forecast area with
readings up near 80 degrees west of I-95.
A weak sfc trough will remain off shore, extending north toward
Hatteras while a mid to upper low will swing slowly east through
the Carolinas through Tues, pushing a boundary slowly east.
There were some showers associated with this boundary out west
toward the mountains where better lift was located. Still expect
some isolated showers later today as some afternoon heating
combines with modest height falls associated with mid to upper
level trough moving in from the west. Expect a similar scenario
Tues aftn with stratus lifting and stratocu through the aftn
with max heating and cool air aloft to produce isolated shwrs
although the mid to upper levels will remain quite dry.
A cooler northerly flow will continue through the period with
some higher gusts. Lows tonight will drop into the mid 50s to
around 60, and will rebound back into the mid 70s to the
northeast portion of forecast area and up closer to 80 over
Florence and southwest portion of forecast area.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...Surface ridge axis extends south into the
Carolinas Tuesday night from a center all the way up on Ontario,
Canada. In the upper levels a trough will be moving off the coast.
Most of the column will be quite dry according to forecast soundings,
but a very shallow surface-based layer of saturation below the
subsidence inversion. This moisture is more prevalent at the coast
compared to inland. On Wednesday the ridge axis gets pinched off
from its parent high and a weak high pressure center becomes
established across the Carolinas. Expect mostly sunny sky (some cu
should develop) and seasonable to slightly mild temperatures.
Wednesday night again finds some low level moisture trapped beneath
inversion and some fog may develop with the high overhead bringing
such light winds.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 300 PM Monday...A ridge of high pressure will be situated
offshore. Mainly weak mid level shortwaves, residing in the stronger
flow, will pass by to our N late in the week. Weak low pressure in
the Gulf of Mexico coupled with high pressure further east will help
steer increasing moisture N during the weekend and early next
week. This area of low pressure may drift N across portions of
the Southeast states early next week ahead of a trough and
surface cold front approaching from the W. Will therefore show
POPs increasing, especially early next week. Will keep it dry
Thu, but expect as precipitable water values begin increasing,
mainly isolated diurnal showers/thunderstorms will develop Fri
through Sun with the seabreeze and Piedmont trough aiding in
focusing this better supply of moisture. Precipitable water
values will peak between 1.75 and 2 inches Mon as the depth of
moisture increases significantly, signaling the potential for a
greater coverage of convection by then.
Warm temperatures are expected this period with highs well up in the
80s Thu and lower 90s inland Fri and Sat. As you near the coast,
temps will not be quite as warm due to seabreeze influences, but
still above seasonable normals. As the atmosphere moistens, more in
the way of building diurnal clouds and showers and thunderstorms
should keep temps from getting quite as warm Sun and Mon. What will
be quite evident during this stretch is the influx of higher
dewpoints and thus higher relative humidity and many will likely
begin noticing the higher levels of humidity this weekend and
Mon.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
As of 00Z...Surface low pressure centered off Cape Fear this
evening, coupled with a surface ridge nosing down across the
interior Carolinas will result in a northeast surge overnight. Low-
level moisture across eastern NC will push southward overnight and
expect IFR ceilings to impact KILM at times. IFR ceilings may also
develop along the SC coast after midnight, but moisture decreases
further inland. Skies should scatter out by Tuesday afternoon,
although MVFR ceilings may persist longer at KILM, as it will be
impacted longer by wraparound moisture.
Extended Outlook...VFR.
&&
.MARINE...
NEAR TERM /THROUGH TUESDAY/...
As of 930 PM Monday...The north-northeasterly wind surge is here.
Gusts as high as 20-22 knots inside the coastal waters near Cape
Fear are spreading southward down the coast. Areas of drizzle
are possible near the thicker low clouds near the leading edge
of this wind surge, and visibility could be lowered to 4-5
miles at times. Sea heights currently only 3-4 feet should build
due to increasing wind speeds overnight, and the `exercise
caution` headline will remain posted for the NC coastal waters.
-TRA
Discussion from 300 PM follows...
A trough will linger and run up from weak low pressure well off
the SC coast up toward Hatteras tonight into Tuesday. As this
trough becomes better defined through tonight and as a weak
upper level disturbance swings closer toward the coast, expect a
northerly surge in winds. Overall, expect northerly winds
becoming slightly more NE through tonight into Tues, reaching up
to 15 to 20 kts overnight, mainly in the outer waters. Issued a
precautionary statement for mainly outer waters from Cape Fear
northward as seas reach up to 5 ft and winds up near 20 kts. A
SE swell will combine with wind wave to produce seas up to 3 to
5 ft overnight, with peak right around daybreak on Tues.
Northerly winds and seas will subside slowly heading through
late Tues into Tues night.
SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...North to northeast winds Tuesday night
will be the product of high pressure extending into the
Carolinas from Ontario, Canada as well as weak low pressure well
offshore. Lingering swell energy paired with the relatively
small wind waves will still yield 3 to 4 or even a few 5 ft
seas, the latter towards the outer reaches of the 20nm zones. On
Wednesday the low moves off to the NE and the high settles into
the Carolinas. This lightens the gradient allowing for a
decrease in wind wave energy. Swell energy will also be on the
wane. Winds become light and variable by Wednesday night but
there will still be enough of a lingering swell to prevent seas
going minimal as they do with such light winds.
LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 300 PM Monday...The last of the NE flow Thu morning will
shift to the S Thu afternoon and eve as a robust seabreeze
circulation develops. S winds will veer to SW Thu night and Fri
with another robust seabreeze expected to develop Fri afternoon
and eve. The wind direction will back slightly due to seabreeze
influences both days. On Sat, as the area of high pressure
offshore loses some influence and low pressure in the Gulf of
Mexico drifts a little closer, the prevailing surface winds will
back to S across the Carolina waters. The highest winds this
period will be sustained at 10 to 15 kt with gusts near or above
20 kt during the peak of the seabreeze circulation. Seas will
be 2 to 3 ft Thu and mainly 3 ft Fri and Sat.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...
NEAR TERM...TRA
SHORT TERM...MBB
LONG TERM...RJD
AVIATION...CRM
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1125 PM EDT Mon May 7 2018
.UPDATE...
Issued at 1120 PM EDT MON MAY 7 2018
A few showers still linger across the Big Sandy region, but
this should continue to diminish overnight. Grids were refreshed
accordingly with temperatures also freshened up.
UPDATE Issued at 925 PM EDT MON MAY 7 2018
With the loss of daytime heating, convection has been weakening in
intensity. However, convection still lingers across parts of the
Big Sandy region and pops have been included there over the next
hour or two to account for this. Otherwise, hourly grids have been
adjusted based on recent observation and radar trends. With
clearing or breaks in the clouds in locations outside of
convection already in place along with winds becoming light, fog
is expected to develop generally around or after 2 AM.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 440 PM EDT MON MAY 7 2018
19z sfc analysis shows low pressure lingering over the Southern
Appalachians helping to generate scattered showers and thunderstorms
for the eastern 2/3rds of the CWA. The convection is a bit more
robust and further northwest than initially forecast with the HRRR
doing a better job at capturing it than the NAM12. This has also
created a decent cu field, but the clouds did little to hold back
temperatures so that readings reached the low and mid 70s most
places. Meanwhile, dewpoints are mainly in the low to mid 50s
while winds away from any storms are light blowing from the north
to northwest.
The models are in good agreement aloft through the short term
portion of the forecast. They all have the trough over the Ohio
Valley sinking into the Southern Appalachians and closing off
tonight along with a swirl of mid level energy. This low moves
slowly east through Wednesday morning taking the core of its
energy along with it and allowing heights to rise in its wake for
a time through 12z Wednesday. Given the agreement among the models
aloft will favor a general blend, though with a lean toward the
higher resolution HRRR and NAM12 for details.
Sensible weather will feature scattered diurnally driven
convection taking advantage of fairly decent sfc moisture in
place and a cold pool aloft. Look for these to fade out toward
sunset leaving mostly clear skies behind. Similar to last night,
radiational cooling will likely encourage fog to form in the river
valleys - becoming dense toward dawn. The inversion and
radiational cooling will also set up a decent ridge to valley
temperature split tonight. Similar weather conditions follow for
Tuesday with still a chance for isolated to scattered showers and
storms developing in the afternoon - though they should be more
easterly than today`s batch. Another ridge to valley temp split is
anticipated Tuesday night along with some patchy valley fog
toward dawn.
Again used the CONSShort and ShortBlend for all the grids through
the short term portion of the forecast. Did make the most
significant adjustments to the temperatures each night for terrain
effects. As for PoPs, went higher than guidance this afternoon and
again on Tuesday afternoon.
.LONG TERM...(Wednesday through Monday)
Issued at 340 PM EDT MON MAY 7 2018
As a surface low pressure system makes its way across the Plains,
upper level ridging will be in place over the OH Valley for
Wednesday. This will lead to a brief period of generally dry weather
before a cold front progresses over the Commonwealth Thursday. The
front will stall over the region on Friday as a stationary front
before lifting to the north over the weekend. This pattern will
incite southerly flow, bringing warm and moist air up from the Gulf.
The GFS shows the best instability later on Thursday, with about
1500 J/kg of MUCAPE. Therefore, the best chance at precipitation and
storms will be on Thursday. However, rain/storms will be possible at
times through the weekend, diminishing Sunday afternoon. Another
system is possible for Monday, but will continue to monitor future
model runs to assess development and trends.
High temperatures will be in the low 80s Wednesday through Thursday.
With the southerly flow, temperatures will be on the increase for
Friday and into the weekend where temps will reach the mid to upper
80s. Low temps for the extended will generally remain in the 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 840 PM EDT MON MAY 7 2018
Generally VFR conditions will prevail over the next few hours
outside of isolated to scattered convection in the far southeast
part of the area. Most of the convection should diminish by 3Z or
4Z. Opted to include VCTS at KSJS for the first few hours of the
period for this. Lingering cumulus outside of the remaining
convection should diminish by 2Z with some mid level ac lingering
in some locations. With winds slackening and skies clearing
following precipitation that has fallen over the past couple of
days, fog likely will form again after 06Z. Vis in this should
fall to at least the MVFR range in several locations with some
valley locations experiencing some dense fog and VLIFR vis. The
fog should lift and dissipate between 12Z and 14z. Outside of
initial convection, winds should remain light and variable
tonight, before averaging out of the northeast to east at 5 to 10
KT from 16Z on.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...GREIF
LONG TERM...CGAL
AVIATION...JP
Area Forecast Discussion
National Weather Service Miami FL
744 PM EDT Mon May 7 2018
.AVIATION...Seabreeze collision ongoing over interior with most
convection away from TAF sites, but isold SHRA can`t be ruled out
vcnty KFLL-KTMB through 02Z. Winds become light/vrb overnight with
front passage, picking up out of the NE after 13Z. East coast
sites expected to see gusty ENE winds 12-15kts through afternoon
hours with WNW Gulf breeze at KAPF after 18Z. Rain chances lower
tomorrow with drier air, with main threat once again over interior
with seabreeze collision.
&&
.UPDATE...
Late seabreeze-initiated showers and isolated thunderstorms over
the Everglades and inland SW Florida this evening will drift east
and gradually wind down over the next 2-3 hours. The HRRR model
continues to insist on further development to the east over at
least the western suburbs of Miami/Fort Lauderdale, and while that
model has been somewhat overdone with the precipitation so far
today, it`s certainly not out of the question that at least a few
of these cells could affect the populated areas of the east coast
metro area. Therefore have left in 30% POPs for the general
Miami/Fort Lauderdale through the late evening hours, with 10-20%
elsewhere. Diffuse front moves through area later tonight, causing
winds to become more NE-N with lingering isolated showers over far
SE Florida and the Atlantic waters.
&&
.PREV DISCUSSION... /issued 339 PM EDT Mon May 7 2018/
DISCUSSION...
REST OF TODAY AND TONIGHT: Latest WPC surface analysis shows the
cold front currently oriented NE to SW from Palm Beach to Collier
County and the pre-frontal trough has moved offshore over the
Atlantic waters and the Bahamas. The front will continue to slowly
move south this afternoon and passing through later tonight.
Scattered showers and a few storms are expected to develop with
the daily heating and along the sea breeze. Development should
initialize over the interior and then work its way towards the
east coast later this evening. Most of the showers and storms will
be concentrated in Broward and Miami-Dade counties.
As the front moves through most of the convection should begin to
diminish. The front will reach the Florida Straits stall and wash
out across the area. Low temperatures tonight will range from the
lower 60s across the interior and Lake Okeechobee region to near
70 along the Gulf coast and the mid 70s along the east coast.
SHORT TERM: After the frontal passage a much drier and stable
airmass will slowly filter into South Florida. Rain chances on
Tuesday will decrease with some lingering moisture a few showers are
possible but POPs will remain below 30 and continue to decrease as
the drier air continues to filter in Tuesday night and Wednesday.
Low to no rain chances Wednesday and during the day on Thursday.
Wind flow will be northeasterly becoming more easterly through the
middle of the week. High temperatures will be in the mid to upper
80s with temperatures around 90 in the interior and Gulf coast
regions. Morning lows will be in the mid 60s near Lake Okeechobee
region to mid 70s along the east coast.
LONG TERM (Thursday through the Weekend): Models continue to show a
moisture surge back into South Florida from the Caribbean towards
the end of the week and into the weekend. Model soundings show
precipitable water values rising to above 2 inches Friday through
Sunday well above the average of 1.3 for this time of year. Models
are beginning to hint at a mid-level low pressure system possibly
developing off the west coast of Central Florida which would
continue to pump moisture over the Florida Peninsula. Rain chances
will begin to increase Thursday night continuing through the
weekend. Confidence continues to increase that a wet weekend is in
store across South Florida. In the long term high and low temps will
be around normal for this time of year.
MARINE...A weak front is currently moving through South Florida
this afternoon and this evening. Scattered showers and a slight
chance of thunderstorms will be possible over the Atlantic waters
through tonight. Light to moderate northerly winds are expected
the rest of today and tonight, before winds turn more to the east
for the middle of the week. Seas will be generally 3 feet or less.
Rain chances increase for the end of the week through the
weekend.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 71 86 72 86 / 20 10 0 10
Fort Lauderdale 74 87 73 86 / 30 20 10 10
Miami 73 87 73 87 / 30 20 10 10
Naples 70 90 69 91 / 10 10 10 0
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
GM...None.
&&
UPDATE...59/Molleda
AVIATION...88/ALM
Area Forecast Discussion
National Weather Service Marquette MI
658 PM EDT Mon May 7 2018
.SHORT TERM...(This evening through Tuesday)
Issued at 352 PM EDT MON MAY 7 2018
WV imagery and RAP analysis indicated wnw mid/upper level flow
between through the nrn Great Lakes between a trough from Hudson Bay
into far nrn Ontario and a ridge from the cntrl plains into the
southern Great Lakes. An upstream shortwave trough was located over
central Montana. At the surface, sw to s winds have increased across
Upper Michigan as a ridge builds southward into the srn Great Lakes.
Tonight, winds will diminish, but will remain strong enough to
maintain mixing and keep temps in the 40s central and the lower 50s
west.
Tuesday, warm and relatively dry conditions will persist as 850 mb
temps remain in the 10C-12C range with sunshinse/mixing dropping RH
values into the 20-30 percent range inland. However, winds will be
lighter at 5-10 mph with gusts only to 10-15 mph. Otherwise, a weak
cold front will drop through nrn Upper Michigan which will result in
falling temps during the afternoon and keep readings in the 40s
along Lake Superior. WAA/isentropic lift could be enough to support
some sct light rain showers into the west by late afternoon. The
forecast leans more toward a gradual movement of pcpn into the
area, given the dry antecedent airmass.
.LONG TERM...(Tuesday night through Monday)
Issued at 313 PM EDT MON MAY 7 2018
After heightened fire weather concerns much of the last couple
weeks, expected pattern will become cooler and more moist so may see
the fire concerns begin to lessen somewhat as spring green up gets
more underway. Temperatures will be on a bit of a roller coaster the
next week. Temps will start this week well above normal but will
trend toward normal by Wed and then well below normal for Thu-Sat
before bouncing back toward normal by next Mon. A chilly night Thu
night with readings in the 20s likely inland.
A bit early for specifics, but there are indications that some areas
of Upper Michigan could see total precipitation amounts over 1 inch
through next weekend. If this works out that would definitely help
alleviate the fire weather concerns at least in those areas, but
there is still uncertainty in whether all areas will see appreciable
rainfall. Appears the rain would come in two main waves, first with
the passage of a cold front/low pressure system late Tue night
through Wed. Main low is expected to track from the northern Plains
across WI and lower MI on Wed. Strongest moisture advection and
elevated instability should remain south of Upper Michigan but since
the low is tracking along to the south, parts of especially western
Upper Michigan could see heaviest rain due to fgen and upper
divergence. Heaviest rain, 0.5 to 1.00 inch, would occur late Tue
night through midday Wed. After this low exits to east of Lk
Superior and Upper Michigan late Wed night, high pressure building
southeast out of Manitoba will bring dry weather for Thu. Winds will
be from the northwest on Thu and could see gusts over 30 mph on Thu
morning, especially east half of Upper Michigan.
Late this week with quick west flow aloft and main sfc low well to
southwest over southern Plains and a warm front extending toward WI
and lower MI, think batch of moderate to heavy rain to stay south of
Upper Michigan late Thu night through Fri. Should see cool
conditions along with a lot of clouds and maybe some fog as well due
to east to northwest winds persisting north of the front over WI and
Lower MI.
Next chance of rain moves back in later Fri into next weekend. Main
question is how far north will wave of rain slide into Upper
Michigan. Latest ECMWF trended farther south so a bit drier
especially over the far north and northeast forecast area. Southern
U.P. will be most favored to see the rain with potentially rest of
our forecast area missing out as west to east frontal boundary and
right entrance region of upper jet stay just south of Upper Michigan
as upper level flow remains zonal/parallel with the front. Another
trough moving through in what looks like more of a northwest flow
aloft could bring smaller chance of rain by end of the long term.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 658 PM EDT MON MAY 7 2018
VFR conditions are expected at all sites through the TAF period.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 313 PM EDT MON MAY 7 2018
Mainly light winds of 20 kts or less can be expected through Wed as
the pressure gradient remains weak. Next chance of stronger winds of
25 to 30 kts develops late Wed night through Thu morning, especially
over the east half of Lk Superior, as winds shift to the northwest
behind a low pressure system/cold front. Winds diminish to 20 kts or
less late Thu into next weekend.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...07
MARINE...JLA