Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/27/18
Area Forecast Discussion
National Weather Service Wakefield VA
848 PM EDT Thu Apr 26 2018
.SYNOPSIS...
Low pressure quickly tracks northeast from the Deep South
tonight, then crosses the local area Friday morning. Dry
weather is on tap for Saturday and Sunday, although a cold front
passing Saturday night may cause a few showers. Warmer weather
arrives next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 840 PM EDT Thursday...
The going forecast is on track. Main change this evening is to
add some locally heavy rainfall across the Piedmont counties
this evening. Latest HRRR guidance continues to show 1 to
locally 2 inches of rain in just a few hours after midnight
across the Piedmont as the 850mb low moves over the area leading
to strong low level convergence associated with the 850mb jet.
Despite the potental for locally heavy rainfall, do not expect
QPF to be any more than 2 inches simply due to the precipitable
water values not being that high (only around 1.3).
Otherwise, temperatures should only drop into the 50s tonight
under clouds and rain.
Previous discussion below...
As of 320 PM EDT Thursday...
Weak high pressure traversing the area this afternoon will slide
offshore this evening. Meanwhile, low pressure currently over
northern AL will quickly track northward tonight. Clouds have
thinned so far today allowing for a partly to mostly sunny sky.
However, do anticipate clouds to be on the increase from S to N
by this evening and overnight as the aforementioned low begins
to lift NE from the Deep South. Will continue to watch the
seabreeze boundary across eastern NC, which so far has not
generated any isold shwrs, to see if a stray shower eventually
is able to track into NE NC (~20% PoPs remain).
For tonight, a quick increase in PoPs is expected this evening,
then especially after 06z as the low enters the FA from the SW.
Have chc PoPs 30-50% across the Piedmont thru 03z, then
spreading east to the I-95 corridor by 06z when PoPs will
increase to 50-90% across the Piedmont. After 06z, likely to
categorical PoPs (60-100%) spread across the entire area,
highest across the NW half of the FA. Lows tonight from the nr
50 NW to the upper 50 SE.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
As of 320 PM EDT Thursday...
Keeping PoPs 50-75% NE half of the FA Fri morning...tapering to
30-40% far SW as the low reaches the Delmarva. Models show
ribbon of CAPE (to 500-750 J/KG) moving across the FA late
tonight/Fri morning w/ period of enhanced UVM. Have kept a SLGT
CHC of tstms from about 06Z- 18Z/26. Locally heavy rain is
possible. The low pressure area lifts to the NE of the local
area Friday afternoon, but with an attendant cold front nearby
eastern VA that pushes offshore by 00z Sat. This will
necessitate keeping 20-30% (for SHRAS/tstms) over the FA.
Otherwise...mostly cloudy Fri morning, then VRB clouds-becoming
partly sunny in the afternoon. Total QPF ranging from the
0.1-0.2" in SE VA/NE NC to 0.50-1.25" across the NW. Highs
Friday from the upr 60s N-NW and at the coast to the mid/upr 70s
central/southern locales.
Improved conditions Fri night and Sat, although do expect a weak
cold front to approach from the NW late Sat afternoon. Partly
to mostly clear during this time. Lows Fri night from the upr 40s
NW to the mid 50s SE. Highs Saturday mainly in the mid/upr 70s,
except upr 60s-low 70s at the beaches. A potent upper low
meanders across the eastern Great Lakes Saturday night and will
force the weak cold front through the local area. Models now
more bullish with indicating the possibility of showers with the
fropa Saturday night. Thus, have added 20-30% PoPs for all but
the far SW FA. Lows Saturday night from the low 40s NW to the
low 50s SE.
High pressure arrives for Sunday in the wake of the
cold front. Cooler with plenty of sunshine. Highs in the 60s.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 350 PM EDT Thursday...
Upper low centered over New England slowly moves offshore Mon/Mon
night. This will allow an upper level ridge to build over the
eastern third of the country starting on Tuesday. Once the upper
ridge arrives, it will be slow to break down. This will set the
stage for our warmest stretch of the year so far. No rain/t-storm
chances through the extended period. Long range guidance
indicates that rain chances return next weekend as the ridge
slowly breaks down.
Highs around 70 Monday warming to ~80 on Tuesday (with 70s on the
Ern Shore). Expect mid 80s in central VA/low 80s over the Ern
Shore on Wed/Thu. Cool with lows in the 40s on Mon/Tue. Milder
with lows between 55-62 on Wed/Thu.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
As of 820 PM EDT Thursday...
VFR conditions continue through ~06z, then SHRAs move in from SW to
NE around or just after 06z tonight. SHRAs will be most widespread
at RIC/SBY, but all sites will likely see some rain. Any lingering
rain will exit all terminals by 12-15z Friday.
Low end MVFR ceilings will accompany the SHRAs at all sites. Have
included IFR ceilings at RIC/SBY starting around 10z. IFR CIGS will
persist the longest (until ~16z) at SBY. Confidence in IFR
conditions at RIC/SBY is moderate. There is a low prob of IFR
conditions from 10-13z at PHF, but did not include it in the
TAF. Ceilings will slowly improve after 15z Wednesday, and will
be VFR (BKN between 3-5k feet) at all sites except SBY by 18z.
There is a low chance of a few ISO showers/tstms after 18z
Friday at all terminals. Mainly VFR conditions expected Sat/Sun.
&&
.MARINE...
As of 355 PM EDT Thursday...
SCA Headlines remain in effect into this evening for southern
coastal waters and decided to extend them through Fri aftn
farther north. This is marginal and due primarily to long period
ESE swell, but general trend is for some increase in easterly
flow later tonight and on Fri so think its going to be difficult
for the seas to fall below 5 ft.
Otherwise, E to SE winds avg 5-10 kt and will increase to 10-15
kt most areas later this evening/overnight. As the low pressure
system moves NE and across the VA coastal plain Fri morning and
eventually to the Delmarva fri aftn, winds will shift to the
SSW. This area of low pressure is not very strong, so winds
during this period are only expected to avg 10-15 kt and at this
point have not raised any additional SCA headlines other than
those over the Ocean. Relatively light winds Sat, then as a
cold front crosses the waters Sat night, expect that we will
need some SCA headlines over the Bay and possibly the
rivers/sound as there will be some cold air advection moving
across the area into Sun morning. Winds stay somewhat elevated
and another secondary surge is likely Sun night (though Sun-Sun
night will probably stay slightly below SCA thresholds). Genly lighter
winds Mon-Tue.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ654-
656-658.
Small Craft Advisory until 4 PM EDT Friday for ANZ650-652.
&&
$$
SYNOPSIS...JDM
NEAR TERM...JDM/MRD
SHORT TERM...ALB/JDM
LONG TERM...ERI
AVIATION...ERI/JDM
MARINE...LKB/TMG
Area Forecast Discussion
National Weather Service Bismarck ND
935 PM CDT Thu Apr 26 2018
.UPDATE...
Issued at 935 PM CDT Thu Apr 26 2018
The forecast is on track, so only minor adjustments were made with
this update. A surface low is located near Winnipeg at 02 UTC and
that has placed western and central ND in the warm sector of that
cyclone with a north-south-oriented warm frontal zone extending to
the south of the low across the James River valley region. An area
of mid-level clouds associated with the warm front will continue
to exit the area as the surface low continues moving eastward, and
a trailing dry cold front will move southward across the area from
06 to 12 UTC. Upstream observations behind the front suggest that
initial post-frontal cooling is not very robust, so we made little
in the way of change to forecast lows overnight.
UPDATE Issued at 715 PM CDT Thu Apr 26 2018
Quick update to let the Red Flag Warning expire. Although winds
and humidity values are still in warning criteria at some RAWS,
ASOS, and AWOS stations as of 00 UTC, we still expect conditions
to improve quickly in the next 60 to 90 minutes as the boundary
layer begins to cool and decouple.
UPDATE Issued at 604 PM CDT Thu Apr 26 2018
Only minor changes were made with this update based on observed
trends and recent rapid-refresh model guidance, most notably of
which was increasing cloud cover in the Rolla and Rugby areas
through early this evening given satellite trends. Otherwise,
model-simulated soundings offer a strong consensus in calling for
the boundary layer to decouple sufficiently for surface winds to
decrease quickly by about 01 UTC, which in turn means we expect to
be able to let the Red Flag Warning expire as planned at 00 UTC.
&&
.SHORT TERM...(This evening through Friday)
Issued at 216 PM CDT Thu Apr 26 2018
Fire weather issues are the main short term concerns
Near full sunshine this afternoon with temperatures climbing into
the 60s. We don`t have an overly strong pressure gradient over the
state today, but with a well mixed atmosphere, expect gusty
northwest winds into the early evening. Dormant vegetation and low
humidities of 15 to 20 percent across most of the forecast area.
However, with a little stronger gradient across the north, we
expect critical fire weather conditions in much of the northwest
and north central. Near critical fire weather conditions will
remain through the afternoon southwest and south central, but
winds are a little lighter in these areas and afternoon minimum
humidities are expected to be a bit higher over the James River
Valley.
Winds will diminish early this evening with mostly clear skies and
cool temperatures expected again. A dry cold backdoor cold front
will make its way through the forecast area tonight. Lows will
range from the mid 30s to lower 40s, not quite as cool as last
night.
Another sunny day on Friday, but slightly cooler behind the cold
front, especially northeast. With cooler temperatures and lighter
northerly winds, critical fire weather conditions are not
expected. We could see near critical fire weather conditions in
the southwest, where forecast afternoon humidities are expected to
be lowest (near 20 percent). However, with north winds of 10 to
15 mph, fire weather conditions are probably not going to reach
critical values. But we will continue to monitor. We did use a
blend of drier short range HRRR dewpoint guidance Friday, with
our given guidance which lowered afternoon humidities quite a bit
in the southwest.
.LONG TERM...(Friday night through Thursday)
Issued at 216 PM CDT Thu Apr 26 2018
Dry weather with above average temperatures will continue through
the weekend with chances for precipitation returning for Monday
and Tuesday, in the form of showers and thunderstorms.
The 12z iteration of the NAM and GFS continue to show a high
amplitude ridge building into North Dakota Friday night, with the
ridge axis located over central North Dakota by Sunday. Expect a
warming trend as this ridge moves eastward, with temperatures in
the lower 70s on Saturday across western North Dakota and mid 60s
across central North Dakota. Temperatures will peak on Sunday when
the entire state looks to be in the 70s, with many spots
approaching 80 degrees in western and central North Dakota. The
latest suite of model guidance appears to have a good handle on
the forecast temperatures this weekend as model snow depth is now
representative of current observations, which show all leftover
snowpack has melted across North Dakota. In addition, the bias
corrected model guidance appears to have finally caught onto the
recent pattern change to warmer weather.
A large upper level low will begin moving into western and central
North Dakota Sunday night, bringing with it sufficient moisture,
lift and instability for showers and thunderstorms Sunday night
through Tuesday. Chances for severe thunderstorms Monday afternoon
and evening look like a possibility in south central North Dakota
near the border of South Dakota. Both the GFS and the ECMWF show
forecast CAPE values in excess of 1000 J/kg in this region,
collocated with low CIN and 0-6km bulk shear values between 30
and 40 kts along an axis of high equivalent potential
temperatures. Uncertainty still remains high regarding the threat
for severe hail and wind given the marginal conditions, however
this threat will need to be monitored closely leading up to the
event.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 935 PM CDT Thu Apr 26 2018
VFR conditions are expected across western and central ND tonight
and Friday, though there is a chance that brief low VFR to MVFR
ceilings could occur Friday morning in the Turtle Mountain region
behind a southward-moving cold front. Impacts from that dry front
will be minimal elsewhere and relegated to a switch to northerly
surface winds. Gusts to around 25 kt are expected Friday in east
central ND, including at the KJMS terminal.
&&
.FIRE WEATHER...
Issued at 935 PM CDT Thu Apr 26 2018
A dry cold front will pass through late tonight and will shift
winds to a northerly direction for Friday. However, post-frontal
gusty winds across east central ND are not currently expected to
overlap with lower humidities of 15 to 20 percent in western ND,
so no headlines are in order at this time. This will be monitored
closely though.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CJS
SHORT TERM...TWH
LONG TERM...TK
AVIATION...CJS
FIRE WEATHER...CJS
Area Forecast Discussion
National Weather Service Burlington VT
743 PM EDT Thu Apr 26 2018
.SYNOPSIS...
The unsettled weather pattern is expected to continue into the
weekend with periods of showers late Friday and then again late
Saturday through Sunday. Temperatures will trend below normal
into the weekend, but much warmer temperatures are expected to
return for the middle of next week.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 733 PM EDT Thursday...Water vapor shows closed circulation
has moved east of our cwa, while some mid level moisture has
returned on northwest flow on backside of system as drier air
develops aloft. This moisture and weak surface boundary helped
to produce a light rain shower here at BTV around 23z...but this
has since moved into central/eastern vt and is dissipating.
Expecting a dry night with the potential for some br/fog to
develop in the deeper sheltered valleys. Some uncertainty on how
quickly we clear and if winds decouple in the boundary layer
enough to support the temps to reach cross over values. Have
continued to mention some br with temps in the m/u 30s to l/m
40s valleys. Have adjusted hourly temps/dwpts to match crnt
trends and updated pops based on radar, which was to mention chc
pops further south thru 01z. Rest of fcst in good shape.
previous discussion below:
the upper low we`ve been tracking all day is now just about
over the Champlain Valley as I type this discussion. Tried to
see if I could see a big "L" in the sky to mark the center, but
no such luck. Still just a few showers scattered about,
primarily with the upper low. Visible satellite imagery still
shows a good amount of lower clouds, evidence of low level
moisture, across the region. Breaks in the clouds are out there
as well. The upper low seems to be behaving itself, so by late
evening it will be east of the region, and that should mean any
chances of showers will also be long gone. Have used combo of
the 12z BTV 4km WRF and 18z HRRR hi-res models to drive the
hourly evolution of where those showers are expected (primarily
the Champlain Valley and across northern VT). Expect the low
clouds to slowly clear as well. They won`t totally go away, but
we`ll have periods of mostly clear. Given all the recent rain,
I`d expect at least some patchy fog to form after midnight,
especially where the winds lighten up. Not the best fog
situation, so not over the top confidence in such development.
Lows tonight will drop into the upper 30s to mid 40s, which will
be near normal.
Friday starts dry. 12z guidance not showing any big changes to
what we had been looking at, so although I did blend some of the
12z guidance into the forecast, the net result was minimal
changes. Generally looking for clouds to increase and thicken up
by mid-day, with rain showers spreading from south to north in
the afternoon. This will be from the system that is currently
down across the southern US which will lift rapidly
northeastward and across our region thanks to the deepening of a
upper level longwave trough well to our west. With the southerly
flow, and at least a little sun to start the day and 925mb
temperatures in the 7-10C range, we should top out well into the
50s to lower 60s in most of the region -- which is about 2-4
degrees above normal.
Rain showers will be most concentrated across Vermont, with
lesser chances across northern NY. Not looking for a lot of
precipitation, perhaps 0.2-0.4" across VT and less for northern
NY. Showers end late Friday evening, with temperatures Friday
night mainly in the 40s under plenty of clouds.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 355 PM EDT Thursday...The short term forecast will consist
of a continuation of our showery pattern driven by a persistent
upper low overhead. Going into the weekend, shortwave energy
diving down the backside of the trough will further amplify the
pattern and form a closed low at the base of the trough. The
closed low will then linger over the northeastern US for the
remainder of the weekend, providing a cold pool of air aloft
that will increase instability in the low/mid levels. In terms
of sensible weather, this setup will bring us continued
convective precipitation, and a trend towards cooler/breezier
weather to finish out the weekend.
Timing/positioning the individual features that will provide the
forcing for the showers remains the main forecast challenge, however
the bigger picture for how the weekend will playout is becoming
clearer. Since the shortwaves responsible for this weekend`s
weather have moved inland over western Canada overnight, they are
now able to be better sampled by our observational network and thus
better handled by the forecast models. Q-vector convergence progs
the best synoptic forcing within the upper low to setup over the
North Country/southern Quebec/southern Ontario border Saturday
afternoon/evening, so continued the idea of a drier Saturday
morning, ramping up PoP to chance/likely through the
afternoon/evening. In addition to the more widespread precip under
the dynamic upper low, higher resolution models are indicating the
formation of a north/south oriented zone of enhanced low level
frontogenesis that will be the focus for some more localized banded
heavier rain Saturday evening through Saturday night. Given the
amount of cold air aloft, there will be enough instability in the
low/mid levels to support some convective heavier rain along this
front, particularly during the Saturday evening time frame. The NAM
is being particularly aggressive with pivoting a zone of strong
surface to 800 mb fgen forcing and low level instability over
the forecast area, suggesting the potential for some locally
heavier banded rain moving through Saturday night/Sunday. The
dynamic upper- level support is definitely there to support this
scenario, however the amount of mesoscale forcing than will pan
out along with the amount of moisture flux into the area could
be limiting factors. We will be monitoring this closely as the
forecast area has already received quite substantial rainfall
from the mid-week system, so the amount of rain that falls this
weekend will further impact area rivers and streams. See the
Hydro Section of the AFD for further details.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 355 PM EDT Thursday...Showers from the upper low will taper off
through the day Monday before ridging finally builds in from
the west and brings a pattern change. Southwesterly return flow
around a strengthening high will advect in warmer, moist air
that will support temperatures warming into the 60s Tuesday and
into the 70s towards the middle of the week. The amount of
sunshine we see during this time will depend on the
amplification of the ridge and the amount of Gulf moisture that
will advect into our area. The core of the high pressure and the
best subsidence will be centered our south over the Mid-
Atlantic/Southeast Coast. This will leave those of us further
north still potentially vulnerable to any shortwaves that move
through that may bring some clouds or showers. Regardless of
whether any disturbances transit our area of not during this
time frame, the amount of warm air advection within the broader
flow is impressive and will likely support temperatures 10+
degrees above normal. Chances for more widespread unsettled
weather return during the second half of the week as the ridge
begins to weaken.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Through 00z Saturday...Another challenging aviation forecast
with regards to clouds/winds and potential fog/br development
aft 06z. Crnt obs show a mix of vfr to mvfr to ifr with general
improving trends expected at all taf sites by 03z to mvfr/vfr.
If we see more clearing and winds decouple expect areas of
fog/br to develop, given plenty of boundary layer moisture from
recent rains. Have mention tempo between 07z-11z for ifr vis
btwn 1-2sm at mpv/slk/mss. Winds should limit fog potential at
rut/btv and pbg. Any fog/br will quikly lift btwn 10-12z Friday
as mid/upper level clouds develop from south to north ahead of
our next system. Expect rain to arrive aft 18z with mvfr cigs
possible at mpv toward mid afternoon. Elsewhere...vfr vis/cigs
should prevail.
Outlook...
Friday Night: Mainly VFR, with local IFR possible. Slight chance
SHRA.
Saturday: Mainly VFR, with local MVFR possible. Chance SHRA.
Saturday Night: Mainly VFR, with local IFR possible. Chance SHRA.
Sunday: Mainly MVFR, with areas VFR possible. Chance SHRA.
Sunday Night: Mainly MVFR, with local VFR possible. Chance SHRA,
Chance SHSN.
Monday: Mainly MVFR, with areas VFR possible. Chance SHRA.
Monday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Tuesday: VFR. Slight chance SHRA.
&&
.HYDROLOGY...
As of 400 PM Thursday...the widespread 1/2 to 1" of rain, along
with continued steady snowmelt from the remaining snow at the
highest elevations has resulted in most area rivers, especially
in the northern sections, running fairly high. Additional
precipitation for late Friday/Friday night will keep river
levels from dropping much. No flooding is expected the next
couple of days, but there is some concern for what could happen
later in the weekend. There will be another round of rain late
Saturday/Saturday night. Some guidance indicates some
significant rainfall amounts, though there is quite a bit of
uncertainty in those details. If the heavier rain scenario does
pan out, with rivers already running somewhat high, this would
suggest we may be looking at some flooding issues for Sunday. At
this point it`s a low confidence scenario, but worthy of at
least mention.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Nash
NEAR TERM...Nash/Taber
SHORT TERM...RSD
LONG TERM...RSD
AVIATION...Taber
HYDROLOGY...Nash
Area Forecast Discussion
National Weather Service State College PA
1043 PM EDT Thu Apr 26 2018
.SYNOPSIS...
A weak storm system entering Virginia will move northeast
along the coast Friday and into New England Friday night. An
upper air disturbance will swing into the region from the Great
Lakes Saturday and early Sunday.
A stretch of fair weather with a warming trend will start
Monday as high pressure builds over the Atlantic Coast. Above
normal temperatures are likely for the middle of next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
High clouds continue to increase ahead of the next storm system
currently over the SERN states beginning to eject off to the
NE. The latest HRRR shows some showers reaching far SRN PA by
around midnight, but the bulk of the rain is expected to hold
off until just a few hours before sunrise. This timing looks
reasonable as the first echoes begin to show up on our radar
south of the Mason-Dixon line.
Overnight lows ranging from the mid 30s over the north to mid
40s south will be near to a bit above normal.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
Rain will overspread the SERN 2/3 or so of the forecast area by
mid to late morning. Steady rain will taper off to scattered
showers in the afternoon as the lead shortwave shears out to the
NE of the state. QPF will not be terribly impressive, but will
be fairly widespread.
Highs will average in the 50s.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
A shot of arctic air will move into the area Saturday night and
Sunday with 8H temps near -10C and 1000-500 thickness less than
530dam. The consistency across the models is pretty good with
this mass field result, so confidence in cold temps and a gusty
NW wind is high. The lake/8H temp difference will support SHSN
at Saturday night/Sun AM across the far north and west.
The fcst not bad, main change was to up winds longer on
Monday, and lower dewpoints some Sunday into Monday, given the
winds aloft and airmass source.
With some clouds and a breeze Sunday night, this will help
taper the risk of frost early Monday across the region.
Will still be too breezy early Monday for burning brush and
leaves. Better chance for that after Monday.
Temperatures moderate Tuesday into Thursday, as high pressure
moves east of the area. Given how dry it is over portions of the
Great Plains, I did not rush higher dewpoints into too fast,
given that as the source region of the warm up.
Green up is largely controlled by nights with mild temperatures
and higher dewpoints at night than we have seen. Only night
that way was back in February. Need to stay above 50 degrees to
get much response from the grass and many trees.
Looking at some showers late Thursday, as the cold front moves
into the area.
Mean trough tries to kick back in after this warm up. Some
hints it could be wet for several days, especially if the 12Z EC
is correct.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
VFR will prevail through daybreak across much of Pennsylvania
with cloud bases lowering from 25 KFT AGL to 8-10 KFT AGL around
08Z Friday. The exception will be over the southern few layers
of counties, where a MVFR Nimbostratus deck (and the leading
edge of a large area of light rain) will move in from the south
during the predawn hours on Friday.
Low pressure lifting up the eastern seaboard will likely spread
rain and generally MVFR (to briefly high end IFR) Cigs and MVFR
to VFR vsbys across roughly the SE half to two thirds of the
state during the mid to late morning, and the mainly light rain
will continue through the late morning hours Friday across
Scent PA and the Middle Susq Valley, and into the mid afternoon
hours over the Middle Susq Valley and Ncent Mtns.
Outlook...
Fri...Rain/low cigs possible, mainly eastern Pa.
Sat...Showers, especially early.
Sun...Breezy. AM low cigs/flurries possible W Mtns.
Mon...No sig wx expected. Breezy early.
Tue...No sig wx expected.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...La Corte
LONG TERM...Martin
AVIATION...Lambert
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
1000 PM CDT Thu Apr 26 2018
.UPDATE...
The forecast has been updated to add a mention of sprinkles across
northern Burnet and Williamson counties for early Friday morning.
Ongoing convection moving into far northwest Texas is picked up well
by the last few runs of the HRRR model. The HRRR along with several
other hi-res models show this activity will continue to move south-
southeastward overnight. We should see a gradual weakening overnight,
but we could see a light shower or sprinkles move into our region
early Friday morning. We will continue to monitor radar and model
trends and may need to spread the mention of light precipitation
farther south in subsequent updates. Otherwise, minor changes were
made to the winds, dew points and sky cover.
&&
.PREV DISCUSSION... /ISSUED 629 PM CDT Thu Apr 26 2018/
AVIATION...
The cold front is just about through the Panhandle and should be on
schedule to arrive at the TAF sites between 08-10Z. Winds will
initially go from southeast to light and variable, then after 15Z
pick up from the northeast at 7-10 kts. Look for a lower deck of
clouds between 040 and 050 starting around 09Z and lasting until
15Z...except until 18Z at KDRT.
PREV DISCUSSION... /ISSUED 230 PM CDT Thu Apr 26 2018/
SHORT TERM (Tonight through Friday Night)...
An upper level shortwave trough moving southeast across the Plains
into the Mississippi Valley will bring a weak cold front/reinforcing
surge of high pressure overnight into Friday morning. Though there
is some upward forcing, moisture will be limited to the mid and
upper levels. For now, will go with 10 POPs and no rain mention.
However, recent model runs started showing light QPF over Central
Texas late tonight into early Friday morning while some Hi-Res
models (ARW, NMM, TTU-WRF) even show this light QPF shifting to the
southwest toward the Edwards Plateau into the Rio Grande Plains
during the morning to midday Friday. Later forecasts may have to
introduce mention should these model trends continue.
LONG TERM (Saturday through Thursday)...
Flat mid/upper level ridge moves across Texas over the weekend while
strengthening southerly lower level flow brings a steady increase in
moisture. Larger upper level troughing drifts east across the western
and central states early into middle of next week sending weak
impulses across Texas. The dryline across western Texas and Serranias
del Burro over Mexico may allow for the development of showers and
thunderstorms each day, with the steering flow possibly sending them
across our area. Otherwise, mainly streamer showers are expected. By
mid week, it will begin to feel like early summer with dewpoints
reaching into the upper 60s to lower 70s and highs in some spots in
the 90s. The next frontal system appears to be next Friday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 57 82 57 83 59 / 10 - 0 0 0
Austin Bergstrom Intl Airport 54 81 54 82 56 / 10 - 0 0 0
New Braunfels Muni Airport 55 81 56 82 56 / - 0 0 0 0
Burnet Muni Airport 54 79 54 82 57 / 10 0 0 0 0
Del Rio Intl Airport 63 80 61 84 61 / 0 10 - - -
Georgetown Muni Airport 53 80 53 82 56 / 10 - 0 0 0
Hondo Muni Airport 57 82 57 84 57 / 0 10 0 0 0
San Marcos Muni Airport 54 81 56 82 55 / - - 0 0 0
La Grange - Fayette Regional 55 80 55 81 56 / 0 - 0 0 0
San Antonio Intl Airport 58 80 59 82 59 / 0 0 0 0 0
Stinson Muni Airport 58 83 59 85 59 / 0 - 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...26
Synoptic/Grids...24
Area Forecast Discussion
National Weather Service Wilmington NC
942 PM EDT Thu Apr 26 2018
.SYNOPSIS...
Low pressure will pass across northern North Carolina late
tonight bringing a good chance of showers. A pair of cold fronts
will push offshore late Friday and Saturday night, bringing
unseasonably cool temperatures for Sunday and Monday. Canadian
high pressure will push offshore late Monday, and temperatures
should warm rapidly Tuesday and Wednesday, with dry weather
continuing.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 900 PM Thursday...Have re-adjusted overnight POPS,
Skycover thru 15Z Fri, using the latest 88D trends, HRRR and
18Z Superblend models respectively. All of this to take into
account the latest band of mainly showers with embedded
thunderstorms associated with the upper low that will affect the
ILM CWA late this evening thru the overnight and exiting NE-E
of the area by daytime mid-morning. QPF was also updated using
the latest WPC guidance. Some tweaking of temps/dewpts using
current trends applied to 18Z Superblend model guidance.
Previous......................................................
As of 300 PM Thursday...Combination water vapor imagery and
regional radar mosaic show a large spin across northern AL into
GA representative of both a closed upper low and surface
reflection. These will slowly eject to the NE tonight to become
over VA on Friday. As this occurs, 500mb diffluence increases as
the flow spreads out ahead of the mid-level low, in conjunction
with 300mb divergence in the RRQ of an exiting upper jet. At
the same time, moist advection peaks in the warm sector ahead of
the associated weak cold front, and this combination of
moisture and lift suggest precip chances will increase from west
to east and this is echoed by all available high res guidance.
However, despite mins expected to remain around 60 tonight,
diurnal instability will wane significantly and this will limit
both coverage and intensity of showers overnight. Have
maintained high CHC showers with SCHC tstms since elevated
instability is progged to remain 300-500 J/kg which could
support a few lightning strikes in any stronger updrafts, aided
additionally by a robust 30-40 kt LLJ. Most of this activity
will occur after midnight, moving from SW to NE and leaving the
area by daybreak on Friday.
Another very nice day forecast Friday with a ridge of high
pressure building in from the west while yet another weak cold
front pushes down from the NW. This front is driven by another
spoke of vorticity moving through the longwave eastern CONUS
trough, and will exit offshore just beyond this period. Despite
temps climbing into the mid 70s once again, do not anticipate
convection Friday even with the added lift of the FROPA thanks
to very dry air aloft keeping PWATs around 0.75 inches. There
should be rather extensive diurnal Cu Friday however as
soundings saturate at the LCL beneath a pronounced subsidence
inversion.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...Quiet, rain-free, and seasonable
weather expected through the short term period. The area will
find itself between two cold fronts and under a broad mid level
trough. The second cold front will come through Saturday night
with far too dry an antecedent airmass to bring any weather. It
will mark the turn to slightly cooler weather.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 300 PM Thursday...Model differences are very small
through the extended portion of the forecast and have only
minor impacts on sensible weather. Confidence is rather high.
The tail-end of an upper trough will pass over the Carolinas
Sunday as high pressure, centered over the Midwest, builds
southeastward toward the area. Chilly air beneath the upper
trough (850 mb temps only +2C to +3C Sunday) should give us
another unseasonably cool day despite nearly full sunshine:
highs only 69-72. The upper trough pushes offshore Monday,but a
lobe of that chilly low-level air remains behind with highs not
expected to be warm much from Sunday.
Nighttime lows early in the week should be quite chilly for this
late in the year. Diminishing winds and clear skies Sunday night
should allow lows to fall into the low-mid 40s, and it wouldn`t
surprise me if a few of the typical cold spots get into the
upper 30s. We`re not expecting a freeze, but it`s interesting
that the latest freeze on record in Elizabethtown, NC was May 2,
1963, and for Lumberton was May 10, 1980.
By Tuesday, the surface high should push offshore with upper
level ridging building across the Carolinas. Our high and low
temperatures should quickly warm as 850 mb temps rise to +12C
Tuesday and +14C Wednesday and Thursday. The orientation of the
mid and upper level ridge should prevent any inflow of moisture,
and skies should remain very clear through the extended
forecast period. Dewpoints dipping into the 30s Sunday and
perhaps Monday should moderate through the week, finally
reaching 55-60 by Thursday which may develop the first flat
cumulus we will have seen all week!
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
As of 23Z...An upper level disturbance will push into the western
portion of the CWA just before midnight, with scattered
convection expected. The upper low will weaken as it turns the
base of the longwave trough, and this should weaken the showers
as they approach the coast. Have not introduced IFR at this
time, but it is a possibility, particularly along the coast
around 10-12Z. Friday, becoming scattered with a moderate
southwest wind.
Extended outlook...VFR.
&&
.MARINE...
NEAR TERM /THROUGH FRIDAY/...
As of 900 PM Thursday...Winds likely at their lowest for the
night, 5 kt or less. Should see an increasing trend as well as
a veering trend during tonight. And by daybreak, winds should be
from the SSW-SW at 10 to possibly 15 kt. Significant seas will
continue to be governed by the ESE ground swell at 9 second
periods. Along with a noteworthy increase in wind chop by
morning. Could see vsby briefly reduced to 1 to 3 nm from
showers associated with the rotating band of pcpn extending out
from the upper low and associated with the cold front.
Previous......................................................
As of 300 PM Thursday...Light S/SE winds this eve will veer
gradually to the SW as a weak cold front moves across the waters.
Wind speeds will generally increase to 10-15 kts tonight, and
then slightly higher towards 15-20 kts Friday as the gradient
becomes more pinched ahead of another weak cold front which will
approach late on Friday. Seas this even will remain 2-3 ft, but
a gradual amplification to 3-5 ft is expected as the winds
increase to drive a growing 6 sec wind wave, which will combine
with the 8-9 sec SE swell.
SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...West to southwest flow to dominate
through the period as the area spends most of the time in
between two cold fronts. The second boundary is slated for
passage near the end of the period, and it may bring a sharp
turn to the north towards daybreak. Swell energy will be quite
minimal, seas will be comprised of a series of fairly diminutive
wind waves.
LONG TERM /SUNDAY THROUGH TUESDAY/...
As of 300 PM Thursday...High pressure will build southeastward
behind Saturday night`s cold front, finally reaching the
eastern Carolinas Monday afternoon or evening. Northerly winds
as strong as 15-20 kt at daybreak Sunday should subside to
around 10 kt Sunday afternoon. An upper level disturbance
passing just to our north late Sunday night should bump winds
back up toward 15 knots, but winds should diminish again as the
high pressure area approaches later Monday. Westerly winds
behind the high Monday night will turn more southerly along the
beaches Tuesday afternoon with the daily seabreeze circulation.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...TRA
NEAR TERM...DCH/JDW
SHORT TERM...MBB
LONG TERM...TRA
AVIATION...DL
Area Forecast Discussion
National Weather Service Lubbock TX
637 PM CDT Thu Apr 26 2018
.AVIATION...
Stiff northerly winds this evening will be slow to diminish with
a 1023 MB surface ridge pushing in overnight. Pressure gradient
will gradually ease later tonight but a light northerly component
likely to hang on close to daybreak Friday. High-based convective
activity in the eastern Panhandle will redevelop southward behind
the cold front and most likely stay east of KCDS - but retained a
vicinity thunderstorm remark at KCDS between 02Z and 04Z. Dry,
VFR and lighter winds likely much of Friday until surface ridge
gives way to renewed surface pressure falls and troughing over
eastern New Mexico and the western Panhandle late Friday afternoon.
RMcQueen
&&
.PREV DISCUSSION... /issued 435 PM CDT Thu Apr 26 2018/
UPDATE...
As of 4:30 pm, the cold front is currently stretched from
Childress to Plains. North winds behind the front are 25 to 35
mph with 32 mph sustained at Morton, Plains and Dimmitt.
Increased the wind forecast to reflect this and issued a Wind
Advisory for much of the western South Plains until 7 pm this
evening. Expect winds to fall below advisory criteria shortly
after sunset.
PREV DISCUSSION... /issued 311 PM CDT Thu Apr 26 2018/
DISCUSSION...
Another dynamic upper level short wave trough is moving across
western Kansas this afternoon, hot on the heels of Tuesday`s
system. Strong surface pressure rises on the central High Plains
is resulting in a period of advisory level wind speeds behind
another stout cold front. Bulk of evidence suggests these pressure
rises will decrease in intensity as they move to the south. We
should see some advisory level winds across the northwestern part
of the forecast area as we finish out the afternoon, but currently
think that this period will be rather brief. The next issue is
potential for the western end of a batch of showers/thunder that
several models project developing just ahead of the upper trough
clipping the northeastern corner of the forecast area. The last
several runs of the HRRR have favored this solution with support
from the WRF-NAM. Will insert a small area of 20-30 percent PoPs.
Finally, there is the potential for a few spots to touch the
freezing mark Friday morning. That happened at several West Texas
mesonet and NWS coop observation sites this morning. Conditions
should be similar in the morning. However, any widespread freeze,
or a long-duration freeze is unlikely.
The other point of concern this afternoon is related to
thunderstorm chances next week. Upper level troughing over the
western CONUS will see the current northwest flow over the Plains
states replaced by southwesterly flow. This will promote a
southerly component to the low level flow and low level moisture
return being acted upon by a dryline that will likely shift
eastward each day from eastern New Mexico Saturday afternoon to
the Rolling Plains or even as far east as Northwest Texas by
Tuesday or Wednesday afternoon. The last few forecast cycles have
shown this evolution, and no significant changes have been made
this afternoon.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 7 PM CDT this evening for TXZ021>023-027>029-
033>035-039>041.
&&
$$
99/99/05
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1038 PM EDT Thu Apr 26 2018
.SYNOPSIS...
A strong mid-level area of low pressure will move across the
region and to the north overnight. Another weak cold front
will cross the area late Saturday followed by strong high
pressure building over the area Sunday into early next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 1030 PM Thursday...Showers continue to be elusive across
much of the area this evening with only isolated
showers/thunderstorms now east of Cape Hatteras. Still
expecting coverage to increase along the coast after midnight,
then moving into the coastal plain from the west late as low
pressure lifts into the mid Atlantic. Evening update mainly to
adjust PoP and T/Td trends toward latest guidance.
Closed low over Alabama will start to lift out to the east and
north tonight with deeper moisture and mid-level energy
approaching later tonight. Latest runs of the HRRR and 3km NAM
have been consistent all day in showing small area of showers
and perhaps a few tstms moving along the southern coast after
midnight. After about 08z or 09z, more widespread showers will
accompany the main upper low and have continued likely PoPs into
the early morning hours. Cloudiness, showers and southerly
winds should hold overnight lows in the mild upper 50s to lower
60s.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
As of 325 PM Thursday...Showers will be ongoing at the beginning
of the second period, but deep dry layer will descend in the
afternoon decreasing support for showers with lowering PoPs by
midday. With moderate SW flow, Friday will be a pleasantly warm
Spring afternoon with highs in the mid to upper 70s for most
areas.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
As of 330 AM Thursday...Models remain in decent agreement during
period with several disturbances moving through Friday night into
Saturday, followed by upper low finally moving across to NE of
area late Sunday into early Monday. After brief cooling trend,
heights building surface and aloft will result in warming trend
Tue-Wed.
Friday Night and Saturday...Approaching elongated shortwave
trough will produce isolated convective threat over western and
northern sections Fri night. Models have trended drier for
Saturday with shortwave moving off coast early and have dropped
POPs given limited moisture and lift. Guidance has trended
warmer for max temps both days and raised highs to near 80
inland sections.
Saturday night through Wednesday...Dry cold front will move
through Sat night followed by initial surge of CAA late Sat
night into Sunday. Then strong but dry upper trough associated
with upper low will move through Sunday evening, resulting in
secondary CAA surge late Sun night into Mon morning. Cooling
trend will be short-lived as heights will be building quickly
Mon night into Tuesday with upper ridge extending over area from
S-SW. No precip expected through the period and main focus will
be temp forecast with readings 5-10 degs below normal for Sat
night through Mon night, then moderating to above normal
midweek. It is noted that ECMWF MOS is indicating min temps in
mid to upper 30s for Monday morning while GFS MOS supports lower
40s.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Short Term /through 00Z Friday/...
As of 8 PM Thursday...Pred VFR expected through much of the
period, however will see showers with isolated thunderstorms
lift across the area late tonight into Friday morning which
could bring periods of sub-VFR conditions across rtes, with best
chances between 09-15z. Generally VFR conditions expected after
15z but a few showers may continue into the afternoon across the
coastal plain with bring periods of sub-VFR conditions possible
Long Term /Friday Night through Tuesday/...
As of 330 AM Thursday...VFR expected most of period. Brief sub-
VFR possible with scattered showers/isolated tstms Friday
Night.
&&
.MARINE...
Short Term /Tonight and Friday/...
As of 1030 PM Thursday...Latest obs show S/SE winds around 5-10
kt, except SW winds up to 15 kt near the Gulf Stream. Seas have
subsided to 3-5 ft most areas but still seeing up to 6 ft at
Diamond Buoy. Have made slight adjustments to the going SCA,
having cancelled it north of Oregon Inlet where latest models
keep seas below 6 ft through the period. Will continue the SCA
south of Oregon Inlet but adjusted the start time until Friday
morning.
A strong mid-level disturbance approaches from the west
overnight, southerly winds will increase to 10-15 knots and
become SW 15 to 20 kt Friday afternoon. This will allow seas to
build up 4 to 6 feet once again, highest over the outer
periphery of the southern and central coastal waters.
Long Term /Friday night through Tuesday/...
As of 330 AM Thursday...A weak front will result in a brief
wind shift late Fri night into Saturday, then a stronger front
will move through Saturday night followed by a northerly surge
of 15-20 KT winds Sunday. Secondary front moving through Sunday
night will result in another period of NW 15-20 KT winds early
Monday.
Seas will gradually subside to 3-4 ft by late Saturday and
persisting into Monday.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Beach Hazards Statement through Friday evening for NCZ095-098-
103-104.
MARINE...Small Craft Advisory until midnight EDT Friday night for
AMZ152-154.
Small Craft Advisory from 7 AM to 10 PM EDT Friday for AMZ156-
158.
&&
$$
SYNOPSIS...CTC
NEAR TERM...CTC/SK
SHORT TERM...CTC
LONG TERM...JBM
AVIATION...CTC/JBM/SK
MARINE...CTC/JBM/SK
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1045 PM CDT Thu Apr 26 2018
.SHORT TERM...(This evening through Friday)
Issued at 255 PM CDT Thu Apr 26 2018
Sky should clear to the east early with winds diminishing. The
next frontal system is fast on its heals and will sweep through
late tonight to the northwest and exit the southeast CWA Friday
morning. Strong northwest winds expected in its wake with just a
small chance of showers mainly over northwest WI region.
Temperatures will warm close to readings of today/mid 50s to some
lower 60s to the southeast.
.LONG TERM...(Friday night through Thursday)
Issued at 255 PM CDT Thu Apr 26 2018
The longer term trends continue to show warming ahead of the
frontal system that is currently forecast to move through around
Tuesday.
Ahead of the front, southerly flow increases Sunday and a weak
short wave lifts northeast with the surface warm front Sunday
night and Monday. Instability/Moisture increases ahead of the
warm front and may be enough to generate some convection along the
LLJ. Temperatures should warm through the the 60s to some lower
70s possible Sunday and into the 70s for Monday, which looks like
the warmest day of the period.
The warm front shifts off to the east Monday with the front
moving through Tuesday. Will continue low chance PoP for thunder
with the system at this time. The unsettled pattern will continue
into the later part of next week but we should see drying develop
as upper ridging/warmer air tries to return. The GFS is most
bullish in driving the western CONUS ridge east into next weekend.
The ECMWF not so much as it retains more of the eastern CONUS
trough and northwest flow across the western Great Lakes.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1045 PM CDT Thu Apr 26 2018
Minimal changes to 00z TAFs with timing of cold front that is
currently on the doorstep of Grand Forks, ND. Based on winds we
saw behind todays front and what we are seeing with forecast
soundings behind the front for Friday, did nudge wind speeds a bit
above what the LAV had. Again, looks like moisture is lacking in
the HRRR is showing precip remaining northeast of all MPX
terminals, so have maintained a dry forecast. In addition, we
should see a sct-bkn cu field drop down from northern MN during
the afternoon, that will mainly impact areas along and east of the
MS River. By the time they get here though, cigs should be 4k to
5k feet AGL.
KMSP...FROPA still looks good for the 14z to 15z timeframe. This
will result in crosswinds for the morning push as winds will be
turning from the SW to NW during that time.
/OUTLOOK FOR KMSP/
SAT...VFR. Winds N 5 kts or less bcmg SE.
SUN...VFR. Winds S increasing to 15G25kts.
MON...Chc MVFR/-shra/-tsra. Winds S 15G25kts.
&&
.FIRE WEATHER...
Issued at 250 PM CDT Thu Apr 26 2018
Will leave Red Flag Warning going with strong northwest wind to 40
mph over parts of west central MN. Lowest RH level seen has been
26 percent. Still have strong subsidence moving through that
region per latest satellite water vapor imagery. Still could see
RH levels dropping off around 25% by late afternoon. Winds are
expected to diminish quite rapidly after 7 PM.
Windy conditions will develop in the wake of the next cold front
Friday morning to the west and region wide in the afternoon. May
not be as strong s today and RH levels drop off through the upper
20s to lower 30s percent. Continues the elevated fore weather
conditions for Friday afternoon. Low RH levels continue into
Saturday but winds will be light under surface ridging. We will
have to monitor Sunday afternoon as winds increase again ahead of
the frontal system developing to the west. RH levels are expected
to drop off into the upper 20s/low 30s percent again and it will
be modulated by how quickly we can advect higher dewpoints into
the area.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&
$$
SHORT TERM...DWE
LONG TERM...
AVIATION...MPG
FIRE WEATHER...DWE