Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/02/18
Area Forecast Discussion
National Weather Service Boston/Norton MA
1015 PM EDT Sun Apr 1 2018
.SYNOPSIS...
Weak high pressure builds over the region with cooler drier air
tonight. Low pressure moves offshore along the Mid-Atlantic coast
and heads east, brushing Southern New England with some snow Monday
morning. Unsettled weather returns Tuesday afternoon into Wednesday
with rain at times along with milder temperatures, then blustery
and colder weather follows Thursday. More unsettled weather is
possible sometime Friday into next weekend.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
10 pm update...
Forecast challenges remain even within 12 to 18 hours. Precipitation
amounts coupled with intensity, snow ratios, surface temperatures.
All factors to potential snowfall amounts, hazards.
Certain, W-E sweeping open-wave H5 vortmax / trof axis, beneath RRQ
of a cyclonic H3 jet axis yields Mid-Atlantic cyclogenesis. Advance
SW 290-310K isentropic flow against a H925-7 cold airmass in place,
S-N thermal packing / frontogenesis, should yield W-E snow banding,
especially around H85, towards Monday morning through midday. Can`t
rule out snow ratios around 15:1 per H925-85 -4 to -6C temperatures.
Fluffier snow, efficient accumulation, more so if 2m temperatures
are at or below freezing. Ageostrophic flow, N/E, should maintain
lower surface dewpoints 20s to teens S to N, drier boundary-layer
airmass, potentially aiding lower 2m temperatures with wet-bulbing.
Uncertain is frontogenetical extent N into S New England, whether it
remains mainly along or offshore the immediate S-coast. Omega within
snow-growth regions under scrutiny, upwards of 25 microbars / second
yet to what breadth and extent N? This lends to lower confidence on
exact snowfall intensity into S New England. However, given the cold
airmass, even if light, should accumulate early Monday morning. SREF
continues to signal 1"/hr snowfall rates into SW New England by Monday
morning, diminishing while peeling offshore towards midday. Echoing
the prior forecaster, such rates would overcome any marginal 2m
temperatures yielding efficient accumulation on all surfaces.
Close eye on HRRR / RAP / HREF trends. Continued confidence advisory
level snows across S-coastal New England. Will hold with the present
forecast, headlines. Can`t rule out Outer Cape / Martha`s Vineyard
advisory-level snows but perhaps not widespread per warmer ocean
influence.
Greatest concern for the Monday morning commute across the Hartford-
Springfield metro areas. Low visibility along with accumulating snow-
fall will make for hazardous travel conditions. Snow moving in around
9 am for areas E around the Providence-metro, perhaps less impact
to the commute which should be concluding, however expect hazardous
travel conditions with light to moderate snow to spread E.
As to the near term, weak high pressure settling in, winds on a down-
ward trend. High clouds settling in, window of decoupling boundary
layer / radiational cooling is closing. Lows down into the 20s to
low 30s as snow settles in by morning.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Daybreak Monday...
* Accumulating snowfall could impact the morning commute
Open wave and associated surface low pressure system will pass S
of the region Monday morning. At the onset of precip, appears to
be a strong temp/dewpoint spread. However bufkit and model cross-
sections suggest that strong omega in the snow growth region will
help overcome this spread resulting in temperatures to wet-bulb.
Several hi-res guidance members including the HREF, HRRR and SREF
show good probability in an inch an hour snowfall rates as the
system passes. These snowfall rates will help overcome and marginal
surface temps resulting in accumulations not just on grassy surfaces
but on area roadways as well. One thing to note, appears that the
best F-gen is still just offshore, so if this low scoots a bit
northward than advisories will need to be expanded.
Timing of this system appears to be around 6-8 am. Heaviest snowfall
closest to the 8am hour which could lead to some impact to the later
half of the morning commute, esp for the I-195 corridor. This is
a quick moving wave due to lack of any blocking across the Atlantic,
thus expect snow to end from west to east between 10 am and 1 pm.
Overall updated this portion of the forecast towards a GFS/EC/RGEM
blend resulting in 1-2 inches of snowfall south of the Mass Pike.
2-4 inches of snowfall across the southern half of RI and into MA
south coast. Still some uncertainty on how much will accumulate
across the Cape and the Islands. Snow will be moving in a bit
slower in that region and with high sun angle and warming temps,
may limit how much would actually accumulate. Anticipate most
of the snowfall to occur across the grassy surface and elevated
roadways. Locations along the south coast could see area roadways
accumulate snowfall. No changes to the headlines at this time.
Monday afternoon and evening...
Weak high pressure re-builds over our region. This will bring
clearing skies and light wind. Fair skies should allow temperatures
to warm near 40 during the day and then to drop below freezing in
most areas at night.
Increasing mid and high level moisture moves in after midnight.
Expect increasing clouds at that time.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Highlights...
* Moderate temperatures and active weather Tuesday into Wednesday
* Blustery and cooler for Thursday
* Active weather returns for the end of the week
Overview...
Active weather pattern remains for southern New England with just a
few breaks here or there. Broad upper level trough continues to be
anchored with upper level low over Hudson Bay. Strong Pac NW wave
will get captures in the broad cyclonic trough and push towards the
Great Lakes and into northern New England by mid-week. Expect a few
bouts of rainfall with this low as PWAT values are nearing 2-3 +STD
with increasing LLJ. As the system`s cold front moves offshore,
blustery and cooler temps will usher into the region on Thursday.
Ridging for the West will allow for Arctic shortwave to dive into
the trough and rotate towards southern New England by Friday.
Depending on timing and strength, this system could bring snow/rain
to the area. Reinforcing arctic airmass will be in place as southern
stream wave approaches from the Ohio River Valley by next weekend.
Details...
Tuesday into Wednesday...Moderate confidence.
Mid-level ridge and surface high pressure to start the period will
exit offshore as low pressure system approaches from the west.
Showers will begin to move into the region by the late morning/early
afternoon as warm front approaches from the south and higher theta-e
values advect into the region. This overrunning precip event is not
expect to amount to to much. Depending on the timing, could see some
wet flakes or sleet mixed in at the onset, but overall p-type will
be in the form of rain.
Warm front will push through Tuesday night allowing for temps aloft
to quickly warm. Trended the forecast towards a mild night and used
a non-diurnal trend. Cannot rule out the potential for dense fog,
esp across the south coast, as higher dewpoint air advects over the
cooler ocean. Pretty strong LLJ will strengthen overnight but lapse
rate suggest that mixing will be limited. Thus with this type of
inversion the potential for fog to move into the interior is
possible.
Southern New England will be in the warm sector by Wednesday
morning. With a break in the precip during the morning, and perhaps
some breaks in the clouds could help increase surface temps into the
low to mid 60s. Since temps will warm into the 60s, lapse rates
could steepen enough to allow for mixing of the 40-50 kt LLJ down to
the surface. If this occurs than a wind adv will be needed.
Confidence is higher with mixing behind the front, but LLJ is
weaker.
As the cold front sweeps through, heavy rainfall is possible thanks
to strong LLJ and high PWAT airmass. However, the better dynamics
will be closer to the surface low which is pulling away from the
region so not expecting any flooding concerns at this time. Overall
is appears to be a soggy Wednesday afternoon as rainfall quickly
moves through the region.
Thursday and Friday...Moderate confidence.
Behind the cold front, anomolous cold airmass will filter back into
the region. This will knock temps back to below average for this
time of year, esp on Thursday. Blustery conditions are expected
thanks to strong northwest flow. Another shot of rain and snow will
usher into the region on Friday as a quick moving wave swings
through. Still some uncertainty on exact location and timing as the
EC is more progressive compared to the GFS.
The weekend...Low confidence.
Reinforcing arctic airmass will be in place as southern stream wave
approaches from the Ohio River Valley by next weekend. This system
could bring another bout of rain or snow. Something to watch in the
coming week.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Monday Night/...High confidence.
Tonight...
VFR. Mid-high level CIGs thickening, lowering towards early
morning Monday. Light north winds turning from the northeast.
Monday...
MVFR-IFR cigs move across CT-RI-SE Mass during the morning.
Vsbys lower to IFR in snow with brief LIFR vsbys possible.
Farther north across Springfield/Worcester/Boston a period of
MVFR cigs/vsbys is possible in snow during the morning.
Conditions should improve to VFR in clearing during the
afternoon. Airports along the immediate south coast have the
best potential for snow accumulation.
Monday afternoon...
VFR. Fair weather with increasing mid and high clouds after
midnight.
KBOS Terminal...High confidence in TAF through 5 AM, then
moderate confidence. Most snow is expected to pass south of the
airport, but it is possible for a few hours of lower conditions
Monday morning which could impact the morning rush.
KBDL Terminal...High confidence in TAF through 5 AM, then
moderate confidence Monday morning. A brief period of mod SN is
possible which could lower conditions.
Outlook /Tuesday through Friday/...Moderate Confidence.
Wednesday: Mainly VFR, with areas MVFR possible. Windy with
gusts to 35 kt. Chance RA, isolated TSRA.
Wednesday Night: VFR. Windy with local gusts to 30 kt.
Thursday: VFR. Breezy.
Thursday Night: VFR. Breezy. Slight chance SHSN.
Friday: Windy with gusts to 35 kt. Chance SHRA.
Friday Night through Saturday: Breezy. Chance SHRA, slight
chance SHSN.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Monday Night/...High confidence.
Tonight...
Gusty west winds through the evening with gusts to 25 knots.
This wind will diminish 8-11 PM with light winds overnight.
Lingering 5 foot seas on the outer waters through midnight, then
less than 5 feet overnight.
Small Craft Advisory lingers for the first part of the night.
Monday...
Snow/Rain spreads over the southern waters early morning and
possibly reaching the Merrimack River. Precipitation then tapers
off midday or early afternoon. Vsbys 1 to 3 miles in snow around
the South Coast during the morning. Winds will be less than 20
knots and seas less than 5 feet.
Monday night...
Winds below 20 knots. Seas less than 5 feet.
Outlook /Tuesday through Friday/...Moderate Confidence.
Wednesday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 13 ft. Rain likely,
isolated thunderstorms.
Wednesday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 25 kt. Areas of rough seas.
Thursday through Thursday Night: Low risk for Small Craft
Advisory winds with gusts up to 25 kt. Local rough seas.
Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 12 ft. Chance of rain showers.
Friday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Slight chance of rain
showers.
Saturday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers.
&&
.EQUIPMENT...
Due to our move to the new forecast office in Norton, MA, we
are still trying to resolve some communication issues. The
following NOAA Weather Radio transmitters are back on the air:
Somers, CT transmitter........WXJ41.....162.475 MHz
Paxton, MA transmitter........WXL93.....162.550 MHz
Johnston, RI transmitter......WXJ39.....162.400 MHz
Gloucester, MA transmitter....WNG574....162.425 MHz
However, the following NOAA Weather Radio transmitters are not
yet on the air:
Blue Hill, MA transmitter.....KHB35.....162.475 MHz
Hyannis, MA transmitter.......KEC73.....162.550 MHz
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Winter Weather Advisory from 2 AM to 2 PM EDT Monday for
MAZ020-021.
RI...Winter Weather Advisory from 2 AM to 2 PM EDT Monday for
RIZ006>008.
MARINE...Small Craft Advisory until 11 PM EDT this evening for
ANZ230>237-250-251-254.
Small Craft Advisory until 2 AM EDT Monday for ANZ255-256.
&&
$$
SYNOPSIS...WTB/Dunten
NEAR TERM...WTB/Dunten/Sipprell
SHORT TERM...WTB
LONG TERM...Dunten
AVIATION...WTB/Dunten/Sipprell
MARINE...WTB/Dunten
EQUIPMENT...WFO BOX Staff
Area Forecast Discussion
National Weather Service Columbia SC
1038 PM EDT Sun Apr 1 2018
.SYNOPSIS...
High pressure over the Southeastern States will weaken Tuesday.
Above normal temperatures and dry weather are expected through
Tuesday. A cold front will cross the area Wednesday, bringing a
chance for showers and possible thunderstorms. Dry high pressure
will take hold Thursday and Friday. Another cold front may
affect the region next weekend.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Forecast continues to be on track will little change needed for
this mid evening update. The thin cirrus that has been overhead
this afternoon and early evening is moving away from the area.
There are a few patches of mid clouds in the upstate that might
try to brush through Lancaster county in the next few hours, so
the sky grids are a bit higher up there, but still not enough
to worry about any ceilings that might effect overnight
temperatures.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
Surface high pressure over the Southeastern States will
gradually weaken and slip off the south Atlantic coast
Tuesday. Above normal temperatures and generally dry weather is
forecast.
A Westerly 500 mb flow Monday will back to more southwesterly
Monday night and Tuesday and heights will rise in response to
digging shortwave energy over the middle part of the country and
associated cold front. Warming 850 mb temperatures and deep
mixing along with plenty of sunshine will allow temperatures to
warm well into the 80s both Monday and Tuesday. Several runs of
the MAV MOS indicated highs in the upper 80s Tuesday. Overnight
lows will be in the mid and upper 50s Monday night then in the
lower 60s Tuesday night.
Low-level moisture will continue to increase across the region
with deep southwesterly flow and precipitable water values
increasing to around an inch by Tuesday afternoon and up to 1.25
of an inch Tuesday night. Since upper-level forcing remains to
the west of the forecast area along with an approaching cold
front, will continue chance pops in the western Midlands and
upper CSRA with slight chance pops elsewhere late Tuesday night.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The upper-level flow pattern will become more amplified during
the extended forecast period with a couple of systems that will
impact the forecast area bringing chances of showers and
thunderstorms.
An upper-level trough and associated low pressure system will
lift into New England Wednesday pushing a cold front through
the forecast area. Still some timing differences among the
operational GFS/ECMWF/CMC but the front will cross sometime
during the day Wednesday bringing a period of showers and
possibly some thunderstorms depending on the timing and
available instability. Severe weather does not appear likely at
this time. Will continue to carry likely pops Wednesday with
pops diminishing by late afternoon Wednesday as the front moves
into the Coastal Plain. Cool high pressure will build into the
region from the west with clearing skies by the evening.
Rainfall amounts generally expected in the quarter to half inch.
Thursday and Friday look to be dry and much cooler behind the
front with surface high pressure settling over the forecast
area. The next weather system will impact the region Saturday
into Sunday as another shortwave trough drops into the Plains
and shifts eastward. Temperatures through this period will be
near to above normal Wednesday followed by below normal
temperatures Thursday and near to slightly below normal Friday
through Sunday.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Expect mainly VFR conditions during the TAF period. There may
be a period of MVFR or IFR during the early morning hours.
High pressure has shifted off the Southeast Coast. Some increase
in low-level moisture has occurred. This moisture combined with
nocturnal cooling may result in stratus and fog toward dawn.
The SREF guidance indicated greater chances of restrictions in
the southeast section closer to higher moisture affecting the
AGS, DNL, and OGB terminals. Most of the NAM and GFS MOS plus
HRRR guidance maintained VFR conditions but based on the period
of fog the previous morning at AGS we leaned toward the more
pessimistic guidance and forecasted a period of MVFR fog at AGS,
DNL, and OGB. Believe heating and mixing will bring improvement
after 14z. Followed the GFS and NAM MOS for the wind forecast
with wind light tonight and mainly southwest near 10 knots
Monday. The NAM Bufkit momentum transfer tool and GFS LAMP
suggested gusts around 16 knots Monday afternoon.
EXTENDED AVIATION OUTLOOK...Late night and early morning
stratus and fog is possible through Wednesday. Showers and
possible thunderstorms Wednesday.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
SYNOPSIS...99
NEAR TERM...99
SHORT TERM...99
LONG TERM...99
AVIATION...99
Area Forecast Discussion
National Weather Service Charleston SC
949 PM EDT Sun Apr 1 2018
.SYNOPSIS...
High pressure will prevail through Tuesday. A cold front will
move through late Wednesday, followed by high pressure into
Saturday. Another cold front will impact the area next Sunday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Surface high pressure building over the Atlantic is forecast to
extend west overnight with a tranquil weather pattern in place
for the region. The main forecast challenge overnight continues
to be fog and stratus development. The setup is quite good with
respect to dry air and light winds atop fairly moist near-surface
layers. The latest HRRR surface condensation pressure deficit
progs along with LAMP/SREF data suggests the better potential
for low stratus may end up to the east of I-95 in SC. We made
some adjustments to fog potential in our grids but the message
is generally the same, patchy to areas of fog nearing daybreak.
No significant changes to lows in the mid 50s most areas with
light to calm winds.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
Monday: Dry and unseasonably warm conditions will again prevail,
with a zonal flow aloft, while Atlantic high pressure stretching
across the local area at the surface. A cold front extending
westward from a Clipper-type low off the Delmarva will struggle to
make much headway southward, blocked by the high and also aligned
parallel to the westerly flow aloft. A deep offshore flow, H8 temps
that are as warm as 13-14C (or near the 90th percentile for early
April), deep mixing and plenty of insolation will boost max temps
into the lower or middle 80s inland from the Intra-Coastal Waterway
(ICW). With sea breeze circulations across lower 60 water temps,
locations at or near the shoreline will be significantly cooler.
Monday night: Little change in the overall synoptic scenario, with
high pressure at the surface and a zonal flow persisting aloft. Weak
warm advection within a SW synoptic flow won`t allow for temps to
get any cooler than 58-62F, which is far above climo. There is at
least some potential for fog to develop, as shown by the SREF
probabilities of 60% or greater. But geostrophic winds are a little
too high around 15 kt, and condensation pressure deficits are no
lower than 10-20 mb. So for now we have nothing more than "patchy"
wording, and some of that could actually be as sea fog. If it does,
coverage could be greater and dense fog would be a concern.
Tuesday: A deepening short wave in the central states will cause
some increase in heights atop the SE, while a frontal system tracks
NE through the upper Midwest and the Atlantic ridging holds firm
locally. There is some increase in low level moisture within a
deepening S-SW flow, and that along with a little bit of instability
and a weaker subsidence cap might allow for a couple of showers to
initiate on the sea breeze, mainly in GA. But since we still have
quite a bit of dry air above 850 mb, and omega fields are limited,
we have maintained a rainfree forecast with PoP no higher than 14%.
It`ll be another exceptionally warm day with H8 temps again around
13-14C, leading to highs similar to Monday. Places closer to the
coast and on the beaches could actually be a tad cooler than Monday,
with an earlier start to the sea breeze. If there is any sea fog it
would shift into the Atlantic by mid to late morning.
Wednesday: The mid and upper flow becomes more amplified, as a deep
surface low passing into eastern Canada, while it`s associated short
wave pushes through the Great Lakes and Ohio Valley toward the NE
states. A trailing cold front from the low will approach the NW,
before passing into the ocean late. Moisture will continue to
increase, both of amount and in depth, with PWat reaching near or
greater than 1.5 inches. This along with modest QG forcing with
height falls aloft, and upper difluence with RRQ of the upper jet
nearby to our NW, will support high probabilities of light to
moderate showers. Since there are sill some timing differences
between the various model solutions, we won`t go any higher than 70%
at this time. However, categorical PoP`s are likely as the event
draws closer. Despite the elevated PWat, given the progressive
nature of the convection, we have presently have up to about 1/4
inch of QPF.
We continue to mention slight chance of t-storms in the forecast
with some instability, shear and adequate lapse rates. But the
overall thermodynamics are rather insignificant, so the risk of
severe weather is extremely low.
Temps are highly dependent on the timing of convection, but since
we`re starting the day some 12-16F warmer than average, max temps
should again be well above normal.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
High pressure will prevail, bringing dry conditions. Another cold
front should impact the area by next Sunday. Coolest conditions will
be on Thursday, before another warming trend develops late in the
week into next weekend.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
VFR until later tonight when fog and stratus look to pose a risk
limiting flight restrictions. Since coastal GA appears to have
a slightly higher potential for IFR conditions, we maintained
persistance with the 00Z TAF cycle. Latest NAM forecast soundings
show favorable fog stabilities indices progged in the single
digits at KSAV and teens at at KCHS later tonight. Southwest
synoptic flow is not all that favorable, since advection fog/stratus
is unlikely. VFR conditions will return by late morning on Monday.
Extended Aviation Outlook: Flight restrictions are possible in
fog/stratus late Monday night into early Tuesday morning, then again
with SHRA and possible TSRA in association with a cold front on
Wednesday.
&&
.MARINE...
Tonight: High pressure centered over the western Atlantic will
allow winds to veer to the south overnight but no significant
winds/seas are expected. Could see some fog impact areas near
the coast late.
Monday through Tuesday: Sub-tropical high pressure will remain in
control early this week, and even with sea breeze influences, winds
and seas will remain below any advisory conditions.
Wednesday and Thursday: A cold front will approach from the NW
during mid week, passing through the waters by late Wednesday,
followed by continental high pressure behind the front into
Thursday. Warm advection will limit the amount of mixing on
Wednesday in advance of the front, so even though winds and seas
will climb, conditions still look just shy of any Small Craft
Advisory levels. Instead, large isallobaric pressure rises and cold
advection behind the front allows for the better chance of obtaining
advisories Wednesday night into Thursday, on at least parts of the
marine area. Mariners can expect showers and at least a few stronger
t-storms to occur in association with the cold front.
Friday and Saturday: Much better conditions on Friday with Atlantic
high pressure directly atop the waters, before conditions
deteriorate again next Saturday ahead of a cold front.
Sea Fog: There seems to be about a 12-15 hour period where sea fog
is possible from late Monday evening into midday Tuesday, with the
most favorable wind fields and dew points to occur during this time.
We continue to mention "patchy" sea fog in the forecast and in the
Hazardous Weather Outlook.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1105 PM EDT Sun Apr 1 2018
.UPDATE...
Issued at 1105 PM EDT SUN APR 1 2018
Did a quick update to mainly to fine tune the PoPs in the south
along with adding a bit more QPF down there. Also touched up the
T and Td grids per the latest obs and trends. These have been sent
to the NDFD and web servers.
UPDATE Issued at 850 PM EDT SUN APR 1 2018
00z sfc analysis shows an area of low pressure riding northeast
along a stalled frontal boundary that is bisecting the JKL CWA.
This is bringing with it a healthy slug of moisture with over-
running rains quickly spreading into eastern Kentucky from the
west. Winds across the area are generally light and from the
northeast under overcast skies. There is quite a temperature
gradient across the JKL CWA running from the mid 40s north to the
low 60s in the far southeast. Dewpoints vary similarly from the
mid 30s north to the upper 40s and low 50s south. As the pcpn
moves in, wetbulbing will lower temperatures significantly across
the area. However, they will remain enough above freezing (and
with warmer air riding in aloft) to preclude snow despite
temperatures likely to fall into the mid 30s by dawn north of
I-64. Cannot rule out some brief partially melted snowflakes
mixing with the rain north late tonight, but this will be
immaterial should it even occur. Otherwise, the forecast is on
track with just some adjustments to PoPs and Wx made through the
night per the latest HRRR and NAM12. Also added in the latest obs
and trends to the T and Td grids. Look for an updated set of zones
shortly. The grids have been sent to the NDFD and web servers.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 349 PM EDT SUN APR 1 2018
Current conditions across the area feature a boundary draped
across eastern Kentucky with extensive cloud cover associated with
a passing wave along the boundary. Much of the precip from this
morning has exited off to the southeast. To the west, another
system takes aim at the region. This wave will quickly push east
along the boundary bringing a good shot of rainfall across mainly
northern Kentucky. In fact, models suggest a good 0.50 to 0.75
inches of rainfall to the Bluegrass region tonight. Surface temps
for this will be too warm for any snowfall so all rain will be
anticipated for tonight. In fact, PWAT values will be around an
inch which is still a bit wet. Just like the previous wave, this
feature will quickly pass to the east as the boundary once again
pushes to the south. This will again divide the CWA with cooler
temps to the north and warmer temps to the south of the boundary.
By the day on Monday, a surface low will deepen out west and will
begin to push east as southerly flow increases in strength. This
will develop a warm front that will lift north Monday evening and
into Monday night. Instability on the increase will allow for the
potential of a few thunderstorms. There is some uncertainty here
as the instability will be a bit elevated. Thus will go for a
slight chance of thunder and mainly in the Bluegrass for late
Monday night. If this instability is realized better then the
thunder chances will be more prevalent. Will still mention this in
the HWO.
Still a tricky temperature forecast seems to be on tap with a
boundary that will waiver across the area for tonight and
tomorrow with a couple passing waves that will cause the gradient
to shift from north to south and then shift north again Monday
night with the development of the warm front.
.LONG TERM...(Tuesday through Sunday)
Issued at 329 PM EDT SUN APR 1 2018
The models are in fairly good agreement at the start of the forecast
period, but begin to diverge as we move into next weekend. Outside
of Tuesday the long term portion of the forecast will feature below
normal temperatures, with several systems poised to bring repeated
rounds of precipitation to the area.
The forecast period begins with a short wave mid level trough moving
east from the plains and a surface low in eastern KS or western MO
set to move into the Great Lakes Tuesday night. As the surface low
moves northeast a cold front will push southeast, and move across
our area Wednesday night. A significant warm up should occur ahead
of the cold front on Tuesday, with high temperatures in the 70s.
With a tightening pressure gradient and some mixing Tuesday
afternoon wind gusts of 30 mph or more will be possible, especially
in the Lake Cumberland area. Best dynamics still remain to our west,
but there will be enough shear and instability, at least across the
western part of the area that any thunderstorms that develop ahead
or along the cold front could be strong late Tuesday afternoon into
Tuesday evening. The best chance for strong storms remains in the
western part of the forecast area.
After the frontal passage much cooler air will once again spread
into the area, with high temperatures on Wednesday 10 to 15 degrees
below normal. High pressure will build into the area Wednesday night
and set the stage for clearing skies, light winds, with frost and
sub freezing temperatures becoming more likely. Will continue to
highlight the frost threat in the HWO for Wednesday night into
Thursday morning.
With the high shifting east and ample sunshine on Thursday
temperatures will be several degrees warmer than Wednesday, but
still remain below normal. A second cold front will move across the
area late in the week or next weekend, with the GFS showing the
front moving across our region Thursday night into Friday, but the
ECMWF showing the front moving across our area about 24 hours later.
Needless to say confidence in the latter part of the forecast is
low. While there are timing differences the main theme is that there
will be another precipitation chance late in the week and into the
weekend, and a reinforcing shot of cold air for next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 820 PM EDT SUN APR 1 2018
With moisture and pcpn riding east northeast into the area along
a boundary currently lying across eastern Kentucky, VFR
conditions will fall to MVFR and then quickly to IFR from west to
east. Conditions will also deteriorate with respect to visibility
through the bulk of the night in the rain before backing off to
VCSH around dawn. Look for some improvement in cigs later Monday
afternoon. Winds are expected to remain rather light through the
period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...SHALLENBERGER
LONG TERM...SBH
AVIATION...GREIF
Area Forecast Discussion
National Weather Service Memphis TN
855 PM CDT Sun Apr 1 2018
.DISCUSSION...01Z Surface analysis this evening places a cold
front between Savannah, TN back through Northwest Mississippi
south of Tunica. Temperatures north of the front have dropped back
into the 40s with 60s to lower 70s present south across portions
of Northeast Mississippi.
Latest 00Z HRRR and NAM indicate showers should stay mostly north
of the I-40 corridor overnight. Potential for low ceilings, patchy
fog and perhaps some drizzle is anticipated for the remainder of
the night north of the front.
Will make some adjustments to the forecast given current trends.
Updated forecast will be available shortly.
CJC
&&
.PREV DISCUSSION... /issued 611 PM CDT Sun Apr 1 2018/
UPDATE...
Updated to include the 00z aviation discussion.
PREV DISCUSSION... /issued 232 PM CDT Sun Apr 1 2018/
DISCUSSION...
Currently...a wide range of temperatures across the Midsouth with
40s in the far northwest and near 80F in the southeast...the
result of a nearly stalled out cold front near I-40. A few light
showers were tracking east over the area...with elevated
thunderstorms just upstream along the Arkansas and Missouri
border. Winds north of the front were breezy from the northeast
providing for wind chills down near freezing...while south of the
front winds were generally from the southeast.
For tonight through tomorrow. Aforementioned front will get
another push to the south tonight as a shortwave swings through
the Midwest and Ohio valley. With that showers and a few elevated
cracks of thunder will be possible tonight...along with some
patchy drizzle and fog closer to the boundary. Temperatures will
fall into upper 30s north to mid 50s south. By midday tomorrow the
front will start to lift north as the surface flow turns towards
a developing lee-side Low in Colorado. This should in turn
diminish rain chances in the area as well...drying out the I-40
corridor and points south for the evening and overnight hours.
Temperatures will warm back into the 60s and 70s south of the
front...but cooler 50s will hang on across the far north.
Tuesday...models are in good agreement that the surface wave in
Colorado will deepen as it first tracks east across Kansas and
then northeast to the southern Great Lakes. Arriving in the
Chicagoland area with a 991mb central pressure by evening. Strong
south to southwest winds out ahead of the low will likely prompt
the issuance of a wind advisory across a large portion if not all
of the area during the day. Most of the morning appears dry but by
afternoon 850mb winds in the 45-60kt range will aid in the
production of storms along an approaching cold front. Breaks of
sunshine will allow CAPE values to potentially reach 1000-1500
j/kg...while midlevel lapse rates of near 8C stream in from the
west. A few supercells along the line will be capable of damaging
winds...hail of golf ball or larger size...and an isolated
tornado...especially points along and west of the Mississippi
River. Convection will slowly wane in intensity during the evening
hours with the both the loss of instability and better dynamics
shifting into the mid/Upper Ohio Valley. Highs will generally be
in the 70s to near 80F...with lows Tuesday night in the 40s.
Wednesday through Sunday...cooler temperatures this period...with
the coldest of days being Wednesday. Clouds will start off the
day...with clearing expected in the afternoon as high pressure
builds in from the Lower Missouri Valley. This should set the
stage for some freezing overnight lows and areas of frost for
Thursday morning. Highs will climb into the 50s and 60s for
Thursday and Friday. Rain chances will ramp back up late Friday as
well and continue into Saturday. A few elevated storms will be
embedded in the precipitation shield...but unlike Tuesday`s system
the instability axis is progged to slide along the I-20 corridor.
JAB
&&
.AVIATION...
/00z TAFs/
The stalled front has begun moving back to the south again and
will continue through the remainder of the Mid-South through 06z.
Winds will shift from the north in the wake of this front and
flight conditions will deteriorate as ceilings drop to IFR (or
even LIFR in some areas). Patchy drizzle and rain showers are
expected to develop overnight and will reduce visibility at times.
An elevated thunderstorm cannot be ruled out late tonight and
early Monday, but probabilities are low at this time. The surface
boundary will lift back north as a warm front on Monday, shifting
winds back from the south, primarily after 18z. This will result
in improving ceilings and visibility and will reduce rain chances
as well.
Johnson
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service New York NY
1013 PM EDT Sun Apr 1 2018
.SYNOPSIS...
A quick moving low pressure system will pass to the south and
east of Long Island late tonight into Monday. Another frontal
system will impact the area Tuesday into Wednesday, followed by
high pressure passing to the south Thursday and Thursday night.
A cold front will then pass through the area on Friday and stall
over the Mid Atlantic states. Low pressure forming along the
front may impact the area over the weekend.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Mdt to loc hvy snow has been reported across portions on IN
tngt. The fcst is on track. NW winds this evening will usher in
a colder, drier air mass that will help set the table for the
snow event expected to begin late tonight. Precip could briefly
mix with rain right at the onset especially in NYC metro, and
could begin as early as 2-3 AM. Likely-cat PoP looks to hold off
until the very end of the forecast period, and at the start of
the AM commute. Given NYS Mesonet ground temps in the upper 40s
and lower 50s, much of the snow at the onset likely to melt on
roads, and accumulate only on grassy/elevated surface, with
close to an inch possible by daybreak. Temps by daybreak should
be 30-35, warmest in urban NYC metro.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Still some questions as to exactly where bands of highest QPF
will set up on Monday as fast-moving low pressure passes to the
south. GFS/RAP, which were performing well with the position of
banding in the Plains states this afternoon, show this axis
passing just S of NYC/Long Island, while the latest extrapolated
HRRR aims for Long Island, and the NAM/SREF set up more
squarely over the entire area. Taking a blend of these and
accounting for usual southerly model bias with frontogenetically
force banding suggests this axis will skirt NYC and Long
Island, running roughly from RDG-JFK-MTP.
NAM 2m boundary layer temps may be a touch cold and tempered
them with slightly warmer MOS, but the end result per resulting
wet bulb temps still yields a precip type of snow, but with
perhaps slightly lower SLR in urban NYC metro and NE NJ.
Meanwhile, fcst soundings indicate a quick-hitting 3-4 hour
period of moderate to even locally heavy snow possible, with
snowfall rates of as much as 1-2 inches per hour as lift is
maximized in the dendritic snow growth region, while lapse rates
will be neutrally stable, approaching moist adiabatic. Those
snowfall rates should overwhelm the warmer ground temps and
allow snow to accumulate on roads mainly during and just after
the AM commute. When all is said/done, expect 2-4 inch
accumulation along the northernmost portion of the CWA, and 3-5
inches for NYC metro, Long Island, and coastal CT. There is
potential for total accumulation of 6 inches in the higher
elevations of NE NJ west of the Garden State Parkway, perhaps
extending up along the Rockland/Orange border. Total
accumulation on roads likely to be less than the storm total
snow, so previously issued advisories for late tonight into
early Mon afternoon remain in effect.
Snow may briefly mix with rain before ending west to east
during the mid morning to around midday, with plenty of melting
Monday afternoon as temps rise into the 40s. Lows Mon night
will drop into the 30s, and there is a chance for some light
snow NW of NYC and a rain/snow mix in NE NJ late as the next
frontal system approaches.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
The greatest forecast uncertainty comes next weekend with the
amplification of the upper flow, with global models pointing at
an amplifying trough over the eastern third of the country.
There is though still much uncertainty with the details and
whether there is phasing of the two streams.
Before then though, an amplifying southern stream shortwave
trough moves across the mid Mississippi Valley, lifting across
the Great Lakes and into eastern Canada Tuesday through
Thursday. This system will send a deepening surface low across
the same area, sending a warm front across area the Tuesday
night, followed by a strong cold frontal passage Wednesday
afternoon. Overrunning rain will spread across the area during
the day Tuesday with a possible dry slot Tuesday night as the
area enters into the warm sector. A brief period of wintry
precipitation is also possible across the interior Tuesday
morning. On Wednesday, deep-layered shear coupled with marginal
instability and strong frontal forcing will produce a band of
moderate to heavy rain showers right along the cold front. There
is even the possibility of an isolated thunderstorm. Rainfall
totals for the event look to be between one-half to one inch,
barring any strong convection.
Strong gusty winds will likely precede and follow the cold
frontal passage Wednesday with the potential for gusts up to 30
mph. Post-frontal winds could even be stronger should deeper
mixing be realized behind the cold front.
High pressure follows before another frontal system impacts the
area Friday into Saturday. There are differences with the
progression of this front through the area on Friday, with the
GFS the more progressive of the operational solutions. The GGEM
and ECMWF are slower and stall the front farther north across
the Mid Atlantic states on Saturday with frontal wave
development over the Tennessee Valley. The GFS is slower and
farther north with the low track. Once again, its way to early
to be specific with the details, but an inclement weekend is
possible.
As for temperature, it will be a roller coaster ride as a
series of frontal systems impact the area.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Weak high pressure then builds to the north through as low pressure
moves to the Mid-Atlantic coast by Monday morning. This low then
tracks well south of Long Island into early Monday afternoon.
VFR through 06z. Conditions should lower to MVFR through LIFR
in snow from 7-13Z from W to east (first to MVFR KSWF last to
LIFR KGON), then improve to VFR by around midday (early
afternoon eastern terminals) as the snow comes to an end. The
snow may briefly mix with rain at the onset/offset.
Projected Snowfall Accumulations:
KJFK/KLGA/KEWR/KTEB/KISP/KHPN/KBDR: 3-5" on grassy surfaces, up to 1
to locally 2 inches on runways. KSWF/KGON: 2-4", up to 2 inches on
the runway at KSWF and up to 1" on the runway at KGON.
N winds veer to the NE this evening at speeds around 10 kt or
less. Winds should back to the NNE early Monday afternoon.
.OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY...
.Monday night...VFR.
.Tuesday-Wednesday...IFR or lower possible, mainly in rain or rain
showers. LLWS possible Tuesday afternoon-Wednesday morning.
NW winds G15-25+KT possible Wednesday afternoon.
.Wednesday night-Thursday...VFR. NW-W winds G20-30kt possible.
.Thursday night...VFR in the evening then a low chance of MVFR late.
SW-W winds G20-30+KT possible.
.Friday...MVFR or lower possible in any showers. W winds G20-30KT
possible.
&&
.MARINE...
Have pushed back the starting time on the SCA for the ocean
waters. Winds and seas are below criteria at this time and will
likely not come up until Monday morning with a strengthening
northerly flow ahead of low pressure moving off the Mid Atlantic
coast. For Monday, NE-N winds on the ocean will gust up to 25
kt and seas on the outer waters will build to 5-6 ft.
Winds and seas again increase to SCA levels Tuesday night and
Wednesday as a frontal system moves through the waters. Gales
are possible Wednesday afternoon and night. Winds and seas will
be gradually subside on Thursday. Another frontal system will
impact the waters on Friday preceded by a strong SW flow
&&
.HYDROLOGY...
QPF around 1/2 inch (give or take 1/10 of an inch) expected on
Mon, primarily as snow. Snow melt should be fairly rapid, and
then followed by a potential 1/2 to 1 inch of rain with a
frontal system mid week.
&&
.EQUIPMENT...
NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off
the air.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory from 2 AM to 2 PM EDT Monday for
CTZ005>012.
NY...Winter Weather Advisory from 2 AM to 2 PM EDT Monday for
NYZ067>075-078>081-176>179.
NJ...Winter Weather Advisory from 2 AM to 2 PM EDT Monday for
NJZ002-004-006-103>108.
MARINE...Small Craft Advisory from 2 AM to 2 PM EDT Monday for ANZ350-
353-355.
&&
$$
SYNOPSIS...Goodman/DW
NEAR TERM...12/Goodman/DW
SHORT TERM...Goodman
LONG TERM...DW
AVIATION...12
MARINE...Goodman/DW
HYDROLOGY...Goodman/DW
EQUIPMENT...
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Monday)
Issued at 250 PM CDT Sun Apr 1 2018
20Z water vapor imagery showed broad cyclonic flow across the
eastern two thirds of the country. A subtle low amplitude
shortwave was noted within the flow moving along the KS/NEB state
line. Further west, a closed low was propagating southeast along
the British Columbian coast while another area of low pressure
aloft remained nearly stationary off the southern CA coast. At the
surface, high pressure was centered over the mid MO river valley
with the associated cold front across northern AR and into west
TX.
For the late afternoon and tonight, models are in agreement that the
forcing for precip will continue to diminish as the shortwave passes
east of the forecast area. Radar trends already show the back edge
of precip entering northeast KS. The HRRR has been reasonable with
the timing of the precip so think much of the activity will exit to
the east by 6 PM. Will likely be able to cancel some of the advisory
early. The bigger question mark may be with the cloud cover. The RAP
an to some extent the NAM keep low clouds across much of the
forecast area. Because of this have kept overnight lows in the lower
and middle 20s. But if clouds can clear out, lows could end up being
a little cooler.
For Monday the models develop a low level warm air advection pattern
with moisture moving north keeping the low clouds in place across
eastern KS. Additionally some decent isentropic upglide looks
supportive for a chance of drizzle by mid morning and through the
day. Of course with temps below freezing, there could be some light
freezing drizzle during the mid to late morning. At this point, the
saturation and lift look to hold off until just after the morning
rush hour. With surface temps still in the upper 30s and lower 40s,
the main impact from any freezing drizzle would be more likely on
bridges and overpasses. Have lowered highs for Monday anticipating
mostly cloudy to overcast skies over eastern KS. Here forecast
soundings only mix the boundary layer to 900MB. So have highs in the
middle 40s. There looks to be some clearing across north central KS
which should help highs reach the lower 50s. If the clouds mix out
sooner, temps over north central KS could be warmer with 925MB temps
progged to warm to around +10C.
.LONG TERM...(Monday night through Sunday)
Issued at 250 PM CDT Sun Apr 1 2018
While models generally agree in moving a shortwave impulse and
associated surface low over the area in the overnight hours Monday
evening into early Tuesday morning, they continue to vary in the
amount of moisture and available instability that make it into the
forecast area before the low passes. NAM remains strongly capped
and takes most instability to the east, while GFS and EC are
similar with the cap but enough uncertainty to keep some
potential for a storm to get going along then north of the warm
front. Not high confidence in this but if so, hail would be the
hazard and mainly between midnight and 7am. Overnight lows hold in
the upper 30s to lower 40s. Rain showers end west to east through
Tuesday morning as the next cold front sweeps across the area and
leaves highs from around 40 north to lower 50s southeast.
Wednesday and Thursday bring us back into the 50s then 60s for a
short reprieve as warmer southerly flow returns to the area before
the next front comes through later Thursday into Thursday night.
With this will come colder temperatures once again and more
chances for rain or snow, with another wave skimming over the
front and keeping it cool and cloudy with a chance for
precipitation into Saturday. Another break between systems could
bring some recovery in temperatures on Sunday, but overall still a
cool pattern for early April.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 639 PM CDT Sun Apr 1 2018
MVFR cigs are expected to continue through 08Z with a transition
to LIFR cigs as most model guidance suggests. Some mvfr vsbys are
also possible with mist. Conditions are forecast to improve to IFR
for TOP and FOE by 17Z, with MHK improving to MVFR, then to VFR
after 21Z. Winds light to calm will increase to around 10 kts from
the southeast and south after 10Z.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Wolters
LONG TERM...67
AVIATION...53