Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/05/17
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
550 PM MDT Tue Apr 4 2017
.UPDATE...
Updated forecast to cancel winter highlights and decrease 1st period
PoPs/QFP and snow amounts given latest radar and HRRR model trends.
Otherwise, forecast on track.
11
&&
.PREV DISCUSSION...540 PM MDT Tue Apr 4 2017...
.AVIATION...
00Z TAF CYCLE
Aviation impacts tapering off this evening as the upper wave pulls
well east into the Great Plains. A band of -SHRA/SN over the northern
high terrain will dissipate thru 04Z, but not before producing some
brief MVFR cigs/vsby restrictions for KLVS. Otherwise, clearing from
west to east overnight with very dry and cold conditions. A few high
clouds will spread over NM Wednesday with overall light winds.
Guyer
&&
.PREV DISCUSSION...311 PM MDT Tue Apr 4 2017...
.SYNOPSIS...
The Pacific storm system will exit to the east early this evening,
with winds and precipitation gradually diminishing. Areas of snow
will persist early this evening across north central New Mexico,
where a few inches of additional accumulation are possible. A warming
trend will begin Wednesday, with temperatures rising above normal
areawide by Friday. Saturday will be windy, with above normal
temperatures persisting ahead of an approaching Pacific cold front.
Windy to very windy conditions will prevail Sunday both ahead of and
behind the cold front. Temperatures will dip below normal behind the
front briefly before warming back up early next week.
&&
.DISCUSSION...
The upper low is currently pulling east into the Texas Panhandle per
the latest water vapor satellite imagery, with areas of wrap-around
precipitation persisting across north central and eastern New Mexico.
Surface temperatures are currently several degrees above freezing
behind the backdoor portion of the cold front across northeast New
Mexico and precipitation is diminishing there, so will cancel the
winter storm warning for portions of the Northeast Plains/Highlands.
The latest NAM and HRRR develop more precipitation over the
Tusas/Jemez Mountains early this evening and then spread it east
across the Upper Rio Grande Valley into the Sangres, so will hold
onto the winter weather highlights for those zones for now. Will also
cancel portions of the wind advisory and high wind warning given
current observations below thresholds and placement of the backdoor
front. A cold night is on tap, with lows below normal and a number of
lower elevation locales forecast to experience a solid freeze.
A long wave ridge, currently progressing east from the west coast,
will transition across the Intermountain West the next couple of days
and lead to a warming trend that will send temperatures above normal
areawide by Friday. Afternoon breezes will develop by Friday, but
winds will really ramp-up over the weekend as a trough and attendant
Pacific cold front progress east into the Rockies. New Mexico will
remain at the base of the trough, so the main impacts will be wind
and fire weather related. Saturday is looking windy with above normal
temperatures persisting given the timing of the frontal passage
sometime Sunday. Very windy conditions are likely Sunday both ahead
of and behind the cold front. Look for cooling behind the front to
send temperatures below normal briefly, prior to a warm-up early next
week.
11
&&
.FIRE WEATHER...
The upper low which brought widespread rain and snow to much of New
Mexico today is lifting east-northeast into the Texas panhandle this
afternoon. Strong northwest and north winds on the backside of the
low will subside early this evening. Drier and warmer condtions
remain on track for Wednesday as dry northwest flow aloft moves
overhead. High temperatures will remain around 5 to 10 degrees
below average levels for the date.
Models remain in very good agreement for Thursday and Friday. An
upper level ridge moves overhead Thursday, then shift east of the
region Friday. West and southwest winds increase Friday afternoon.
Models continue to bring up a weak subtropical wave from the
southwest Thursday night and Friday. This feature is expected to
result in an increase in mid and high clouds and not much else.
Winds increase further over the weekend with an upper level
trough/closed low moving eastward through the northern and central
Rockies. A few showers may graze the northern mountains but
increasing wind expected to be the main impact. Areas of critical
fire weather conditions will likely develop across much of the area
primarily Sunday afternoon.
Ventilation rates increase markedly Friday, remaining very good to
excellent through the weekend.
33
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
11
Area Forecast Discussion
National Weather Service Caribou ME
937 PM EDT Tue Apr 4 2017
.SYNOPSIS...
Low pressure will track south of the Gulf of Maine tonight. The
low will continue east into the open Atlantic on Wednesday. Weak
high pressure builds Wednesday into early Thursday. An occluded
front will cross the region Thursday night.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
930 PM Update. Updated POP and WX grids to reflect current and
expected conditions, used HRRR which seems to have a good handle
on current conditions. Minor adjustments to HRLY temps.
.Previous discussion...
A very complex situation unfolds this evening and tonight. A
weakening shortwave is crossing the state now with some rain and
snow. This shortwave is weakening as it moves into a blocking
upper ridge over Eastern Canada. A somewhat vigorous and compact
upper low that is sparking some thunderstorm activity will move
out of upstate New York towards the Gulf of Maine later
tonight. Cyclogenesis will occur ahead of this upper low off
Cape Cod. This new surface low will move under the blocking
upper ridge towards a position south of Nova Scotia by Wednesday
morning. Meanwhile the original low pressure system in Ontario
will drift into Quebec and fill as it moves into the blocking
ridge. The net result is that all of the energy in this pattern
will be with the developing offshore low. The heaviest
precipitation with this low will be southwest of the forecast
area this evening, but affect an axis from southern Piscataquis
County southeastward towards the Bangor area and Hancock County
after midnight. By this time, boundary layer temperatures will
have cooled towards the freezing mark and precipitation should
be all snow. In terms of snowfall, these areas could see as much
as 2 to 4 inches of snow after midnight into early Wednesday
morning when the axis pulls out. Will have to closely monitor
the situation for a possible expansion of current winter weather
advisories. Elsewhere, the influence of the blocking high has
led to a reduction in snowfall forecasts along the eastern
border of the state where an inch or less will fall by Wednesday
morning. The low will slide away by Wednesday morning and
strong subsidence is expected to keep low clouds in the forecast
area through the day. Northern zones may see a few light rain
and snow showers as the remnants of the upper trough moving up
the blocking ridge crosses. The cloud cover will limit
Wednesday`s highs to the upper 30s to near 40F.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
Any lingering showers quickly dissipate Wed night, but
increasing POPs expected across the CWA from 12z Thu onward as
the next system pushes into the region. The 12z CMC shows a weak
sfc low moving west across the Gulf of Maine and getting
absorbed into the larger system Thu, bringing precip to the
southern CWA before 12z. However, this appears to be an anomaly
and was largely discounted. The short term POPs were mostly a
blend of the GFS, NAM, and ECMWF, all of which show a roughly
similar evolution of the system and track of the sfc low. This
sfc low actually looks to hang back over NY or Lake Ontario,
while the occlusion triple point moves over Maine. Wx grids are
a bit messy Thu night into Fri, as there are hints across a
couple models that some warm air may overrun a subfreezing layer
at or just above the sfc. This could allow for some sleet or
even freezing rain at times before the entire lower part of the
column gets above freezing during the day Fri. Highs will be
near to below normal for Thu, and near normal Fri. Winds will be
E-SE Wed night into Thu night, turning more SE-S Fri as the
triple point lifts north of the CWA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Rain and snow showers will likely linger over the area Fri night
into Sat as the sfc trough that had been hanging back over NY
and southern Quebec finally swings across the area, concurrent
with the passage of the upr trof. Once these features pass
between 18z Sat and 00z Sun, POPs drop off significantly, and
dry weather with party to mostly clear skies are expected Sun
and Mon. There are hints that some weak sfc feature may bring
some precip to the CWA between Mon night and Tue night, but
models don`t show very strong upper level support, so POPs were
kept under 50 pct for now.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
NEAR TERM: A brief period of IFR is possible in snow north of
HUL this evening and tonight, but it will be VFR otherwise.
For southern sites such as BHB and BGR, conditions will
deteriorate to IFR this evening in snow and become LIFR for a
period of several hours late tonight. The snow will end towards
daybreak and conditions will improve to MVFR cigs at these
sites.
SHORT TERM: Wld expect VFR vsbys for all terminals Wed night
and Thu AM, but some lingering low-lvl moisture could keep some
patchy MVFR or IFR CIGs across the region during that time. CIGs
and vsbys both drop to widespread IFR and patchy LIFR Thu PM
thru Fri AM as the next system moves thru, with mostly rain for
Downeast, while KHUL to KFVE could have mix with or change to
snow Thu night. Lingering MVFR to IFR conditions possible for
KHUL northward on Sat, with MVFR or VFR more likely down south.
All sites should clear to VFR Sat night into Sun.
&&
.MARINE...
NEAR TERM: Have held to a strong SCA tonight with a few gusts to
35 kts referenced rather than an upgrade to a gale warning. Did
extend the SCA another three hours to 2pm Wednesday as winds
will take longer to decrease.
SHORT TERM: Gentle E-SE`ly winds and seas under 5 ft expected
Wed night into Thu, before winds and seas both increase above
SCA criteria lvls Thu aftn and night. Winds lkly to drop below
criteria by Fri AM, but seas could remain elevated into Fri eve.
&&
.HYDROLOGY...
Currently, NOHRSC maps show 10-20 inches of snow depth and SWE
of 3-6 inches for parts of southern Piscataquis and central
Penobscot. This area could also receive around an inch of rain
Thu PM into Fri AM. Today`s river survey covered rivers in this
area, and reports that the Piscataquis was largely ice free up
to Milo. Thus, it does not appear that ice jam flooding is a
major threat for this region. However, across the Northern Maine
rivers, the ice jam flooding threat still remains above normal.
If the QPF forecast increases, the snowmelt/runoff combination
could cause issues on rivers and streams.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory until 8 AM EDT Wednesday for MEZ003-
004-010-031.
MARINE...Small Craft Advisory until 2 PM EDT Wednesday for ANZ050>052.
&&
$$
Near Term...Norton
Short Term...Kredensor
Long Term...Kredensor
Aviation...Norton/Kredensor
Marine...Norton/Kredensor
Hydrology...Hewitt
Area Forecast Discussion
National Weather Service Dodge City KS
600 PM CDT Tue Apr 4 2017
...Updated Aviation...
.SHORT TERM...(This evening through Wednesday)
Issued at 324 PM CDT Tue Apr 4 2017
More numerous shower activity redevelopment appearing in the
developing warm sector across western Oklahoma, disjointed from the
more mid level frontogentic forcing across the panhandles. The
WRF/NMM/ARW show the advection of these rain showers northward with
the mean flow, as well as additional frontogentically forced rains
(if temperatures are maintained above freezing) moving through the
bulk of the CWA through roughly mid-evening. In the far southwest a
winter weather advisory for snow has been issued where at least an
inch has already fallen near Elkhart impacting roads as seen in KDOT
cams and at least a couple of more hours of precipitation will
continue through late afternoon. We will need to monitor the
temperature trends immediately to the north to determine if
additional areas will see snow accumulation, however the models
themselves were far overdoing the snow amounts, with unverified
significant snow accumulations already at 21z this afternoon. At
that point the forcing should begin weakening dramatically across
central Kansas, as winds turn more northwesterly with time. The
lower clouds will become scoured out after midnight, allowing for
decent radiational cooling towards 12Z Wednesday. Looking ahead,
no true cold advection develops even tomorrow under the northwest
surface winds, so models bring highs in the afternoon to near 60s
degrees in the lower plains.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 324 PM CDT Tue Apr 4 2017
A gradual warming trend is expected through the middle of the
weekend with dry weather at least through the end of the week.
Temperatures by Saturday afternoon will reach the 80s. Another
synoptic wave will bring a regime change at least in wind pattern
by Sunday or Monday, with low confidence of precipitation chances
at this time.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 600 PM CDT Tue Apr 4 2017
Poor flying weather will continue through about 06z, with
widespread moderate rain and IFR cigs/vis. Some minor wet snow
accumulations will continue on grassy surfaces at LBL. Forcing
for precipitation will end rapidly tonight, with HRRR model
showing rainfall become light and showery by 06z, and ending
completely by 09z Wed. After 15z Wed, VFR/SKC expected at all
airports. N/NW winds will remain gusty and elevated overnight, and
increase further after 15z behind the departing storm system. NW
wind gusts near 35 kts can be expected after 15z.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 36 57 33 63 / 90 0 0 0
GCK 33 58 31 63 / 80 0 0 0
EHA 29 55 32 63 / 40 0 0 0
LBL 33 56 31 64 / 60 0 0 0
HYS 39 57 33 61 / 80 10 0 0
P28 42 60 34 64 / 80 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 PM CDT this evening for KSZ084-
085.
&&
$$
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...Turner
Area Forecast Discussion
National Weather Service Wilmington NC
943 PM EDT Tue Apr 4 2017
.SYNOPSIS...
Broad high pressure off the coast will maintain seasonable
warmth through Wednesday night. The approach of a strong upper
level system will bring strong to severe thunderstorms late
Wednesday into early Thursday followed by cooler and drier air
as Thursday progresses. The late week and weekend will remain
sunny and dry but cooler than normal.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 930 PM Tuesday...Breezy southwest winds have died away
leaving a very pleasant evening across the eastern Carolinas.
Clear skies should continue overnight with lows dipping into the
upper 50s inland and lower 60s near the coast. This is virtually
unchanged from the previous forecast. Where surface dewpoints
are highest (along the coast) there continues to be the
potential of low stratus or perhaps some patchy fog late
tonight, mainly after 4-5 AM. Models show this moist layer
literally only extends upward 300-500 feet before significant
drying occurs aloft. This is probably too shallow for a
widespread fog/low stratus event.
Enjoy this calm before the storm. The discussion I`ll be writing
24 hours from now will look at a lot different!
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
As of 330 PM Tuesday...A multi-round severe weather event likely
underway by Wednesday night. Early in the period the forecast is
complicated by the surface low developing on the warm front as
depicted by the WRF. Conversely the absence of this feature makes
the warm front hard to pinpoint locally in other guidance-it appears
to be well north of here. Either solution should favor fairly
widespread storms early Wednesday night with the latter solutions
favoring mixed severe weather mode whereas the WRF solution could
favor an elevated tornado risk. Through the second half of the night
all severe weather modes will be favored again, with wind and
tornadoes likely eclipsing hail threat. Wind shear profiles are
forecast to remain favorable and adequate for supercells and
hodographs show some disconcerting maxima of SRH values of 300-400
m^2/s^2 mostly in the lowest 1 km, all in the presence of at least
1000 J/Kg of 0-6 kilometer CAPE. GFS forecasts are not quite as
dramatic especially with respect to the instability but given the
expected windy and warm nature of the warm sector I`d put more stock
in the WRF. With the mid level forcing strong as the trough goes
negatively tilted coupled with the left exit of the upper jet moving
overhead we should manage to wring out any and all available
instability.
Thursday morning could bring one last round of storms, especially
along the NC coast. The directional shear will have abated but
instability maybe not so much. The final and strongest vort max
rotates through keeping wind fields very strong and a linear squall
line still seems possible especially in areas not overturned by the
prior deep convection. These strong wind fields remain Thursday
afternoon in the cool and dry advection regime and the afternoon
will be quite windy especially as sunshine returns. Too early to
think much about a Wind Advisory but certainly would not rule one
out at this point.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 330 AM Tuesday...The closed low over the Eastern Great
Lakes early Friday will migrate across the Northeast States Fri
into Sat...and will fully open up into a mid-level s/w trof as
it further moves away from the lower 48 states by late in the
weekend. The FA will be under cyclonic flow sfc thru aloft with
850mb temps hovering around the 0 degree C line Fri, Sat and
partially into Sun. As a result, expect max/min temperatures to
run up to 10 degrees F below the climatological norms for this
time of the year. For the most part, it will remain dry with
more clouds across the north portions of the ILM CWA then the
south Fri into Sat. Isolated showers are possible across north
portions of the FA due to s/w mid-level trofs or vorts rotating
around the expansive closed low aloft. By Sun and into Mon,
ridging aloft becomes the dominant upper feature with moderating
temperatures at the sfc. Winds will stay active Fri into Sun
with a progged sfc high to migrate to the FA on Mon further
dropping the winds.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 00Z...VFR conditions should prevail through 09Z as
gusty southwest winds along the coast subside with the loss of
daytime heating. The latest NAM and RAP models suggest a small
area of thin stratus clouds with bases as low as 300 feet AGL
could develop along the coast early Wednesday morning between
09Z-13Z. The probability of this occurring is 50-60% for the
coastal airports, but only 20-30% farther inland for Florence
and Lumberton.
After daybreak, increasing mid-level clouds between 16-18Z will
herald increasing deep moisture which should allow the
development of showers and t-storms later in the afternoon.
Models suggest this will be the first wave of a significant
weather system that will continue well into Wednesday night.
Extended outlook...MVFR/IFR conditions are likely in convection
Wed night into early Thursday morning ahead of a strong cold
front. Strong westerly winds Thursday could gust to 35-45 knots.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 930 PM Tuesday...The strongest of the winds driven by this
afternoon`s seabreeze have died away. Within the past hour wind
gusts have been recorded at 17 knots at Wrightsville Beach, 21
knots in downtown Southport, and 19 knots at the buoy 5 miles
southeast of Wrightsville Beach. Wind speeds should continue to
gradually diminish overnight, and the Small Craft Advisory has
been cancelled a little early for the South Carolina coastal
waters. As seas drop below 6 feet late this evening the advisory
should be allowed to expire on schedule for the NC waters.
SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
As of 330 PM Tuesday...Conditions will deteriorate rapidly
Wednesday night as an approaching upper trough pushes a surface
cold front into the Carolinas. As this happens the wind field
will strengthen dramatically through a deep layer including at
the surface. Some SST/airmass stability issues that are tough to
resolve this far out in time will likely dictate whether we end
up with a strong SCA or a Gale Warning. Gale force gusts
certainly seem likely. Frontal passage comes Thursday morning
with little to no easing of the gradient so the sharp windshift
will steep wave faces and further enhance the environmental
treacherousness. In the cold advection regime Thursday night the
deepening mixing will offset any slight decrease in gradient
and we will likely remain near thresholds of Gale Warning vs
Small Craft Advisory.
LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 330 AM Tuesday...Expansive and very mature low sfc thru
aloft will be centered over the Eastern Great Lakes at the start
of this period. The sfc pg will remain tightened all the way
down the Eastern Seaboard to Florida. As a result, W to WNW
offshore winds at SCA levels will be ongoing when the long term
commences. Models push a sfc trof across the local waters Fri
night resulting in a slight veering of the winds to NW
direction. Wind speeds will initially remain at SCA levels but
do expect them to drop below SCA thresholds during Sat. As the
sfc high moves closer to the area waters late Sat into Sun,
winds will further drop along with significant seas. With an
offshore wind thruout this period, will observe a decent range
of seas due to a non-existent long period ground swell. The
Cape Fear to Little River Inlet zone will have seas higher than
the surrounding marine zones due to a westerly wind direction
that is parallel to the coastline, for a good portion of this
period. Seas will peak at the start of this period.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory until 11 PM EDT this evening for AMZ250-
252.
&&
$$
SYNOPSIS...MBB
NEAR TERM...TRA
SHORT TERM...MBB
LONG TERM...DCH
AVIATION...TRA
MARINE...
Area Forecast Discussion
National Weather Service Lincoln IL
853 PM CDT Tue Apr 4 2017
.UPDATE...
Issued at 853 PM CDT Tue Apr 4 2017
01z/8pm surface analysis shows a 998mb low over northeast
Oklahoma, with a warm front extending eastward into the Ozarks.
Further north, a weak bubble of high pressure is noted over
southern Lake Michigan, which is keeping a dry northeasterly flow
in place across central Illinois this evening. Radar is
indicating a band of light precip associated with warm advection
aloft: however, a distinct dry layer below 650mb as evidenced by
the 00z KILX CWA is preventing measurable precip from reaching the
ground. Updated the forecast earlier to include scattered
sprinkles with this band. Meanwhile further west, widespread
showers and thunderstorms are tracking across western and central
Missouri in advance of the low. Based on radar trends and the
latest HRRR data, it appears this precipitation will remain
largely W/SW of the KILX CWA until after midnight. Have adjusted
rain chances accordingly, to feature likely to categorical PoPs
across the western half of the CWA overnight. Convection will be
weakening as it pushes into the more stable airmass over Illinois,
so will only mention chance of thunderstorms late tonight.
&&
.SHORT TERM...(This evening through Wednesday)
ISSUED AT 230 PM CDT Tue Apr 4 2017
Main concern this forecast period will be the track of
deepening surface low and severe threat tomorrow afternoon
over parts of east central through southeast Illinois.
Impressive upper wave seen on satellite data over the Texas
Panhandle and is forecast to track north and east with a
northern stream wave eventually dropping into the Northern
Plains late tonight into Wednesday which will help deepen
not only the upper trof but also the surface low, which models
continue to track along or just north of the I-70 corridor.
Showers and elevated thunderstorms will start to push into our
west later this evening and over most of the remainder of the area
overnight with our far eastern and southeastern counties holding
off much in the way of rain chances until closer to dawn on
Wednesday. A few of the storms pushing into west central Illinois
late tonight may pose a risk for some hail, but most high
resolution models suggest a weakening trend as they push east of
the Mississippi River late tonight.
There may be a break in the thunderstorm activity over south
central and southeast Illinois late tomorrow morning into the
afternoon hours before the scattered cells develop in the highly
sheared and unstable atmosphere to the east and south of the low
track. Latest high resolution convective allowing models continue
to develop discrete supercells along and just south of the surface
low track and the those will race east-northeast into Indiana after
21z. Forecast soundings and instability parameters suggest the
initial storm mode will feature discrete supercells with the threat
for large hail, damaging wind gusts and a few tornadoes, especially
along and east of the surface low and warm front, before the storms
start to congeal more into a line and race east of our area by late
afternoon. To the north of the low track, not a very pleasant day
with frequent showers and isolated thunderstorms and an increasing
east to northeast wind. As you would expect with such a dynamic
storm, a large temperature gradient is expected across the area
Wednesday afternoon with 70s possible over far southeast Illinois,
while over our far northern counties, the mercury will struggle
to get to 40 degrees.
.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 230 PM CDT Tue Apr 4 2017
Forecast challenge, at least with the start of this forecast
period, will be the threat for some wet snow across the north
Wednesday night into Thursday morning as the deep surface low
tracks off to our northeast, and that will be coupled with
strong northerly winds will gust up to 40 mph Wednesday night
into Thursday. Forecast soundings for Wednesday night into
early Thursday continue to exhibit rather warm boundary layer
temperatures, plus with the fact soil temperatures are on the
warm side should hold down any accumulations across the north.
However, some impressive dynamic cooling expected with the
deepening upper system coupled with strong lift in the dendritic
zone (shown on the NAM-WRF soundings) for several hours later
tomorrow evening is a concern for the potential for a few inches
of wet snow across our north. For now, with the majority of the
forecast soundings still too warm to support a full changeover to
snow, will continue to follow the more conservative guidance which
suggests less than an inch.
Winds are expected to be rather brisk on Thursday as the low
departs but the chill will remain as the coldest mornings look
to be on Friday morning with several sites across our north
dropping a few degrees below freezing so some frost headlines
will probably be needed for that time frame, if not also for
parts of east central Illinois early Saturday morning as the
surface ridge edges slowly off to our east. For Saturday
afternoon and beyond, a nice recovery in temperatures will occur
with an increasing southerly flow which should result in afternoon
temperatures in the mid to upper 60s Saturday, and in the 70s for
Sunday and Monday as our next storm system/frontal boundary
approaches increasing the chances for showers and storms again
Sunday night and Monday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 651 PM CDT Tue Apr 4 2017
VFR conditions will prevail at the central Illinois terminals
through the evening before lower clouds and showers arrive after
midnight. Latest radar mosaic shows widespread convection across
eastern Kansas/western Missouri in advance of a deep upper low.
This activity will track northeastward and weaken as it comes into
the area later tonight. Based on radar trends and latest HRRR/18z
NAM data, have delayed the onset of MVFR ceilings and showers
until 09z at both KPIA/KSPI...with precip spreading further east
to KCMI by 11z. Once this initial band of showers/thunder passes
through late tonight into early Wednesday morning, it appears a
lull in the steady precip will develop...so have gone with just
VCTS at the TAF sites after the 15-17z time frame. Have maintained
MVFR ceilings through the period until low pressure tracks along
I-70 into Indiana and winds veer to the N/NE by late Wednesday
afternoon and evening. At that time, IFR ceilings and showers will
spill into central Illinois from the north.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Barnes
SHORT TERM...Smith
LONG TERM...Smith
AVIATION...Barnes
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
920 PM CDT Tue Apr 4 2017
.UPDATE...
920 PM CDT
For Evening Update...
Only adjustment made to going forecast this evening was to slow
northeastward advance of higher pops overnight per suite of high-
res guidance solutions. Otherwise, only tweaks made to hourly
temps based on observational trends.
Evening raob data and GOES-R water vapor imagery depicts strong
mid-level wrapping up across Kansas-Oklahoma. Guidance in good
agreement in continuing to deepen this system as it lifts toward
the forecast area through Wednesday. Strong warm air/theta-E
advection developing into the lower Missouri Valley this evening
will spread northeast into IL/IN by morning, with rain developing
into the area in the hours after midnight. While some elevated
light radar returns and spotty light rain at the surface has
developed into parts of west central IL at mid-evening, increasing
easterly low level flow north of the warm front across our
forecast area looks to work against this precip lifting up too
quickly this evening, and various high-res model guidance focuses
better northeastward surge of precip after midnight. Based on this
and particularly successive runs of the HRRR, have slowed the
arrival of higher pops especially far north/northeast a bit from
previous forecast. Still, most of the area should see rain by
sunrise Wednesday morning.
No changes made into Wednesday at this point, with no 00Z model
data available yet. Some of the high-res, short term guidance is
running a little warmer with surface temps into north central IL
than some of the synoptic scale models and our forecast, though
the 18Z 4km WRF does maintain colder mid-30`s readings across
northwest IL/southern WI during the day. Certainly potential for
strong dynamic cooling is cause for not making changes at this
time. Gusty northeast winds, precipitation and chilly conditions
will make for a pretty unpleasant day in any case.
Updated digital grids/text products available.
Ratzer
&&
.SHORT TERM...
335 PM CDT
Through Thursday...
A significant and very dynamic storm system will impact the
region late tonight through Thursday. This is a very complex
forecast, with numerous forecast concerns, which include:
1.) Good threat for locally heavy rainfall amounts of 1-2 inches,
which will likely lead to additional rises on area rivers.
2.) Potential for Rain mixing with or changing to moderate to
heavy snow over far northern Illinois on Wednesday, with snow
possible over Northeastern Illinois and portions of northwestern
Indiana Wednesday night with accumulations possible.
3.) Strong damaging winds Wednesday night and Thursday, especially
for areas along the lake shores. 4.) Coastal flooding along the
lakeshore with 14+ foot waves likely By Thursday morning.
Our storm system is already taking shape over the Texas panhandle
early this afternoon. Model and ensemble forecast guidance
continues to be in good agreement in tracking this surface low
east-northeastward near KSTL by midday Wednesday, then over
central portions of Indiana by Wednesday evening. This is
typically a track very favorable for an accumulating snow event
over northern Illinois. The main issue however, is the fact that
this southern stream storm system does not have any cold air to
work with. Therefore, in order for conditions to become favorable
for snow, the storm system will have to dynamically produce its
own cold air. Given the strength of this storm, this is certainly
feasible, and I wonder if some of the global guidance is have
trouble handling the cooling potential of the boundary layer
Wednesday night.
Its likely that as the precipitation shifts begins to develop
over the area late tonight into early Wednesday morning that it
will be in the form of rain. A band of strong frontogenesis is
expected to develop over northern Illinois Wednesday morning, in
response to the approach of the storm system. The strong
ageostrophic response associated with this frontogenesis is
likely to result in very strong forcing for ascent. So, while
instability is rather lack luster, the presence of steep mid-
level lapse rates could support some thunderstorms and a period of
moderate to heavy rain during the morning.
The other concern is for a change over the heavy wet snow,
especially over far northern Illinois. Forecast soundings indicate
that the lower level thermal profile will become marginal for
snow potential. However, with the potential for mesoscale
convective precipitation, the dynamical ascent could result in
enough cooling to result in some wet snow during the morning on
Wednesday. It appears at this time the main threat of this would
be along and north of I88 in north central Illinois. If this
change over to snow occurs, there could be a few hour period
favorable for some heavy wet snow, with some slushy accumulations
possible over far north central Illinois.
A slightly better chance for a change over to snow looks to occur
early Wednesday evening over northern Illinois as the mid-level
system closes off over the area. The mid-level deformation band is
likely to set up over northeastern Illinois and northwestern
Indiana during this time, so addition bands of moderate to heavy
rain/snow will be possible. Accumulation potential is very tricky
given marginal surface temperatures and a warm ground. Overall,
at this point it appears that up to 1 to 3 inches of wet slushy
snow could occur, mainly on grassy surfaces, over portions of
northern Illinois into northwestern Indiana. With this being
said, the possibly for some higher amounts is not zero, especially
if convective heavy snow occurs. As a result, confidence on snow
amounts is low.
Some lighter rain and/or snow looks to continue over eastern
Illinois and northwestern Indiana into Thursday as rap around
precipitation continues to feed southwestward into the area.
However, it appears that much of this precipitation may become
light enough to result in little chance of accumulations during
the day Thursday. Expect the precip to end from west to east
during the afternoon on Thursday.
Overall, snow accumulation potential with this system will be
tricky as surface temperatures will be marginal for accumulating
snow, and ground temps will be warm. As a result, it will take
some heavy snow rates to result in any accumulations of snow,
mainly on grassy and elevated surfaces. Some periods of heavier
precipitation is definitely possible with this dynamic system, so
at least some wet snow accumulations will be possible over
portions of far northern Illinois.
The other concern, with this storm system continues to be the
winds, particularly Wednesday night and Thursday as the surface
low shifts towards New England. Strong damaging northerly winds
are looking more and more likely, especially near the lake shore
areas, where 60+ MPH wind gusts will blow in off of Lake
Michigan. As a result of this potential, we have put out a high
wind watch for the lake shore counties. Counties farther inland
will also experience strong winds during this period, but
magnitudes may remain in the 45 to 50 mph range. Therefore, a
wind advisory will likely be needed for the inland areas as we get
closer to the event.
These strong winds are expected to produce 14+ foot waves, which
will be crashing into the southern Lake Michigan shores Wednesday
night and on Thursday. This may result in some impactful lake
shore flooding and erosion. In spite of this, we have opted to
hold off on upgrading to a warning at this time.
KJB
&&
.LONG TERM...
341 PM CDT
Friday through Tuesday...
Once the major storm system shifts out of the area, a surface
ridge of high pressure will shift over the area by late Friday.
This will result in lighter winds for a period late in the week. A
few days of dry weather are also likely Friday through the
weekend before the next storm system approaches the Upper Mid-
West. Southerly winds will develop over the area this weekend
allowing a much warmer airmass to shift northward over the area.
Therefore, temperatures are expected to warm significantly this
weekend, with 60s and possibly some low 70s possible. Shower and
thunderstorm chances return to the area by Monday as another cold
front approaches the area.
KJB
&&
.AVIATION...
For the 00Z TAFs...
Low pressure, currently centered near Oklahoma City, will lift
across Missouri tonight and eventually reach central Indiana
Wednesday evening. Fairly steady state conditions are expected the
rest of this evening and much of the overnight hours with
northeast flow and primarily VFR conditions. Stratus persists
across the region early this evening between 035-045 but is
expected to clear the northern terminals (RFD, DPA, ORD) by around
01Z then MDW and GYY within the next hour or so leaving mid and
high clouds in place for the remainder of the evening into the
overnight hours. As the low lifts into central Missouri during the
predawn hours Wednesday, clouds will gradually build down with
precipitation, initially virga, eventually reaching the surface
around daybreak. Ceilings will drop back to IFR by mid to late
morning. Rain is then expected to continue off and on, heavy at
times, throughout the day. Late tomorrow evening, winds will begin
to back to the north allowing colder air to filter into the
region allowing a transition to a wintry mix and eventually snow.
Accumulations may be possible near the very end of the 30 hr ORD
TAF, but seem more likely just beyond the current TAF period.
Slushy light accumulations should primarily be limited to grassy
and elevated surfaces, but will have to monitor pavement temps and
snow rates closely.
Meanwhile, tightening pressure gradient will result in
increasingly gusty winds early tomorrow morning through the
afternoon, eventually peaking with gusts into the low to mid 30 kt
range during the afternoon. Northeast winds much of the day will
gradually back towards the north tomorrow evening. Winds just off
the deck increase into the high 50kt range near the end of the 30
hr ORD TAF, and further increase to over 60KT just beyond the TAF
period which could produce low level wind shear.
BMD
&&
.MARINE...
209 PM CDT
A strong system will impact the Great Lakes beginning
Wednesday and continuing into Friday. Expect an extended period of
gale force winds with an embedded period of storm force winds. The
peak winds expected late Wednesday night into Thursday.
A strong low pressure system over the southern plains will
strengthen as it moves to south of Lake Michigan Wednesday night
into Thursday. Expect northeast gales as early as Wednesday later
afternoon. The low will move into northwest Indiana late Wednesday
night into Thursday, which will shift winds to northerly. This will
also be the period where storm force winds are most likely. Expect a
rapid buildup of waves across southern Lake Michigan, approaching
20 ft. Expect gale warnings and storm warnings to be issued.
This low will strengthen further as it moves to the eastern Great
Lakes, and therefore gales will likely continue through at least
midday Friday. High pressure will bring some relief later Friday
into early Saturday, with winds shifting back to southerly for the
weekend.
KMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...High Wind Watch...ILZ006-ILZ014...1 AM Thursday to 4 PM Thursday.
Lakeshore Flood Watch...ILZ014...4 AM Thursday to 1 AM Friday.
IN...High Wind Watch...INZ001-INZ002...1 AM Thursday to 7 PM Thursday.
Lakeshore Flood Watch...INZ001-INZ002...4 AM Thursday to 1 AM
Friday.
LM...Gale Warning...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...3 PM
Wednesday to 4 AM Thursday.
Storm Warning...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
LMZ779...4 AM Thursday to 7 PM Thursday.
Gale Watch...LMZ743-LMZ744-LMZ745-LMZ777-LMZ779...7 PM Thursday
to 3 PM Friday.
Gale Warning...LMZ777-LMZ779...4 PM Wednesday to 4 AM Thursday.
&&
$$
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Area Forecast Discussion
National Weather Service Melbourne FL
939 PM EDT Tue Apr 4 2017
.UPDATE...
Band of higher moisture that slipped down into our northern areas
was starting to lift back to the north. This, combined with loss of
daytime heating, has led to a decrease of convection across east
central Florida. Some lingering light rain was occurring in the far
north and will continue to diminish/lift north. A few lingering
boundaries have been generating isolated showers/storms around Lake
Okeechobee, but this should dissipate before midnight.
Considerable mid-high level debris cloudiness should gradually lift
north and allow skies to become partly cloudy in the north while the
south looks mostly clear late tonight. With areas of rain wetting
that occurred today, am a bit concerned about patchy dense fog, but
the GFS shows southerly boundary layer flow 10-15 knots. The HRRR
and local WRF show a few patches of low visibility, but not
confident enough to add fog to the forecast.
Temperatures will again be mild overnight with lows in the upper
60s to lower 70s.
Wednesday...Strong trough digging into the deep south and the
associated deepening surface low in the mid section of the country
will swing a cold front through north Florida late in the day. We
will be in the warm sector with southerly winds causing temps to
soar into the 90s. Some record highs are possible (see below)
The front should approach east central Florida late Wed night with a
pre-frontal band of convection ahead of it. Atmospheric wind
fields will be quite strong but the models show frontal convergence
weakening and are not very bullish on POPs Wed night. A few strong
storms look possible though.
&&
.AVIATION...
Mainly VFR into Wednesday. With rain wetting and diminishing
clouds overnight, will have to watch for some stratus and/or patchy
fog. The GFS shows boundary layer winds 10-15 knots, so would lean
towards low stratus, but have not included in the TAFs yet. The
atmosphere will be more stable on Wed, so we are not forecasting
afternoon storms. Breezy southerly flow 15-20 knots will affect
most terminals by afternoon, while a sea breeze may kick in from
about KVRB-KSUA and produce gusts to around 25 knots.
&&
.MARINE...
Tonight-Wed...The pressure gradient has eased some, but on Wed
the gradient will start to tighten as a cold front approaches
the eastern Gulf of Mexico. The morning looks to have southerly
winds 10-15 knots and then by afternoon speeds should pick up to 15-
20 knots. More gusty conditions to around 25 knots are expected
along the coast, especially the Treasure coast as a sea breeze forms.
&&
.CLIMATE...
Current warm temperature records for April 4th and 5th:
LOC DATE HI-MAX HI-MIN
DAB 4-Apr 93 1974 70 1991
MCO 4-Apr 93 1918 69 1974
MLB 4-Apr 92 1977 71 1974
VRB 4-Apr 92 2012 73 1960
DAB 5-Apr 90 1957 70 1954
MCO 5-Apr 91 1999 68 1957
MLB 5-Apr 91 1977 72 1957
VRB 5-Apr 90 1977 73 1957
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 69 90 68 79 / 20 10 50 30
MCO 69 92 69 79 / 20 10 40 30
MLB 71 90 71 83 / 10 10 30 30
VRB 71 89 70 84 / 10 10 30 30
LEE 70 92 68 77 / 20 10 50 30
SFB 70 93 68 79 / 20 10 40 30
ORL 71 92 70 79 / 20 10 40 30
FPR 70 89 69 85 / 10 10 20 30
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Forecasts...Lascody
Impact Wx...Blottman
Area Forecast Discussion
National Weather Service Marquette MI
740 PM EDT Tue Apr 4 2017
.SHORT TERM...(This evening through Wednesday)
Issued at 357 PM EDT TUE APR 4 2017
Water vapor imagery and RAP analysis show a continued active
southern stream with one batch of shortwave energy lifting ene
across the Lower Great Lakes region and a second vigorous wave
moving out of the southern Rockies. To the n, a mid-level low was
over southern Hudson Bay. At the sfc, low pres associated with Great
Lakes shortwave was over southern Ontario while upstream wave was
suporting low pres over the southern Plains. Another low was over
southern Hudson Bay. Northerly gradient wind btwn the low over
southern Ontario and high pres over Manitoba was bringing drier air
into Upper MI. In fact, in the last hr or so, sfc dwpts have fallen
well down into the 20s over portions of western Upper MI. As a
result, low clouds and some fog that dominated early in the day have
cleared out steadily from nw to se, leaving behind thinning high
clouds. Under a brisk northerly wind, temps currently range from
around 40F near Lake Superior to well into the 50s s central.
Expect a quiet night tonight with fcst soundings showing dry low to
mid levels beneath lingering high level moisture/ci cloudiness.
Diminishing gradient wind will allow for a cool night with some high
cloudiness preventing a colder night. Favored the lower side of avbl
guidance for mins. Normal cold areas will fall to the low/mid 20s.
Expect mostly 30s at lakeside locations along the Great Lakes.
On Wed, the next southern stream low pres system lifting ne to
central IL/IN by evening will be too far s to bring any pcpn into
Upper MI. However, it is noted that a few models, GFS and CMC in
particular, do develop some -shra over parts of central Upper MI Wed
aftn along a weak sfc trof that pushes se into the area. This trof
is associated with the tail end of a shortwave swinging thru
northern Ontario. There has been quite a bit cu/stratocu development
upstream from nw MN into northern Ontario this aftn, but no
indications of pcpn yet per Environment Canada radars. There are sct
shra/tsra farther w in eastern ND where a little more instability is
present along with assistance from shortwave over western ND. Not
out of the question that a -shra or two/some sprinkles could develop
Wed aftn, but with more limited moisture/instability over Upper MI
on Wed, a mention in fcst is not warranted attm. Increasing clouds
and developing e to ne winds will limit warming. Expect highs mostly
in the 40s, though a few spots will probably top 50F in the interior.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 324 PM EDT TUE APR 4 2017
Nam has a trough in the central U.S. 00z Thu with a ridge over the
Rockies and a trough off the west coast. This trough moves into the
ern U.S. 00z Fri with the ridge moving into the Rockies. The ridge
moves through the plains on Fri.
System stays to the south and east of the area Wed night into Thu
with slight chance pops only for the far east. There will also be
slight chance for upslope pcpn for Thu morning and there could be
some mixed pcpn of freezing rain, rain and snow with this. Will then
be dry through fri.
In the extended, GFS and ECMWF show a 500 mb ridge over the plains
into the upper Great Lakes 12z Sat with troughing on both coasts.
The ridge builds into the Great Lakes region with troughing in the
western U.S. 12z Sun. The trough moves into the plains 12z Mon and
then into the upper Great Lakes 12z Tue with colder air coming back
into the area on Tue. Temperatures will be above normal this
forecast period until Tue when the colder air comes in and drops
temperatures to near normal. Dry weather continues into Sun morning
before a slow moving cold front approaches the area and brings in a
chance of rain. There could be some snow mixed in for Tue morning
across the far west and north.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 728 PM EDT TUE APR 4 2017
Lingering gusty winds at SAW wl diminish quickly this evng as a hi
pres rdg blds over Upr MI and daytime heating/mixing ends. Then
expect VFR conditions and light winds to prevail this fcst period
with the dry hi pres dominating. There wl be some diurnal cu dvlpg
on Wed with daytime heating especially at SAW, but cigs wl remain
above 4k ft.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 357 PM EDT TUE APR 4 2017
Initially this evening, nw winds may be as high as 20-25kt over
eastern Lake Superior. Otherwise, diminishing pres gradient will
allow winds to diminish to under 15kt across Lake Superior tonight.
Winds will be under 20kt on Wed. As low pres tracks ne to the Lower
Lakes/Upper Ohio Valley Wed night/Thu, n to ne winds will increase
to 20-30kt. Could be some gale force gusts over the eastern part of
the lake. Winds will diminish from w to e Thu night/Fri with winds
blo 20kt across the lake by Fri evening as a high pres ridge
arrives. With the departure of the ridge on Sat, southerly winds
will increase, more notably over the eastern part of the lake as is
typically the case for southerly winds. Expect winds of 15-25kt
across the eastern Lake. Winds should diminish some for a time on
Sun as a low pres trof settles over the area.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...07
AVIATION...KC
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Mount Holly NJ
944 PM EDT Tue Apr 4 2017
.SYNOPSIS...
A cold front will move offshore later this evening, then weak high
pressure follows for Wednesday. Intensifying low pressure in the
Ohio Valley Wednesday night becomes quite strong as it tracks across
Pennsylvania on Thursday. It then drifts northeastward over New
England Friday and Saturday. High pressure eventually builds in from
the west by Sunday and becomes nearly stationary off the Mid
Atlantic coast early next week.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Low pressure that developed along a triple point continues to move
northeast of our region. The leftovers of a warm front while
initially near our northern zones, has slipped back southwestward.
This appears to have been enhanced by several showers during the
afternoon across the northern part of New Jersey, and added to the
cooler boundary layer there. This colder and more dense airmass was
then pushed southwestward as significant warmth was occurring on the
other side of the boundary. This boundary seems to have mostly
dissipated as it moved farther southeastward, however there is an
area of low clouds across northern and central New Jersey. This has
even expanded south and west some early this evening. Some guidance
which shows this tends to not expand it much more. We therefore
increased the cloud cover quite a bit into the overnight hours over
these areas, and added fog for a time closer to the coast although
we are not anticipating widespread dense fog.
A cold front entering our western zones will clear the coast later
this evening with some drying. The dew points have already dropped
across the western areas. However, the damage may have been done
with the low-level moisture stuck in place for awhile where it
currently is. This update is of lower confidence given the low
clouds, however hopefully this latest update tipped the forecast in
the right direction.
Some lingering showers up across the northern areas are expected to
dissipate by Midnight. As a result, the PoPs were adjusted once
again to reflect this along with radar trends. The temperature, dew
point and wind grids were adjusted based on observational trends
along with some helpful guidance from the HRRR model.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
A nice day is expected Wednesday, the calm before the storm per
say. Weak high pressure affects the area during the first half of
the day, before shifting offshore. There may be a period of at least
some stratocumulus development during the first part of the day as
convective temperatures are reached and before the moist layer near
the inversion can mix out. Some forecast soundings indicate this and
therefore the cloud cover may need to be increased for a time.
Thereafter, some cirrus should arrive. No precipitation is forecast
through the daytime hours. Northwesterly winds strongest in the
morning hours then should lessen and turn west and southwest in the
afternoon, before becoming light southeasterly as we approach early
evening.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
**Stormy Thursday with attendant hazards**
500 mb: A strengthening closed low in the Ohio Valley Wednesday
night marches northeastward across PA on Thursday and into NYS
Thursday night, before weakening over and east of New England
this weekend. Very strong ridging follows early next week with
potential for near record warmth!
Temperatures: Calendar day averages 5 to 10 degrees above normal
Thursday (5 north 10 south), near normal Friday-Sunday, then
warming rapidly early next week with calendar day averages about
15 degrees above normal next Tuesday.
Forecast basis: a 50 50 blend of the 12z/4 GFS/NAM guidance Wed night-
Thu night, unless otrw noted, then the 12z/4 MEX MOS for Fri,
and thereafter, the 15z WPC guidance Fri night-Tue.
Wednesday night into Thursday...
Note the forecast for Thurs"day" from the vicinity of RDG-ABE-
SMQ northward was mostly the colder NAM temps!
Flood potential: Flood watch issued. Please see the hydro section
for more information. Widespread rain develops during late
Wednesday night and becomes heavy at times for 3 to 6 hours
ahead of the 985-988MB triple point low that develops east of
the parent W PA 985MB low. That triple point low is currently
mesoscale modeled newd just west of I-95 during the day Thursday.
That pattern favors se flow e of I-95 with a reduction in
potential rainfall there (NJ coast) but enhancement along and
west of the path of the sfc low where 1-2" of rain should fall
in 6-12 hours. That will result in spotty small stream flash
flooding depending on the axis of heaviest rain...hopefully
northwest of the I-95 highly urbanized corridor.
Wind: 15 mb 6 hr pres falls should induce a period of strong se
winds that shift southwest late in the day with the passage of
the cold front. Suspect a smattering of se gusts 40 to 50 mph
in the se inflow axis and then an hr of sw wind caa 40 to 50 mph
gusts south to north 19z-23z in the brief shot of strong caa
and asstd pressure rises. We may need a short fuse wind advisory
for NJ/DE I95 eastward to the coasts Thursday for sct gusts
around 45 mph.
Coastal Flooding: Ekman transport favors pulling water away to
the right, into the Atlantic on southerly flow but in this
case....sfc pressure down to 990 mb on the coast and a period
of 35-45 MPH ese gusts ahead of 7mb 3 hr pres falls, should
build positive departures near 2 feet more in line with SIT
NYHOPS for Sandy Hook region (likely minor threshold, tiny chc
mdt), and certainly much greater than the ETSS and ESTOFS.
Confidence is above average that the SIT will be more accurate
to use, especially considering ETSS performance this morning
with near minor threshold inundation flooding in NJ.
SVR: Pls follow SWO DY3,2,1 as the days pass, as well as our
office discussions. It appears to me that we will be seeing
strong or svr tstms racing newd from Va during the early
morning hours and weakening as they move north of the Delmarva
during midday. Strong wind fields and bulk shear both 0-3 and
0-6km, subzero LI, TT 50-55 suggest the potential is
significant for the Delmarva prior to Noon Thursday.
Very little effort was put into this latter portion of the
forecast and have relied heavily on WPC.
Thursday night through Friday...some bands of precip may
linger, especially in the higher terrain of the Poconos and NW
NJ given cyclonic flow, cooling aloft asstd with the strong 500
mb trough passing overhead Friday. Snow may mix in with the rain
at higher elevations Friday or Friday evening, though at this
point accumulating snow appears very unlikely. Gusty west winds
develop later Friday.
Saturday...drier with sunshine and a gusty northwest wind to 25
mph.
Sunday through Monday...With the high building in, tranquil
weather should return. This could set the stage for efficient
radiational cooling conditions on Sunday night leading to
possibly a frost advisory across northern Delmarva (frost/freeze
program has yet to begin for NJ or southeastern PA. At this point
however, it is highly unlikely temps will drop to 35F or less
for anything more than an hour.
A major warmup develops Monday that could build to near record
warmth Tuesday The records for the 11th are 84 at ACY and PHL
(1887) ILG-1922 and ABE-84 2011. GED is 83 in 2013. RDG 85-2011, TTN
86-2011, MPO 77-1955. I did raise temps next Tuesday with 13C
overhead at 850mb, southwest flow and a probable 2m temp at PHL
near 75F. It may be that cooling sea breezes keep temps a few
degrees cooler than fcst in far southern NJ.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Tonight...VFR overall. However MVFR/IFR ceilings (MVFR visibility)
should impact TTN and may get close to ABE, PNE and ACY for awhile
as a marine layer occurs ahead of a cold front. There is low
confidence in how far south and west the low ceilings get for awhile
tonight. A few lingering showers this evening mainly north of ABE to
TTN. The winds should mostly be westerly 10 knots or less, or even
locally light and variable.
Wednesday...VFR with some cloud bases between 3500-5000 feet.
Northwest winds around 10 knots in the morning, then winds become
west to southwest in the afternoon before turning light southeast
approaching early evening.
Outlook...
Wednesday night into Thursday...Conditions (both ceiling and
visibility) will deteriorate to intermittent IFR as showery
rains arrive late Wednesday night and continue through at least
mid day Thursday. There is a good chance for thunderstorms.
Additionally, there is a risk of low level wind shear Wednesday
night through mid day Thursday as there will be a sharp
directional shear through this time from southeasterly at the
surface to southerly or southwesterly in the low to mid levels.
Winds at 10000 to 1500 ft are likely to be 50-55 kt for a 2 to 4
hr period Thursday morning.
Thursday night through Friday...Bands of showery rains may
rotate eastward across the forecast area but in general,
conditions should gradually improve to VFR CIGS through this
time. West or northwest winds may gust 30 kt Friday evening
asstd with pres rises and trough passage.
Saturday and Sunday...VFR. Northwest winds gust 25 kt Saturday
and 15 kt Sunday.,
&&
.MARINE...
Some fog looks to persist in the Atlantic coastal waters mainly for
the two northern zones. It appears dense fog should not be
widespread or long in duration, therefore no advisory at this time.
The Small Craft Advisory continues across the Atlantic coastal
waters mainly for elevated seas. Seas should be 4-7 feet but
slowly subsiding through the night and Wednesday.
OUTLOOK...
Gale watch issued most of the waters...marginal both in
duration and above threshold.
Wednesday night and Thursday...E-SE winds increase Wednesday
night then veer out of the S Thursday behind a warm front. A
strong SCA will occur with wind speeds forecast to increase to
20-25 kt. Model soundings show a very strong wind field aloft w/
50 kt winds only a few hundred feet off the ground. Normally
this not a set up for downward transfer of stronger wind but
nearshore...with the pressure being so low and 15 mb 6 hour
pressure falls....odds increase for sely gale force wind
transfer of 35-40 kt for 2-4 hrs ahead of the cool front and 1
hr of gale force sw wind gusts behind it as pressures start
rising rapidly.
Special marine warnings may also be needed where bands of showers
and embedded thunderstorms imply concentrations of surface wind
momentum transfer, especially Thursday morning into early
afternoon.
Friday and Saturday...winds will slowly diminish, but should
generally remain near or just above 25 kt for much of this
period.
Sunday...no headlines anticipated.
&&
.HYDROLOGY...
Flood potential: Flood watch issued. Widespread rain develops
during the night and becomes heavy at times for 3 to 6 hours
ahead of the 985-988MB triple point low that develops east of
the parent W PA 985MB low. That triple point low is currently
mesoscale modeled newd just west of I-95 during the day
Thursday. That pattern favors se flow e of I-95 with a reduction
in potential rainfall there but enhancement along and west of
the path of the sfc low where 1-2" of rain should fall in 6-12
hours. That will result in spotty small stream flash flooding
depending on the axis of heaviest rain...hopefully northwest of
the I-95 highly urbanized corridor.
1. MMEFS etc. Two to three inches of rain, from about Philly
north, were inserted into the hydro models this morning over
the next 72 hours. River forecasts assume that this rainfall
will occur. If is doesn`t, crests will be lower.
2. The Passaic River is running high. Pine Brook will remain above
Action Stage until the next surge of rain on Thursday. It appears
the gauge will crest just under flood stage early on Wednesday.
Water levels will begin climbing once again late Thursday into
Friday. All of our Passaic River forecast points will see
rises.
3. Across the Raritan basin, forecasts points have dropped below
Action Stage. More flooding is possible beginning Thursday. Flooding
could persist into the weekend on the Raritan and Millstone.
4. With the 12z models showing a slight lowering in the qpf
amounts, especially across our southern zones, we only issued
the Flood Watch from about the I95/I78 intersection
northeastward, considered most vulnerable at this point in time.
The watch runs from 12z Thu through 18z Fri. If future precipitation
totals increase across our southern zones, the Flood Watch could
be expanded southwestward to include PHL/ILG and points northwest
to the Poconos. So if you live along the Rancocas, the Schuylkill,
or along the quicker responding streams across SE PA and NRN
DE, remain informed.
5. The potential for flooding can be broken down into three different
types. Low lying and poor drainage flooding would occur first
during the day Thursday soon after the rain begins. The runoff
will drain and potentially produce flooding later Thursday into
Thursday night along smaller creeks and streams. Lastly, some
larger rivers and mainstems will rise and could flood Thursday
night into Friday. The river flooding could easily last into or
through the weekend, depending on the magnitude of the rainfall
Thursday.
6. Please refer to AHPS for the latest. Confidence is higher that a
number of forecast points will hit their Flood Stage. But with
rainfall still 36-48 hours in the future, confidence is much
less regarding any moderate flooding that is modeled.
7. The potential for flooding increased during the last week
because of three successive rain events. With each event,
waters are starting to rise from a higher point/level. The
rivers have not had a chance to return to their base flow.
&&
.TIDES/COASTAL FLOODING...
In case you noticed... the Tidal DE near Philly came within an
inch minor flood this morning around 830 am. Guidance was less
than what occurred.
Ekman transport favors pulling water away to the right, into
the Atlantic on southerly flow but in this case....sfc pressure
down to 990 mb on the coast and a period of 35-45 ese gusts
ahead of 7mb 3 hr pres falls, building positive departures more
in line with SIT NYHOPS for Sandy Hook region (likely minor
threshold, tiny chc mdt), and certainly much greater than the
ETSS and ESTOFS. Confidence is above average that the SIT will
be more accurate to use, especially considering ETSS performance
this morning with near minor threshold inundation flooding in
Elsewhere...The upper MD Eastern Shore has a smaller chance of a minor
tidal indunation flood episode Thursday afternoon in the southerly
flow, though there, the risk appears to be less than near Sandy
Hook NJ.
Finally: its not impossible to see approaching minor flood
threshold for the Thursday evening high tide vcnty PHL.
All this will be reviewed again tomorrow, especially with regard
to timing the inflow wind shift abatement.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Flood Watch from Thursday morning through Friday afternoon for
NJZ001-007>010-012-013-015.
DE...None.
MD...None.
MARINE...Gale Watch from Thursday morning through Thursday afternoon
for ANZ431-450>454.
Small Craft Advisory until 6 AM EDT Wednesday for ANZ450>455.
&&
$$
Synopsis...Drag
Near Term...Gorse
Short Term...Gorse/Robertson
Long Term...Drag
Aviation...Drag/Gorse
Marine...Drag/Gorse/Robertson
Hydrology...
Tides/Coastal Flooding...
Area Forecast Discussion
National Weather Service Pueblo CO
813 PM MDT Tue Apr 4 2017
.UPDATE...
Issued at 810 PM MDT Tue Apr 4 2017
Radar trends and HRRR guidance indicates a chance of some accum
snow, especially across the Pikes Peak region (especially N
facing slopes) and along the US50 corridor from ~Salida to ~Canon
City. Have upped pops and QPF these regions. Accums should be
~1-4"
This precip is associated with a well advertised 2nd disturbance
coming down the backside of the trough that moved across us
earlier today. /Hodanish
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 352 PM MDT Tue Apr 4 2017
Satellite images this afternoon are showing the upper level low over
the OK panhandle. Radar shows some convective snow showers wrapping
around the low into southeast CO. Although pcpn is not as widespread
as it was this morning, under the heavier showers there could be a
quick inch or two of snow accumulation. Temps have been warming a
little as pcpn has ended or lightened and some locations have switch
from snow to rain.
Tonight the upper level low will continue its eastward track away
from southern CO, however a weather disturbance to our north will be
moving south through CO and is expected to bring another round of
snow, mainly to the central CO mtns, Pikes Peak, Teller county, the
Sangre de Cristo and Wet mtns, and the I-25 corridor. For this
reason, I am reluctant to take down the winter weather highlights
that are in effect thru 06Z, even though some of these areas are
currently seeing a lull in the snow activity. Will downgrade
remaining Warnings to Advisories and will remove the highlights for
the southwest mtns. The best chances for snow with the approaching
disturbance are expected from late this evening through late
tonight, with pcpn ending from north to south along the eastern mtns
and I-25 corridor. El Paso and Teller counties may see the best
chances for snow end around 2-3am, while the Trinidad area could see
snow until around 5 or 6 am. Some areas of fog may develop late
tonight as well.
Wed will be a dry day as an upper ridge starts to build over the
area. Temps are expected to warm into the 40s and 50s at the lower
elevations.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 352 PM MDT Tue Apr 4 2017
Overall, more subdued meteorological conditions are anticipated
over the majority of the forecast district during the longer term,
especially when compared to the previous 10 days or so.
Primary longer term meteorological issues during the longer term
include generally above seasonal temperatures, gusty winds at
times as well as basically low grade pops at times(including the
potential for isolated thunderstorms).
Recent longer term PV analysis, computer simulations and forecast
model soundings indicate that an upper ridging pattern will
develop over southern Colorado from Wednesday night into Saturday
morning allowing for generally dry conditions in combination with
warmer temperatures during this time-frame.
Then, next upper disturbance is expected to impact the forecast
district from later Saturday into Sunday evening allowing for
increased pops, including the potential for isolated primarily
afternoon thunderstorms(favoring higher terrain locations) both
Saturday and Sunday.
Then another round of unsettled conditions(including thunderstorms
favoring far eastern portions of the forecast district) will be
possible from later Tuesday into next Tuesday night with next
system.
Regarding winds, at this time, it appears that the highest
potential for gusty winds should be noted from later Friday into
Sunday night.
Finally, during the longer term, generally near to above seasonal
early April temperatures are anticipated during the majority of
the longer term with the warmest temperatures expected from Friday
into Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 352 PM MDT Tue Apr 4 2017
Showers will be possible in the vicinity of KCOS and KPUB through
late tonight. At times VFR conditions can be expected, but periods
of MVFR conditions will continue at least into the late night hours.
A new weather disturbance moving south through the area later
tonight, could bring a period of heavier snow to KCOS and KPUB,
which could result in IFR ceilings and visibility, there may also be
some fog in the early morning hours on Wed. VFR conditions are then
expected by about midmorning.
KALS could continue to see some showers in the vicinity into this
evening, which could bring lower CIGS and VSBY at times. Late
tonight some fog may develop in the area, reducing the VSBY and
there could be a low ceiling, otherwise VFR conditions can be
expected Wed.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight MDT tonight for
COZ058>063-072>076-078>082-084-087-088-094.
&&
$$
UPDATE...HODANISH
Area Forecast Discussion
National Weather Service Topeka KS
913 PM CDT Tue Apr 4 2017
.UPDATE...
Issued at 909 PM CDT Tue Apr 4 2017
Have made adjustments to the POP/QPF forecast through 06Z to
better reflect the effects of the dry slot punching into the
southern CWA and the erosion of the northern periphary of the def
zone as dry air intrudes from the north. How quickly the def zone
pivots around will affect rainfall totals across the SE CWA, which
will also have a direct effect on river response in the coming
hours/days.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 315 PM CDT Tue Apr 4 2017
Mid/upper level low pressure currently located over the Texas
panhandle and northern New Mexico. Ahead of this low pressure is a
band of frontogenesis that stretches northeastward through eastern
KS. A band of rain has developed is in response to this forcing.
Current radar shows convective elements and the latest RAP soundings
have shallow elevated instability. This band is forecasted to
gradually lift northward through the afternoon. As the main system
progress eastward a surface low pressure will track through extreme
southeast KS. Widespread convection is expected to develop in the
vicinity of the warm front. It is during this time that mid level
lapse rates steepen which will result in 100-300 j/kg. This elevated
instability will move over east central KS during the late evening
and early morning hours. Perhaps one of the stronger cells could be
capable of producing large hail mainly along and south of I-35. It
is during this time frame that persistent convergence north of the
warm front and upper level support could lead to cell training as
well. The other expansive area of rainfall will develop in the
trowal of the mid level low pressure in central KS, which will track
through eastern KS through tomorrow morning.
A widespread 1-2 inches of rainfall is possible by noon tomorrow.
There are several models suggesting that rainfall totals could
exceed 3 inches in some areas. In fact the ARW ensembles have a 100
percent chance of 2 inches of total rainfall within 25 miles of a
point. In the same exact area the nested NAM has an area of greater
than 3 inches of total rainfall. The best chances for these higher
amounts will be where the elevated convection and trowal
precipitation overlap. As of now the strongest signal for this is
along and near the KS turnpike. Unfortunately all of this region has
seen above normal rainfall therefore the soil is already saturated.
Given these conditions and the going forecast flash flooding could
not be completely ruled out. River flooding is more likely after the
event wraps up so a flood watch has been issued. As the system
passes through the low pressure gradient will cause surface winds to
become gusty overnight. Temperatures tonight drop into the 40s so
the combination will cause winds chills just above freezing. This
along with rainfall will make for some miserable conditons. Tomorrow
morning the low pressure systems lifts northeastward causing the
rain to end from west to east. Most of the rain should come to an
end in the late morning hours.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 315 PM CDT Tue Apr 4 2017
Wednesday Night through Tuesday...
The start of the extended period will consist of decreasing clouds
and cool temperatures. A surface and upper-level low will continue
progressing away from the outlook area. In doing so, winds will
begin to lighten and skies will begin to clear. Morning lows are
expected to dip into the mid and upper 30s Thursday morning and low
to mid 30s Friday morning. RH values are expected to approach the 80-
90 percent range both mornings, therefore have a mention for patchy
to areas of frost. Upper-level ridging will then dominate for the
reminder of the week into the first half of the weekend. Southerly
flow will return by Saturday as a surface high progresses into the
southeastern US. In response, temperatures will surge into the low
to mid 70s.
We then turn our attention to the potential for thunderstorms Sunday
afternoon and evening. Starting in the upper levels, guidance
suggests an open H500 wave with an embedded shortwave across the
central US. At the surface a trough will progress across the
forecast area during the afternoon and evening hours. Forecast
parameters continue to hint at the possibility for a few strong to
perhaps severe thunderstorms. Zonal flow will then dominate the
remainder of the period with high temperatures in the 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 649 PM CDT Tue Apr 4 2017
Widespread showers will persist throughout the evening and
overnight hours with current VFR/MVFR cigs/visbys falling to low
MVFR/IFR levels. Scattered thunderstorms will be possible across
east central Kansas through this evening with the threat for
thunderstorms waning by midnight. N/NW winds will increase through
the night behind the departing low with sustained winds of 20-25
kts and gusts of 30-35+ kts expected for the morning. This winds
will persist through much of the day but gradually subside by the
afternoon.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Wednesday afternoon for KSZ010>012-021>024-
026-035>040-054>056-058-059.
&&
$$
UPDATE...Skow
SHORT TERM...Sanders
LONG TERM...Baerg
AVIATION...Skow