Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/04/17
Area Forecast Discussion...Updated
National Weather Service Billings MT
904 PM MDT Mon Apr 3 2017
.UPDATE...
Broad amorphous upper level low continues a slow progression
southward along the MT Continental Divide this evening. There area
several meso-circulations within the synoptic system each
producing areas of precipitation. Will continue to see scattered
areas of mainly light snow overnight as this system slowly slides
south and opens up into tomorrow as a kicker wave arrives.
Red Lodge webcams showed a period of snow result in maybe half an
inch around 8pm, however confidence in moderate snowfall for the
Beartooth front tonight is dropping as winds haven`t turned to a
favorable direction for heavier snowfall so far this evening. Hi-
Res models keep winds just a bit northwest through the night and
just bring a few bands of snow through for the rest of the night
there. However if winds turn just a bit more northerly (20 degrees
might do it) there is sufficient lift and instability for a quick
accumulation of several inches in these areas. In addition, Metro
model runs showing road temperatures dropping to freezing by
1030pm, so even lighter snow may bring some enhanced travel
difficulties by morning in these areas. Given the above, tweaked
snow accumulations down just a bit but will hold on to the
advisory for now based mainly on travel icy road potential.
Will also keep an eye on some light snow accumulation potential
along and south of US212 across southeast MT overnight into
tomorrow morning as HRRR and RAP showing a bit more qpf in those
areas lined up with some upper divergence. Chambers
&&
.SHORT TERM...valid for Tue and Wed...
Latest 500mb analysis shows a weak low over western MT and a
stronger circulation in northeast MT near Malta. To our east,
instability axis resides on the Dakotas side of our eastern
border, with scattered showers and a few recent lightning strikes
just outside of our cwa. Western low and its cold pool aloft is
resulting in increasing shower coverage across our west/central
parts...but no lightning noted yet.
Showers over our west will continue to increase over the coming
hours with diurnal destabilization and as western trof drops
southward allowing for winds to veer more northerly. P-type will
be a combination of rain/snow/graupel with very low freezing
levels in place and surface wet bulb temps that are in the low-
mid 30s. The veered mid level winds will favor the north slopes of
the Beartooth/Absarokas and have already issued a winter wx
advisory for a few inches of snow for Red Lodge/Mcleod. Given the
steep lapse rates and dendritic layer below mtn top, snowfall
rates may reach or exceed an inch per hour for a short time.
Moisture will shallow out over time, and snow showers should
become lighter or diminish overnight.
Trowal associated with NE MT low will wrap some light rain/snow
into our central and eastern parts late tonight and Tuesday. Some
increased NW wind will accompany the pcpn, along with cool temps,
so a somewhat raw day in store for our eastern CWA tomorrow. The
Bighorns should pick up a few inches of snow per the NW flow.
For Billings, best chance of rain/snow showers appears to be early
this evening with wind shift, then late tonight into early Tuesday
with trowal from the north...the latter of which may be trumped by
downsloping NW winds. Best chance of pcpn tomorrow will be east of
Billings.
Ridging/anticyclonic flow will spread in from the west Tuesday
afternoon and evening, marking the beginning of a period of dry
weather. Dry conditions will prevail Wednesday and Wednesday
night.
Temps will remain seasonably cool tomorrow with highs in the 40s
to lower 50s. Highs will return to the 50s/lower 60s Wednesday per
the ridge and downslope winds.
JKL
.LONG TERM...valid for Thu...Fri...Sat...Sun...Mon...
Dry weather in the first part of the extended period will give
way to unsettled conditions in the latter portion of the period. A
high amplitude ridge should dominate our weather on Thursday. The
ridge axis will shift into the Dakotas Thu. night, allowing SW
flow to overtake the region. It will be dry and warm under the
ridge with temperatures around 70F on Thursday due to 850 mb
temperatures of +14 to +16 degrees C. Some shortwave energy and
diffluence moves over the region on Friday bringing some low PoPs
to the western high elevations. 850 mb temperatures will reach +18
degrees C, so highs will be in the 70s from Billings and east.
For the weekend and early next week, the large-scale upper flow
pattern turns cyclonic with several shortwave troughs or
potentially upper lows moving over the region. This pattern
favors rain showers across the lower elevations and snow showers
in the mountains. Models agree on the large-scale cyclonic flow
pattern but differ on the smaller-scale features. There will be
periods of dry weather as well...but timing these periods is
difficult this far out. High temperatures should generally trend
cooler, from the 60s on Saturday to the 50s on Sunday and Monday.
RMS/JKL
&&
.AVIATION...
VFR will prevail tonight. Scattered showers and isolated
thunderstorms will affect the region this afternoon and evening
with associated MVFR/IFR conditions. Rain and snow showers with
areas of fog will continue over the area tonight with MVFR/IFR
conditions. There will be areas of mountain obscuration through
tonight. RMS/JKL
&&
.PRELIMINARY POINT TEMP/POPS...
Tue Wed Thu Fri Sat Sun Mon
-----------------------------------------------------------
BIL 031/049 030/061 041/070 047/072 047/062 041/055 036/051
55/O 00/B 00/B 01/B 23/W 23/W 33/W
LVM 024/047 027/059 037/067 040/066 041/058 034/052 030/051
44/S 00/N 00/B 02/W 33/W 33/W 23/W
HDN 031/050 027/060 035/072 041/073 044/064 039/056 034/052
55/O 00/U 00/B 01/B 23/W 33/W 33/W
MLS 033/049 030/060 037/071 044/076 047/067 041/056 035/051
35/O 10/U 00/B 01/B 13/W 33/W 33/W
4BQ 029/047 026/057 034/070 043/075 046/066 040/056 034/051
24/O 00/U 00/B 00/B 13/W 23/W 33/W
BHK 030/047 026/055 031/067 040/075 045/067 039/055 032/049
25/O 20/U 00/B 00/B 13/W 33/W 23/W
SHR 028/044 024/057 032/066 038/069 041/061 037/054 032/050
44/O 00/U 00/B 01/B 13/W 23/W 33/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory in effect until 6 AM MDT Tuesday FOR
ZONES 56-66.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Columbia SC
841 PM EDT Mon Apr 3 2017
.SYNOPSIS...
Dry and warm weather is expected Tuesday before yet another
strong system impacts the area Wednesday with another round of
severe weather possible. Cooler and dry Thursday into the
weekend as high pressure settles over the region but windy
conditions expected Thursday.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Update 745 pm - Round One of a busy severe weather week moved
out of The Midlands before 7 pm. We are collecting reports of
probable tornado damage as well as downed trees. Two teams will
be out tomorrow to survey the worst damage. Scattered showers
will be possible overnight mainly south of I-20 as a band over
southeast Georgia may skirt the region.
Update 505 PM - A line of strong to severe thunderstorms was
along a north to south line from east of Charlotte through
Columbia to Orangeburg as of 5 pm. We have received reports of
possible tornado touchdowns, numerous trees down, and localized
flash flooding. This line will continue to push east across The
Midlands and Pee Dee Region and should clear our service area
by 7 pm.
Moisture and instability continue increasing across the forecast
area with showers and thunderstorms becoming more numerous.
Main concern through tonight remains the front currently moving
through eastern GA and the potential for severe weather. With
very strong winds aloft and plenty of instability have
coordinated with SPC in the issuance of tornado watch 119
through 9 pm. Expect the main threat of severe weather to begin
arriving in the CSRA between 3 and 4 pm and the Midlands between
4 and 5 pm. Along with the potential for tornadoes the freezing
level and wet bulb zero heights support potential for hail.
Although the cells will be progressing rapidly to the northeast
there is the potential for locally heavy rainfall with rainfall
rates up to 2 inches per hour. Main line of convection will
move east of the forecast area by 9 pm with a few showers and
thunderstorms lingering overnight. Winds will also remain strong
and gusty as the system crosses the area so the lake wind
advisory will remain in effect through 4 am. With cloud cover
and winds persisting overnight expect low temperatures in the
lower 60s.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
For Tuesday and Tuesday Night: A return to dry weather expected
behind the front. Do not anticipate much in the way of cooler
temperatures behind the weak front. With more sunshine expected,
afternoon temperatures should climb back into the 80s. The dry
weather will continue for the majority of the overnight hours
Tuesday night. Moisture will begin increasing once again late in
the night across the western counties in advance of the next
approaching weather system, but any rainfall will hold off until
sunrise or later on Wednesday. Lows Tuesday night will remain
mild in the 50s to around 60 degrees.
Wednesday and Wednesday night: Active weather returns. More
severe weather will be possible. Another strong upper trough
will be moving towards the region, with southwesterly flow aloft
in advance of the trough. A surface warm front will once again
be lifting northward through the cwa during the morning, while
the main cold front will still be well west of the area. In
advance of this cold front, a warm, moist, and unstable airmass
is expected to be setting up across the cwa through the day.
Aloft, a strong 850 mb jet will be moving through the area, with
55-60+ knots. The combination of a 500 mb flow that will be
diffluent over the region, and a strong jet max at 250 mb, will
both help to enhance lift over the region by the afternoon.
Strong thunderstorms are expected to develop in a moderately
unstable airmass by the afternoon hours. With the strong low-
level jet, a damaging wind threat will be possible with the
storms. With the expected instability, the threat for hail and
an isolated tornado will also remain. There could be a couple
of rounds of strong storms as well, the first during the
afternoon in the vicinity of the retreating warm front, then the
second round late Wednesday afternoon and into Wednesday night
ahead of the approaching cold front. High temperatures Wednesday
around 80 to the lower 80s, and lows Wednesday night in the
middle 50s.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
The front will be exiting the region by Thursday morning, and
very windy conditions are forecast to develop behind the front.
Sustained winds around 20 mph, with wind gusts over 30 in many
areas, appear to be possible during the day. A Lake Wind
Advisory will likely be required during the daytime hours on
Thursday, with the possibility of another one on Friday.
As high pressure builds in behind the front, a return to dry
weather is expected through the entire long term period.
Winds will be out of a northwesterly downslope direction for
much of the period. There will be a noticeable cool down in
regards to temperatures behind this front associated with the
high pressure. Temperature readings will be at or below normal
Thursday through Saturday. By Sunday temperatures return back to
normal, with Monday above normal.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Strong convection has shifted east of the terminals. There will
be lingering low-level moisture. Observation trends and the HRRR
suggested IFR ceilings moving into the area from the northwest
tonight. These ceilings were also supported by the GFS LAMP.
Boundary layer wind should limit fog. The KCAE 88D VAD Wind
Profile supported the NAM with a strong low-level jet. Expect
either gusty winds or low-level wind shear continuing tonight.
Believe there will be enough of an inversion to lessen surface
wind so we have included low-level wind shear in the TAFS.
Mixing and dry advection should result in VFR conditions after
14z. The GFS LAMP and NAM Bufkit momentum transfer tool
supported gusts 15 to 20 knots after 14z.
EXTENDED AVIATION OUTLOOK...Expect widespread restrictions
Wednesday and Wednesday night as another strong system crosses
the region with thunderstorms which may be severe. It will
likely be breezy Thursday through Friday.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...Lake Wind Advisory until 4 AM EDT Tuesday for GAZ040-063>065-
077.
SC...Lake Wind Advisory until 4 AM EDT Tuesday for SCZ015-016-018-
020>022-025>031-035>038-041.
&&
$$
SYNOPSIS...99
NEAR TERM...99
SHORT TERM...99
LONG TERM...99
AVIATION...99
Area Forecast Discussion
National Weather Service Peachtree City GA
1059 PM EDT Mon Apr 3 2017
.UPDATE...
After a busy day of severe weather...conditions have quieted down
this evening and this trend will continue through Tuesday. Have
adjusted POPs to keep up with current trends...largely coinciding
the most recent HRRR solutions. Have also been adjusting
temps/cloud cover as necessary.
Latest analysis of the mid levels indicates that the negatively
tilted shortwave trough /responsible for today`s squall line/ has
pivoted into the OH Valley/Midwest. A weak shortwave is currently
rotating amidst the broad cyclonic circulation associated with
this trough and was located over northern AL/south-central TN as
of 03z. Synoptic lift with this wave has triggered convection
across this general area and it is not out of the question a few
cells could move into or develop across far north Georgia over the
next couple of hours. Although shear/helicity are still
high...lack of sufficient CAPE argues for weaker updrafts and at
best the potential for some gusty winds as the main threat with
these cells.
Should begin to clear out tonight. Some patchy fog is not out of
the question...especially across central Ga...but winds will
likely remain too elevated to warrant mention in the grids at
this time. Tuesday still looks pleasant in the wake of the cold
frontal passage. Wednesday system is still a concern in terms of
severe weather.
Kovacik
&&
PREV DISCUSSION... /Issued 349 PM EDT Mon Apr 3 2017/
SHORT TERM /Tonight through Tuesday Night/...
Current regional radar loop shows the main line of severe storms
moving east across the state and should exit our eastern CWA with
in the next hour. There are still some showers and thunderstorms
behind the line but they are much weaker. All in all things are
winding down across our CWA but these storms are expected to
continue as they push into SC. As the rain ends this evening we will
keep some clouds over the region then begin to clear out around 2am
to 4am Tuesday morning. Should see mostly clear skies across the
region Tuesday with day time highs in the 80s. Precip begins to
move back into the forecast area from the west as the next frontal
system developing over the central and southern plains Tuesday
pushes its frontal boundary into SW GA Late Tuesday in Wed morning.
01
LONG TERM /Wednesday through Monday/...
No changes have been made to the extended. Wednesday still on
track for another round of strong to severe storms. Previous
discussion is included below.
41
PREV DISCUSSION... /Issued 347 AM EDT Mon Apr 3 2017/
LONG TERM /Tuesday Night through Sunday/...
Another round of wet and stormy weather is in the cards Wednesday
into Wednesday night. This due to a strong cold front forecast to
move across the area Wednesday night and associated with a sharp
upper level trough moving across the mid U.S. The airmass becomes
unstable quickly on Wednesday ahead of the front as warm moist
air moves over the area. Low level wind shear increases as well
in the 30-45 kt range. This will lead to an Enhanced risk of
severe storms. Storm potential will end quickly Wednesday night
with the cold front passing. The only concern then will be shower
chances from wrap-around moisture in the upper level trough
Thursday into Friday. Temperatures could get cold enough for a
rain/snow shower mix for the higher elevations of the mountains
late Thursday night/early Friday.
Saturday and Sunday will be dry as high pressure moves across the area.
Temperatures are expected to be above normal until the cold front
moves through Wednesday night then temperatures will cool off to below
normal until about Sunday. Friday and Saturday mornings will be
the coolest with lows in the 30s and 40s.
BDL
AVIATION...
00Z Update...
Storm complex that brought thunderstorms to the TAF sites has
largely cleared the area. Biggest concern in its wake will be the
potential for MVFR/IFR cigs overnight tonight along with some
patchy fog...mainly across CSG and MCN where rains have been most
recent. MVFR/IFR cigs likely across all sites tonight...with
clearing at all sites by sunrise Tuesday. Tuesday looks
pleasant...with increasing cirrus and perhaps a few afternoon cu.
Winds will remain on the SW side tonight...with gusts dying down
after sunset but remaining sustained towards 10kts. Winds likely
to flirt with or briefly shift northwest Tuesday morning before
returning southwest again around 10kts Tuesday afternoon.
//ATL Confidence...00Z Update...
Medium on timing/coverage of MVFR/IFR cigs
High on all other forecast elements.
Kovacik
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 70 56 82 58 / 90 10 0 10
Atlanta 68 58 81 60 / 90 10 0 30
Blairsville 64 52 75 52 / 100 20 5 10
Cartersville 68 55 80 57 / 100 10 0 20
Columbus 74 60 84 62 / 90 10 5 30
Gainesville 66 56 78 57 / 90 10 0 10
Macon 76 59 84 60 / 90 10 5 20
Rome 68 55 80 56 / 100 20 0 20
Peachtree City 69 55 82 57 / 90 10 0 30
Vidalia 84 64 85 64 / 100 70 10 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Kovacik
LONG TERM....Baker
AVIATION...Kovacik
Area Forecast Discussion
National Weather Service Wilmington NC
851 PM EDT Mon Apr 3 2017
.SYNOPSIS...
Showers and thunderstorms will move across the area this
evening into tonight ahead of a cold front and some of these
storms could be strong to severe. Dry and warm weather will
follow for Tuesday and early Wednesday. Another storm system and
cold front will bring renewed thunderstorm chances late
Wednesday into early Thursday. Cooler and drier high pressure
will build in Friday into Saturday, with a warming trend
starting early next week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 850 PM Monday...Updated forecast to cancel Severe
Thunderstorm Watch. Last of the strong convection is in process
of moving offshore the Cape Fear Region. Previous discussions
follow:
Strong convection racing across the forecast area faster than
high-res guidance has forecast. Expect the worst of it will be
offshore most places before 9 PM, followed by a bit of light
stratiform rain, then stratus and some patchy fog. Damage
reports have fortunately been few and far between. Will be
updating forecast to reflect accelerated end to this event.
Previous discussion from this afternoon follows:
Winds will continue to veer around and increase through this
afternoon as coastal trough lifts north and a frontal system
makes its way east. This will help to increase low level
moisture with dewpoint temps making there way into the 60s. A
line of strato cu and spotty showers associated with coastal
trough have shifted north leaving plenty of sunshine to
destabilize the atmosphere. The spotty showers left higher
dewpoint in their wake, while the rest of the area had readings
in the mid 50s. Temps well into the 70s to around 80 most places
will remain warm into tonight.
A potent storm system will lift northeast towards the Great
Lakes through tonight. An associated well defined squall line
has been marching across the south and will reach into the
Carolinas early this evening. SPC continues to highlight the
potential for severe weather into tonight with watches issued
associated with the squall line upstream into SC this aftn. Best
chances will be inland, especially across inland SC. Initially
a warm front will lift north leaving warm and increasingly moist
air in its wake. Gusty southerly winds ahead of the front will
remain strong behind it with a strong low level jet up to 50 to
60 kts. The earlier arrival of the convection will leave a more
unstable atmosphere and greater potential for stronger to severe
storms through this evening. The latest HRRR show the line
arriving to our W-SW portion of forecast area between 6 and 8 pm
and then holding together quite well as it traverses the area
toward the E-NE reaching the coast between 9 and 11 pm. Also
shows some lingering cell development behind the squall
overnight. The greatest upper level support is aligned with
squall line, but shortwave energy and decent jet dynamics linger
into the overnight hours to support this. The greatest QPF will
also be aligned with squall line, but cells developing ahead
and behind the line could also produce a quick quarter of an
inch or so. The total rainfall should range between 1 to 2
inches most places.
Clearing will occur from west to east through the morning hours
on Tuesday. A deep west to southwest flow will leave plenty of
warm air over the region but dewpoint temps will begin to drop
through the afternoon as front moves off to the east. Overall
expect plenty of aftn sunshine with temps reaching well above
normal after a very warm start to the day.
Temps will drop initially this evening, especially in convection
that moves through, with overnight low this evening and plenty
of WAA to stabilize or push temps a little warmer through the
night. With temps close to 70 at daybreak expect a rise into the
80s Tues aftn.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...Very warm temperatures this period will be
followed by yet another strong impulse and possible severe weather
event late Wednesday into Wednesday night.
Initially, surface high pressure will be offshore, and mid-level
ridging will be amplifying in response to a strong shortwave digging
through the middle of the country. This will create a very warm
Tuesday night with lows dropping only to around 60, followed by an
equally warm Wednesday with highs in the 80s. Clear sky conditions
are expected through Wednesday aftn with the exception of increasing
high level cirrus, but the approach of a warm front will change
that. This front is progged to lift across the CWA late Wednesday
aftn into Wednesday evening, accompanied by increasing clouds and a
good chance for tstms. As this front lifts north, instability and
shear increase, and a chance for strong to severe tstms exists
beginning with this feature. Behind this front, the CWA enters a
broad warm sector ahead of a cold front which will cross offshore on
Thursday driven by an anomalously deep upper trough. MUCape over
1000 J/kg will combine with strengthening LLJ (to 60+ kts) to
produce an unstable and highly sheared environment capable of
producing severe tstms. At this time, the strongest dynamics appear
to stay just west of the CWA, and SPC has our Pee Dee counties in a
SLGT risk, with MRGL elsewhere, but at least an isolated risk for
damaging winds and a tornado exists late Wednesday through Wednesday
night. Once again, the strongest instability is elevated thanks to a
weak inversion at night, but could also be sufficient for hail, and
all threats are possible. Additionally, WPC has the area in a MRGL
risk for excessive rainfall this period, with training of storms in
an environment with diffluent 500mb and 300mb flow combined with
high PWATs supportive of very heavy rainfall in some locations.
Convection will push offshore by daybreak Thursday, but cold
advection lags until beyond this period, so mins will be warm
Wednesday night, falling only into the low 60s.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 300 AM Monday...Cold FROPA Thursday morning will usher in
very cool and dry air, bringing a cooling trend and dry weather
into the weekend. Overnight minimums Thursday night through
Saturday night will dip back in the 40s with highs Friday and
Saturday only in the mid 60s. Monday will see temperatures
rising back towards seasonal norms as the airmass modifies and a
SW flow begins to set up.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
As of 00Z...Primary threat to aviation interests this evening is
a line of showers and thunderstorms racing across the forecast
area. This line will be offshore by around 9 or 10 PM and has
already moved past our inland terminals.
Strong gusty southerly winds will continue into tonight with
higher gusts through this evening. Patchy strato cu and cirrus
will produce intermittent MVFR/IFR this evening after
convection moves east of the terminals. Expect VFR all terminals
after daybreak on Tuesday.
Extended outlook...Chance for MVFR/IFR late Wed thru early Thu from
convection ahead of a strong cold front. Possible MVFR from showers
Thu night thru Fri. Strong synoptic winds in excess of 25+ KT gusts
possible Tue and Thu.
&&
.MARINE...
NEAR TERM /THROUGH TUESDAY/...
As of 730 PM Monday...Small Craft Advisory remains in effect as
dangerous conditions continue over the coastal waters. Most
immediate threat is a line of showers and thunderstorms now
moving offshore our SC waters, followed a little later this
evening by the waters off of the Cape Fear region. Previous
discussion from this afternoon follows:
Small craft advisory conditions on target for this evening into
tomorrow. Strong and gusty southerly winds have increased
through this afternoon and will remain strong through tonight.
South to southwest winds will peak in the 25 to 30 kt range late
tonight. There is potential for much higher gusts within any
storms that move across the waters. Cold front does not reach
the waters during the period and winds will remain out of the
south or southwest into Tue. Seas currently 2 to 3 ft will
respond to increasing southerly flow later today, building to 4
to 6 ft by early evening and peaking near 10 ft as the period
ends.
SHORT TERM MARINE/TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/
As of 300 PM Monday...Decreasing SW winds will ease to around
10 kts by Wednesday morning before shifting to the NW as a weak
boundary shifts offshore. This period of NW winds will be short
lived and light, as a warm front lifts north across the waters
during Wednesday bringing a return to southerly winds. By
Wednesday night, speeds will ramp up to 15-25 kts, and the
period will likely be bookended by SCA`s. After seas fall from
3-6 ft very early Tuesday night to 2-3 ft much of Wednesday,
they will ramp back up to 5-8 ft late in the period. Widespread
showers and thunderstorms are possible Wednesday night as well,
with locally higher winds and seas, along with torrential
downpours and cloud to sea lightning.
LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 300 AM Monday...Expect advisories will be in place into
Friday as strong SW to W winds continue. Conditions will
moderate on Friday night and Saturday as high pressure moves in
from the west.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory until 11 PM EDT Tuesday for AMZ250-252-
254-256.
&&
$$
SYNOPSIS...RGZ
NEAR TERM...REK/RGZ
SHORT TERM...JDW
LONG TERM...REK
AVIATION...REK
MARINE...REK/JDW/RGZ
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1005 PM EDT Mon Apr 3 2017
.UPDATE...
Issued at 1005 PM EDT MON APR 3 2017
First of two broad lines of scattered convection is just entering
our area from the west. Thus far the HRRR has been handling the
trends in convection fairly well through the early evening. That
being said expectations are that the line will weaken and break
up a bit in the north and intensify a bit across the central and
southern portions of the area. Maintained likely to low
categorical PoPs through the remainder of the evening into the
early morning based on radar trends and the HRRR. GOES IR seems to
support this scenario as well with the regional loop indicating
occasional cloud top cooling with the cells in the south as they
pulse in a cyclical fashion and a hint of some warming with cloud
tops along the northern portions of the line as storm cells get
closer to our Blue Grass. Updated the grids for latest thoughts
and to bring grids in line with sfc obs. Also freshened up the
zones for evening wording.
UPDATE Issued at 811 PM EDT MON APR 3 2017
Forecast is generally on track. Did make some adjustments to the
grids for short term trends, such as some temporary clearing.
Otherwise brought hourly temps and dew points in line with recent
observations. Line of convection to our west continues to push
eastward and should be on our doorstep within the next two to
three hours. At present there are generally two broken lines of
activity. The first line moving through central Kentucky is
showing some signs of weakening. HRRR showed something similar and
the more recent runs have generally shown the same thing, except
with some intensification after activity move into our forecast
area. Inherited likely PoPs seemed reasonable so decided to
maintain them along with Isold thunder.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 405 PM EDT MON APR 3 2017
Surface analysis shows a warm front advancing NE across the area
and a few showers and perhaps a storms could pop in the Bluegrass
this evening. This as CAMs continue to indicate this, however not
seeing much developing in the west this hour. The bulk of the
showers and isolated storms will progress east later this evening.
The caveat that remains will be if any instability will can be
seen this evening. In fact, the latest SPC Day 1 risk has pull
the marginal risk out of the outlook. This seems reasonable given
the lack of CAPE to support to environment. Did opt to keep the
CAT POPs as most places will likely measure not the mention the
better height falls this evening. There is good agreement that as
this upper level and surface low eject northeast a dry slot will
move into the region by dawn Tuesday morning.
This will aid is POPs quickly fleeting by Tuesday morning and
perhaps some sun by the afternoon. Decent mixing by Tuesday
afternoon could also lead to some gusty winds in the afternoon of
15 to 20 mph in general. The clearing on Tuesday will lead to a
temperature split overnight Tuesday. However, high clouds will be
on the increase ahead of surface low and upper level trough in the
midwest by Wednesday morning.
.LONG TERM...(Wednesday through Monday)
Issued at 504 PM EDT MON APR 3 2017
There is only one storm system to contend with during the period,
but it`s a doozy, with a 979 mb surface low expected over western
NY state by Thursday night.
A shortwave trough currently over the southwest CONUS will
amplify as it tracks east, phasing with additional troughing to
the north. Surface low pressure in association with it is expected
to start deepening over west TX tonight and Tuesday, and then
track northeast to OH by Thursday, with development then taking
the system further northeast. The circulation around the system is
expected to draw warmer and more humid air north over our region
on Wednesday, before the system`s cold front arrives. At this
point, low level flow is expected to be downslope over at least
the eastern part of the JKL forecast area, which would cut down on
low level moisture, and hence instability. Our western counties
would be less affected by this, and stand the best shot at
thunderstorms and severe weather. In terms of severe weather,
ample shear should be present, and the questionable ingredient is
instability. The area is currently in a slight risk category by
SPC, which seems reasonable.
The cold front should pass through Wednesday evening, with a
relative lull in precip for a short time after it goes through.
However, comma head deep moisture under the upper low should
rotate back into our area late Wednesday night into Thursday, with
light rain and showers redeveloping. Models still differ as to
how quickly it pulls out, and a blend is still being used for the
forecast. It looks more likely that enough cold air will be drawn
in before the precip ends that it will mix with or change to snow
at times. For most of the area, temperatures will be too warm for
accumulation, but the highest elevations near the VA border could
see a bit.
By the weekend, fair weather should return, but we will have a
couple of cold mornings, with frost and/or freezing temperatures
being a threat. Warmer weather should return to start the new
week, as surface high pressure passes to our east and upper level
ridging passes over.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 811 PM EDT MON APR 3 2017
A cold frontal boundary will push through the area tonight.
Scattered showers and a few thunderstorms associated with the
front are moving through western and central portions of the
Commonwealth this evening. The initial wave of this activity
should begin moving into our area from the west around sunset or a
bit after. The initial line is showing some weakening at present.
However, the HRRR did initialize fairly well with the ongoing
activity and also suggests a trend of intensification as it
reaches our area. Consequently did mention some thunderstorms in
the vicinity of each terminal for about a 2 to 3 hour window as
the main line transits our forecast area. Models also advertise a
period of MVFR CIGS through the early morning time frame on
Tuesday. This is associated with some lower cloud bases behind the
front itself. Saw no reason not to follow along with guidance as
this is typically the case. Winds will be generally out of the
south, southwest until the front gets through the area. With FROPA
winds will shift out of the west and become gusty for a few hours
directly behind the front. Winds then slacken a bit through the
remainder of the day Tuesday.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...RAY
SHORT TERM...DJ
LONG TERM...HAL
AVIATION...RAY
Area Forecast Discussion
National Weather Service Melbourne FL
915 PM EDT Mon Apr 3 2017
.UPDATE...
Tonight-Tue...Gradient wind oriented parallel to the peninsula has
delayed a merger of the east/west coast sea breeze boundaries. Some
interaction was likely occurring in north Lake and Volusia counties.
This convection has been shallow as the interaction looks weak and
we`ve lost daytime heating. These showers will diminish or push
offshore before midnight.
The HRRR model has been showing a band of convection dropping down
out of north Florida at varying speeds. We have a slight chance for
showers/storms in the far north just before/after 12z. The GFS is
much less aggressive in dropping the band to the south and hangs up
the remnant moisture band across our northern areas on Tue. There`s
still time to monitor radar and short range model trends to fine
tune the forecast of this feature. Whether the convection occurs
Tue morning, or holds off until daytime heating, the chance for
showers/storms looks to be mainly northward from about Kissimmee to
Cocoa Beach.
Little change planned to the current forecast.
&&
.AVIATION...
Low level southerly flow will keep the boundary layer well mixed so
the prospect for fog is low though LAMP/MOS is highlighting some
stratus toward daybreak. On Tue...winds will veer a bit out of the
S/SW 10-15 knots and gusty turning onshore in a sea breeze during
the mid to late afternoon at terminals south of the Cape. Timing of
shower/storm chances is tricky but generally those that occur are
expected to be northward from KISM-KMCO-KTIX.
&&
.MARINE...
Tonight/Tue...Marginally hazardous boating conditions indicated
offshore north of Sebastian Inlet, due to a moderate-fresh southerly
wind, where a small craft advisory is in effect into Tue morning.
The pressure gradient is only forecast to ease a little into Tue
afternoon, so conditions for small craft operation will remain poor
across all of the waters.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory until 10 AM EDT Tuesday for Flagler Beach
to Volusia-Brevard County Line 20-60 nm-Volusia-Brevard
County Line to Sebastian Inlet 20-60 nm.
&&
$$
Forecasts...Lascody
Impact Wx...Blottman
Area Forecast Discussion...UPDATED
National Weather Service Paducah KY
640 PM CDT Mon Apr 3 2017
.UPDATE...
Issued at 640 PM CDT Mon Apr 3 2017
Updated the AVIATION discussion for the 00Z TAF issuance.
&&
.SHORT TERM...(Tonight through Wednesday night)
Issued at 106 PM CDT Mon Apr 3 2017
While no model is perfectly capturing ongoing convection, wrf and
hrrr data appears a reasonable facsimile. Hrrr swings the action
thru by about 02Z, with thunder threat diminishing thereafter.
Troffy shower threat may linger into/thru the overnight, but Pops
drop markedly.
Synoptic modeling then gives a pause in Pops Tuesday, before
bringing in another circulation system that pinwheels across
the mid Mississippi valley Tuesday night-Wed.
Both systems encounter similar airmasses and we are outlooked by
SPC in a marginal risk svr for both time periods, mainly for
isolated hail/damaging wind threat.
Temps are warm with 70s/50s, but begin to get cooler/damper under
the big trof/Low by Wed night, heading into the long term ptn of
the forecast.
.LONG TERM...(Thursday through Sunday)
Issued at 243 PM CDT Mon Apr 3 2017
The medium range models were in good agreement in the extended
forecast period.
At the beginning of the period, lower mid level heights and cyclonic
upper flow will prevail on Thu, with lingering showers east of the
MS River during the day. Cool northerly flow aloft will continue
just behind a low pressure system, with clearing skies and a
northwesterly breeze at the surface. This will provide unseasonably
cool temperatures on Fri, just like Thu, but with sunshine. Fri
morning, if the wind lets up a bit, there may be patchy frost across
parts of southeastern MO and southern IL, with temperatures in the
30s over much of the area. Sat morning, frost should be more
widespread across much of the region, especially in the north, due
to lighter winds.
Afternoon highs are expected to rebound about 8-10 degrees by Sat,
with a surface ridge axis passing through the PAH forecast area
around noon. Southwesterly flow aloft and increasing southerly or
south southwesterly low level flow Sun will encourage even warmer
highs in the lower half of the 70s Sun and Mon. This will be in
advance of deeper moisture and lift in our region associated with a
vigorous low pressure system moving near the Canadian border. Thus,
showers and possibly tstms will return to the forecast Mon.
&&
.AVIATION...
Issued at 640 PM CDT Mon Apr 3 2017
With the passage of a front, MVFR cigs/vsbys and TSRA at
KPAH/KOWB early, possible MVFR cigs at KEVV/KOWB overnight,
otherwise VFR conditions. Gusty southwest winds up to 18-20 knots
will subside to AOB 10 knots after 06-07Z.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
LONG TERM...DB
AVIATION...JP
Area Forecast Discussion
National Weather Service Mount Holly NJ
953 PM EDT Mon Apr 3 2017
.SYNOPSIS...
Low pressure over Missouri will intensify as it moves into southern
Ontario Tuesday morning. The associated warm front will move north
into our region Tuesday with the cold front heading east, off
the coast Tuesday evening. Weak high pressure briefly follows on
Wednesday. Another intensifying low in the Ohio Valley Wednesday
night becomes quite strong as it tracks across Pennsylvania on
Thursday. It then drifts northeast over New England Friday and
Saturday. High pressure eventually builds in from the west by
Sunday.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
An upper air analysis this evening showed a trough from the Midwest
to the Ohio and Tennessee valley`s. On the east side of this trough,
several areas of focused 850 mb warm air advection is occurring
including into our region. Meanwhile, surface low pressure is
centered near Chicago with a warm front southeastward to North
Carolina.
As we go through the overnight hours, a southerly low-level jet on
the order of 40-55 knots is forecast to overspread our area. This
will drive increasing isentropic lift/ascent along with theta-e and
warm air advections. The main forcing looks to be focused after 06z.
It is during this time where much of the model guidance indicates an
axis of increasing instability overspreading much of the area. This
should be mostly elevated especially with a northern extent, however
with a southerly flow temperatures may hold steady or rise some
(after an initial drop due to lower dew points and rain to start)
toward daybreak helping to boost some instability. As a result, we
maintained isolated thunderstorms in the forecast during the late
overnight hours.
As the moisture increases and deepens, embedded convective elements
will contribute to some areas of heavier rainfall. Given the low-
level jet though, motion of the rain and any embedded thunder should
be quick moving. The Flood Watch however remains as is (see the
hydrology section below for more details).
The hourly temperature, dew point and wind grids were adjusted based
on the latest observations, then the LAMP/LAV guidance was blended
in for the next few hours. No major changes were made to the low
temperatures at this time, and the PoPs were adjusted based on input
from the HRRR and radar/observational trends. The mention of the
isolated thunder was delayed a few hours.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
Widespread showers should quickly depart most of our area during the
early morning hours Tuesday as a warm front lifts across the area
and the robust southerly low-level jet departs. Much of the area
should get into the warm sector for a time, before a cold front
sweeps through by about 18z. Boundary layer cooling looks to be
delayed though as we await a surface trough or secondary cold front
later in the afternoon.
The forecast soundings indicate drying occurs with the initial wind
shift, however some instability is also present through the
afternoon. It will be a race between drier air and lingering lift
and instability. How much sunshine breaks out during mid to late
morning into the early afternoon will determine how much instability
can be realized. As of now, looks like CAPE on the order of 500-1000
j/kg develops along with the K-Index approaching 30-35 and LI`s
going negative. Therefore, we expect some showers and a few
thunderstorms from late morning into mid afternoon. While severe
thunderstorms are not anticipated, the forecast soundings are
hinting at an inverted-v signature due to efficient boundary layer
mixing in the afternoon which may result in locally strong wind
gusts with some thunderstorms.
The showers/thunder are expected to end toward the late afternoon as
drier air moves in. Winds during the afternoon look to gust to
around 35 mph at times more many areas given enough boundary layer
warming and vertical mixing.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
**Potentially the biggest impact storm of the past 10 days for
our area Thursday**
500 mb: Brief ridging occurs Tuesday night into Wednesday ahead of
a developing large closed low that reaches western PA late
Thursday, New England Friday and then rapidly weakens over the
Maritimes next weekend. Very strong and very warm ridging
follows early next week.
Temperatures: Calendar day averages approximately 10 degrees
above normal Wednesday, maybe again Thursday, near normal
Friday - Sunday, then warming to 5 or 10 degrees above normal
Monday.
Forecast basis: the 330 PM forecast unless otherwise noted was
a 50 50 blend of the 12z/3 GFS/NAM MOS Tuesday night - Wednesday
night, 12z/3 MEXMOS blended 50 50 with the 12z/3 EC 2m t/td
Thursday and thereafter the 15z/3 WPC guidance elements Thu night
- Mon.
The dailies...
Tuesday night...from the mid shift: Westerly flow in wake of
cold fropa that occurs late in the day Tuesday will promote
drying across the region. a slight chance of showers early in
the evening I-80 north. Breaks in the clouds should develop in
the evening although CAA stratocu may yield a return of clouds
later in the night (primarily N/W of the Fall Line). With the
double-barrel low positioned to our north and northeast, the
pressure gradient should be strong enough over the forecast area
to continue a breeze through the night, especially with CAA
helping to keep the boundary layer mixed overnight.
Wednesday...begins the third and last heavy rain event this
week (31st, 4th and this last one focused on Thursday the 6th;
we started this wet episode with an event on the 28th, so
ultimately this should be the 4th and last in this series over
the past 10 days). Partly sunny during the day with a west to
northwest wind gusting 20 mph and above normal temps in the 60s
to around 70, but cooling sea breezes developing during mid or
late afternoon along the coasts. Showery rains develop from
southwest to northeast later at night with min temps 10 to 15
degrees above normal.
Thursday...STORMY! Widespread moderate to locally heavy showery
rains with a band or two of thunderstorms, some of which may be
severe on the Delmarva into S NJ between 6 AM and 2 PM, when TT
rise into the lower 50s, MLC increases to 500J or greater and
very strong 0-3K and 0-6K shear develops, along with SWI subzero.
These storms will probably be remnants of potential strong or
SVR tstms racing newd from the Carolinas and e VA. For our area:
Damaging winds would be the primary threat but a conditional
tornadic threat may exist with models showing backed flow near
the warm front/ negatively-tilted trough axis.
Thursday night...There may be a temporary lull in the showery
pattern Thursday night once the surface low passes to our north
into NYS.
Friday...Upper low crossing the area should yield periods of wrap
around showers and sprinkles, most common nw of I-95. There is
a small chance mixed with wet snow over the Poconos and extreme
northwest NJ above 1500 feet.
Saturday...Considerable cloudiness then becoming partly sunny
by days end.
Saturday night...Possible radiational cooling. Small chance frost
advisories may be needed for our MD and DE counties where the
growing season is already active. However, as of this afternoons
forecast... chances are small.
Sunday...Looks nice.
Monday...Warm air advection. Eventually possibly a period of
showers.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Through the overnight...VFR ceilings lowering to MVFR late this
evening, then to IFR overnight as periods of rain overspreads
the region. Some of the rain will be heavier at times mainly
after 06z. A few thunderstorms are possible after 06z, however
given the low coverage at this time a mention is not included in
the TAFs. Southeasterly winds around 10 knots with some local
gustiness at times, however southerly winds around 2000 feet are
expected to increase to 40-50 knots ahead of a warm front. As a
result, low- level wind shear is included starting later this
evening and continuing through the overnight.
Tuesday...IFR to MVFR to start as showers taper off for a time for
most areas. As a warm front lifts northward conditions should
improve to VFR by midday. Some additional showers and isolated to
scattered thunderstorms should develop from near midday through mid
afternoon, with brief MVFR/IFR conditions. South to southwest winds
around 15 knots with gusts to around 30 knots (especially in the
afternoon), becoming westerly toward late afternoon.
OUTLOOK...
Tuesday night...VFR with clearing skies during the evening. W
winds with scattered gusts of 15 kt. Confidence: above average.
Wednesday...VFR. W-NW winds gusting 15 to 20 possibly 20 kt
early becoming light variable late in the day. Confidence: above
average.
Wednesday night and Thursday...VFR in the evening, lowering to MVFR
and IFR as the next round of rain arrives. Rain will be heavy
at times on Thursday with a chance of thunderstorms, especially
in southern terminals. LLWS possible late Wednesday night and
Thursday morning before a warm front arrives. Similar to Tuesday.
Winds will probably gust 25 to 30 kt at times due to rapidly
lowering sfc pressure and strong inflow. Winds in the warm
sector Thursday afternoon on the Delmarva could gust 35 to 40
kt. Confidence in these values are low this far in advance?
Otherwise Confidence: above average on the primary scenario
described above.
Thursday night and Friday...A brief lull in the precip may
develop Thursday night. There would be an opportunity for
improvement to VFR during this time. Chance of showers on
Friday, which could result in localized MVFR conditions.
southwesterly winds 10-15 kt with gusts to 25 kt, especially
coasts. Confidence: average.
Saturday...VFR cigs to start, then probably becoming VFR clear
by night. Northwest winds gust to 25 kt during the day.
Confidence: average.
&&
.MARINE...
The Small Craft Advisory for Delaware Bay has been started early as
southeasterly flow (funneling direction) and resulting in gusts to
around 25 knots already this evening.
Small Craft Advisory remains across the area overnight through
Tuesday. Winds will increase overnight and continue into the day
Tuesday with gusts of 25-30 knots expected. Winds could gust around
35 knots for a brief period early Tuesday morning, which may be able
to be covered by Special Marine Warnings since it may coincide with
convection. Winds may diminish some Tuesday afternoon, but seas will
remain elevated through the day.
Rain will spread across the are tonight through early Tuesday
morning. There could be a break in shower activity during the
morning, but additional showers and some thunderstorms may be
possible during the afternoon Tuesday.
OUTLOOK...
Tuesday night...SCA was extended into Tuesday night for the De
waters. Winds decrease below 25 kt late.
Wednesday...Winds and seas likely below SCA thresholds by Noon
and no headlines anticipated...though we may need to advise for
hazardous 5 foot seas during the morning.
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 some gale force wind transfer of 35-40 kt.
Special marine warnings may also be needed where bands of showers
and embedded thunderstorms imply concentrations of sfc wind
momentum transfer.
Friday...VFR cigs, with possible brief MVFR conditions possible in a
shower. Southwest wind gust 15 to 25 kt.
Saturday...VFR cigs clearing at night. Northwest wind gust 25
kt.
&&
.HYDROLOGY...
A Flood Watch is in effect overnight and continues through the day
on Tuesday for central and northern NJ and for northeast PA. This
NNJ area will be more susceptible to flooding with soils saturated
and creeks and streams running high after recent heavy rainfall.
Additionally, the majority of model guidance targets the highest QPF
(1-2") in the watch area with the primary risk area, NNJ north of I-
78.
There is a potential for our third and heaviest rain event in
just a week`s period to occur on Thursday. One to two more inches
is possible in 12 hours. The very wet antecedent conditions
from earlier in the week will prime our region for additional
flooding. MMEFS guidance shows some risk for minor or moderate
flooding in our larger NNJ basins to extend into the weekend if
the second and third heavy rainfall events materialize as
currently outlooked.
&&
.TIDES/COASTAL FLOODING...
Since surface pressure will lower to about 985 MB near the surface
low in PA, the associated tidal departures will increase
considerably and some of our guidance is suggesting minor flood
thresholds to be exceeded during the late afternoon high tide cycle
along the NNJ Atlantic coast. 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.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch through Tuesday evening for PAZ054-055-062.
NJ...Flood Watch through Tuesday evening for NJZ001-007>010-012>015.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ450>455.
Small Craft Advisory until midnight EDT Tuesday night for
ANZ430-431.
&&
$$
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
912 PM MDT Mon Apr 3 2017
.UPDATE...
Issued at 910 PM MDT Mon Apr 3 2017
Based on continued HRRR runs and NAM runs, have upgraded advisory
to winter storm warning for lower elevations of the Spanish Peaks
region. Also added eastern Las Animas to the advisories. /Hodanish
UPDATE Issued at 630 PM MDT Mon Apr 3 2017
Based on latest HRRR runs and 3 km NAM guidance, added Pueblo and
E Fremont counties to winter weather hilites. Precip in these
regions should change to snow between 1 am and 3 am early Tuesday
morning. The snow could be quite heavy as a band of heavier
precip is likely going to develop from roughly the El Paso/Pueblo
county line down towards south of Walsenburg, and this heavier
band will push east. Some of the guidance is showing rather very
heavy snowfall amounts over the lower elevations in the above
mentioned areas, but believe melting due to the warm ground will
hamper accumulations.
I am quite concerned that if the snow falls heavy enough, we
could see 2-3" of very slushy snow on ALL of the roadways which
would make travel very difficult tomorrow morning. /Hodanish
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 312 PM MDT Mon Apr 3 2017
Satellite images this afternoon showing the upper level trof over
NV, with mstr and clouds spreading across CO. The upper trof is
expected to move into the Four Corners area by about 06Z, and then
close off a low that should track eastward across extreme northern
NM through midday Tue and then into OK thru the afternoon. At the
same time, an upper trof over western MT and ID is expected to drop
southeast into WY tonight, phasing with the other upper trof.
Currently there is some convective pcpn over southern portions of
the forecast area, as expected. The HRRR shows pcpn increasing
early this evening acrs the San Juan and La Garita mtns, and
possibly across the southern San Luis Valley. Otherwise, the HRRR
shows mainly just some isold to possibly scattered pcpn over the
rest of the area through around 03Z. The HRRR also shows a front
working its way south thru the southeast plains this evening,
bringing gusty northeast to east sfc winds, and then develops more
widespread pcpn acrs the plains behind this front thru 06Z...mainly
from around Highway 50 and southward. Pcpn also increase before
midnight over the rest of the mountain areas, but northern Pueblo
and El Paso counties are looking fairly dry thru midnight. Pcpn
then starts to spread north into these area after midnight and
continues to be widespread acrs the rest of the plains, eastern
mtns, central mtns and the Pikes Peak and Teller county areas. Both
the HRRR and NAM are showing pcpn chances decreasing in the late
night hours over about the southern two-thirds of the San Luis
Valley. The best chances for accumulating snow look to be from
around 5000 ft and higher, with areas below 5000 feet probably
seeing a little bit of snow or a mix of rain and snow.
The models are showing a decrease in the amount of pcpn over El Paso
and Teller counties early Tue morning, especially southern portions,
with gusty north winds. Although snow will still continue over the
central mtns as well, that area will also likely see a decrease in
the morning hours. The highest impact areas Tue morning are
expected to be acrs the southeast plains from around Highway 50 and
southward and along the Wet mtns and Sangres, especially the
southern Sangres. The far southeast plains will likely see a mix or
rain and snow, but some locations may just see rain. However,
locations along the southern I-25 corridor are expected to see snow,
and the fairly strong and deep northeast winds will likely focus the
best accumulations in Huerfano and western Las Animas counties,
including Raton pass. Central portions of the San Luis Valley may
just see some light accumulations Tue morning, but areas near the
valley edges may see high amounts.
As the upper low starts to pull away from the area Tue afternoon,
pcpn chances over the San Luis Valley will decrease or mostly end.
They will also decrease over the southwest mountains and the eastern
mtns, with only some light additional accumulations possible. The I-
25 corridor will also see a decrease in pcpn, but the far southeast
plains will continue to see pcpn. Temps on Tue are expected to
reach highs in the mid 30s to around 40 acrs the southeast plains
and the San Luis Valley, while the Upper Arkansas River Valley
should mostly see 30s.
.LONG TERM...(Tuesday night through Monday)
Issued at 312 PM MDT Mon Apr 3 2017
Tuesday night...Models indicate that the upper low pressure system
will be located over the Panhandles Tue eve, and will quickly exit
to the east through the night. Therefore, rain and snow is forecast
to rapidly diminish across the forecast area by midnight, with cool
and dry nw flow settling in by Wed morning. Assorted winter wx
highlights for the eastern and central mts as well as for the Palmer
Dvd last until midnight, which may be a bit long, but for now will
maintain. Expect a cold night with min temps in the teens and 20s
for most locations.
Wednesday through Friday...High pressure ridging across the region
will provide for about 3 days of dry conditions and gradually
warming temps. Highs in the 40s and 50s on Wed, will climb into the
50s on Thu, then into the 60s to mid 70s for Fri as west-southwest
flow aloft begins to increase.
Saturday through Monday...A lot of variety when it comes to model
solutions for the weekend and Monday. EC and GFS both indicate a
longwave trough over the Pacific pushing onshore, and increasing
moisture across the Great Basin and western Colorado by Fri eve. The
GFS paints a quick-hitting system for Sat through Sun morning, then
drying out on Mon. The EC, on the other hand, drops a slightly
stronger disturbance further south on Sun, prolonging pcpn across
the forecast area well into Mon. Given the variability, went with
the extended procedure output of isolated to scattered pops over the
higher terrain, more focused on the ContDvd over the weekend. Look
for a very warm Sat with highs in the 60s for the high valleys, and
70s to near 80F for the e plains. Max temps cool about 5 to 10
degrees for Sun, then another 5 to 10 degrees for Mon. Moore
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 312 PM MDT Mon Apr 3 2017
VFR conditions are expected at KCOS thru probably late evening.
Some showers may move into the VCNTY of KCOS late this evening, but
chances for pcpn increase overnight, especially after 05Z with CIGS
lowering into MVFR or even IFR and remaining that way thru midday
Tue, and then improving some in the afternoon.
KPUB should have VFR conditions thru mid to late evening, and then
showers may move into the VCNTY and CIGS will lower into the MVFR
category. By about 06Z, chances for showers will be high thru midday
Tue and CIGS/VSBY may at times lower into the IFR category,
conditions should improve during the afternoon hours.
KALS may see showers in the area this afternoon, but chances
increase this evening and CIGS will lower by mid to late evening.
Chances for snow in the VCNTY look fairly high by around 04Z and
continuing thru much of the night. By 12Z Tue chances for pcpn
should decrease. MVFR conditions are expected from around 04z thru
midday Tue with improving conditions in the afternoon.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight MDT Tuesday night for
COZ058>063-076-077-081-084.
Winter Storm Warning until midnight MDT Tuesday night for
COZ072>075-078>080-082.
Winter Weather Advisory until noon MDT Tuesday for COZ069>071.
Winter Storm Warning until midnight MDT Tuesday night for COZ087-
088.
Winter Weather Advisory from 3 AM Tuesday to midnight MDT
Tuesday night for COZ094.
Winter Weather Advisory until noon MDT Tuesday for COZ083-086.
Winter Weather Advisory until 6 PM MDT Tuesday for COZ065>067.
Winter Storm Warning until 6 PM MDT Tuesday for COZ068.
&&
$$
UPDATE...HodanishSHORT TERM...28 LONG TERM...MOORE AVIATION...28
Area Forecast Discussion
National Weather Service Raleigh NC
1120 PM EDT Mon Apr 3 2017
.SYNOPSIS...
A potent upper level low lifting out of the southern Plains will
cross the region overnight and Tuesday. Weak high pressure will
build briefly over the area Tuesday night and early Wednesday,
before another low pressure moves through the region Wednesday night
and Thursday.
&&
.NEAR TERM /OVERNIGHT/...
As of 1120 PM Monday...
Have adjusted the forecast to depict a lull in the precip as
atmosphere has stabilized in wake of the departing convective band
that crossed central NC late this afternoon/early this evening. Rain
has cooled late evening temperatures in the 60-65 degree range.
Still appears that we may see another round of convection later
tonight as main trough aloft and attendant sfc front cross the
region. While low level buoyancy is lacking, plenty of kinematics
remain across the coastal plain with effective bulk shear 40-50kts.
Low level air mass expected to destabilize in response to mid level
lapse decreasing in response to s/w aloft. The destabilization and
approach of the sfc front should trigger scattered convection with
an isolated low topped supercell possible, suggested by good turning
in the lowest 3k ft. Overall convective coverage no worse than
scattered and primarily confined to locations east of highway 1,
more so I-95 and east. Will note that successive runs of the HRRR
have trended with weaker intensity and less coverage.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 340 PM Monday...
The effective front will have moved offshore by early Tuesday,
while the main cold front lags west of the mountains and doesn`t
really push into the area until early Wednesday. Thus westerly flow
and an airmass characterized by low level thicknesses of 1380m will
result in highs around 80, with wind gusts to 25-30kt. The synoptic
cold front is forecast to push into NC from the north Wednesday
night, but the airmass change is delayed and lows will be mild in
the lower 50s.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
As of 315 PM Monday...
Wed-Thu Night: Dry conditions are expected in the wake of the cold
front Tuesday night through at least noon Wed. Cloud cover will
increase from the SW during the day as upstream convection outruns
the primary forcing (upper level low and associated cold front) into
GA/SC (similar to today). The aforementioned convection is progged
to propagate downstream into W/SW portions of NC by mid/late
afternoon, affecting the SW Piedmont by 21-00Z, progressing NE
through the remainder of central NC between 00-06Z Wed evening/
night. Expect increasing cloud cover to result in slightly cooler
temps in the W/SW Piedmont, with highs ranging from the mid 70s
(W/SW) to lower 80s (SE). A short lull in precipitation will be
possible in the wake of the first round of convection Wed night,
however, additional activity will likely accompany the cold front
progressing eastward into the region Thu morning as shortwave energy
rounding the base of the upper level low (tracking NE from the
central MS river valley to the lower Great Lakes) ejects NE into the
Carolinas 12-18Z Thu. Expect lows Wed night in the mid 50s (W) to
lower 60s (E). Although diurnal timing of the frontal passage will
be poor, strengthening deep layer forcing in the presence of steep
mid-level lapse rates (assoc/w an elevated mixed layer progged to
advect into the region from the SW) may compensate enough to support
thunder along with a potential for severe weather. Expect precip to
end from west-east by early afternoon as the cold front crosses the
area, however, scattered showers could re-develop late Thu afternoon
(prior to the onset of CAA) as the upper level low tracks east
across the northern Mid-Atlantic. Strong westerly winds will develop
Thu afternoon as the MSLP gradient tightens over the region,
becoming sustained at 15-25 mph with frequent gusts to 35mph.
Although the equilibrium level will barely extend up to the
-10C isotherm Thu aft/eve (suggesting thunder is unlikely), a low-
end potential for damaging winds cannot be ruled out given steep 0-
3km lapse rates and strong westerly flow in the low/mid levels.
Expect the potential for showers to end within a few hrs of sunset
Thu evening as a drier airmass advects into central NC and upper
level forcing shifts to the Mid-Atlantic/Carolina coast. Highs Thu
in the 60s to 70F, warmest E/SE. Lows Thu night will be driven by
CAA, in the low/mid 40s, coldest NW.
Fri-Mon: Shortwave energy digging SE on the western periphery of the
upper level low along progressing slowly offshore the Mid-Atlantic
coast may result in a small potential for showers along/east of I-95
in the NE Coastal Plain Fri afternoon. Otherwise, expect dry/cooler
conditions with highs ranging from the mid 50s (NW) to near 60F
(S/SE). The latest 12Z long range guidance suggests dry conditions
will prevail this weekend and early next week as an upper level
ridge builds over the eastern US. Expect high temperatures to
gradually rebound over the weekend, reaching the 70s again by Mon.
Although lows may dip into the upper 30s Fri night, a very dry
airmass and W/NW breeze will likely preclude a potential for frost
Sat morning. Winds will decrease by Sat night, and some potential
for frost may exist Sunday morning, depending on the degree of
airmass modification on Sat. -Vincent
&&
.AVIATION /00Z TUESDAY THROUGH SUNDAY/...
As of 730 PM Monday...
24-Hour TAF period: A line of showers and thunderstorms is currently
moving through Central NC at 00Z. Rain has largely ended or will end
shortly in the Triad (KINT and KGSO). The heaviest rain/thunder has
just passed through KRDU and KFAY and will move through KRWI within
the hour. As a result, visibilities have improved at the western
terminals and will continue to do so as rain tapers off to the east.
Still expect a period of visbys around 1SM-2SM at KRWI when the
storms move through. Confidence on how long a return to VFR cigs
will last, as many of the models indicate a chance for a period of
cigs around 1-2 kft overnight. Dry air will take over from west to
east around daybreak, resulting in a return to VFR conditions. Also,
expect winds to remain strong and gusty through the period,
initially south-southeasterly then veering around to more west-
southwesterly overnight. -KC
Looking ahead: VFR conditions are expected to last through Wed
morning. Another low pressure system now over the Western U.S. will
strengthen over the central part of the country then track to the
ENE, dragging a cold front with sub-VFR conditions ahead of it into
central NC starting Wed afternoon, with these poor aviation
conditions persisting through Thu with numerous showers and storms
and gusty winds. VFR conditions should return Thu evening, although
winds will remain brisk and gusty through Thu night. VFR conditions
likely Fri/Sat as the storm system moves off the East Coast. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...WSS
NEAR TERM...WSS
SHORT TERM...SMITH
LONG TERM...Vincent
AVIATION...KC/Hartfield
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Tuesday)
Issued at 308 PM CDT Mon Apr 3 2017
19Z water vapor imagery Shows the upper low slowly lifting northeast
into IL while a couple additional shortwaves dig southeast through
the intermountain west, one over southern NV and the other over
western MT. At the surface, an area of low pressure was noted over
the middle MS river valley with a broad area of high pressure over
the northern plains.
The forecast for tonight calls for a break from the rain before the
next round moves in on Tuesday. There is a weak perturbation
propagating across NEB with an area of showers across north central
NEB. The HRRR thinks there could be a few showers along the state
line this evening so have kept a small POPs across the northern
Counties this evening. Visible imagery shows a Cu field across
north central KS within an area of low level convergence. So while
the southern extent of the shower activity across NEB as retreated,
think there is still some potential for an isolated shower. Lows
tonight should be in the lower and middle 40s aided by some partly
cloudy skies.
For Tuesday, the next upper low if progged to become better
organized with PVA and upper level difluence increasing through the
afternoon. The expectation is for isolated showers in the morning to
become more widespread by the afternoon as the dynamics improve
through the day. Models are continuing to show the track of the
surface low to be just southeast of the forecast area keeping a
north and east wind over east central KS. As a result, the models
keep the stronger instability to the south of the forecast. Although
some elevated instability of a couple 100 J/kg is still possible
over east central KS. So there should be some thunder with the
showers, but any severe threat looks to remain south of the area.
Highs Tuesday should be cooler with clouds and precip likely through
the afternoon. So have kept the forecast for middle and upper 50s
going for much of the area. Parts of Anderson CO could sneak into
the lower 60s.
.LONG TERM...(Tuesday night through Monday)
Issued at 308 PM CDT Mon Apr 3 2017
The final major upper low forecast to track directly over northeast
Kansas Tuesday night and Wednesday bringing a strong deformation
zone and band of rainfall over northeast Kansas. Forecast totals are
from a half to in upwards of an inch across the CWA, resulting in
total qpf amounts tomorrow through Wednesday from half of an inch to
an inch and a half of rainfall. Could easily see higher totals with
any convective driven rainfall. And given the continuous days of
rainfall, the potential for flooding continues to increase.
Highest totals were concentrated towards east central KS where model
guidance is fairly similar between the NAM, ECMWF, and Canadian
models with the upper low centered a bit further south. Wednesday
morning will overall be a wet and cool afternoon with highs in the
50s. Precipitation gradually clears by the evening with dry
conditions returning for most of the week. A 1028 mb sfc high
spreads southward in the systems wake Thursday and Friday morning,
bringing near freezing temps to the region. Current forecast lows
has middle 30s in the 34-38 range so have mentioned the potential
for patchy frost.
Shortwave ridging builds in the central conus Thursday onward as the
next upper trough slowly deepens off the western CONUS. Towards the
sfc, induced troughing over the western high plains returns the
southerly flow and warmer temperatures. Highs in the 70s are
expected Saturday and Sunday with sunny skies and winds gusting in
upwards of 20 mph. As the upper trough deepens as it swings over the
northern plains, a frontal boundary will bring back
chances for showers and thunderstorms as early as Sunday
afternoon.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 629 PM CDT Mon Apr 3 2017
VFR conditions are expected through the rest of the afternoon and the
first half of tonight, with MVFR cigs overspreading the area
towards sunrise and persisting through the day with periods of IFR
conditions. Aside from some isolated light showers towards MHK
this evening, the next chance of rain arrives during the day
tomorrow, with the better chance of rain coming after 18-21Z
tomorrow. Patchy fog may also develop tonight ahead of the low
clouds, but confidence was not high enough to mention in the TAFs.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Wolters
LONG TERM...Prieto
AVIATION...Skow
Area Forecast Discussion
National Weather Service Albuquerque NM
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
&&
.AVIATION...
18Z TAF CYCLE
Closed upper low moving eastward through northeast NM this
afternoon and into west TX after 05/00Z. Areas of mt obscurations in
MVFR to IFR cigs/vsbys in precipitation/br/fg and isold tstms will
prevail mainly northeast of a Dulce to KABQ to KCVN line through
05/0Z. Lcl LIFR/VLIFR condtions are likely across far northeast NM
through approximately 04/23Z including KRTN and KCAO. Scattered snow
showers will continue in the northern mountains btwn 05/00Z-05/06Z.
Strong north winds will push southward along and behind a backdoor
cold front through the eastern plains during the afternoon and early
evening. A dry north to northwest flow aloft moves in after 05/06Z.
33
&&
.PRELIMINARY POINT TEMPS/POPS...
Farmington...................... 21 59 29 68 / 0 0 0 0
Dulce........................... 19 55 23 64 / 20 0 0 0
Cuba............................ 22 54 28 64 / 10 0 0 0
Gallup.......................... 17 60 21 69 / 0 0 0 0
El Morro........................ 18 58 21 67 / 0 0 0 0
Grants.......................... 19 60 22 69 / 0 0 0 0
Quemado......................... 24 61 31 70 / 0 0 0 0
Glenwood........................ 32 72 34 78 / 0 0 0 0
Chama........................... 14 49 21 58 / 70 0 0 0
Los Alamos...................... 26 53 35 63 / 20 0 0 0
Pecos........................... 24 53 32 62 / 50 0 0 0
Cerro/Questa.................... 16 50 22 59 / 60 0 0 0
Red River....................... 16 38 19 51 / 70 0 0 0
Angel Fire...................... 18 39 18 51 / 70 0 0 0
Taos............................ 16 51 23 61 / 60 0 0 0
Mora............................ 20 51 29 59 / 70 0 0 0
Espanola........................ 25 59 32 69 / 30 0 0 0
Santa Fe........................ 26 54 35 64 / 30 0 0 0
Santa Fe Airport................ 24 58 30 68 / 20 0 0 0
Albuquerque Foothills........... 32 60 39 70 / 5 0 0 0
Albuquerque Heights............. 33 61 38 72 / 0 0 0 0
Albuquerque Valley.............. 29 63 34 74 / 0 0 0 0
Albuquerque West Mesa........... 32 62 37 72 / 0 0 0 0
Los Lunas....................... 29 64 34 74 / 0 0 0 0
Rio Rancho...................... 31 62 37 72 / 5 0 0 0
Socorro......................... 34 65 38 75 / 0 0 0 0
Sandia Park/Cedar Crest......... 25 54 31 65 / 10 0 0 0
Tijeras......................... 24 55 30 66 / 10 0 0 0
Moriarty/Estancia............... 23 57 28 68 / 10 0 0 0
Clines Corners.................. 23 56 31 65 / 20 0 0 0
Gran Quivira.................... 28 57 36 67 / 0 0 0 0
Carrizozo....................... 31 62 37 71 / 0 0 0 0
Ruidoso......................... 31 58 34 66 / 0 0 0 0
Capulin......................... 22 42 25 52 / 40 5 0 0
Raton........................... 23 48 26 59 / 30 5 0 0
Springer........................ 24 51 27 61 / 30 0 0 0
Las Vegas....................... 22 52 28 62 / 50 0 0 0
Clayton......................... 28 46 30 59 / 30 0 0 0
Roy............................. 26 49 28 61 / 20 0 0 0
Conchas......................... 32 59 36 67 / 20 0 0 0
Santa Rosa...................... 31 61 35 69 / 20 0 0 0
Tucumcari....................... 31 63 34 70 / 20 0 0 0
Clovis.......................... 32 61 36 72 / 10 0 0 0
Portales........................ 33 62 37 73 / 10 0 0 0
Fort Sumner..................... 33 62 36 72 / 10 0 0 0
Roswell......................... 35 66 37 78 / 0 0 0 0
Picacho......................... 33 61 38 73 / 0 0 0 0
Elk............................. 30 60 35 71 / 0 0 0 0
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 10 PM MDT this evening for the following
zones... NMZ510-512>515-527.
High Wind Warning until 6 PM MDT this evening for the following
zones... NMZ524-526-536-538>540.
Winter Weather Advisory until 10 PM MDT this evening for the
following zones... NMZ511-516.
Wind Advisory until 6 PM MDT this evening for the following zones...
NMZ507-521-525.
&&
$$
11
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
341 PM CDT Tue Apr 4 2017
.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 18Z TAFs...
Concerns
- MVFR clouds today
- Rain starting tonight w/ t-storms possible late into early Weds
- Cigs lowering to IFR and possibly LIFR
- Increasing northeasterly winds
- Mixed precipitation near RFD
Aviation concerns initially are limited, but ramp up considerably
later tonight and through the day Wednesday and even into
Thursday. MVFR clouds will continue to stream southward this
afternoon in wake of departing low pressure. High pressure behind
this low will nose in from the northwest and will shift winds to
north-northeast through tonight while the clouds then slowly lift.
Focus will turn to a strong upper low across the Texas panhandle
that will shift to the Great Lakes region Wednesday. Expect a band
of showers to break out ahead of this low tonight. Instability is
limited initially, but there could be a few thunderstorms late
tonight into early Wednesday. The main push with this first batch
of precipitation will be through midday. Snow may mix in near KRFD
but it will be rain most areas and no accums are expected.
Surface low pressure will strengthen through the period and shift
to central Illinois Wednesday afternoon. Expect northeast winds to
respond with gusts in the afternoon in the 30s. Expect off and on
rain through the day.
For the flying radar screen: Expect to see snow falling in some
areas as early as later Wednesday evening, but will save those
details for a future discussion.
KMD
&&
.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 Marquette MI
358 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 18Z TAFS through 18Z Wednesday afternoon)
Issued at 130 PM EDT TUE APR 4 2017
Drier air mass that has spread over w and central Upper MI this
morning will largely remain in place during this fcst period,
allowing VFR conditions to continue at KIWD/KCMX/KSAW. Some stratocu
is expected to develop Wed morning, but cloud bases should be above
4000ft.
&&
.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...Rolfson
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Topeka KS
318 PM CDT Tue Apr 4 2017
.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 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1215 PM CDT Tue Apr 4 2017
A very active taf period will result in various flight conditions.
MVFR ceilings may lift later this afternoon although drop back
down to MVFR later this evening. Scattered showers will be likely
this afternoon, but more widespread rainfall moves in this
evening. There may be IFR ceilings after midnight especially at
TOP/FOE. Periods of moderate to heavy rainfall is possible during
the overnight. Late in the period conditions may improve as the
rain moves off to the east.
&&
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 7 PM CDT this evening through Wednesday
afternoon for KSZ010>012-021>024-026-035>040-054>056-058-059.
&&
$$
SHORT TERM...Sanders
LONG TERM...Baerg
AVIATION...Sanders