Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/02/17
Area Forecast Discussion
National Weather Service Charleston SC
923 PM EST Wed Mar 1 2017
.SYNOPSIS...
A cold front will cross the region tonight. High pressure will then
return into early next week. Another cold front could impact the
area for the middle of next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
A well defined squall line extending from the North Carolina
coastal plain southwest through the South Carolina Midlands and
into southern Alabama continues to march east at around 30
knots. The line is currently timed to reach the inland zones
between 12-2 am and the coast 3-5 am. The pre-frontal environment
remains weakly unstable with MLCAPE 500 J/kg and lifted indices
as low as -4C. Although surface based instability will continue
wane with time, RAP analysis shows the squall is aligned with a
narrow corridor a steep mid-level lapse as low as 7-7.2 C/km.
This should be enough to maintain the line all the way to the
coast while slowly weakening. Still can not rule out an isolated
severe tstm across far inland areas, especially as the line
encounters a tongue of slightly higher dewpoints left over from
an earlier passage of the resultant sea breeze, but generally
think storms will remain sub-severe overnight as the line
pushes across the area.
For the late evening update, increased pops to 80-100% (highest
inland) and made minor adjustments to dewpoints, hourly
temperatures and winds. Lows from the upper 50s inland to the
lower 60s along the Georgia coast look on track, but may be a
bit too cool across the far south if the latest RAP verifies.
However, with the convective line expected to clear this area
prior to sunrise, am hesitant to increase lows there with this
forecast cycle.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
A cold front will be pushing offshore Thursday morning with some
lingering showers and breezy conditions. Drier and cooler high
pressure will then build in the wake of the front and persist
through the end of the week. Temperatures will be the main concern,
as they will be significantly cooler than recent days, especially on
Saturday. Lows on Friday and Saturday mornings will be in the 30s
most locales away from the coast, and some frost will be possible,
although it may be too dry Friday morning and too dry/windy Saturday
morning. Can`t rule out some freezing temperatures in the normally
colder rural inland spots Saturday, mainly in SC. Given that we have
resumed our Frost/Freeze program as of today, Frost Advisories
and/or Freeze Watches/Warnings will be issued as conditions
warrant.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
High pressure over the mid-Atlantic states Sunday will slide off the
coast Monday and persist into Tuesday. Models continue to show a
cold front crossing the area towards the middle of the week, however
there are still significant timing differences. Regardless, rain
chances will accompany the front. Southerly flow developing on the
backside of the high will allow for another warming trend to get
underway.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Monitoring KCLX VWP for possibly inclusion of low-level wind
shear at both KCHS and KSAV for a few hours later this evening
ahead of an approaching squall line.
VFR this evening with deteriorating conditions expected by late
evening as as squall line, or its remnants, move through the
terminals. A brief stint of stratus could impact KSAV just ahead
of the line, possibly bringing high-end IFR cigs, but there is
not enough evidence to support introducing these conditions
just yet. The squall line is on target to push through KSAV
roughly 07-09z and KCHS 08-10z, plus or minus an hour or so.
Limited conditions in the line to MVFR for now, but will need to
adjust later depending on how the line evolves over the next
few hours. Also did not introduce tstms just yet as the line
will be weakening as it moves east. The cold front will cross
the terminals right around 12z with a sharp wind shift to the
north. This should end any substantial risk for shower/tstm
activity with cigs lifting back to VFR.
Extended Aviation Outlook: No significant issues through the
weekend. Restrictions possible Sunday night/Monday.
&&
.MARINE...
Expanded the Small Craft Advisory south as the last several
models runs show winds increasing to 20-25 kt behind the cold
front Thursday morning.
Tonight: Moderate south to southwest flow will continue across the
local waters ahead of the approaching front. Winds will continue to
gust to around 25 knots in the Charleston Harbor, as well as across
the Charleston County waters. A cold front will push through the
waters late tonight and winds will turn more westerly by sunrise.
Wind speeds will remain 15-20 knots, with gusts to 25 knots in the
Charleston County waters and perhaps the outer Georgia waters.
Confidence in any Small Craft Advisory conditions in the outer
Georgia waters is still too low to introduce an advisory, but one
may eventually be needed. Seas will increase by late tonight to
become 3-5 feet across most of the waters, with 6 footers possible
out near 20 nm in the Charleston County waters.
Thursday through Monday: Elevated winds/seas Thursday will subside
through the day a cold front pushes farther offshore. Advisory
conditions likely off the Charleston county coast and are possible
over the offshore GA waters. High pressure will then build into the
region and persist through the weekend. A wind surge is expected
Friday night into Saturday and Small Craft Advisories may be needed
again, mainly in the offshore Georgia waters and Charleston county
waters. Fairly quiet marine conditions expected thereafter through
Monday.
&&
.CLIMATE...
A record high temperature of 83 was set at KCHS which breaks the
old record of 82 set in 1997.
A record high temperatures of 86 was tied at KSAV, last set in
1918.
Record high minimum temperatures for March 1:
KCHS: 61 degrees set in 2012.
KCXM: 63 degrees set in 2012.
KSAV: 65 degrees last set in 2012.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory from 6 AM to 2 PM EST Thursday for AMZ352-
354.
Small Craft Advisory from 6 AM to 6 PM EST Thursday for AMZ374.
Small Craft Advisory until 2 PM EST Thursday for AMZ350.
&&
$$
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1013 PM EST Wed Mar 1 2017
.UPDATE...
Expansive area of light snow now encompassing all but the far south,
as mid level deformation washes across the region. Lead edge of the
moisture plume defined by a pronounced frontal passage and ensuing
uptick in cold air advection, the process maintaining a profile
favorable for gusty conditions. Winds still holding within the 35 to
40 mph range immediately in advance of/and trailing the frontal
passage. This will continue to promote a heightened area of snow
squall activity right along the frontal slope from M-59 southeastward.
This will provide a quick coating for points across the south, while
northern sections /I-69 north/ appear on track to land 1 to 2 inches
total given the longer residence time. Meaningful exit of the
existing forcing set for the 06z-08z window, a rapid downturn in
snowfall coverage expected through this time.
&&
.PREV DISCUSSION...
Issued at 545 PM EST Wed Mar 1 2017
AVIATION...
Snow squalls are shown advancing toward FNT on latest radar imagery.
The more intense snow squalls are expected to pass into FNT by 00Z,
then slowly push south into PTK and metro Detroit during the
evening. The intensity is expected to decrease as they move south.
Brief periods of moderate to heavy snow are possible within these
snow squalls considering the steepening low level lapse rates and
increasing moisture depth early this evening. Accumulations around
an inch are possible at FNT and PTK. Ongoing cold air advection will
also sustain gusty winds through the evening, with gusts in excess
of 30 knots expected to persist through midnight. The snow will exit
east after midnight, while winds slowly decrease during the
overnight as the low pressure system continues to exit the region to
the northeast.
For DTW...Wind directions will hold fairly steady out of the west
through 05Z. Although there may be a slight dip in wind speeds over
the next hour or two, a secondary push of low level cold air around
02Z will support either a continuation or slight uptick in wind gusts
at or above 35 knots. Chances for snow squalls will occur this
evening. It is possible for a light coating of snow as temperatures
quickly fall below freezing by mid to late evening.
//DTW THRESHOLD PROBABILITIES...
* High for cig aob 5kft this evening. Low overnight through Thursday.
* High for precipitation type to be all snow after 00Z.
* High for exceeding crosswind threshold from 270 to 280 degrees
this evening.
PREV DISCUSSION...
Issued at 354 PM EST Wed Mar 1 2017
DISCUSSION...
A long-winded update discussion was sent out earlier regarding the
wind potential and the wind advisory headline. Much of the forecast
reasoning provided earlier remains valid. Main point to stress is
the HRRR and RAP trends have been steadfast on two fronts. 1. Winds
are expected to remain strong throughout the evening, weakening
rapidly after midnight. In fact, there is increased support that a
secondary period for highest winds will occur during the mid evening
hours as meat of low to midlevel cold air advection kicks in for
areas south of I 69. The most favorable time period for the second
wind pop is centered between 01-04Z. There is some uncertainty on
whether or not wind advisory criteria wind gusts will hang around
after this initial shower line until the wind pop in the evening
hours, however, fairly high confidence in winds of 35 to 40 mph
until then. 2. The forecast sounding this evening is a good one for
the development of snow squalls. Also spoke to this in the earlier
update discussion. RAP, HRRR, 4km NAM-NMM are all suggesting that
the sheared out near surface low pressure trough will harbor enough
convergence to illicit shallow convective response. The tail of
which is forecasted to dip southward across the Detroit Metro area
from 02-05Z. To convey the message, will carry higher PoP, lower qpf
this evening for all of the area. Main impact will not be snowfall
accumulations considering the warm, moist ground conditions, rather
reduced visibilities in heavies snow squall activity.
Farthern north...Precipitation will changeover to snow during the
next hour or two across the Tri Cities and Thumb. Currently some dry
air issues with a dry slot in place from Saginaw Bay clear up to
Oscoda. Expecting this dry slot to fill in very rapidly with crisp,
cyclonic vorticity advection progged in addition to increase in left
exit region dynamics. The thermal trough will be able to hold
initially before vaporizing and succumbing to 850mb cold advection
from +4C this afternoon to -12C by 00Z. So, there will definitely be
accumulating snow across the north, with the question only being how
much. HRRR and RAP trends are again adamant that snowfall
accumulations will stay in the 1 to 2 inch range. Given the degree
of the cold air advection and well developed structure of midlevel
deformation axis would not be shocked if a more widespread 1 to 2
inches were able to fall southward through the I 69 corridor before
tapering off.
There was a concerted southern drift with the Thursday evening
clipper system in the 01.12Z nam solution. There had been
considerable track difference between the NAM and ECMWF by as much
as a couple hundred miles. The SREF trend today has also, and not
surprisingly, followed the operational NAMs lead by suggesting less
support for a Michigan (northern) track. Therefore, the inherited,
muted forecast remains a good call. The integrity of the wave and
resultant cyclonic vorticity advection, along with the low to
midlevel airmass hanging around the in the magical -14 to -16C 850mb
range suggests some widespread flurries or light snow shower
activity will be possible, particularly later on Thursday night.
High pressure located over the eastern Great Lakes on Saturday will
keep conditions dry with general clearing of cloud cover expected.
As high pressure continues to push east, a thermal ridge will start
to edge into the CWA, elevating 850 mb temperatures from an average
of -10 C on Sat 18Z to an average of 2 C by Sunday 18Z. The gradual
lift will provide the slight chance to see a light wintry mix/rain
solution throughout the morning and afternoon hours. Much higher PoP
values are forecasted Monday afternoon into Tuesday, as WAA ramps
up. With surface temperatures in the 50s forecasted for the CWA by
Monday afternoon, an all-rain solution will be expected for the
majority of the event, with a very slight chance for lingering snow
possible late Tuesday into early Wednesday, as colder air enters the
region.
Much like yesterday`s solutions, uncertainty still exists regarding
the track of the low pressure system responsible for the
precipitation, and thus timing of precipitation. Highest confidence
for precipitation remains between the Tues 00Z - 06 time frame as a
strong LLJ noses into the CWA across the GFS/ECMWF/GEM models. ECMWF
and GEM solutions are fairly aggressive with swinging the cold front
through Tuesday afternoon, with polar dry air in place by Tuesday
evening. The GFS pulls the cold front, along with a heavy band of
QPF, through the late afternoon and early evening hours on Tuesday,
and brings the lingering chance for light snow Wednesday morning and
afternoon. Additional considerations for the rain associated with
WAA will be the chance for thunderstorms. Otherwise, high pressure
is expected to build in late Wednesday into Thursday, keeping
conditions dry.
MARINE...
North to northwest gales over Lake Huron will persist through late
tonight as colder air spreads into the area. Westerly gales over
Lakes Saint Clair and Erie diminish this evening. Moderate to fresh
northwesterly flow will linger through the end of the week across
the lakes then followed by a gradual increase in southerly flow over
the weekend.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Wind Advisory until midnight EST tonight for MIZ063-068>070-075-076-
082-083.
Lake Huron...Gale Warning until 4 AM EST Thursday for LHZ361>363-441>443-462>464.
Small Craft Advisory until 4 AM EST Thursday for LHZ421-422.
Lake St Clair...Gale Warning until 4 AM EST Thursday for LCZ460.
Michigan waters of Lake Erie...Gale Warning until 4 AM EST Thursday for LEZ444.
&&
$$
UPDATE.......MR
AVIATION.....SC
DISCUSSION...CB/AM
MARINE.......CB
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Gray ME
907 PM EST Wed Mar 1 2017
.SYNOPSIS...
Expect warming temperatures to continue into early this evening
in southern New Hampshire as a warm front slowly lifts north.
Periods of showers are possible. A strong cold front will cross
through the area tonight with showers and thunderstorms along
and ahead of it. Winds will increase out of the west behind the
front, ushering in much colder weather. The cold weather will
last through the weekend. A gradual warm up occurs early next
week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
9 pm update: Have discontinued the Dense Fog Advisory. The
widespread areas of dense fog with areas of less than 1/4 mile
vsbys have become patchy and generally dissipated over most
areas. Will continue to keep a mention of some areas of fog and
patchy areas of dense fog across central and eastern areas of
Maine and a few areas in central NH through midnight.
Made some adjustments to pops for the rest of the evening and
overnight period based on latest radar. Have one area of showers
currently moving through northern NH and Western Maine moving
rapidly east. The next line of showers are associated with the
cold front across upstate NY and will be arriving later tonight.
Input latest obs data for temps with only minor tweaks in near
term.
645 pm update: Continuing the Dense fog advisory until midnight
although a continued push north of the southwest winds is
allowing southern areas of the advisory area to see the fog
lift and dissipate. Currently though, still enough areas of
dense fog in the advisory area and also the possibility of it
reforming over some of the areas where it dissipated. Made some
adjustments and fine tuned the grids for the fog advisory.
On this update took out any mention of thunder with the
approaching cold front since conditions the rest of the night
will not be favorable. But, still expecting a band of showers
associated with the cold front tonight. Made adjustments to pops
based on current radar and then blending HRRR thru 05z period.
Temps appear to be close to forecast based on latest mesonet
data so only a few tweaks needed...mainly in the southernmost
areas in the warm sector.
Previous Discussion:
A very complex weather situation will continue through late
this evening as a strong warm front remains across southern and
central New Hampshire. This front may make some additional
progress into this evening to the north. Over Maine, the front
will make slower progress due to the cool onshore flow, snowpack
and dense fog in place.
North of this front, areas of dense fog will continue until
convection and winds increase ahead and along the the cold
front. Will be a challenging fog forecast as some portions of
the region may briefly mix out, with fog potentially
redeveloping in some locations.
South of the front, considerable shear will combine with
continued destabilization to allow for thunderstorms in any fast
moving line segments. Temperatures will continue to climb
through the 60s with surface dew points in the 50s over southern
NH and perhaps portions of far southwestern interior Maine into
this evening. Fast moving showers and isolated storms in this
region have the potential to contain very strong, gusty winds.
Have peaked the forecast temperatures around 23Z before readings
begin to slowly cool.
Surface cold front will cross the region between approximately 07Z-
10Z from west to east with showers and the isolated storms.
Winds will increase rapidly with the frontal passage towards
morning.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
As the surface low continues to deepen Thursday morning as it
crosses northern Maine, the gradient will continue to tighten.
Strong cold air advection will allow for increased mixing as
well as H8 winds remain at roughly 50 kts. Surface winds will
gust to around 50 mph and have therefore continued the Wind
Advisory for portions of Maine and New Hampshire. Downslope
areas will allow for additional drying and therefore more
sunshine. Mixing may be deep over southern downslope areas
resulting in locally higher wind gusts.
Have created a non-diurnal curve with max temperatures around
noontime on Thursday, followed by readings beginning to drop.
Very cold and breezy conditions expected by Thursday night with
air temperatures falling to near zero in northern areas. Models
in relatively good agreement with this latest deep freeze.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
The models are in decent agreement on the longwave pattern through
early next week. We begin the period with an upper trough stretching
from the Great Lakes eastward into New England. This trough will
lift out by the tail end of the weekend to replaced by a strong
ridge in response to digging shortwave energy over the western
CONUS. Thereafter, considerable model uncertainty exists
regarding how fast the upper ridge will breakdown across the
eastern CONUS as we enter the midweek period. In the
dailies...the upper trough delivers a brief period of well below
normal temperatures to the area Friday night through Sunday
before we rebound to above normal values by early next week.
Another cold front will drop south across the area Friday and
reinforce the cold air for Friday night and Saturday. Outside of
a few upslope mountain snow showers...we should be dry across
the area Friday and Saturday. Strengthening post frontal
Northwest winds will produce potentially dangerous wind chills
Friday night into Saturday. During the daylight hours on
Saturday...Northwest winds may gust up to 40 mph at times. Winds
will drop off for Saturday night and Sunday as a surface ridge
of high pressure builds across New England. On Monday and
Tuesday...a warm front will gradually lift northward into the
region with some light mixed overrunning precipitation likely
across the area.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Short Term...LIFR conditions over northern areas with mixed MVFR
and IFR conditions at times in showers over southern sites.
LLWS is possible, especially over the Central and Northern areas
which still have an inversion in place. Conditions improving
outside the mountains by Thursday morning, however strong winds
will develop.
Long Term...
Fri - Sat...Sct MVFR psb in mtn -shsn.
Sat...NW sfc wnd gusting to 35 kt.
Mon...Areas of MVFR psb in -shsn.
&&
.MARINE...
Short Term...Gales remain in effect. Winds will be increasing
rapidly late tonight into Thursday with an increasing gradient
and strong cold air advection over the waters.
Long Term...
Fri......SCA`s are likely.
Sat...SCA`s likely...wth gales outside the bays.
Sun......SCA`s are likely.
&&
.HYDROLOGY...
A couple ice jams remain in place at the Swift River and
Carrabassett River. However, no flooding is occurring. There is
a small risk for ice jams for the next several hours as warm
temperatures remain in place over southern/central areas.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Wind Advisory from midnight tonight to 7 PM EST Thursday for
MEZ012-018>021-023>028.
NH...Wind Advisory from midnight tonight to 7 PM EST Thursday for
NHZ004-006>015.
MARINE...Gale Warning from 6 AM Thursday to midnight EST Thursday night
for ANZ150>154.
&&
$$
NEAR TERM...Marine
SHORT TERM...Marine
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1028 PM EST Wed Mar 1 2017
.UPDATE...
Issued at 1028 PM EST WED MAR 1 2017
Shower activity has exited and weakened off to the southeast. West
to northwest winds have also gradually diminished, although there
are still gusts in the 25 to 30 mph range, which will linger
for another few hours, before further lessening. Temperatures
have fallen off into the mid 40s, and forecast lows in the low to
mid 30s look on target. Freshened up the hourly temperatures
according to the latest trends in observations.
UPDATE Issued at 649 PM EST WED MAR 1 2017
A line of showers and isolated thunderstorms blossomed along the
cold front. This line will gradually exit the far southeast by
around 8 pm. Updated to increase POPs accordingly. Also updated
the hourly temperatures, as readings have dropped off into the
lower 50s behind the front, while some 60s hang on in far
southeastern Kentucky. Wind gusts up north have been holding in
the 30 to 40 mph range, with gusts of this magnitude becoming less
frequent with time. As such, will likely allow the Special
Weather Statement expire at 9 pm as scheduled. Updates have been
sent.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 336 PM EST WED MAR 1 2017
Main area of showers and thunderstorms has exited the state, but
radar shows a few showers developing ahead of the approaching cold
front. The cold front is on the door step of the forecast area at
3 PM. Based on current radar trends and recent HRRR runs have
decided to continue with at least a slight chance of showers or
thunderstorms until the front passes. However most areas will not
see a shower and initially was not going to include any rain
chances. Much colder air will move into the area in the wake of
the cold frontal passage this evening, with lows by Thursday
morning in the lower to middle 30s. It will also be much cooler on
Thursday with highs from 45 to 50.
A clipper like system will affect the area Thursday night, with
even colder air moving into the area in the wake of this system.
Initially this system will bring a chance of rain showers to the
northern part of the area Thursday night, but some snow may mix
in, and any lingering precipitation may end as some very light
snow showers by Friday morning. However this is a very low
probability and no impact is expected.
.LONG TERM...(Friday through Wednesday)
Issued at 336 PM EST WED MAR 1 2017
Colder air moving into the area in the wake of Thursday night`s
clipper like system will hold maximum temperatures in the 40 to 45
degree range Friday. With cold surface high pressure settling over
the area Friday night, minimum temperatures by Saturday morning
are expected to fall into the middle 20s. The high will slide to
our east on Saturday and a warming trend will begin with highs
mostly in the 50s on Saturday and well into the 60s by Monday and
Tuesday. Along with the warmer temperatures next week, will come a
chance for showers as moisture flows into the area in advance of a
short wave trough moving east from the plains and an associated
cold front. There is quite a bit of uncertainty in the timing of
next week`s system. Have followed the standard blend for the
forecast which in this case favors the GFS solution with a cold
front moving across the area on Tuesday. With this in mind the
best chances for showers will be Monday night and Tuesday, with
dry weather returning for Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 649 PM EST WED MAR 1 2017
A line of showers and isolated thunderstorms will exit a line from
KPBX to K1A6 through 01z. MVFR or worse visibilities/ceilings will
occur within this line, along with wind gusts in excess of 25 kts.
West to west northwest winds of 10 to 15 kts, with gusts of 20 to
30 kts will continue across the rest of eastern Kentucky through
around 02 to 03z, before gusts diminish. Ceilings will generally
range from 3-4k feet agl, and will maintain VFR conditions at the
TAF sites through tonight. Clouds will scatter out on Thursday,
with west winds picking up to around 10 kts during the afternoon.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...SBH
LONG TERM...SBH
AVIATION...GEOGERIAN
Area Forecast Discussion
National Weather Service New Orleans LA
655 PM CST Wed Mar 1 2017
...SOUNDING DISCUSSION...
The sounding sampled the atmosphere ahead of a cold front and
broken line of showers and storms that is crossing the area this
evening. It was warm today and the temperature trace follows the
dry adiabat to the top of the boundary layer at 850 mb. Above
there are a couple elevated inversions at 620 and 470 mb, though
still instability. Mixed layer CAPE is 1000 J/KG. There is some
weak speed shear but winds are generally southwest through the
profile. PW is well above average at 1.5 inches.
Krautmann
&&
&&
.PREV DISCUSSION... /issued 328 PM CST Wed Mar 1 2017/
SHORT TERM...
An upper analysis shows a ridge over the Gulf of Mexico
suppressing further south as a trough tracks east across the upper
and mid Mississippi Valley. A cold front associated with this
feature is currently analyzed locally along a line from near Lake
Charles LA to Jackson MS. Regional radars shows a relatively thin
line of showers and thunderstorms just ahead of to right along the
cold front. This convection is entering SW MS zones of the CWA at
this time. The HRRR appears to have a good initialization of the
convection and shows the line progressing southeast across the
forecast area from now through just before midnight.
Surface observations show temperatures in the lower 80s and
dewpoints ranging from 60 to the NW to 70s on the coast. Dewpoint
depressions of near 20 degrees suggest convection is elevated but
certainly being enhanced in the mid levels by surface heating. CAPE
values range from around 500 to over 1000 J/KG. This along with
effective bulk shear near 50 knots suggests the potential for severe
storms. Lack of sfc based storms means hail and possibly damaging
winds as the main threats. Instability should steadily reduce with
loss of daytime heating this evening. Thus expecting the intensity
of storms to dwindle with time after sunset.
LONG TERM...
Post frontal air mass and surface high pressure will build in from
the north for the remainder of the week. This will bring
temperatures down from well above normal to right at normal first,
then slowly nudging up each day thereafter. Upper ridge will begin
building across the center of the country and the CWA Saturday.
Moisture will begin to return Sunday as the surface ridge centered
to the north shifts east. A few showers will likely begin to develop
then but shouldn`t have much intensity with them. From this point,
the GFS and ECMWF solutions differ significantly. The GFS shows a
strong trough swinging through the country Tuesday while the ECMWF
indicates one weaker and much further north. Therefore, just went
with blended models for the extended forecast.
MEFFER
AVIATION...
VFR conditions will prevail for the majority of the forecast period.
There will be a brief window of MVFR and possibly IFR restrictions
as a broken band of thunderstorms moves over the terminals this
evening. The highest likelihood of thunderstorms will be at KMCB
and KBTR, and have placed TEMPO wording to reflect the risk of
convection in the forecast. The main threat should exist from
around 22z through 02z. At the other terminals, have opted to place
only VCTS wording as confidence that the line will maintain itself
as it loses support of daytime heating is lower. After the front
moves through, expect to see strong north winds of 15 to 20 knots
with higher gusts affect KNEW and KMSY tonight and tomorrow morning.
32
MARINE...
Strong offshore flow of 20 to 25 knots will develop over the coastal
waters tonight and then persist through at least Saturday over the
open Gulf waters. In the sounds and lakes, winds should back off to
15 to 20 knots tomorrow afternoon and remain at those levels through
the weekend. Seas should turn quite rough at 5 to 7 feet over the
open Gulf waters tonight and remain elevated through the weekend.
Given these conditions, Small Craft Advisory flags are out for all
of the waters tonight into tomorrow morning. By Sunday, winds
should veer to a more onshore component, but also remain elevated at
15 to 20 knots as a tight pressure gradient lingers over the
northern Gulf. This onshore flow pattern is expected to persist
through Tuesday as another storm system develops to the west. 32
DECISION SUPPORT...
DSS code: Blue.
Deployed: None.
Activation: None.
Activities: None.
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or
high visibility event.
Yellow = Heightened impacts with short-fused watch, warning or
advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby tropical
events; HazMat or other large episodes.
Red = Full engagement for Moderate risk of severe and/or
direct tropical threats; Events of National Significance.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 45 65 38 68 / 10 0 0 0
BTR 49 66 41 68 / 20 0 0 0
ASD 53 65 43 67 / 50 10 0 0
MSY 56 64 49 67 / 40 10 0 0
GPT 54 65 45 67 / 60 10 0 0
PQL 54 64 42 67 / 50 10 0 0
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory until 6 AM CST Saturday for GMZ536-538-550-
552-555-557-570-572-575-577.
Small Craft Advisory until noon CST Thursday for GMZ530-532-534.
MS...None.
GM...Small Craft Advisory until 6 AM CST Saturday for GMZ538-550-552-
555-557-570-572-575-577.
Small Craft Advisory until noon CST Thursday for GMZ532-534.
&&
$$
East Central Florida Forecast Discussion
National Weather Service Melbourne FL
924 PM EST Wed Mar 1 2017
.DISCUSSION...
Despite a prevalent dry vertical airmass some slow moving showers
drifting north across the Lake Okee region and into rural St. Lucie
Co. have potential to perhaps make it into Indian River Co. by
midnight. High res HRRR and to some degree WRF are indicating
potential for this and some additional isold showers to develop
during the overnight across the southern half of the forecast area.
The latest forecast update keeps a small rain chc overnight for
these southern areas and the adjacent Atlc waters. Patchy fog is
likely to develop by daybreak with visibility remaining above
hazardous levels.
&&
.AVIATION...
VFR conds areawide aside from isold rain areas producing very
localized MVFR late tonight. Patchy BR especially inland 02/09Z-
02/13Z with vsby 3-5SM.
&&
.MARINE...
Tonight...Sfc/bndry lyr winds will veer from a gentle to moderate
S/SE breeze to W/SW thru the predawn hrs. Seas 2-3FT nearshore and 3-
4FT offshore. Isold shras mvg offshore thru the overnight
esp S of Sebastian Inlet.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
JP/DKW
Area Forecast Discussion
National Weather Service Tallahassee FL
825 PM EST Wed Mar 1 2017
.UPDATE...
No significant changes to the previous forecast below appear
necessary. The cold front continues to push southeast towards the
area. Just ahead of it, a long line of convection stretches from
North Carolina southwestward to Louisiana. The atmosphere ahead of
it continues to be marginal for any severe weather in our local
area with the 00z KTAE sounding showing marginal CAPE and low
level shear, although the deep layer shear is fairly high at 48
knots. Overall, the RAP forecasts a gradual weakening of
parameters through the night, and the HRRR forecasts the line of
convection to gradually weaken as well. Therefore, the threat of
severe weather remains low in our area tonight.
&&
.PREV DISCUSSION [644 PM EST]...
.NEAR TERM [Through Tonight]...
Our approaching cold front continues to push eastward, stretching
from OH down to southwestern LA. Surface obs show a particularly
distinct contrast in winds ahead of and behind the front with
strong, gusty southwest winds from our local area west to the front
and strong, gusty northwest winds in its wake. National radar mosaic
shows a narrow line of thunderstorms ahead of the cold front.
Scattered convection may develop ahead of the line locally in the
late afternoon/evening hours, but the main line won`t begin to cross
through until around 9 PM CT.
The dynamics for this system are potent for neighbors to our north,
but as the front approaches our local area, instability will be
dropping quickly and the low level, mid and upper level jets will be
lifting northeastward. Deep layer shear will peak around 60 kts
coinciding with the frontal passage, so isolated damaging winds will
be possible with these thunderstorms as they come through. SPC has
highlighted northwestern portions of our area in a marginal risk for
tonight.
.SHORT TERM [Thursday Through Friday Night]...
The eastern CONUS trough will gradually lift out of the Southeast
through Friday night. While showers associated with the
aforementioned cold front will be just clearing the southeast Big
Bend around dawn Thursday, some higher resolution guidance
suggests that a slug of isentropic ascent between 10-15kft will
result in some light post-frontal rain along and southeast of a
line from Valdosta through Apalachicola. All rain should come to
an end by Thursday evening. Highs and lows will be much closer to
normal Thursday through Friday night, with highs in the 60s and
overnight lows in the upper 30s to lower 40s.
.LONG TERM [Saturday Through Wednesday]...
Deep layer ridging will prevail through Tuesday morning, with no
rain, and temperatures climbing back to above average values. The
next frontal system will approach the region Tuesday, possibly
bringing rain by Tuesday afternoon through the day Wednesday.
.AVIATION...
[Through 00z Friday] The main event tonight will be a cold front
moving through the area from west to east. The convection along
the front is expected to be thinning out as it moves east, so
most of the precip is expected at our most western terminals. MVFR
cigs will prevail throughout the night with IFR cigs possible
around ECP and VLD.
Behind the front, winds will become northerly and increase is
speed. Cigs are expected to improve to VFR levels a few hours
behind the frontal passage.
.MARINE...
Advisory level winds will overspread the northeast Gulf late
tonight behind a cold front, with on and off Advisory/Cautionary
conditions prevailing through early next week.
.FIRE WEATHER...
Much drier air will move into the area behind a cold front for
Thursday and Friday. However, at this time, winds and ERC values
do not appear to meet red flag criteria.
.HYDROLOGY...
Rainfall amounts through Thursday are expected to be less than a
half of an inch. This will have little to no impact on area rivers
and creeks. Water levels should continue to fall or hold steady.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 58 68 41 69 39 / 70 30 0 0 0
Panama City 58 64 46 66 44 / 80 20 0 0 0
Dothan 52 63 40 66 37 / 90 10 0 0 0
Albany 54 64 39 66 36 / 80 20 0 0 0
Valdosta 58 67 41 68 39 / 70 40 0 0 0
Cross City 62 72 43 70 41 / 10 50 10 0 0
Apalachicola 60 69 48 67 47 / 60 40 0 0 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk until 10 PM EST /9 PM CST/ this evening
for Coastal Gulf-South Walton.
GA...None.
AL...None.
GM...Small Craft Advisory from 1 AM to 7 PM EST Thursday for Coastal
Waters From Ochlockonee River to Apalachicola Fl out to 20
Nm-Coastal waters from Apalachicola to Destin FL out 20 NM-
Waters from Suwannee River to Apalachicola FL from 20 to 60
NM-Waters from Apalachicola to Destin FL from 20 to 60 NM.
&&
$$
UPDATE...DVD
NEAR TERM...Moore
SHORT TERM...Harrigan
LONG TERM...Harrigan
AVIATION...DVD/FDC
MARINE...Harrigan
FIRE WEATHER...DVD
HYDROLOGY...Harrigan