Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/01/17
Area Forecast Discussion
National Weather Service State College PA
1124 PM EDT Sun Apr 30 2017
A nearly stationary front will remain draped across central Pa
tonight. A strong cold front will move across the region on
Monday followed by brisk west to northwest winds and cooler air
for Tuesday. Fair weather with milder temperatures will occur
Wednesday under a weak ridge of high pressure. Deep moisture
will flow north into the state Thursday afternoon through Friday
bringing a return to inclement weather.
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Earlier convection has completely dissipated late this evening,
as boundary layer cooled/stabilized. Expect a dry remainder of
the night for most of central Pa. However, can`t rule out a
shower/storm working into Warren County toward dawn, as low
level jet shifts eastward from the Grt Lks. Persistent easterly
flow off of the Atlantic will likely yield low clouds and
possible ridgetop fog across eastern Pa late tonight, while a
partly cloudy night appears likely across the central mountains
A blend of latest HRRR and LAMP support overnight min temps from
around 50F over the high terrain of eastern Schuylkill County,
to the low 60s across the south central counties and Allegheny
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
Monday represent the most active day in the forecast period.
A potent cold front is expected to pass through the region
during the afternoon and early evening Monday. Strong deep
layer shear and respectable instability are generated by all the
near term deterministic models. SPC has elevated the RISK to
ENHANCED with EHI`s forecast in the 2-3 range (anything above
1.0 is considered significant). The mitigating factor to be
aware of (as always) will be the amount of cloud cover in the
warm air ahead of the cold front. The cool air damming as
defined by low level stability is forecast to mix out rapidly
early in the day. With the cold front and upper flow strongly
aligned, I would expect the warm sector to mix out and at least
a healthy mix of sun and clouds to develop by mid to late
Temps should return/rise to very very warm levels on Monday.
A narrow north/south ribbon of +3-4 sigma PWAT air along and
just ahead of the cold front will support some locally heavy
downpours and QPF up over one inch in some spots. WPC highlights
a small portion of my NERN zones with a MARGINAL risk of heavy
rain/flooding. It`s too soon to get into watches at this point.
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Expect significant convection to be ongoing/near to exiting the
CWA at the start of the period Monday night. Cold front forcing
the convection will move east through the state overnight into
Tuesday morning, advecting much chillier air into the state
Cyclonic flow with a gusty NW wind and unsettled light showery
weather will persisting mainly for the northern part of the
state right into Wednesday.
A chance for a more widespread (potentially MDT to HVY) rain
arrives Thu into Fri as latest 00Z Operational GFS/EC run and
their EFSs are coming into decent/converging agreement with an
area of low pressure progged to develop along the southern
Appalachians and the lift north-northeastward.
Although this event shows some pretty strong signals (even at
this long time range) for a potential, widespread 1-2 inch
rainfall late in the upcoming week, A wide and varying array of
models solutions has been present prior to the latest model run
or two to throw some uncertainty into the mix w/respect to the
specific timing and amount of showers across the CWA.
Fri night and Saturday will turn windy and quite cool with
isolated rain showers falling across the central mtns, while
the Alleghenies experiences more numerous rain showers (and
yes, maybe even the last gasp of show showers until later this
.AVIATION /04Z MONDAY THROUGH FRIDAY/...
Some showers and thunderstorms across western NY. At
this point, left them out of BFD.
03Z TAFS adjusted for current and expected conditions.
Western areas have the best chance to remain VFR overnight,
as a cooler southeast flow of air remains over the far east.
Main issue later Monday is a strong cold front from the midwest
that will move across the region later in the day with showers
and storms. Strong winds will be possible with some of the
storms. Main question remains, is drier air to the east this
evening going to taper the intensity of the storms on Monday.
After the front moves east of the area, a dry slot will likely
result in clearing later Monday night into Tuesday. As winds
shift more to the northwest late Tuesday into Wednesday, this
will bring more clouds and showers to the area, mainly across
the west and north Tuesday Night into early Wednesday morning.
A complex low pressure system will likely bring more wet and
stormy conditions to the area after Wed.
Mon...Breezy. Showers/thunderstorms likely with periods of
sub-VFR. A few strong-severe storms possible wrn 1/2 Monday
afternoon/evening. FROPA Monday night.
Tue-Wed...Breezy with a chance of showers NW.
Thu-Fri...Widespread sub-VFR with rain likely.
SHORT TERM...La Corte
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1203 AM EDT Mon May 1 2017
An extension of low pressure over Illinois will move toward southern
Lake Michigan during the rest of tonight. This will nudge the warm
front a little farther north into southern Michigan and allow some
of the VFR conditions over Ohio to spread northward. Improved
conditions could reach as far north as FNT before the occluded front
arrives toward sunrise. At the same time, a close watch for fog will
be warranted in the weakly supported warm sector supporting a
relatively light southeast to south wind. The front will then bring
another round of showers and possibly some storms northward from
Kentucky while the ongoing storms over Illinois stay to the west and
north. Borderline IFR/MVFR ceiling will accompany the showers/storms
until the front sweeps it all eastward by late morning. VFR will
follow with southwest wind gradually increasing to gusts in the 30-35
knot range during the afternoon. Generous coverage of showers is
also likely by mid afternoon through early evening as daytime surface
heating interacts with cooler air aloft.
For DTW... Monitoring prospects for VFR to move in from Ohio and also
some fog potential during the remainder of tonight. A more certain
downward trend back to MVFR/IFR will follow as the front moves in
along with another round of showers and possible storms, timing of
which will be refined with later updates. Gusty southwest wind will
become the main concern by afternoon.
//DTW THRESHOLD PROBABILITIES...
* Moderate for ceiling 5000 ft or less through morning.
* Low for thunderstorms through morning.
Issued at 917 PM EDT Sun Apr 30 2017
Evening satellite imagery depicts a textbook mature mid latitude
cyclone affecting a broad swath of the central U.S. which will drive
the precipitation trend over southern Michigan during the rest of the
night. Smaller scale upper waves/MCVs and their interactions with
the warm/stationary front have been the main forcing over the last
24-36 hours, and will be for the evening pattern, followed by the
primary low pressure system becoming more involved overnight. The
good news here is that rainfall rate has been light overall during
the late afternoon and early evening, especially over the flood watch
area of the Saginaw Valley and northern Thumb, and storm totals
south of the watch area have averaged about 0.5 inch according to
surface obs and radar estimates. Any upgrades to or expansion of the
watch are therefore not anticipated at this point. Statements and
graphics will be issued to cover trends with the main short term
concern possibly being some urban ponding of water on roads in the
The primary low pressure system and frontal occlusion will enter
Lower Michigan late tonight and bring another round of showers and
scattered thunderstorms to the region. This activity will move
quickly through SE Michigan while possibly disrupting the morning
peak travel period before being swept eastward into Ontario by late
Issued at 251 PM EDT Sun Apr 30 2017
Rapid fire upper level disturbances/MCV`s embedded in moist airmass
with next weaker one seen on Goes R Ice Channel 5 already lifting
north through Western Ohio Valley. Blossoming area of showers on the
northeast flank has limited the destabilization over northern
Indiana, but still enough to maintain showers and possible
thunderstorms into southeast Michigan late today/this evening. With
the failure of warm front to lift into the State during daylight
hours and limited instability it remains highly doubtful we will see
any severe weather in our CWA. Still, 12z NAM/Regional Gem do
indicate 1000-850 mb capes nearing 1000 J/kg close to Lenawee county
at 00z, while RAP is displaced farther east with the pocket of
instability, which looks better based off the temps in the 80s over
Eastern Ohio. Much like the QPF bulls-eyes, models running a bit too
hot. None-the-less...one is always weary with such a strong low
level jet (50+ knots at 850 mb), even overnight as the jet
strengthens further, 65+ knots, but surface based inversion is
expected to hold.
Flood watch will remain in effect for Tri-Cities and adjacent
counties, as we received solid rainfall today pushing totals to
around 1 inch. Will get additional rain (half an inch to maybe 1
inch) late tonight with the cold front, as the large upper level low
over the Central Plains is finally booted off to the northeast from
the upper level energy working through the northern Rockies.
Moisture axis will slide east of southeast Michigan between 12-14Z
with good part of the day under influence of mid level dry slot.
However, good low level cold advection and cyclonic flow will
eventually spread scattered to numerous showers back into the area,
right into Tuesday as 850 mb temps of -4 C settle overhead.
Certainly plausible for graupel to fall with that amount of cold
air. Based of forecasted nam soundings and local probabilistic wind
forecast, wind gusts of 35 to 40 mph look to be common late in the
day Monday, with gusts at above 30 mph continuing right into Tuesday,
as 992 mb low slowly tracks through the northern Great Lakes. Highs
around 50 degrees on Tuesday will likely be the best we can do.
High pressure building in across the Ohio Valley will keep
conditions dry throughout Wednesday as temperatures remain moderate,
with daytime highs capped in the upper-50s. The next chance for rain
showers will enter Thursday morning into Friday as a low pressure
system pushes in from TN into PA. PoP values will continue to remain
sub-30 across the Metro Detroit area for this potential system as
only the GFS and to some extent the ECMWF solution bring the low
north enough, allowing the precipitation shield to clip southern
Michigan. Breezy conditions and a slightly better chances for rain
showers look to take place throughout Friday as moist-laden
conditions wrap around the low pressure system to its northwest.
Lastly, an upper-level disturbance pushing in from southern Ontario
into the Great Lakes throughout Saturday will bring additional
chances for rain showers. High pressure is then expected to build
over Michigan Sunday into Monday, bringing some relief from the
rain. Otherwise, temperature trends will remain fairly consistent
through the middle and end of the week, with daytime highs remaining
in the upper 50s to lower 60s and lows in the 40s through Sunday.
Moderate easterly winds over northern and central lake Huron will
begin to ease this evening as the gradient relaxes. A secondary
increase in easterly flow remains possible across northern Lake
Huron tonight and early Monday. Winds will turn to southerly and
increase on Monday as low pressure lifts west of Lake Michigan.
Gusts as high as 30 knots look to develop by afternoon and continue
through the overnight hours. The combination of higher waves under
the easterly flow through tonight, transitioning to gusty conditions
on Monday will maintain an extended period of small craft advisory
conditions for Saginaw Bay and portions of the nearshore waters.
Winds are expected to shift to the west behind a cold front on
Tuesday, with windy conditions persisting through Tuesday night.
Widespread rainfall is expected through Monday morning, with
periodic heavy rain possible. There will also be a chance for
thunderstorms during this time. This additional rainfall in
combination with rain that has fallen already this weekend will
result in total rainfall amounts up to 2 inches. The highest
amounts will be focused along and north of a line from Flint to
Harbor Beach. Locally higher totals are possible for areas that
experience thunderstorms, as storms will bring brief periods of
torrential rainfall. Rivers and streams will see significant rises
through the middle of the week, and ponding of water may develop in
low-lying areas and roadways. Flooding is possible, particularly
over the Saginaw Valley.
MI...Flood Watch through Monday morning for MIZ047>049-053-054-060-061.
Lake Huron...Small Craft Advisory from noon Monday to 4 AM EDT Wednesday for
Small Craft Advisory until 4 AM EDT Wednesday for LHZ421-422-441.
Lake St Clair...Small Craft Advisory from noon Monday to 4 AM EDT Wednesday for
Michigan waters of Lake Erie...Small Craft Advisory from noon Monday to 4 AM EDT Wednesday for
You can obtain your latest National Weather Service forecasts online
Area Forecast Discussion
National Weather Service Wilmington OH
930 PM EDT Sun Apr 30 2017
Thunderstorms will occur ahead of a cold front that will move
across the area late tonight into Monday morning. Much cooler
air will move in behind this system with below normal
temperatures expected through the rest of the week. Wet weather
will return during the latter part of the week as low pressure
slowly tracks across the Tennessee Valley.
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A complex of thunderstorms that moved into the area from the
southwest has significantly weakened as instability has
decreased. Still though, DCAPE values are around 800 J/kg so
can`t rule out some gusty winds with it. Another thin band of
showers and thunderstorms in association with the cold front
towards the Illinois/ Missouri border will push east this
evening. This band will then cross the CWA border around 06z.
As the band heads east it should remain mostly weak but given
the strong bulk shear can`t completely rule out gusty winds
(even though the bulk shear is boundary parallel). During the
day tomorrow the vertically stacked low pressure will head
across Wisconsin with a tight pressure gradient across the
region. 850/ 700 mb winds will be around 40 kts with low level
mixing allowing 35 kts gusts. GFS forecast soundings show
slightly higher values on momentum transfer while the NAM is
slightly less. For now have kept wind gusts in the 30 to 35 kt
Scattered thunderstorms that have been tracking across far
eastern counties this afternoon will move east of the area over
the next several hours. Appears that MCS lifting out of the mid
South will make it into western counties this evening, although
in a continuing weakening phase.
New convection will develop along a strong cold front and move
into the forecast area late tonight, likely after 2 am. CAPE may
still be around 500 J/kg as this enters our area with
instability waning further towards daybreak as the line
progresses east. 0-3 km shear is forecast to be mainly parallel
to the line which is not particularly favorable. But cannot rule
out the potential for some strong to possibly severe storms
late tonight. System is rather progressive, so while there could
be some locally heavy rainfall, the lack of persistent rain
should minimize flood potential. But with saturated ground in
much of the region, could still be some minor flood issues here
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Line of showers and thunderstorms will still be ongoing at the
beginning of the period but exiting the area by mid morning as a
cold front moves east. Looks like there could be some clearing
right behind the front. But then the combination of moisture
wrapping in behind the system and insolation should result in a
rather extensive stratocumulus deck. Winds will become gusty. At
this point expect them to remain below wind advisory criteria.
A short wave rotating around an upper low in the Great Lakes
will swing across the region Monday night. This may result in a
few showers, mainly to the north and west of Dayton. In the
wake of this short wave clouds may start to erode from the south
later in the night. Winds will decrease a bit from their speeds
during the day but still persist between 10 and 20 mph.
In cold advection, temperature rise on Monday will only be 5-8
degrees from morning readings. Lows Monday night will fall back
into the 40s.
.LONG TERM /TUESDAY THROUGH SUNDAY/...
An upper level low pressure system situated over the northern Great
Lakes Tuesday morning will shift east across Quebec through Tuesday
night. This will help keep our area in cool cyclonic flow through
the day on Tuesday with a few showers possible across the northern
fringe of our fa. With a 35-45 knot 925-850 mb jet rotating across
our area through the day and some developing low level CAA, winds
will be gusty once again through the day.
Mid level short wave energy dropping down across the Plains will
help carve out a trough over the Mississippi Valley through mid
week. This will eventually lead to a closed low developing which is
then forecast to drift slowly east across the Tennessee Valley
through the end of the week. As an associated surface low moves
slowly east across the Tennessee Valley, expect fairly widespread
showers to slowly overspread the area later Wednesday and into the
day on Thursday. A chance of showers will then linger through Friday
and possibly into Saturday as the upper level low slowly pushes
east. High pressure and a drier airmass will then try to build into
the area for Sunday.
With the cool upper level low affecting the region through much of
the long term period, temperatures will remain several degrees below
normal through most of the week. Some moderation back closer to
normal will be possible by the weekend.
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
All TAF sites currently VFR this evening with an area of low
pressure centered over the Kansas/ Missouri border. The
occluded low pressure will pull northeast with a front pushing
east. Ahead of the front several rounds of showers and
thunderstorms will be possible but uncertainty is high as
coverage will be low. Better agreement exists with the cold
front that is forecasted to push across the TAF sites between
09z and 14z. In general, the latest runs of the HRRR and RAP
have slowed down the frontal passage (along with the band of
showers and thunderstorms) but am having trouble believing this.
Usually the front speeds up at night. For now have kept TAF
forecast package showing similar timing as the previous
As the line of showers and thunderstorms crosses the TAF sites
gusty winds and IFR visibilities will be possible. Behind the
front winds will slowly veer and pick up in speed. GFS and NAM
forecast soundings are showing gusts up to 35 kts possible.
Higher wind gusts will be possible towards DAY/ CMH/ LCK or
closer to the low pressure center.
OUTLOOK...Wind gusts to 35 kt possible Monday evening and then
again on Tuesday. MVFR ceilings and visibilities possible
Thursday through Friday.
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
858 PM CDT Sun Apr 30 2017
Updated for evening discussion.
Leftover moisture axis over eastern sections has allowed for
convective development this evening as the cold front has closed
in. Although the latest HRRR data is showing this, it is somewhat
slow in its development. Regardless, convection should begin
picking up some eastward progress as the front holds its course.
As has already been the case, would not be surprised to see
another severe leftmover or two over southeast sections in the
better instability and shear, but should diminish before
Prior discussion below:
along the Mississippi river this afternoon and is working its way
across the area. The bulk of the morning/early afternoon
convection has shifted off to the east of the area, but stratiform
and some embedded thunderstorms are occuring east of the I-55
corridor. Some shower/thunderstorm activity is developing behind
this stratiform shield, but feel these storms will remain below
strong/severe limits as the area has been worked over from the
morning/early afternoon storms.
The cold front will move across the area this afternoon through the
evening hours and this will bring in drier air along with clearing
skies as we get into the overnight hours. The winds will be breezy
out of the southwest after frontal passage overnight.
Monday will be a nice but breezy day across the ArkLaMiss with
mainly clear skies and highs in the mid/upper 70s. The winds will
gusty out of the southwest tomorrow afternoon, with gusts from 25-30
Monday night through Sunday: Monday evening our winds aloft will
become near zonal as the closed low lifts farther to the northeast
across the Great Lakes region. A weak 1015mb surface high is
expected to be centered just off the southeast Louisiana coast.
The surface high will drift over southeast Mississippi and aid in
radiational cooling that will send temperatures into the lower 50s
Tuesday morning. Normal morning lows run in the upper 50s. Zonal
flow aloft will continue Tuesday as the surface high shifts
slightly east. Under decent insolation, temperatures will warm
into the low to mid 80s, which is a few degrees warmer than
normal. The dry weather will last into Wednesday morning but our
winds aloft will back to the southwest and waa will strengthen
over our west in advance of a northern stream shortwave digging
over the Plains. The GFS is perhaps the most aggressive with this
system in closing a low off over Arkansas by Thursday morning and
generating a deeper 1103mb surface low that looks to track across
or northwest zones Wednesday night. Wl start off Wednesday morning
with a PWAT less around three quarters of an inch but by evening
ahead of the cold front, models show PWATs surging to near two
inches across our southwest. The GFS and Canadian depict strongest
convection across our southern zones and south Wednesday night.
Considering the instability and shear, a few strong to severe
storms with heavy rainfall look possible. The GFS appears to be
the outlier this model run with a less progressive evolution of
the system. Model consensus ends the main rain chances over our
CWA late Thursday afternoon although an amplified upper level
trough will remain over our region until lifting out Saturday. As
a result low chances of light rain will continue over our
northeast through Friday. Elsewhere, dry weather is expected
Thursday evening through Sunday. Cooler than normal temperatures
are expected Thursday through Saturday morning. Highs Thursday and
Friday will be in the 60s at most locations. /22/
00Z TAF discussion:
Ceilings will continue to slowly rise through the evening with VFR
conditions returning after 01/03Z. A few showers and possibly a
thunderstorms will still be possible around KMEI and KHBG until
01/03Z. Southerly winds will become southwesterly after 01/06Z,
but speeds will continue at 10 to 20 knots and gusts at 20 to 30
knots, especially after 01/15Z./26/
.PRELIMINARY POINT TEMPS/POPS...
Jackson 52 78 53 83 / 7 0 0 3
Meridian 54 78 49 83 / 72 0 0 3
Vicksburg 51 78 52 84 / 1 0 0 3
Hattiesburg 53 81 51 85 / 87 0 0 1
Natchez 51 78 53 83 / 2 0 0 1
Greenville 51 76 54 81 / 1 0 0 4
Greenwood 52 75 51 81 / 4 0 0 4
Area Forecast Discussion
National Weather Service Jacksonville FL
944 PM EDT Sun Apr 30 2017
Breezy/Windy S/SE flow ahead of approaching cold front will be
main story tonight with the ATLC coast remaining at 15-20G30 mph
through the night while inland areas should fade closer to
10-15G25 mph. It took a while this evening but Sea Breeze mergers
finally took place along the I-75 corridor across inland NE FL
with a few showers/isolated storms tracking off towards the N/NE
while a few showers possible near the merger across inland SE GA
as well. These will last through the late evening hours but
generally expected to fade by midnight. Models still showing the
low level moisture in the moderate southerly flow should be enough
to develop a Broken/Mostly CLoudy stratus deck around 2000 feet
off the ground after midnight which may become overcast in some
locations by morning. This cloud cover along with the sustained
southerly flow will keep overnight temps very mild with lows
around 70 degrees in most places and in the lower/middle 70s near
the coast and other inland bodies of water. Not much change for
Monday as slow progression of pre-frontal trof/cold front
towards the East across the SE U.S. will result in Breezy/Windy
South FLow and much above normal temps well into the mid/upper 80s
all areas with some near 90 degree readings along the I-95
corridor and St Johns River Basin of NE FL. Mainly dry conds in
the morning with a slight chance of a few pre-frontal showers
across inland SE GA and the Suwannee River Valley. Otherwise
expect increase in shower/storm activity by the afternoon hours
with scattered/numerous coverage close to the boundary across
inland areas while late day scattered coverage possible along the
I-95 corridor and St. Johns River Basin as models trying to push a
slowly moving inland Atlc Coast Sea Breeze that will help to
initialize more possible activity. Main threat from the storms
will be possible marginal/damaging wind gusts in both of these
areas but also some large hail across some of the inland SE GA
Gusty S/SE winds will continue through the night and despite 30-35
LLVL jet just off the surface likely not enough to support LLWS in
TAF package. Otherwise SREF and HRRR both supporting decent
chances of MVFR CIGS developing in the 1500-2500 range overnight
at all TAF sites and have trended in this direction with a slight
decrease in winds by 08z time frame. MVFR CIGS continue through
the morning hours while southerly winds increase, then heating
should allow for at least SCT/BKN CIGS in the VFR range around
3500-4000 ft by 16-17z time frame so have trended this way and
have added VCSH to account for possible isolated shower activity,
but too far out to account for any possible Storm activity yet.
Stiff S/SE winds at 15-20 knots continue to build surf at local
buoys and latest 18z NWPS run had 5-7 ft seas in the offshore
waters later this evening so have tweaked the timing and started
the offshore Small Craft Advisory this evening and left the SCEC
headlines for the nearshore waters for now with 4-6 ft seas
nearshore. South flow will continue to increase ahead the cold
front on Monday with 20-25 knots and higher gusts expected and
Small Craft Advisory all NE FL/SE GA waters expected.
Rip Currents: Moderate Risk in the moderate S/SE flow along the
coast. Sunday Breaker reports at the beaches were generally had
surf in the 2-3` occasional 4` range.
Smoke from West Mims wildfire will continue to push NW/N overnight
tonight then shift N/NE towards coastal SE GA on Monday ahead of
approaching cold front. Decent mixing from south winds at 10-15
mph tonight will keep much of the smoke off the surface upwind
from the fire so not likely going to re-issue Special Weather
Statement (SPS) for smoke issues.
April 2017 marks the 14th consecutive month with above normal
temperatures at JAX airport. Last below normal month was February
.PRELIMINARY POINT TEMPS/POPS...
AMG 69 88 59 85 / 20 50 40 10
SSI 74 82 67 80 / 10 50 40 20
JAX 71 90 67 84 / 10 40 50 20
SGJ 72 88 69 80 / 0 40 50 40
GNV 69 89 67 85 / 30 30 50 30
OCF 69 90 69 85 / 30 30 50 50
AM...Small Craft Advisory until 4 AM EDT Tuesday for Waters from
Altamaha Sound GA to Fernandina Beach FL from 20 to 60 NM-
Waters from Fernandina Beach to St. Augustine FL from 20 to
60 NM-Waters from St. Augustine to Flagler Beach FL from 20
to 60 NM.
Small Craft Advisory from noon Monday to 4 AM EDT Tuesday for
Coastal waters from Altamaha Sound to Fernandina Beach FL
out 20 NM-Coastal waters from Fernandina Beach to St.
Augustine FL out 20 NM-Coastal waters from St. Augustine to
Flagler Beach FL out 20 NM.
Area Forecast Discussion
National Weather Service Nashville TN
836 PM CDT Sun Apr 30 2017
New showers and thunderstorms pushing up from northeast
Mississippi and northwestern Alabama, ahead of approaching cold
front, means our temporary lull in precip over western areas is
about to come to a close. A few storms could still be strong
overnight, but potential is decidedly less than what we saw
In addition, will probably cancel our Wind Advisory before 9 pm
and issue a new one for tomorrow.
00Z TAF DISCUSSION.
BNA/CKV/CSV...Line of storms is about to exit Middle Tennessee,
with only a few showers occurring elsewhere across the mid state.
The cold front is still west of MEM, and the HRRR does show a
second line of convection moving into Middle Tennessee from the
southwest later this evening, so look for another round of
SHRA/TSRA in a few hours. Surface winds will remain quite strong
well into the evening, and have included a LLWS remark at CSV for
the strong LLJ. Look for VFR wx tomorrow, although surface winds
will remain brisk.
.PRELIMINARY POINT TEMPS/POPS...
Nashville 58 70 51 77 54 / 90 10 0 0 20
Clarksville 54 65 49 75 52 / 70 10 10 10 20
Crossville 56 67 47 70 50 / 100 40 0 10 10
Columbia 56 69 50 77 54 / 70 10 0 10 20
Lawrenceburg 57 70 49 77 54 / 90 10 0 10 10
Waverly 54 66 50 76 54 / 70 0 0 10 30
Wind Advisory until 10 PM CDT this evening FOR Bedford-Cannon-
Area Forecast Discussion
National Weather Service Raleigh NC
845 PM EDT Sun Apr 30 2017
Bermuda high pressure will extend across the SE states through
tonight. A cold front will approach the Appalachians late tonight,
then cross the region late Monday afternoon through Monday evening.
Cooler high pressure will build in from the southwest Tuesday
.NEAR TERM /THROUGH TONIGHT/...
As of 845 PM Sunday...
The latest radar and satellite data indicate the widely scattered
showers lifted into the western and northern parts of NC. The
convective parameters also show the MLCapes were dropping off
rapidly with nightfall. The latest HRRR and other Hi-Res models
suggest that the chance of showers has essentially ended in all but
the western Piedmont. This is the region where some low level
convergence and a SE flow will continue to support widely scattered
showers late evening into the overnight (gradually shifting back
into the Blue Ridge as the night progresses).
Late tonight, the approaching trough to our west is forecast to move
slowly NE. The pressure gradient is forecast to gradually tighten
overnight. A developing low level jet will aid in increasing surface
winds to between 10 and 15 mph. This will also maintain a warm moist
boundary layer (BL), which when combined with the aforementioned
winds, should result in a low overcast of stratus later tonight.
Lows should hold into the upper 60s and lower 70s.
.SHORT TERM /Monday and Monday night/...
As of 300 PM Sunday...
The closed mid level trough over the Midwest Monday morning will
move NE across the Great Lakes during this period. It`s assoc cold
front will cross our region late in the day Monday and at night. A
pre-frontal band of showers and thunderstorms is expected to move
across central NC Monday afternoon and evening. Isolated severe
thunderstorms will be possible as this band moves across, thanks to
a moist unstable airmass over our area (characterized by ML cape 600-
1000 J/kg) coupled with 40+ kt of 0-6km bulk shear. It`s worth
noting that several CAMs indicate an earlier band of showers and
tstms moving up from GA and SC and across our western zones during
the morning hours. That early activity, and assoc cloud cover,
could impact the evolution of later storms, so we`ll have to watch
that closely. In any event, have brought pops in early (during the
morning hours) across our western zones to account for the potential
for this earlier activity, then likely pops across all of central NC
during the afternoon and evening. Right now, it appears that the
bulk of showers and storms should be east of highway 1 by 03Z, and
exit the coastal plain counties of central NC by 06Z-08Z.
Otherwise, with a tight pres gradient in place ahead of the front,
look for breezy s-sw winds ahead of the front during the day Monday
with non-thunderstorm gusts up to 25-30 mph. Highs will range from
around 80 across the Triad to mid 80s across the Coastal Plain, and
will be largely dependent on early-day rain chance and resulting
clouds. Cooler Monday night behind the front - lows from the mid 50s
Triad to low 60s Coastal Plain.
.LONG TERM /Tuesday through Sunday/...
As of 305 PM Saturday...
More changes in the last 24 hours for the long term forecast as
models are getting a better handle on a progressive longwave trough
that will move across the CONUS this week and cause some problems by
the end of the work week. Yesterday at this time models showed the
trough moving slowly across the deep south and producing a cutoff
low which was going to keep the threat for showers and storms around
though the weekend. It also showed two surface low pressure systems
developing that would have lingered across the Carolinas for days.
Now models are hinting at one surface low pressure system that is
more progressive and spurred on by the developing upper low that
never slows down across the deep south. This will cause the primary
window for showers and storms to be Thursday night through Friday
night with a cold front crossing central North Carolina. The front
moves through by the weekend and aside from a few shortwaves moving
around the upper low behind the front, the weekend should be drier
Aside from this system later in the period, expect mainly dry
conditions with high temperatures in the upper 70s to lower 80s
prior to frontal passage on Friday when temperatures will dip back
into the mid 60s to lower 70s for Friday and Saturday before
rebounding back into the low 70s everywhere for Sunday.
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 720 PM Sunday...
24-HR TAF Period: Southerly flow will strengthen tonight as the MSLP
gradient tightens from the west, in advance of an approaching cold
front. Expect MVFR/IFR ceilings to develop after midnight in assoc/w
low-level warm advection. Ceilings are expected to gradually improve
to MVFR/VFR by noon as mixing deepens and southerly flow further
strengthens to 15G25KT by mid afternoon (20G30KT by late afternoon
at eastern terminals). A line of showers and thunderstorms
along/ahead of the approaching cold front is expected to cross
central NC from west to east late Monday aft/eve, near the end of
the 00Z TAF period. Surface wind gusts as high as 40-50KT will be
possible in association with the aforementioned line of convection.
Looking Ahead: VFR conditions will return in the wake of the cold
frontal passage late Mon night and persist through mid-day Thu.
Widespread adverse aviation conditions are expected in assoc/w a
potent storm system progged to affect the Carolinas late Thu through
mid-day Friday. -Vincent
Daily Record High Minimum Temperatures
May 1 /
Greensboro... 65 (2012)
Area Forecast Discussion
National Weather Service Blacksburg VA
1135 PM EDT Sun Apr 30 2017
A cold front moves through the eastern United States Monday.
Weak high pressure follows the front with drier weather for
Tuesday and Wednesday.
.NEAR TERM /THROUGH MONDAY/...
As of 1123 PM EDT Saturday...
Made minor changes to the forecast to account for location of
showers over the NW NC foothills/piedmont. HRRR and RAP showing
most shower activity through early morning to stay across the
Blue Ridge south of Floyd into the NC mountains/foothills.
Upped winds a little as well but think advisory levels should
not be realized, except perhaps at the higher peaks of far SW
VA. Special WX statement issued earlier to account for gusts up
to 45 mph thanks to 50-55 kt low level jet moving in after 05z.
Previous discussion from early evening...
Satellite/radar showing limited coverage for showers,
much less thunder in our forecast area early this evening. Small
area of low level convergence situated over southside VA
helping with a few showers there. Otherwise will wait until
midnight or so to see better lift/enhancement across the
southern Blue Ridge for more shower development.
Previous discussion from mid afternoon...
Deep upper closed low over western Oklahoma this morning will
track northeast to southeast Iowa by Monday morning then to
northeast Wisconsin by Monday evening. Monday in good agreement
with the timing and track of the low.
Challenging to pinpoint where isolated to widely scattered storms
will develop this afternoon. Some of the Hi-Res guidance including
SPC-HRRR suggests favored areas north of Lynchburg and Lewisburg and
another in southwest North Carolina with the storms tracking to the
north and northeast. Any thunderstorms will dissipate shortly after
sunset with loss of heating.
Winds increase from the ssw, especially just above the surface
tonight. Low level is around 60 knots at Boone and Bluefield by
Monday morning. Enough low level moisture again tonight for a layer
of low clouds. Band of deeper moisture along the front crosses west
to east over the region roughly between 15Z/11AM through 03Z/11PM,
with the GFS still a couple hours faster than the NAM. This slows
down the higher probability of precipitation on Monday morning. Wind
shift to the west will behind the front. This looks like late in the
day for southeast West Virginia.
Still not clear how much pre-frontal precipitation there will be.
Questionable how much instability will increase on Monday if most of
the mountains start out cloudy and the clouds spread east during the
day. Temperatures at mid level not quite as warm just ahead of the
front. Bufkit forecast soundings showed enough slow level heating to
break the cap by 20Z/4PM Monday across southwest Virginia, northern
North Carolina, and southeast West Virginia. Off the 12Z NAM and GFS
the forecast Lifted Index values are -4 to -6 with Convective
Available Potential Energy around 1500 J/KG with the push east of
more stable air in the late afternoon and evening from west to east.
Similar to past couple of nights, forecast area will remain in the
mild humid air mass and with increasing cloud cover late tonight
minimum temperatures will be above normal. Also slightly increased
the maximum temperatures for MOnday since front is coming through a
little later in the day.
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 310 PM EDT Sunday...
Forecast models shift a cold front east of our forecast area around
06z (2 AM EDT) Tuesday. In its wake, a brief period of 40-50kt 850mb
winds are expected, but pressure rises diminish during the pre-dawn
hours Tuesday and the forecast inversion height should keep the
strongest winds aloft. Therefore will continue to highlight gusty
winds in the mountains in the HWO, but not issue headlines.
Breezy conditions continue on Tuesday, and despite cooler 850mb
temps, downsloping wind should push temps up to near normal values
for early May.
Leaned toward the cooler guidance values for lows Wednesday morning
as a large high noses into the western potion of the area. A weak
return flow Wednesday will bring clouds and an increase in dew
points to the southern potion of the forecast area late in the day.
Despite weak low level convergence late in the southern Blue Ridge,
forecast soundings show a healthy amount of dry air in the low
levels, therefore kept a dry forecast in place.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 245 PM EDT Sunday...
This period of the forecast will be dominated by a high amplitude
upper trof/cut off low that lifts out of the southern plains early
in the period, and into New England by the end of the weekend. While
there are still some differences in the models with regard to
intensity and timing, there is growing consensus that widespread
showers and thunderstorms impact our area sometime from Thursday
into Friday with upslope showers lingering into Sunday as
reinforcing shortwaves rotate southward on the west side of the upper
low. Ensemble members seem to be centering around late
Thursday/early Friday morning for the best chance for precipitation.
The 12Z GFS is showing better run to run consistency, but also
aligning more with the 00Z ECMWF with a slightly less amplified
upper trof and more northern placement of the upper low. For our
area, chances for strong storms appear best when instability and
lift align on Friday, but a greater concern may be for the potential
for flooding, as NAEFS and GEFS ensembles off the meteorological
model ensemble river forecasts show some confidence in the potential
for flooding in our area late Thursday/Friday. Will include the
mention for possible flooding during this time in the HWO.
After being wedged in Thursday, warmest temps for this period will
be Friday before below normal temps arrive Saturday into Sunday
under the influence of the upper trof.
.AVIATION /04Z MONDAY THROUGH FRIDAY/...
As of 705 PM EDT Sunday...
Should stay VFR this evening at all sites, then low levels
moisten up as southeast to south flow increases with most sites
falling to MVFR or lower after 06z, especially near the Blue
Ridge, while BLF stays VFR.
Timing of front and pre-frontal showers and thunderstorms looks
to be starting around 15z BLF/LWB to 17z BCB/ROA and 19-20z
LYH/DAN. Ending time will be by 20z BLF/LWB to 23z ROA/BCB and
beyond this taf period out east.
Thunder chances are good, but could be limited by low level
cloud cover. For now will keep VCTS in the TAFs with moderate
rain showers with MVFR cigs, with good possibility for IFR
cigs/vsbys in heavy downpours.
SPC has marginal to slight risk of severe storms, so flying
conditions will be turbulent and poor in the region tomorrow.
Winds will also be strong from the south tonight into Monday,
then stay gusty behind the front Monday afternoon/evening.
Extended Aviation Discussion...
The cold front will move east of KLYH and KDAN by 03Z bringing
the winds around to the southwest then west. Southeast West
Virginia may have MVFR upslope clouds into early Tuesday. VFR
conditions return Tuesday and will continue under high pressure
Tuesday night and Wednesday.
A slow moving low pressure system will bring widespread
precipitation and sub-VFR conditions to the Mid Atlantic region
Thursday and Friday.
Area Forecast Discussion
National Weather Service Tallahassee FL
914 PM EDT Sun Apr 30 2017
.NEAR TERM [Through Tonight]...
The 7 pm surface analysis showed a cold front extending south from
a triple point near Saint Louis, MO, through southeast LA, and
into the southern Gulf of Mexico. A convective band preceded this
front, and a portion of this band was nearing our southeast AL and
FL Panhandle zones this evening. The CAMs, including recent HRRR
runs, indicate this rain band will make little further progress
until late tonight and early Monday, when it (or other developing
rain bands) will move into the Dothan and Panama City areas.
Still, nearly unpredictable, sudden eastward bulges in this rain
band (from organized surface cold pools) could bring periods of
rain to the Dothan area ahead of schedule.
With 0-6km bulk shear values near 40 kt and MLCAPE values of
around 1500 J/kg, there is still a low-end threat of damaging wind
gusts in this region overnight. In fact, the 0-1km shear suggests
that a brief tornado can not be completely ruled out. Elsewhere,
the troposphere remained very dry above 850 mb. While there could
be some showers developing overnight well ahead of the slowly-
approaching cold front, they are unlikely to acquire much vertical
depth given the magnitude of the dry air aloft.
.PREV DISCUSSION [755 PM EDT]...
.SHORT TERM [Monday Through Tuesday Night]...
The cold front and associated convection will progress eastward
across our CWA on Monday. The environment ahead of the front will
be less favorable for an organize severe weather threat as sheer
and instability will be weaker. However, SPC does still show a
marginal risk mainly for our Georgia zones. Drier and cooler
conditions will move into the region behind the front Monday night
with overnight lows dropping into the mid to upper 50s all but
the SE Big Bend (lower to mid 60s). Afternoon highs Tuesday are
expected to be mostly in the mid 80s with lows Tuesday night in
the upper 50s to around 60.
.LONG TERM [Wednesday Through Sunday]...
Mainly dry conditions are expected on Wednesday but global models
continue to show another deep low pressure system developing and
moving into the SE CONUS on Thursday. There will likely be
sufficient instability and shear for organized convection, and a
chance of severe weather can`t be ruled out. Both models move the
system eastward on Friday with dry conditions returning for the
weekend. Near average temperatures are expected behind this
.AVIATION [Through 00Z Tuesday]...
MVFR cigs have developed at ECP just east of a slow-moving line of
showers and thunderstorms that will move eastward into western
portions of our area early Monday morning. MVFR cigs will develop
overnight across the remainder of our terminals ahead of this
line, and as the showers and storms move eastward MVFR visibility
is likely starting around 10-11Z at DHN and ECP, 13-14Z at ABY and
TLH, and during the afternoon at VLD. Brief periods of IFR
visibility are possible in thunderstorms. VFR conditions are
expected to return from west to east during the afternoon-evening
behind the line of showers and thunderstorms.
Moderate to strong south to southwest winds will continue across the
coastal waters through Monday ahead of an approaching cold front.
Advisory conditions are expected at times with the worst conditions
west of Apalachicola. This will lead to high surf, strong rip
currents, and slightly above-normal tides. Much lower winds and
seas are expected by mid-week with winds and seas increasing once
again on Thursday with the approach of the next cold front.
No fire weather issues are expected through tomorrow with increasing
moisture and likely showers and thunderstorms. RH values could drop
to 20-30 percent on Tuesday afternoon along with dispersion values
possibly exceeding critical thresholds then, but winds are expected
to be too light for red flag criteria.
Rainfall amounts will generally be in the 0.50 to 1 inch range
from Tallahassee north and westward with lesser amounts to the
south and east. Another system is likely on Thursday with some
heavier totals possible. However, the risk of river flooding is
low given the recent dry conditions and relatively low river
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 71 79 57 86 58 / 30 60 10 0 0
Panama City 73 75 61 81 65 / 40 60 10 0 0
Dothan 69 75 54 85 59 / 60 60 10 0 0
Albany 71 78 54 83 58 / 40 60 10 0 0
Valdosta 70 83 59 85 56 / 20 60 30 0 0
Cross City 70 84 65 84 60 / 10 30 40 20 0
Apalachicola 74 77 62 81 64 / 20 60 10 0 0
FL...High Rip Current Risk through Monday afternoon for Coastal Bay-
Coastal Gulf-South Walton.
High Rip Current Risk from 6 AM EDT Monday through Monday
afternoon for Coastal Franklin.
High Surf Advisory until 5 AM CDT Monday for South Walton.
GM...Small Craft Advisory until 8 AM EDT Monday for Coastal waters
from Apalachicola to Destin FL out 20 NM-Waters from
Apalachicola to Destin FL from 20 to 60 NM.
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
459 PM MDT Sun Apr 30 2017
.DISCUSSION...(This Evening Through Sunday)
Issued at 159 PM MDT Sun Apr 30 2017
Mean troughing will continue over the region through mid next
week with a few systems bringing chances for precip. Deep closed
low over the southern plains will slowly progress east/northeast.
Precip shield from the this system continues to try and shift NW
into the FA. However, very dry air in the ll/s continues to fight
top down saturation with precip drying up over far eastern
scentral SD. Have cut pops there trough tonight, with only a very
slight chance mention retained for the SE half of Trip county.
Attention turns to the next system which will impact the region
tonight into Monday. Sat trends indicate a cu field over SE MT and
HRRR has consistently indicated a few shra over northern Campbell
county late this afternoon, although dry air in the ll`s will
again fight any showers, with virga more likely. Pac system will
advect into the region tonight and may support a few rain/snow
shra over the western half in a weak FGEN regime. Better chances
(although not great) for precip will arrive Monday afternoon. The
associated cold pool from this system will support steep ll lapse
rates Monday afternoon, generating some small CAPE over the
region, enough to support a few showers perhaps a few TS, esp
across NW SD. It will also be quite breezy Monday given strong
linked flow aloft and expected deep mixing, windiest across NW SD
where adv winds are expected. Have added NW SD to a wind adv for
this where sustained winds of 25 to 35 mph with gusts to 50 mph
are expected, esp in/near any convective shra. A stronger system
will then arrive Tues, supporting a decent chance for rain showers
and possibly a TS, esp across the SW half. A few snow showers
will also be possible Tues evening above 6 KFT with any lingering
After Tues, the pattern begins to shift with massive ridging
progged over the western CONUS. This will support much warmer
conds and dry weather the remainder of the week, with 70s and 80s
expected toward the end of next week. Forecast models are progging
another large closed low over the west coast next weekend, which
would sustain the ridge in place into next week, keeping conds
quite warm here.
.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 456 PM MDT Sun Apr 30 2017
VFR conditions are expected for most areas through the period. The
exception will be for some MVFR conditions with showers that move
through the BLKHLS area from 09-16z, with perhaps spotty MVFR
conditions across northeastern WY during the same time. This will
be in association with a weak storm system that passes through
the area late tonight and Monday. Also with this storm will be
gusty northwest winds of 30-45 kt for most areas on Monday.
SD...Wind Advisory from 10 AM to 7 PM MDT Monday for SDZ001-002-012-