Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/11/18
Area Forecast Discussion
National Weather Service Charleston SC
1027 PM EDT Thu May 10 2018
.SYNOPSIS...
Unseasonably warm Atlantic high pressure will prevail across
the region through the weekend. An upper level disturbance is
expected to bring unsettled weather to the region beginning
Monday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 1020 PM: KCAE Doppler Radar detected the cold pool/outflow
was outpacing the convection across the midlands of SC. As a
result, the convection was steadily weakening. However, an old
seabreeze was located on 10 to 15 miles to the east of the
advancing cold pool. If the boundary collision occurred a few
hours ago I would expect new updrafts to develop over the
boundary intersection. SPC mesoscale indicates that the low levels
of the atmosphere have become quite stable. I will not forecast
additional convection. SCHC PoPs will highlight the passage and
eventual dissipation of weak showers through 1 AM.
As of 755 PM: Sfc observations and regional radar composite
indicated that the leading edge of a cold pool was sliding east
across the midlands of SC. A few thunderstorms were along and
just west of the cold pool. However, a seabreeze was clearly
located on KCLX from Bulloch to Allendale Counties, pushing
inland. SPC mesoanalysis shows very stable conditions across SE
SC and GA. I will anticipate the convection to largely dissipate
upstream of the forecast area. However, I will expect a few
dissipating showers to move over the inland SC counties before
completely ashing out. I will add SCHC PoPs for late this
evening.
As of 555 PM: KCLX detected an isolated thunderstorm over and
south of Sapelo Island. SPC mesoscale analysis showed a pool of
1000 J/kg of CAPE along and west of an advancing seabreeze. East
of the seabreeze, CIN values have increased to 15-25 J/kg. GOES-16
visible indicated on shallow Cu across the inland forecast area,
with coverage gradually decreasing from the east. Given the
trends and the time of the day, I will indicate SCHC PoPs only
for the area of ongoing convection. Latest run of the HRRR shows
the convection over the foothills and Piedmont generally
dissipating during the mid evening across the Fall Line of the
Carolinas.
Previous Discussion:
This Evening and Tonight: A few showers will continue for the next
hour or two over parts of Southeast Georgia where sufficient
instability remains near a seabreeze circulation. Showers will
likely track slowly east, but diminish and/or dissipate while
encountering a slightly cooler marine layer and the loss of
diurnal heating with the approaching sunset. The main issue
during the overnight period will deal with convection that has
developed in the upstate. A mid/upper trough along with sfc lee
trough over the Midlands should help push convection toward
inland areas during overnight hours, but most if not all
convection will likely have a tough time reaching parts of
Southeast South Carolina as instability wanes. A dry forecast
remains in place after sunset and through the overnight period,
but a few showers can not be ruled out before the night is over,
mainly well inland in Southeast South Carolina. Low temps will
remain mild tonight, suggesting the overall threat of fog being
low tonight. Low temps should dip into the low/mid 60s inland
to upper 60s along the coast.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
High confidence this period with unseasonably warm Atlantic high
pressure expected to continue. Increasingly warm and muggy
conditions are likely through at least Saturday, although rain
chances will be very low given the limited moisture, mainly confined
to inland areas during the afternoon each day. Temperatures should
top out in the lower to mid 90s during the afternoon away from the
locally cooler coastal areas.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Models have started coming into a somewhat better agreement for
the long term. An upper level low and surface low will be over
the northeastern Gulf of Mexico Monday. Meanwhile, a front will
be far to our north. The lows will move ever so slightly
northward Tuesday, merging with the front by Wednesday. The flow
around the lows will bring showers to our area Monday through
Wednesday. There are still differences in the models regarding
how much rainfall and when, so expect more adjustments going
forward. For now, we have POPs increasing Monday through
Wednesday.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
VFR conditions are expected to prevail at KCHS and KSAV through
0z Saturday.
Extended Aviation Outlook: Mainly VFR through the weekend except low
chance for restrictions from low clouds/fog each morning near
daybreak. Better chance of restrictions after Sunday from low clouds
and rain.
&&
.MARINE...
This Evening and Tonight: Sfc high pressure over the coastal waters
will slide south while a weak mid/upper trough of low pressure
passes aloft. As this process unfolds, a fair gradient will persist
near the coast between the lee trough inland and high pressure
over coastal waters. In general, south winds should peak near 15 kt
this evening, especially near coastal locations. Winds should
then slightly veer to southwest and remain at or below 10-15 kt
overnight. Seas will range between 2-4 ft, highest in offshore
Georgia waters.
Friday through Tuesday: Atlantic high pressure will prevail through
the weekend before weakening early next week. Overall no significant
concerns expected.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...NED
SHORT TERM...RJB
LONG TERM...MS
AVIATION...NED/RJB
MARINE...DPB/RJB
Area Forecast Discussion
National Weather Service Des Moines IA
629 PM CDT Thu May 10 2018
...Updated for 00z Aviation Discussion...
.SHORT TERM.../Today through Tonight/
Issued at 340 PM CDT Thu May 10 2018
The frontal boundary was south of Iowa across northern Missouri
at 18Z with a surface ridge extending south into northern Iowa.
Aloft, an upper low will drift southeast into the central Rockies
by Friday resulting in split flow across the central US. Iowa
should be influenced by the southern stream in the split flow
pattern with shortwaves ejecting out across the plains into early
next week. The before mentioned surface boundary from the plains
east across northern Missouri/southern Iowa will remain quasi-
stationary.
For tonight...thunderstorms should develop across the western
plains and then move ese tonight. The latest HRRR run moves a MCS
east across Nebraska reaching the Missouri river after midnight.
In the meantime, strong moisture transport over the surface
frontal zone and very good isentropic lift should result in
elevated thunderstorm development across northern Iowa by late
evening. The showers and thunderstorms over Nebraska should reach
central Iowa after 09z and persist into Friday morning.
.LONG TERM.../Friday through Wednesday/
Issued at 340 PM CDT Thu May 10 2018
.../Friday through Monday/...Confidence: Medium
Once the MCS activity and elevated storms over northern Iowa
diminish Friday morning, we should see a minimum in precipitation
coverage Friday afternoon with cloudy and cool weather north of
the surface boundary for all but the southern two rows of counties
in Iowa. In southern Iowa, the surface front may drift into the
area which would result in much warmer conditions. This is the
reflected in the current forecast but confidence is not high. The
NAM/GFS (12Z) both suggest warm air advection over the boundary
around 700 mb resulting in a strong cap over the frontal zone
Friday afternoon. Without any significant forcing, the cap looks
strong enough to inhibit surface based convection Friday
afternoon. However, the low-level jet over the boundary may
initiate thunderstorm development Friday night.
For the weekend, with the surface boundary in place, periodic
shortwaves move through the SW flow aloft and abundant moisture,
low-medium POPS look reasonable through the period with below
normal temperatures Saturday and near normal on Sunday.
.../Monday Night through Wednesday...Confidence: Low to Medium
A split flow upper air pattern remains in the long-range with
Iowa in the southern sw flow regime. In addition, the Gulf of
Mexico remains open with moisture intersecting the surface
boundary in, or near, Iowa. This upper air pattern favors
unsettled weather over Iowa and POPS remain for several in place
for several days. Temperatures will remain dependent upon cloud
cover, precipitation coverage, etc. and generally near normal.
&&
.AVIATION.../For the 00Z TAFS through 00Z Friday evening/
Issued at 631 PM CDT Thu May 10 2018
Light showers over northern Iowa will pass through early this
evening and then the focus is on thunderstorms moving in later
tonight. -TSRA included for most likely time of storms with MVFR
restrictions, though refinements to impacts expected in next TAF
issuance. There should be a lull in showers and storms by late
morning, but low ceilings will linger through the end of the
period at all but OTM. IFR ceilings at MCW may extend farther
south to ALO and FOD, but lower confidence in those locations so
left at low end MVFR.
&&
.HYDROLOGY...
Issued at 340 PM CDT Thu May 10 2018
Flood watches remain in effect of parts of the Cedar and Des
Moines rivers in northern Iowa due to QPF driven rises Friday.
Given the synoptic pattern, hydrology will remain a concern for
the next several days especially over northern Iowa. Looking at
the precipitable water values, Iowa will have values at or above
150 percent of normal into next week. Thunderstorms in this
environment should be proficient precipitation producers. People
which interests along the rivers should remain alert for the next
several days.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Johnson
LONG TERM...Johnson
AVIATION...Ansorge
HYDROLOGY...Johnson
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1007 PM EDT Thu May 10 2018
.SYNOPSIS...
A weak cold front will push through the area late tonight into
early Friday. High pressure will build in from the west into the
weekend. A weak cold front will approach the area early next
week. A trough of low pressure will impact the region mid to
late next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 10 PM Thursday...Convection has moved into the nrn and
wrn tiers as expected. Had one svr storm earlier but overall
trend seems to be grad weakening with loss of heating. High res
HRRR rapidly diminishes remaining storms in next cpl hours so
will maintain likely pops inland and N a bit longer than expect
to see activity weaken as it tries to move twrd srn cst. After
about 06Z expect bulk of shra to be over with grad clearing.
May see some patchy fog try and form as winds go light espcly
where it rained. No change to lows with 60s area wide.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
As of 315 PM Thursday...As upper heights build across the
region, a west to northwest downsloping flow will lead to
slightly lower dewpoints on Friday and consequently warming
temperatures as highs reach the mid/upper 80s inland, low/mid
80s south coast and mid/upper 70s Outer Banks. Skies will be
sunny making for a near perfect May afternoon.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
As of 3 AM Thu...Above normal temps expected through the
period, with increasing precip chances next week.
Friday Night through Sunday...Above normal temps expected this
weekend with mostly sunny to partly cloudy skies, as an upper
ridge strengthens across the area with surface high pressure in
control. Right now Sat looks like the warmest day with highs
around 90 degrees inland, and 80-85 degrees along the coast.
Some guidance shows highs in the low 90s inland Sat. Sun looks
very similar to Sat, with a few more clouds. Overnight lows in
the 60s. Ridge will likely suppress most convection, but
isolated diurnally driven, seabreeze showers and tstms will be
possible inland Sat afternoon/evening and again Sunday.
Monday through Thursday...Below avg confidence in forecast
specifics early next week, with decent amt of model spread. A
weak backdoor front is forecast to approach the area Monday and
Tuesday. The GFS keeps the front stalled to the north, while
the ECMWF pushes the front further south late Monday and Tuesday
before lifting back to the north Tue night. This could aid as a
focus for convection. Models continue to develop a stacked low
over FL and the Gulf of Mexico Monday and Tuesday. Given the
front in the vicinity early next week and increasing moisture
around the low and off the Atlantic, will continue chance pops. At
this time looks like the best chances for widespread precip
will be mid to late week, as low gets absorbed and moisture
overspreads the area. Highs inland in the 80s and mid 70s/low
80s along the coast. Overnight lows in the mid to upper 60s.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Short Term /Through Friday/...
As of 615 AM Thu...Expect VFR to dominate however will have to
watch line of storms that could lead to brief sub VFR later
this evening espcly inland and N where could also see a stronger
gust or two. After threat of convection pass after midnight
cant rule out some patchy light fog or low clouds espcly if it
rains, however most guidance not showing much so will keep as
VFR. VFR conditions will prevail Fri with mclr skies with zonal
flow aloft behind very weak cold front/trof.
Long Term /Friday Night through Tuesday/...
As of 3 AM Thu...Pred VFR conditions expected through the
period. Patchy fog/stratus will be possible Sat and Sun
mornings, and isolated diurnal showers/storms possible Sat and
Sun afternoons. Precip chances increase next week with better
chances for sub-VFR conditions.
&&
.MARINE...
Short Term /Through tonight/...
As of 615 PM Thursday...Fcst looks good with SSW winds 10 to 20
kts this evening ahead of weak cold front/trof. Winds will
diminish and become more W late.
Prev disc...With advancing weak cold front and mid- level
trough, winds will be SW 10-20 knots through the evening into
tonight before diminishing toward morning. The winds become more
W/NW behind the front Friday morning at 5-10 knots before
becoming NE Friday afternoon. Seas are currently 3-4 feet and
may get as high as 5 feet, especially late this evening into the
early overnight hours, before dropping back to 2-4 feet for
Friday per latest NWPS/SWAN model.
Long Term /Friday Night through Tuesday/...
As of 3 AM Thu...Looks like a nice day Sat with S winds 5-10 kt
early increasing to 10-15 kt in the afternoon with seas 2-3 ft.
SW winds 10-15 kt Sun, increasing to 10-20 kt Sun evening and
into Monday with seas 2-4 ft.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...CTC
NEAR TERM...RF
SHORT TERM...CTC/BM
LONG TERM...CQD
AVIATION...RF/CQD
MARINE...RF/CTC/CQD
Area Forecast Discussion
National Weather Service Morristown TN
914 PM EDT Thu May 10 2018
.DISCUSSION...Earlier convection has moved out of the area.
However, some weak short wave energy is helping to force
convection over KY to our northwest, and both the NAM and HRRR
indicate this will affect parts of our northeast after midnight.
Will add some low PoPs to allow for this. Will also make some
adjustments to sky cover, hourly temps, and dew points. update out
soon.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 64 89 65 90 / 20 20 10 10
Knoxville McGhee Tyson Airport, TN 63 87 64 88 / 20 20 10 10
Oak Ridge, TN 62 88 64 89 / 20 20 10 10
Tri Cities Airport, TN 58 84 61 87 / 20 20 10 20
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...None.
TN...None.
VA...None.
&&
$$
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Friday)
Issued at 318 PM CDT Thu May 10 2018
This afternoon an upper level trough was over the western states
while ridge was located over the Plains. Low pressure was located
in the lee of the Rockies while a warm front was located north
into Nebraska. There was a piece of energy moving northeast across
COlorado into Wyoming. Atmosphere across northern Kansas remains
capped to surfaced based convection in the presence of a stout
EML. Temperatures have warmed into the mid and upper 80s this
afternoon. Tonight models continue to show best forcing for
elevated convection to remain north into Nebraska. CAMS,
particularly the NMM and the HRRR show the Nebraska convection
moving across northern Kansas along the border after 05Z tonight
then moving off to the northeast late in the night as the low
level jet increases advecting moisture northward into Iowa where
favorable moisture transport will exist for MCS maintenance. Any
elevated storms tonight will have the potential to produce strong
wind gusts along with hail. Winds will increase later tonight as
the low pressure in Colorado moves eastward into western Kansas.
Forecast soundings show lower boundary layer will remain mixed and
low temperatures will cool into the mid and upper 60.
On Friday, the surface low is forecast to move out into central or
southwest Kansas with a frontal boundary extending from Iowa
southwest into southwest Kansas. During the afternoon hours The
front is forecast to bisect the cwa from southeast Nebraska to near
Salina or McPherson after 21Z. Forecast soundings continue to show a
stout EML in place through the daytime hours. Convergence along the
surface front is fairly weak and will likely not be enough to
overcome the cap to initiate surfaced based convection. If a storm
were to develop it would likely be storing to severe as 0-6km shear
increases to 30 to 50 kts after 21Z and MLCAPE in excess of 2500
J/kg. Friday will be another very warm day as temperatures rise into
the upper 80s to mid 90s.
.LONG TERM...(Friday night through Thursday)
Issued at 318 PM CDT Thu May 10 2018
For Friday night through Sunday, models continue to show a fairly
strong elevated mixed layer (EML) over the forecast area capping
the boundary layer. Meanwhile forcing is not that obvious with
maybe some subtle waves aloft. Models also show heights generally
rising through the weekend and low level convergence along the
surface trough does not look that strong. The GFS seems to be one
of the only solutions with much QPF over the forecast area and
think given the factors working against convection that it may be
overdone. In general I prefer the idea of the NAM/ECMWF with any
MCS Friday night remaining north across NEB. Nevertheless have
maintained a small chance for storms across the northern half of
the forecast area. Precip chances Saturday may be tied more to
whether diurnal heating and low level convergence can overcome the
EML. Again with forecast soundings showing the cap holding, the
forecast only has some 20 to 30 percent chance POPs.
For next week, models show the EML weakening as southwest flow
aloft continues. A moist and conditionally unstable airmass is
progged to remain over the area through at least the first half of
next week. So the forecast continues with some chance POPs through
Tuesday. There are some differences between the GFS and ECMWF by
mid week with the ECMWF trying to bring a weak surface ridge into
the area by Thursday. Confidence in these mesoscale details is not
that great this far out so have continued with some chance for
showers and thunderstorms through the end of the forecast period.
There doesn`t look to be much change in temps over the next
several days. Models suggest the thermal ridge may still be
holding on across east central KS on Saturday with highs in the
lower 90s. But in general temps look to not very much from highs
in the 80s and lows in the 60s. The one question mark is the
potential for some stratus to move into parts of north central KS
Saturday and Sunday. This could hold temps in the 70s if the low
clouds hold in strong.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 636 PM CDT Thu May 10 2018
VFR conditions are expected for the TAF period with a slight
chance of high-based showers and storms tonight. However,
confidence in this precip was not high enough to mention in the
00Z TAFs. Southerly LLWS develops around 04Z and persists for the
night, with gusty southerly surface winds increasing Friday
morning.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...53
LONG TERM...Wolters
AVIATION...Skow