Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/28/18
Area Forecast Discussion
National Weather Service Caribou ME
1034 PM EDT Sun May 27 2018
High pressure over the maritimes will move away to the east
tonight and Memorial Day as a cold front approaches from the
west. The cold front will cross the area Monday night. High
pressure will build over the region on Tuesday and remain across
the area through midweek.
.NEAR TERM /THROUGH MONDAY/...
1040 PM Update...
IR satl imagery continued to show clouds on the increase w/the
thickest cloud cover from the Central Highlands to the coast.
Thinner cloud cover resides across the northern 1/2 of the CWA
this evening but this will change by morning as the cloud cover
advances and thickens. The latest runs of the HRRR and RAP
supported some light rain showers making their way to the
western and far nw area by sunrise. Kept the daycrew`s
assessment of 20-30% POPs for these areas. Temps have dropped
off into the 50s w/the exception of the immediate coast as
readings were down in the upper 40s. Forecast temps of low to
mid 40s for the CWA still look reasonable for overnight.
Moisture wrapping around the high, and within a weak upper
level shortwave ahead of the cold front, will spread clouds over
the area late tonight into Monday. This will bring a mostly
cloudy day on Monday with an increasing south southwesterly
breeze. Some showers may stray ahead of the approaching cold
front during the midday and afternoon. The best chances for
showers will be across the north where some frontal convergence
and upper level divergence will support lift. Any showers should
be light. Highs Monday will range from the low 60s Downeast to
the upper 60s over the north.
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
A cold front mvg thru Mon night wl bring sctd showers to the region
ovrngt, mainly acrs the north where best s/wv mvs acrs. Rmndr of the
region wl see slgt chc-lochc pops drg the ovrngt, coming to an end
by dawn as low tracks into the Gulf of St. Lawrence. Areas of fog
ovr the water and patchy fog along the immediate coast wl be
predominant drg the overnight hrs as low-lvl moisture streams in
ahead of frontal bndry. As fropa occurs btwn 09z and 12z Tue fog
should quickly erode.
High pressure wl be building in from Canada Tue mrng as low departs
to the east. This wl result in a mstly sunny day with gusty nw
winds. Temps in the aftn rise to nr normal values for the north and
abv normal ovr Downeast in the low 70s, especially with winds
Upr lvl ridge wl be building twd the east thru the middle of the
week with 590 high centered off of the southeast coast. This brings
an extended pd of nice, tranquil wx with mins nr to slightly
blo normal under clr skies and lgt winds on Wed. On the flip-
side highs wl be well abv normal with lwr 70s common acrs the
St. John Vly and m/u 70s acrs interior Downeast.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Wed night and Thu wl feature sfc high sliding south of the area. Upr
ridge conts to build thru Thur night bfr finally beginning to break
down due to remnants of Alberto getting captured by wv mvg acrs the
upr Midwest twd the end of the week. At this time there is just a
chc of showers as the wv mvs thru late in the week and ovr the
Temps on Thu wl lkly be the warmest of the week, especially to the
north of the Bangor region. H9 temps increase to +20C and higher ovr
interior sections of CWA and with full sun may see maxes appch m/u
80s acrs the far north. Coastal areas wl be kept cooler by onshore
flow with some areas likely to crack 70F. H9 temps are progged to be
warmer on Fri but with increasing clds and potential for showers
expect maxes wl be several degrees cooler on Fri.
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
NEAR TERM: VFR conditions are expected across the area tonight
SHORT TERM: VFR expected most of the week with the exception of
Mon night as IFR fog develops along the coast with low-level
moisture ahead of the frontal bndry. BHB most likely terminal to
be impacted by IFR restrictions but potential exists for all
terminals to get in on low MVFR/IFR restrictions Mon night ahead
of cold front.
NEAR TERM: Winds and seas are expected to be below SCA through
Monday. Some increasingly humid air moving over the waters on
Monday may produce some light mist.
SHORT TERM: Winds and seas will remain blo SCA levels through
the middle of the week. Areas of fog are expected over the water
Mon night into Tue morning before cold front crosses the waters.
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1154 PM EDT Sun May 27 2018
Ridging will maintain VFR conditions and light winds throughout the
upcoming forecast with just a small chance at shallow, patchy MVFR
fog for a few hours early Monday morning.
.DTW THRESHOLD PROBABILITIES...
Issued at 334 PM EDT Sun May 27 2018
Changes to the forecast include increased PoPs today for the
northern CWA with likely Pops for the Thumb between 21-02Z.
Messaging to include conditional risk for strong to severe
thunderstorms this evening north of I 69 with wind gusts to 60mph
and 1 inch diameter hail possible. The area was upgraded earlier to
a marginal designation for severe weather in midday Swody1
Noisy forecast again today with Southeast Michigan directly within
the dirty summertime ridge. Difference today has been the
development of CIN between 3.5-7.0 kft agl in response to a 825-
700mb anticyclone center pushing across far southern Lower Michigan.
Satellite trends have supported this capping layer with very little
cumulus development to this point. The anticyclone center is one of
a very shortwavelength and presents an issue as midlevel theta e is
progged to wash back in along the northern flank of the anticyclone
center west to east directly into Saginaw Bay region yet this
afternoon. The theta e axis is resolved by the NAM to be respectably
deep from 900 to 700mb. This midlevel moisture in combination with
strong late May insolation and an atmosphere preconditioned for deep
mixing will likely lead to convective initiation in the higher
terrain north of Saginaw Bay. Storm movement will be to the
southeast at approximately 30 mph. Consensus of CAMS and high
updraft probabilities in HREF output supports an increased
confidence in thunderstorm activity from Saginaw Bay southeastward
to Port Huron in the 21-02Z time window. Data supports a steeping of
a convergence axis directly over northern cwa in response to slow to
move deep ridging to the southeast. Uncertainty does with regards to
magnitude of MLCAPES with model resolution/gradient issues in the
northern Thumb. Current thinking is based on model soundings and RAP
based mesoanalysis that at least 1500 J/kg MLCAPE will be available
for thunderstorms this afternoon. 0-6km bulk shear of approximately
25 knots in vicinity of Lake Huron will be more than sufficient for
storm organization. Thunderstorm activity this afternoon will be
capable of wind gusts to 60 mph and hail to 1 inch.
Farther south, including metro Detroit, models keep just enough
CIN/capping to inhibit convective development. Some question with
small amount of capping as skin layer dewpoints in the soundings do
not invoke a lot of confidence. Certainly possible for thunderstorm
activity over the southern cwa with the amount of instability within
the column. Introduced entry level chance PoPs this evening,
however, current data suggests thunderstorms will remain to the
northeast of metro Detroit.
A hot and muggy Memorial Day as the upper level ridge is forecasted
to shear to some extent across the central Great Lakes. Yet again,
forecast is all about the details with models now showing less
focused anticyclonic vorticity advection for the state early in the
day. To what extent is questionable as there is differences between
Euro and NAM. Euro does show some AVA during the late day period.
Regardless, will honor long days and maintain highs in the lower
90s. Question is again on thunderstorm potential as some CAM output
is suggesting convective initiation over the higher terrain of Lower
Michigan, pushing southward into the Saginaw Bay region. Overall
pattern will be conducive for increasing low level deformation and
backdoor front as likelihood for organized northeasterly
anticyclonic flow increases during the evening. Given this potential
trigger, and what should be steep low level lapse rates over the
landmass of Lower Michigan continuing chance PoPs over the northern
cwa. Low certainty in CAPEs with poor surface parameterizations, but
the idea is for less instability on Monday given stronger background
Backdoor front off of the lake is expected to become quasi
stationary over portions of the cwa Tuesday. Net result is for
cooler temperatures over the north half of the cwa with highs still
expected to reach the upper 80s south of I 69. Relief from the muggy
dewpoints will not arrive until a nocturnal release of the Lake
Huron marine layer occurs Tuesday evening.
Abundant tropical moisture associated with the remnants of Alberto
will overspread the region on Wednesday. A cloudy morning will be
followed by an increasing chance for showers and eventually more
steady rainfall through the day and Thursday as PWAT values
gradually rise to above 2 inches. Prolonged rainfall with periods of
heavier rates expected with occasional embedded thunder possible.
Highs will hold in the low 80s through both days. Widespread rain
will be on the way out Thursday evening before potent upper energy
(presently in the form of a cutoff low over the southwest CONUS)
brings in another round of rainfall Friday. As this trough exits
toward the Mid-Atlantic region, a cooler, drier, and more seasonable
air mass will be ushered into SE Michigan for the weekend.
Winds will remain out of the south and light across the lakes today
as a weak low pressure drops south out of northern Michigan and
washes out. This will bring an associated frontal boundary across
Lake Huron and shift winds out of northwest tonight and into
tomorrow morning. Winds continue to remain light with favorable
boating conditions for the most part today with the exception of
decreasing areas of fog across inner Lake Huron and widely scattered
storms this afternoon that may develop across west central Lake
Huron down towards Saginaw Bay this afternoon. Mostly favorable
boating conditions remain for the majority of Memorial Day as high
pressure builds with a return to light southerly winds. Though,
Memorial Day evening may see some scattered thunderstorms again as a
frontal boundary drops southward. Weather conditions deteriorate
midweek remnants of Subtropical Storm Alberto move towards the
Here is a list of record high temperatures for
this holiday weekend.
Monday, May 28th:
Detroit 95 (set in 2012)
Flint 93 (set in 2012)
Saginaw/Tri-Cities 92 (set in 1977)
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
You can obtain your latest National Weather Service forecasts online
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
954 PM CDT Sun May 27 2018
Issued at 250 PM CDT SUN MAY 27 2018
Primary forecast focus is on continued hot and humid conditions.
The story remains our unseasonably hot and humid conditions across
the area. We actually broke the record high for St. Joseph at 11:24
AM, which was 93 F set in 2006, and through 2 PM it`s high was 98 F.
The hottest temperatures remain focused at the leading edge of the
upper ridge axis from southern and southeastern Nebraska into
northeastern Kansas and northwestern Missouri, similar to yesterday.
The Heat Advisory remains in effect for the Kansas City Metro area
through 8 PM this evening.
There remains a low chance a few thunderstorms may crop up along the
very diffuse/weak surface trough in central Missouri. Latest HRRR
and various flavors of the HiRes WRF have backed off quite a bit,
with the WRF`s almost silent, with convection. Additionally, there
has been little change in the cumulus development in eastern
Missouri, with almost no development into central Missouri beyond
the Columbia/Jeff City. However, it`s still worth a mention a storm
or two can crop up given the uncapped, high CAPE environment,
there`s just little to no focusing for ascent and little if any
For Memorial Day, it`s going to remain unseasonably hot, with
afternoon heat index values holding in the mid 90s, overall. Will
hold of on any Heat Advisory at this time, but the night shift may
need to assess given potential impacts with it being a Holiday known
for outdoor festivities. Messaging via social media and our web
pages have advertised unseasonable heat and heat safety for several
Remaining hot on Tuesday, a negatively tilted 500mb trough will
begin to approach the region, lifting off the central Rockies into
the northern Plains through Tuesday. At the same time, the remnants
of Subtropical Storm Alberto will be making it`s way north along the
lower Mississippi Valley. Into early Wednesday, long range solutions
are consistent with the Subtropical Storm formally known as Alberto
being absorbed into the large trough as a mid-latitude cyclone over
the joint Ohio-Mississippi Valleys. This will result in increased
shower and thunderstorm chances across Missouri and eastward. This
isn`t going to bring us much of a cool down, unfortunately, as highs
remain in the upper 80s and lower 90s through the end of the week
into next weekend.
.Aviation...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 954 PM CDT SUN MAY 27 2018
VFR conditions and light winds will prevail over the next 24
KS...Heat Advisory until 8 PM CDT this evening for KSZ104-105.
MO...Heat Advisory until 8 PM CDT this evening for MOZ028-029-037-043.
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
958 PM EDT Sun May 27 2018
High pressure over the maritimes will retreat well offshore
tonight. Weak low pressure passing to our south tonight and
early Monday will spread clouds across the entire forecast area.
Any showers with this disturbance should be spotty and largely
confined to far southern New Hampshire and the southern tip of
Maine. Another low will pass to our north on Monday with a
trailing cold front to cross the region Monday night preceded by
a few showers across the mountains and foothills. High pressure
will build over the region Tuesday and will push offshore south
of New England Wednesday. Low pressure may bring appreciable
rainfall to the region Friday into next weekend.
.NEAR TERM /THROUGH MONDAY/...
955 PM Update...
Keeping an eye on the stratus and shower activity as it moves
into southern NH. Diminishing the PoPs earlier in the afternoon
update seems to have worked out with still some dry air to
overcome in the lower levels per the 00Z KGYX sounding.
Saturation should be improving in the atmospheric column as
onshore flow adds more moisture to the air...and showers should
be reaching the surface more as the night wears on.
617 PM Update...
Minor changes to the forecast for PoPs and sky cover. Otherwise
minor changes as precipitation edges into the southern sections
of the forecast area this evening. HRRR and other CAM models
showing only a few cents worth of QPF so have kept PoPs low.
Drizzle and fog likely offshore with stratus moving in and
becoming a nuisance along the shore and a bit inland.
At 18z...a 1028 millibar high was over Nova Scotia. A wavy
frontal boundary extended from south of Long Island through the
DELMARVA region. GOES imagery showed the cloud shield ahead of
a weak impulse and associated surface wave overspreading the
remainder of the forecast area at the moment. An area of showers
across western New England were creeping eastward and will graze
southern and western sections of the forecast area through early
tonight. Onshore flow between the retreating maritimes high and the
disturbance to our south will complicate matters as it may produce
some low clouds and patchy fog for coastal and southern areas
.SHORT TERM /MONDAY NIGHT THROUGH 6 PM MONDAY/...
Slow improvement Monday as clouds decrease from west to east
behind the departing disturbance and the flow becomes more
southerly. There may be some lingering low clouds east and north of
Casco Bay until early afternoon as the trajectory remains onshore.
Otherwise...becoming partly sunny by afternoon with highs ranging
from around 60 on the coast...to around 70 inland. Low pressure will
be passing by to our north across Quebec Province late tomorrow and
tomorrow night with the trailing frontal system producing a few
showers across northern and mountains sections. Those showers will
quickly end tomorrow night as high pressure builds in from the
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
A cold front will be departing offshore Tuesday morning. High
pressure moves in during the day on Tuesday and moves across the
region Wednesday. On Tuesday, despite the morning cold frontal
passage we`ll still warm up well into the 70s and 80s across the
region. High pressure will settle across the forecast area
Tuesday night. With light winds and dry air in place, we should
see good radiational cooling. Some of the best radiators in
northern NH will likely see lows in the 30s Tuesday night. Frost
advisory not completely out of the question. High pressure
slides offshore on Wednesday allowing for moistening return
flow. This will likely keep the coast cooler on Wednesday.
However, it will remain dry. The remnants of Alberto approach
Tuesday and may bring some beneficial rains to the region
Thursday night through Saturday. However, early indications are
that this period will not be a washout. It`ll feel more
summery/tropical though with dewpoints likely getting well into
the 60s with showers and thunderstorms from time to time.
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Short Term /through Monday night/...VFR gives way to MVFR
tonight in cigs with lcl IFR in -dz and fog and sct -shra. On
Monday...improving to VFR throughout btw 15 and 18z with sct
MVFR aft 20z in mtn -shra.
Long Term...VFR conditions expected Tuesday through Thursday.
Could see lower conditions develop Thu night and Fri with
increased tropical moisture expected.
Short Term /through Monday Night/...Marginal SCA winds gusts
continue through early evening otherwise SCA seas for the
balance of the night into the day Monday. I`ve extended the SCA
through late tonight and expect it`ll be extended into the day
on Monday for hazardous seas.
Long Term...Conditions are expected to remain below SCA
thresholds Tuesday through Saturday.
Moist onshore flow will continue into Monday. The rest of the
week looks warm, with light winds, and moderate humidity.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ150-152-154.
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
915 PM CDT Sun May 27 2018
915 PM CDT
Incredible heat for late May continues with some of the hottest
weather ever in this region for May. Chicago tied for 2nd place
for hottest May day on record (records in Chicago go back 1871).
The 00z sounding from DVN had a 925mb temps of 28.8C which using
SPC`s sounding climo shows that this is a record warm 925mb temp
for the month of May (and June!!). The RAP/HRRR continue to
perform well with the unseasonable heat and did a pretty good job
last evening with today`s highs. The RAP has fairly widespread
upper 90s, a couple degree warmer than today, for Monday. Other
models have 925mb temps about 1C to 1.5C warmer tomorrow than
today, so potential is definitely there for widespread upper 90s
and perhaps even a couple spots tagging the century mark Monday.
Have adjusted high temps up a couple degrees over most of the CWA
for Monday, with the one exception being the Chicago metro area.
The reason I opted not to raise temps over the Chicago metro for
Monday is the potential for an earlier (and stronger lake breeze
than today). A couple models have been developing a fast moving
MCS tracking across the Upper Mississippi Valley with lake charged
outflow from this MCS plowing in off the lake with strong NE winds
and much cooler temps by early afternoon. This probably isn`t the
most likely scenario at this time, but with the NAM and a couple
other CAMs showing it, hard to discount the potential as well.
Given the uncertainty wrt to a potential lake charged outflow
cooling temps off Monday, have opted to just let going forecast
ride. Should this early/strong lake breeze not materialize then
high temps Monday would likely be around if not a degree or two
higher than Sunday. Conversely, should this lake boundary being
advertised by the NAM and friends pan out, then afternoon temps
would likely be in the 80s in the metro area, with 70s probable at
At this point, it would appear that convective threat should be
just about over for this evening. With upper high right overhead
Monday, the threat of isolated storms Monday looks even lower than
304 PM CDT
In an unseasonably warm airmass, but with modest dewpoints,
temperatures are rising into the middle 90s across much of the
region. With dewpoints still only 50s to lower 60s, temperatures
have been able to rise more rapidly than typical diurnal warming
rates with many areas seeing 90F before noon. In the weak pressure
gradient environment, a lake breeze has formed, turning winds along
the lake front to onshore, allowing temps to moderate along the lake
front. The boundary should push inland far enough the bring some
early cooling to the northern suburbs, but the south end of the lake
breeze is making little inland progression and the southern
portions of the Chicago Metro area will likely not be impacted.
Otherwise, main concern for the afternoon and into the early
evening is isolated thunderstorm development over central and far
western portions of the CWA. Latest SPC mesoanalysis shows axes of
enhanced CAPE in these areas, while far nern IL/nwrn IN remain a bit
more stable. This idea is also noted in satellite imagery where the
cu field is much more sparse. While severe wx is not expected in a
weakly sheared environment, some cells have shown the potential to
strengthen rapidly and and produce brief heavy downpours, with small
hail possible. In the weakly sheared environment, storm motion is
nearly stationary, with perhaps a slow south direction. so far this
afternoon, any severe storms have remained south of the CWA, but an
isolated severe storm cannot be ruled out this afternoon for the far
southern portions of the CWA. Convection trends should be largely
diurnal, with activity diminishing with sunset.
Monday should, largely, be a case or wash, rinse and repeat as there
will be little progression to the overall pattern. Other than
perhaps a bit of debris cloud, mostly sunny, warm conditions are
expected for tomorrow, with temperatures once again in the middle
90s. Lake breeze development is also likely again tomorrow,
allowing for some cooling along the lakefront by early afternoon.
337 PM CDT
Monday night through Sunday...
Relatively quiet conditions at the start of the period, with any
precip development to the north tied to surface trough likely
staying to the north. Shower/thunderstorm chances on Tuesday look
to remain low, however, can`t rule out some isolated afternoon
development. Another hot day is expected with high temps in the
90s likely over much of the area, with the exception of areas near
the lake where onshore flow will be in place. Next precip chances
Tuesday night into Wednesday will be tied to the approaching
remnants of Tropical Storm Alberto. Although chances increase
Tuesday night, highest chances arrive Wednesday when the system
lifts through the region. Thunder will be possible during this
time, and given the tropical nature of this system, will need to
monitor higher rainfall potential. This system will linger during
the middle part of the week, while another system approaches from
the west. Although some variability with the evolution of this
approaching system, could provide additional precip chances
through the end of the work week. Temps on Wednesday will be
cooler given the likely extent of the precip/cloud shield, with an
additional day of cooler temps possible on Thursday.
915 PM CDT
The following are daily record highs for Chicago and Rockford for May 28th.
Chicago 95 (2012)
Rockford 93 (2006)
For the 00Z TAFs...
VFR conditions expected through the period, with light winds into
Monday morning. The wind forecast becomes complicated late Monday
morning into the early evening. An outflow boundary from
convection across northern WI and the U.P. of MI overnight may
surge far enough south to reach all of the terminals by noon
Monday. If this were to occur, a 1-2 hour period of NNE wind
gusting over 20 kts will be possible. If the boundary fails to
reach northern IL, a lake breeze is still expected to switch
winds to the east at or slightly above 10 kts by mid afternoon at
345 PM CDT
In the near term, there has been some fog reported over the lake.
Given this possibility, have included fog in the open waters
forecast for tonight. Winds over the lake don`t appear to be
overly strong into the start of the week. Will see high pressure
build south out of Canada by late Monday night into Tuesday, with
a steadier northerly wind expected. By midweek, winds will likely
be variable as the next system approaches from the south and moves
across the lake.
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Area Forecast Discussion
National Weather Service Lubbock TX
605 PM CDT Sun May 27 2018
VFR. Low level wind shear should affect all terminals toward
midnight once surface winds slacken. Otherwise, Memorial Day
should again feature some afternoon TS mainly NW-N of PVW.
.PREV DISCUSSION... /issued 237 PM CDT Sun May 27 2018/
This afternoon the upper level low has shifted east over Utah with
the ridge axis shifted east as well over Oklahoma. A shortwave
moving out of the Rockies is helping initialize showers along the
dryline this afternoon. The HRRR handled the virga showers well this
morning and has isolated showers and thunderstorms along the state
line this afternoon. We are already seeing a few showers in
Amarillo`s area, but expect a few further south in our area as well.
Thunderstorms should be high based and high wind gusts are the main
threat. Monday`s set up will be similar to today, with showers and
thunderstorms possible out ahead of the upper low. Both the NAM and
GFS show precip in the northeastern Panhandle, but the question will
be how far south they extend. Have PoPs at a slight chance for our
northern counties during the afternoon then shifting to the northern
Rolling Plains Monday evening.
The ridge will flatten as the upper low moves across the Northern
and Central Plains early this week. This should decrease
temperatures a few degrees to the upper 90s on Monday. Temperatures
start to increase again on Tuesday and will continue to warm through
the week. A heat advisory may be needed as highs will be 100-106
Wednesday and Thursday. Solutions are showing a weak front
entering the northern Panhandle Wednesday, but have it stalling
out before reaching the South Plains.
The next wave will move across the Rockies to our north this
weekend. The best chance of rain looks to be on Friday and Saturday
evenings if there is enough moisture and we can break the cap. Both
the ECMWF and GFS show a front moving through Sunday, which
hopefully will bring some temperature relief.
Hot and dry conditions will continue through the week. With south
winds 15-20 mph, elevated fire weather conditions are expected this
afternoon and Monday afternoon. A Rangeland Fire Danger Statement
continues through this evening for the extreme southwest Panhandle
and western South Plains. Isolated high based thunderstorms may also
produce dry lightning and gusty winds this afternoon and Monday
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
1037 PM CDT Sun May 27 2018
28/06Z TAFs. VFR conditions expected to continue. Will not include
any SHRA/TSRA in western Oklahoma terminals first part of forecast
as activity over the panhandles continues to diminish. Gusty winds
will be possible through mainly at KWWR. Will include PROB30 at
KWWR for tomorrow evening with TSRA expected to impact at least
far northwest Oklahoma late in the forecast period. Gusty
southeast winds will be seen again tomorrow, especially western
.PREV DISCUSSION... /issued 619 PM CDT Sun May 27 2018/
28/00Z TAFs. VFR conditions expected with continued southeasterly
winds. 15-25KT gusts again expected across western Oklahoma
terminals again tomorrow. TSRA west of KWWR at issuance time
expected to stay primarily west and north of KWWR, at least not
high enough chance for TEMPO or prevailing mention. However,
remnants may affect site with strong wind gusts and will amend as
PREV DISCUSSION... /issued 317 PM CDT Sun May 27 2018/
Convection has developed in the panhandles. The consensus in the
high-resolution models is that the storms should become less
widespread as they move toward northwest Oklahoma this evening,
although the current storms are a little farther east than these
models would suggest at this time and the RAP and mesoanalysis
shows a nearly uncapped airmass in northwest Oklahoma right now,
so will keep an eye on trends. Have kept POPs relatively low to
begin with, but will watch for the need to increase if necessary.
There is a higher chance for storms moving out of the high plains
tomorrow night and moving into at least northwest Oklahoma
overnight, but then focus shifts farther north with the ejecting
shortwave so it may not continue very far east. Another complex
looks to develop Tuesday evening in Kansas and brush across
portions of northern Oklahoma.
Otherwise, we just expect very warm to hot weather with low to
zero precipitation chances through the remainder of the week.
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 69 91 70 93 / 0 0 0 10
Hobart OK 72 94 72 98 / 10 10 20 20
Wichita Falls TX 72 94 72 97 / 0 0 10 10
Gage OK 71 93 69 96 / 20 20 40 20
Ponca City OK 69 93 71 92 / 0 0 0 10
Durant OK 70 90 71 93 / 0 0 0 0
Area Forecast Discussion
National Weather Service Blacksburg VA
941 PM EDT Sun May 27 2018
High pressure centered offshore will maintain a moist southerly
flow of air into the region for the next several days. Subtropical
Storm Alberto moving into the Gulf of Mexico this weekend will
move ashore and into the lower Mississippi Valley early in the
week. Tropical moisture will stream north into the region
making for very rain efficient showers and thunderstorms.
.NEAR TERM /THROUGH MONDAY/...
As of 940 PM EDT Sunday...
The bulk of the precipitation continues to be focused mainly
along and north of Route 460. This trend will continue into the
early morning hours of Monday. Meso-scale models continue to
suggest this precipitation will dissipate within a few hours
after midnight. Precipitation in advance of Alberto will start
to spread north into the far southern sections of the region
around daybreak Monday, however the trend has slowed. Have
reflect this in the forecast during the forenoon hours on
As of 655 PM EDT Sunday...
The forecast through the evening hours has been updated to
reflect a decreased chance of precipitation across the southern
half of the region. The bulk of the precipitation will be
situated along and north of Route 460 through midnight. After
midnight, we are expecting a return of precipitation to the
southern half of the region, especially as we approach daybreak
As of 340 PM EDT Sunday...
Scattered showers and thunderstorms have formed in the moist
unstable air across our region with the better coverage across the
higher terrain and along the Blue Ridge. Ample insolation has
allowed MLCAPE values to climb to around 1500 to 3000 J/KG. The
combination of upper trough over the northern Mid-Atlantic and
tropical moisture streaming north from the Gulf of Mexico has
resulted in a convergence axis along or north of our CWA border.
With healthy PWATS, these storms will be very rain efficient rain
producers. The HRRR and HiresW-ARW-East indicated that the greatest
convection concentration will occur cross the northern half of our
forecast area. The NAM and RAP generates precipitation across the
entire forecast area. The GFS and ECMWF showers widespread storms
with the heaviest north of our forecast area. The excessive rain
fall had marginal potential across the entire forecast area with
slight chance to our northeast across Washington area. We will need
to watch for flooding issues across entire forecast area with deeper
convection or training. The good news is that the storm motion is
faster today around 15 knots compared to yesterday. One weak spots
will be Tazewell county where some rain gages reporting 2-3 inch
amounts Saturday. Attm will hold off on a Flash Flood Watch. Prefer
to see where convergence boundaries will line-up and target those
areas of high confidence as opposed to blanketing a larger piece of
real estate. Low temperatures tonight will range from the upper 50s
in the mountains to the mid 60s in the piedmont.
Refer to the latest advisories from NHC on Alberto for track
and its movement. Alberto comes ashore Monday morning and
continues moving northward into southern Alabama by Monday
evening. The flooding potential for Monday will depend on how
much rainfall is accumulated from several days of locally heavy
tropical rainfall and where the deeper convection forms. The
greatest chances for showers and thunderstorms Monday will occur
across southern portions of the forecast area. Decided to
mention the rain could be heavy at times in the south. The Day
Two excessive rainfall showed a sharp gradient with a slight
chance to our south across North Carolina. Both the GFS and
ECMWF showed richer moisture try to push into the southern edge
of our forecast area before translating east to the coast. High
temperatures on Monday will vary for around 70 degrees in the
mountains to the upper 70s in the east.
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 230 PM EDT Sunday...
NHC forecasts bring Alberto ashore Monday morning and continues the
center on a NNW track into southern Alabama by Monday evening while
weakening the system to a tropical depression by Tuesday morning
over north central Alabama. Forward speed then increases as the NNW
track continues with the depression in southern Indiana by Wednesday
morning and Michigan by Thursday morning. Our forecast area will
remain in deep southerly flow through this entire period with
extremely high moisture for late May. The 12z/27 RNK sounding PWAT
of 1.42 inches is near `all-time` high for the date (1995-2014 SPC
climatology) and chances are very good that this type of moisture
remains over the region for next few days and beyond. As mentioned
in previous discussions the forecast NAEFS anomalies for PWAT are 2
to 2.5 standard deviations above normal through much of the week.
Bottom line is any showers that develop are will be efficient rain
producers and storms that lingers over a particular location or
small basin more than about 1-2 hours are liable to produce minor
flooding and 2-3 hours could initiate flash flooding. Day 3
Excessive rainfall outlook from WPC shows Slight Risk (10-20 percent
chance)for exceeding flash flood guidance 12z Tuesday through 12z
Wednesday. This does not provide much confidence in issuing a Flash
Flood Watch given the lack of focus and the shotgun pattern of flash
flood guidance (FFG) in place across our region. 3-hour FFG ranges
generally from 1.5 to 3.0 inches with the lower guidance mainly in
the mountains. Will hold off on a Flood/Flash Watch as the pattern
is too diffuse in terms of timing and location. A short-fused Watch
targeted to developing organized convection may make more sense than
what could be a 3-day (or longer) Watch. As Alberto lifts into the
Tennessee Valley late Tuesday into Wednesday a Marginal Risk for
Severe will exist with the possibility for isolated tornadoes in the
northeast quadrant of the weakening system as well.
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 300 PM EDT Sunday...
A generally wet pattern is expected to continue late week into next
weekend as the remains of Alberto lift northward into the northern
Great Lakes. But then the forecast becomes interesting as 12z/27 GFS
shows intense upper low over the western North Atlantic blocked by
ridging south of Greenland. This forces the upper low over the Great
Lakes back to the southeast with a broad area of low pressure over
the Mid-Atlantic that deepens with time over VA/NC area providing
continued chances for rainfall. The 00z/27 ECMWF shows similar
longwave pattern with the Greenland block but develops surface low
pressure somewhat further north and east, while 12z/27 CMC closer to
GFS. Obviously pattern details cannot be descried with any real
confidence at this range but the pattern certainly fits the
definition of `unsettled` through the extended period. Used mainly
Super blend for the grids during this time frame.
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
As of 730 PM EDT Sunday...
Showers and a few thunderstorms have been come concentrated
across the northern half of the forecast region. Conditions are
primarily VFR except under the heavier showers/storms. As the
night progresses, look for fog to develop with visibility`s
trending IFR/MVFR. Visibilities will improve to VFR around or a
little after 13Z/9AM Monday. Precipitation will return to the
region from the south on Monday as moisture streams north on the
east side of Alberto. Winds will be calm or light and variable
through the period.
Medium confidence in ceilings, visibilities and winds
during the taf period.
.Extended Aviation Discussion...
Wet pattern anticipated through the upcoming week with periods
of at least diurnally driven sub-VFR conditions associated with
deep convection. Moist low level southerly winds will also favor
lower layers of cloudiness at night, especially along the spine
of the Appalachians with potential for both MVFR Cigs and early
morning MVFR visibilities from mist/haze. The tropical system
over the Gulf of Mexico may begin to impact the region mid-week.
The unsettled weather with showers and thunderstorms may
continue into the end of the week.
As of 315 PM Sunday...
Significant focus in hydro concerns as discussed in portion of the
Near, Short and Long term discussions above. Alberto and associated
effects will be with us through the upcoming week in one form or
another. The question of Flood or Flash Flood Watches will be with
us during much of this time period as mentioned earlier but the
notion of holding onto what could be a very long-fused Watch seems
almost counter to producing real awareness of any flood threat.
There may be opportunities for more short-fused Flash Flood Watches
tied to a more discernible threat such as banded features or
persistent clusters of storms. That said, the ground is fairly
saturated in many places but as noted above very erratic coverage.
River flooding cannot be discounted especially on smaller fast-
reacting streams such as the upper Roanoke, Watauga, or even
something like Mason Creek. All basins will have to be monitored
closely. The latest MMEFS ensembles, mostly from 00z/27 or 06z/27
are painting some a somewhat less robust response on the bigger
rivers than the previous set of runs with minor to moderate flooding
generally in the 30 percent or less chance in most large river
basins. The experience with MMEFS has been that is tends to overdo
the probabilities of reaching high stages at these extended
forecast time periods. Still, the Dan River basin once again
under the highest threat for flooding but that would be a late
week time frame.
NOAA Weather Radio, All Hazards, WZ2500 at Wytheville, VA,
broadcasting on a frequency of 162.45 mHz has been fixed.