Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/23/20
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
948 PM EDT Fri May 22 2020
.SYNOPSIS...
An area of low pressure will move slowly across the Ohio Valley
and into the Mid-Atlantic states through tonight. Unsettled
weather continues into the beginning of the holiday weekend
before high pressure and drier conditions arrive for the end of
the weekend into early next week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 950 PM EDT Friday...
Isolated light showers or sprinkles are moving through the area
as another weak sfc trough rotates through the area around the
Ohio Valley upper low. Best activity remains south and north of
the area and the latest HRRR guidance suggests not much more
than light showers this evening, with a small chance for showers
near the coast overnight. Not much instability at all, and have
removed mention of thunder. In fact, latest satellite imagery
shows some clearing moving into western VA behind this trough.
As such, have removed PoPs from the western areas after midnight
and also introduced a mention of patchy fog across the Piedmont
overnight with the clearing skies. Also mention patchy fog
across the MD eastern shore. Otherwise, temps will drop into the
lower 60s across the west and mid-upper 60s east.
As of 330 PM EDT Friday...
Latest analysis reveals sfc warm front lifting north across the
northern neck and eastern shore attm. Radar analysis showing
most activity ahead of the front now lifting north of the
Mason-Dixon into PA/NJ...but a few isolated showers noted over
NE NC/E VA/Delmarva. Meanwhile, to the south, a compact MCS/MCV
continues to slide across the western Carolinas. This activity
is associated with one last shortwave associated with the
weakening upper low. HRRR and 3km NAM showing this activity
reaching our area after sunset, with areal coverage of showers
and storms diminishing owing to nocturnal stabilization. As
such, still expecting strongest storms to remain to our SSW into
central/east central NC.
Timing looks to be mainly after 00-03z with pcpn moving from
W-E through the night (12z CAMs shifted the timing a bit
later...mainly around or after midnight). Will continue to have
chc PoPs for most of the area tonight (mainly south of US-460) to
account for this sct activity. While this convection will move
into an area of 40-50 kt mid-level westerlies, the previously
referenced loss of diurnal heating will dampen the severe wx
threat over the local area significantly (SPC has MRGL and
SLIGHT Risk areas just to our S/SW into the Carolinas). Still
would not at all be surprised to have some rumbles of thunder
and a few stronger gusts within showers over the southern third
of the area, and will keep this mention in place in the HWO. To
the north of this, will maintain a slight chc shower threat late
tonight. Lows tonight fall into the upper 50s- low 60s NW, with
mainly mid 60s across the SE half of the area.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
As of 320 PM EDT Friday...
Both the weakening upper level low and its attendant sfc low
moves off the Mid Atlantic coast on Saturday. While rain chances
will continue to taper down, lingering low-level moisture will
result in a few showers hanging around through early to mid aftn
(mainly E of I-95). High temps on Saturday range from the upper
70s over the ern shore to lower 80s inland.
Finally begin to see the start of a drying trend for the
remainder of the holiday weekend the upper level low pushes off
the northeast coast during the day Sunday, and weak sfc high
pressure ridges down into the area from the NE (while sfc low
pressure slowly deepens offshore). The flow shifts to the N/NE
by Sun AM into Monday, bringing a short- lived pause to the
moderating temp trend. Highs Sunday/Monday will only be in the
mid- upper 60s over the ern shore (cooler at the beaches), with
mid and upper 70s over inland VA and NE NC, with early morning
lows mainly in the 50s. Only a small chance for an isolated
shower or storm well inland on Sunday has been maintained
(mainly over the piedmont), in association with a weakening
disturbance riding along the periphery of the building upper
ridge.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 320 PM EDT Friday...
Good agreement among deterministic models during the medium
range period, with a ECMWF-weighted model blend used for the
forecast period. Aforementioned upper level ridging will bring
drying conditions next week, with a gradual moderating
temperature trend through much of next week. Still will have
slight chance to chance pops Tuesday through Thursday mainly
across western and far northern portions of the area as moisture
ahead of a cutoff low over the deep south tries to occasionally
sneak weak perturbations/moisture into our area. However, these
will be more typical aftn/evening convection with no one day
being a washout.
Low-level flow veers around to the E-SE Tuesday through
Thursday resulting in moderating temps, with highs in the low to
mid 80s. Early morning lows during the period range from the
mid 50s to lower 60s.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
As of 800 PM EDT Friday...
A surface front pushing east of the terminals has allowed all
sites to remain at VFR for much of the afternoon into the early
evening. An upper disturbance west of the area will spread mid
level clouds and perhaps a few light showers across the area
overnight. Guidance suggests CIGS will drop to MVFR at SBY and
ECG overnight but the remainder of the terminals will remain
VFR. There are some indications that SBY may even drop to IFR
CIGS overnight, but not enough confidence to forecast those
conditions at this time. Generally VFR on Saturday with
clearing from west to east.
Outlook...Conditions are expected to improve Saturday aftn
through the balance of the holiday weekend, as high pressure
builds south into the region.
&&
.MARINE...
As of 330 PM EDT Friday...
Surface low pressure over central VA this afternoon is expected to
slowly move N/NE across the Mid Atlantic before moving off the coast
tomorrow morning. SE winds this afternoon 5-10 kts over the bay and
10-15 kts over the coastal waters will become S/SW overnight.
Westerly winds early on Saturday will become northerly for the
second half of the day. Waves in the bay are running 1-3 ft. Seas
are running 4-6 ft over the northern coastal waters and 4-7 ft over
the southern coastal waters. SCA will remain for coastal zones
through tonight for the elevated seas. By mid to late Saturday
morning the SCA`s should end for all of the coastal zones with seas
subsiding to 2-4 ft.
A back door front will cross the area waters late Saturday into
early Sunday. A N/NE surge behind the front with strong high
pressure over northern New England may result in additional SCA
winds/seas for at least the northern coastal waters.
High risk of rip currents for today. Even though waves will be lower
on Saturday, still looking at 7-8 second periods and N/NE flow for
later in the day, so there will be a moderate risk for rip currents
on Saturday. Continued NE flow and elevated seas on Sunday and
Monday will result in at least a moderate risk of rip currents.
&&
.HYDROLOGY...
As of 325 PM EDT Friday...
Due to recent heavy rainfall upstream, minor flooding is
expected beginning late tonight on portions of the James River.
A flood warning has been issued for the James River at Richmond
Westham and the James River at Richmond City Locks. See FLWAKQ
and FLSAKQ for more site-specific information.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ654-656-
658.
Small Craft Advisory until noon EDT Saturday for ANZ650-652.
&&
$$
SYNOPSIS...MAM
NEAR TERM...MAM/MRD
SHORT TERM...ERI/MAM
LONG TERM...CMF/MAM
AVIATION...MAM/MRD
MARINE...CMF
HYDROLOGY...
Area Forecast Discussion
National Weather Service Denver/Boulder CO
834 PM MDT Fri May 22 2020
.UPDATE...
Issued at 833 PM MDT Fri May 22 2020
Brisk southeasterly winds are expected to continue across the
plains for the next few hours as a surface low pressure area
remains over the central and western portions of the state. Low
level moisture will be increasing overnight with dewpoint
temperatures expected to climb into the upper 40s and lower 50s.
Little impact is expected overnight as the airmass is quite
stable. Satellite imagery shows some high level clouds over the
the mountains which will move out onto the plains overnight. Mild
temperatures are expected across the plains due to increasing low
level moisture and high level clouds most of the night. The only
change to the forecast this evening was to remove the mention of
any showers early on. One or two stray showers may move over Weld
and Logan Counties around midnight, if the latest HRRR is correct.
Some low pops have been left in the forecast overnight.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 250 PM MDT Fri May 22 2020
Satellite pictures are still showing much of the CWA cloud free
at this time. The best Cumulus development is over Logan,
Washington and Douglas Counties and along the Continental Divide.
There are returns on the areas radars at this time. Surface dew
point values are below 30 F over the western 2/3rds of the CWA.
The eastern plains have dew points in the 30s F. The wind field
over the plains and foothills is south-southeasterly. There is a
bit of Denver Cyclone in place. Models keep 30 to 60 knots
southwesterly winds at jet level for the forecast area tonight and
Saturday. There is weak upward vertical velocity on the QG Omega
fields tonight and Saturday. The low levels winds transition right
into normal drainage pattens later this evening from the current
southeasterlies. Models have south and southwesterly flow level
winds for most areas on Saturday. For moisture there is some in
the mid and upper levels tonight and Saturday. Nothing great. For
CAPE, there is a bit over the far eastern plains. Same goes for
Saturday, but values right at the border are fairly high. This all
has to do with how far west the decent low level moisture gets to.
Models are not to good with this. There is a little CAPE in the
alpine areas Saturday afternoon. The QPF fields show a small
amount of measurable rainfall over the northern border area this
evening. On Saturday afternoon, there is a bit in the mountains.
For pops, nothing great this evening 10-20%s over the northern
half of the plains. On Saturday afternoon, 10-30%s for much of the
CWA. For temperatures, Saturday`s highs are 0-1.5 C cooler than
this afternoon`s highs.
.LONG TERM...(Saturday night through Friday)
Issued at 138 PM MDT Fri May 22 2020
Saturday night, a moderate southwesterly flow aloft will
continue over the region. The best instability in the evening will
be along a dry line boundary over the northeast corner of the
state. There is a marginal risk of a severe thunderstorm along
and east of this boundary. Elsewhere, isolated to scattered
thunderstorms with higher bases with more of a wind vs shower
threat in the evening. Late Saturday night into Sunday, another
mid level trough approaches the state from the northwest. A cold
front will move in overnight, with weak mid and upper level qg
ascent developing over northern CO on Sunday. Forecast soundings
on Sunday afternoon and Sunday night show a very moist airmass in
place over the forecast area. PWAT values from the GFS Buffer
soundings are around 0.70 inches and moist adiabatic. Spatial
cross-sections show the deepest northeasterly upslope will be
Sunday afternoon and evening. It still appears to be a cool, wet
and unsettled period. Models also show several inches of snowfall
above timberline. Although the amounts looks like they may be
overdone, could not rule out at least advisory criteria snowfall
above 10 thousand feet. On Monday and Monday evening, weak qg
descent in the mid and upper levels behind the trough axis. The
trough axis hangs around over eastern CO through 00z before
shifting eastward. This will result in another cool, unsettled and
showery period. More showers vs thunderstorms, but maybe enough
instability with afternoon heating to go with a slight chance of
storms most areas in the afternoon and evening. Best chance of
showers will be in and near the higher terrain. Tuesday into
Wednesday will be drier and warmer with temperatures near to
slightly above normal. A ridge axis will be over the west with a
drier and more subsident north/northwest flow aloft. By Thursday,
the ridge appears to keep a dry, warm and subsident airmass over
the western part of the state. An upper level disturbance looks
like it will drop out of WY and into northeast CO Thursday evening.
This feature may stall out a bit and allow for enough
moisture/instability for showers and thunderstorms over the
northeast plains for Friday. The best chance of showers/storms
late next week may actually be in the overnight periods.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 833 PM MDT Fri May 22 2020
South to southeasterly winds should be the only impact for the
next few hours. High clouds and less wind should be the rule after
about 10 PM.
&&
.FIRE WEATHER...
Issued at 250 PM MDT Fri May 22 2020
I went ahead with a Red Flag Warning for South Park and the
southern CWA on Saturday afternoon and early evening. Relative
humidities will be plenty low, winds speeds will be close enough.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 8 PM MDT Saturday for COZ214-241-
246-247.
&&
$$
UPDATE...Dankers
SHORT TERM.....Koop
LONG TERM......Coop
AVIATION...Dankers
FIRE WEATHER...Koop
Area Forecast Discussion
National Weather Service Columbia SC
855 PM EDT Fri May 22 2020
.SYNOPSIS...
The air mass will remain moist and unstable through the weekend
and scattered afternoon and evening showers and thunderstorms
are expected. Temperatures will be above normal. Temperatures
will be more seasonable early next week.
&&
.NEAR TERM /TONIGHT/...
Much of the forecast area has been worked over quite well from
numerous convective clusters during the afternoon and evening
hours. Currently, the forecast area is dry, but regional radars
showing additional showers and thunderstorms moving towards the
southern/western CSRA out of southern and central GA. Portions
of the CSRA did not have convection earlier, so there may still
be some lingering pockets of instability for the activity to tap
into as it moves into the CSRA in the next hour or so. The hrrr
does show scattered activity moving through the CSRA and then
into the central Midlands towards Midnight before falling apart
late tonight. Will increase pops once again later tonight to
account for this scenario. Expect dry weather by morning. Other
issue tonight may be some fog formation. There is a weak low-
level jet being shown later tonight, so confidence in widespread
fog is low. Have gone with some stratus late tonight, with
patchy fog possible. Temperatures in the mid and upper 60s late
tonight.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Saturday and Saturday night...Upper level ridge will build
across the southeastern states over the weekend. The airmass
will remain moist and moderately to strongly unstable with steep
low to mid level lapse rates. With 850mb west flow/warm
advection expect temps around 90 degrees in the afternoon. Weak
surface trough across area. There may be a weak short wave
trough trigger moving to the southeast in northwest flow aloft.
CAM models support scattered convection/pulse severe mainly
across the north Midlands and Pee Dee in the afternoon and
evening. Min temps above normal near 70.
Sunday and Sunday night...Surface ridge over the Northeastern
States builds down the eastern seaboard and appears a back door
front will be approaching from eastern North Carolina late in
the day or in the evening. A sea breeze front is also possible
as low level flow becomes east. The air mass remains at least
moderately unstable with steep low to mid level lapse rates.
Scattered convection...isolated pulse severe...mainly in the
late afternoon and evening. The convection may continue
overnight but diminish as more stable air/front moves into the
area. Blended temperature guidance supports max temps near 90
again with min temps above normal.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
Front moving southwest through the area early monday and weak
shallow isentropic lift may result in considerable clouds and
showers mainly across the CSRA and south Midlands. The ridge will
build in from the northeast with drier air for Monday night and
Tuesday. Temperatures a little cooler/seasonable especially Monday.
Surface ridge extending from offshore Mid Atlantic states through
late week with building ridge aloft over the eastern CONUS as deep
low moves into the southern Plains. Persistent east to southeast
deep-layer flow for most of next week. Low chance convection through
the period. Temperatures warm under ridge but with east flow should
result in near normal values in the mid to upper 80s.
&&
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
Showers and storms now east of all terminals, however additional
showers/storms moving up from south-central Ga will move into
the CSRA in the next few hours. There remains a chance that this
activity could hold together enough to reach the Midlands
terminals by 06z. For now, vfr conditions prevail outside of
those showers/storms. Can not rule out brief mvfr/ifr conditions
if the storms impact any taf site the next several hours. Later
on tonight, guidance shows ceilings/visibilities lowering down
into mvfr towards morning. VFR conditions return by 13z
Saturday. Additional showers/storms may be possible Saturday
afternoon.
EXTENDED AVIATION OUTLOOK...Restrictions possible in mainly
diurnal showers and thunderstorms are possible through the
weekend with improvement early next week.
&&
.HYDROLOGY...
Rainfall amounts over the past 48 hours have ranged from 3 to 8
inches across much of the upper and central portions of the
river basins. This will lead to considerable river flooding on
many of the area rivers through the holiday weekend.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Caribou ME
1050 PM EDT Fri May 22 2020
.SYNOPSIS...
Canadian high pressure will build in overnight into Saturday.
The high will move east through the Memorial Day weekend. The
high will then continue east of the area through the middle of
next week with a return to warmer weather conditions, along with
the chance of showers and thunderstorms.
&&
.NEAR TERM /THROUGH SATURDAY/...
955 PM Update...
Cold front was making its way s moving into the Southern
Penobscot Valley. The observation at BGR showed westerly winds
just along the front. The front is expected to drop across the
coastal waters overnight. Colder air has begun to filter in as
temps across northern areas are dropping off quickly. Northerly
wind staying up around 10 mph keeping temps however, especially
along the elevated sites. Estcourt Station already down into the
lower 40s. The latest RAP keeps winds up a bit overnight keeping
the blyr mixed. NW areas will be prone to seeing frost and
possibly a freeze, especially in Allagash region. Stayed close
to the current forecast and modified the hrly temps and
dewpoints.
Previous Discussion...
Large Canadian high pressure will begin to build south from
Quebec tonight with a much cooler airmass overspreading the
region overnight. 925 MB temperatures across the crown of Maine
fall to around -3C by 12Z Saturday morning. Still some
uncertainty about whether or not winds will decouple overnight,
as it looks as if there will still be a bit of a gradient. Have
lowered mins a few degrees across the colder valleys of the
north from previous forecast, where we are now expecting lows to
fall to the low to mid 30s. This necessitated adding the
mention of patchy frost across the colder valleys of Northeast
and Southern Aroostook counties. Have mentioned areas of frost
across the North Maine Woods, but since the frost/freeze program
has not begun there yet, no advisories have been issued.
Saturday will feature abundant sunshine as high pressure
continues to build down across the region from Quebec. High
temperatures on Saturday will be much cooler than today`s, with
highs generally ranging from the low 60s across the North and
low to mid 60s central and Downeast.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
High pressures moves overhead Saturday night and with a fairly cool
airmass in place, this sets the stage for a frost threat. Went
on the cool side of guidance thanks to expected decoupling, with
30s areawide. Main question is whether mid to high clouds
moving in late in the night can slow the temperature drop.
High pressure moves east Sunday with southerly flow setting up.
Looks warmer than Saturday in the north, but cooler Downeast
thanks to onshore flow. Some mid to high clouds mainly in the
north, but no precipitation.
Airmass continues to warm into Monday, but due to onshore flow,
it will stay somewhat cool Downeast, while far Northern Maine
warms to the mid to upper 70s. Most models keep rain west of the
state through Monday.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
The story for the extended will be warm and unsettled. A strong
blocking upper high looks to set up just to our south while an
upper trough and cold front very slowly approaches us from the
northwest. This will lead to warm daytime temperatures with
highs mainly mid 70s to mid 80s. It also looks a bit muggy with
dewpoints approaching 60 Wed/Thu. Nights will be mild with some
places not dropping below 60. As the upper trough to the
northwest very slowly approaches, precip chances increase
Wed/Thu, and could come in the form of thunderstorms. However,
models are in fairly poor agreement on how long the upper trough
and cold front take to get here. General consensus is for
roughly Thu night for a cold frontal passage, but that could
change.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
NEAR TERM: VFR through Saturday. Gusty NW winds through early evening
will become light N tonight 5 to 10 kt and around 10 kts on
Saturday.
SHORT TERM:
Saturday Night...VFR with light wind.
Sunday through Monday Night...VFR with south breeze.
Tuesday through Wednesday...Chance of mainly afternoon and evening
storms. Mainly VFR, though could be MVFR/IFR near the coast,
and near any storms. South breeze.
&&
.MARINE...
NEAR TERM: Wind/seas will generally remain below SCA levels
through Saturday.
SHORT TERM:
Quiet on the waters until late Tuesday into Wednesday, when
south winds and seas may increase to small craft levels. Could
be low clouds and fog over the waters toward Wednesday.
&&
.FIRE WEATHER...
A Red Flag Warning remains in effect until 7 PM this evening for
critical fire weather conditions for much of Northern and Downeast
Maine.
Minimum afternoon relative humidity percentages are expected to
range from 15 to 20 across far Northern areas on Saturday and the
low to the mid 20s across the central highlands, Upper Penobscot
Valley and Downeast Maine. Winds on Saturday will be lighter and
not as gusty and it will be cooler.
After coordination with the Maine State Forest Service and NWS
Gray, will issue a Special Weather Statement through the
weekend to highlight the heightened fire weather threat with
continued dry weather conditions expected.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service Des Moines IA
823 PM CDT Fri May 22 2020
...Discussion Regarding Marginal Risk for SW Iowa Tonight...
.UPDATE...
Issued at 810 PM CDT Fri May 22 2020
Rain showers and thunderstorms continue to pivot around the
surface low centered over the Missouri River Valley as of 0100
UTC. 0-1 km SRH values have remained between 100-150 m^2 s^-2 this
evening ahead of this. This SRH appears to be augmented by a weak
thermal boundary currently stretched from northeast Kansas into
northwest Missouri. A lot of the initiation of the current
convection has occurred along this boundary. RAP analysis
continues to depict surface CAPE values in the southwest forecast
area over 1000 J/kg heading into the evening. The HRRR over the
last few hours has also been depicting thunderstorms becoming
more widespread across southwest Iowa and areas along the Hwy. 34
corridor. The biggest uncertainty is whether or not convection
will remain surface based as we head into the overnight hours.
Earlier runs of the HRRR were showing most of the CAPE in the
mid-levels, however, a look at more recent RAP soundings indicate
there may be just enough for thunderstorms to remain surface
based in southwest Iowa. As the low level jet kicks in, with an
already moderately sheared in environment in the lower levels, a
weak brief tornado cannot be ruled out. This threat is reflected
in the Marginal Risk that has been expanded eastward by SPC in the
01z Day 1 Convective Outlook. The overall threat is low, but
storms late this evening and during the overnight hours will need
to monitored closely in this environment. There could be a threat
a of severe hail and damaging winds if greater surface based
instability develops, however, a brief weak tornado appears to be
the most likely severe weather feature.
&&
.DISCUSSION.../Tonight through Friday/
Issued at 240 PM CDT Fri May 22 2020
A shortwave rounding the large western trough and deepening off the
Rockies has induced an area of convection stretching from the
southern plains into Missouri and Nebraska. A few areas of sprinkles
or light rain have percolated across southwest Iowa throughout the
early afternoon along the leading edge of warm air advection into
the state. Meanwhile the surface low has been situated near the
Kansas/Nebraska border as view by GOES-East day cloud phase
distinction. The low will gradually lift towards central Iowa by
Saturday morning, bringing showers and a few rumbles of thunder to
the area. With fairly weak instability and weak shear, it is
unlikely that storms will be organized enough to be severe
overnight. This first round of precipitation will bring totals of
around a quarter to three quarters of an inch to the area.
Rain will linger in the morning across northeast Iowa through the
morning, however most of the day on Saturday will be fairly quiet
with subsidence allowing for clearing in the afternoon. With clouds
lingering across northeast Iowa and clearing across southwest Iowa,
highs tomorrow afternoon could vary quite a bit in the low 70s north
to low 80s south.
The parent western trough and surface low shifts east overnight into
Sunday bringing our next round of showers and thunderstorms. The low-
level jet increases overnight into Nebraska and perhaps far southwest
Iowa helping to fuel storms, however becomes diffuse into central
Iowa and will likely have less of an impact here. The severe threat
will be conditional based on how much heating the area receives
Sunday. With morning convection and the weak nose of the low level
jet in the morning, there is some possibility that this will
percolate through the day and reduces the afternoon severe threat.
Warm air advection and moisture transport into the area increases
resultant CAPE to 3000+ J/kg across Iowa Sunday afternoon. Again,
wind shear is lacking so organized storm development may be
difficult to come by. Hail and damaging winds are the main threat.
It appears more likely that multicell storms will grow upscale into
an MCS by the evening.
The slow moving longwave trough allows for moisture transport into
the area through Monday and much of early next week. Monday into
Tuesday morning the boundary stalls across central to southeast IA.
PWATs are between 1.5 to 2 inches across the area and with repeated
rain this weekend it is unclear how well the area will be able to
handle the additional moderate totals. Some localized flooding or
river flooding issues may be possible by Monday into Tuesday. Still
several days out but worth monitoring. Models continue to indicate
lingering precipitation into Tuesday. A cutoff low across the
southern plains will help to cut off some of the moisture supply
into the area by Wednesday, however rain chances linger throughout
the end of week. Don`t expect everyday to be a total washout,
however scattered rain chances will exist each day.
&&
.AVIATION.../For the 00Z TAFS through 00Z Saturday evening/
Issued at 626 PM CDT Fri May 22 2020
Ceilings will become IFR later this evening as a group of rain
showers and isolated thunderstorms moves around the incoming
short-wave feature. Rain showers will result in MVFR visibility
for a few hours, but ceilings will be the main limiting factor
this evening. Rain showers will continue off and on through much
of the TAF period. Ceilings will mainly be low-end MVFR for much
of Saturday.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Krull
DISCUSSION...Hagenhoff
AVIATION...Krull
Area Forecast Discussion
National Weather Service Grand Rapids MI
757 PM EDT Fri May 22 2020
LATEST UPDATE...
Aviation
.SYNOPSIS...
Issued at 315 PM EDT Fri May 22 2020
- Mostly Cloudy Tonight
- Increasingly Warm and Humid; Thunderstorms Saturday Night
- Chance of Showers And Storms Early to Midweek
&&
.DISCUSSION...(This evening through next Friday)
Issued at 315 PM EDT Fri May 22 2020
- Mostly Cloudy Tonight -
The upper low will continue to bring fairly extensive cloud cover
tonight. A few lingering showers mainly to the east and north of
KGRR will taper off late this afternoon and early evening. Patchy
fog will develop during the early morning hours Saturday and could
be a little more prominent over our se fcst area due to a Lake
Erie connection give light east winds as suggested by HRRR
guidance.
- Increasingly Warm and Humid; Thunderstorms Saturday Night -
Fair wx is forecast for most of the day tomorrow with weak
ridging in place. A warm front combined with an upper level
disturbance will bring showers and storms Saturday night into
early Sunday.
Overall guidance trends and the 12Z HREF LPMM show potential for
more rain Saturday night (potential for a half an inch to inch of
rainfall with locally higher amounts across portions of our
lakeshore counties). Deep layer shear will gradually increase but
severe wx is unlikely given fairly weak instability.
Trends in a consensus of latest model guidance suggest extensive
cloud cover will likely linger Sunday morning. Some clearing will
develop later in the day and allow high temps to reach well into
the 70s along with increasing humidity. Due to persistent deep
southwest flow waa high temperatures will reach the lower 80s by
Memorial Day with dew points rising well into the 60s by then.
There is a chance for showers and storms Monday as the
increasingly warm and humid airmass interacts with a sfc/upper
trough to the west. However the majority of the holiday weekend
will be dry.
- Chance of Showers And Storms Early to Midweek -
A stationary frontal boundary will likely focus development of
showers and storms Tuesday through midweek. This potential will be
aided by potentially moderate instability and several upper level
disturbances which will move through as well as forcing from the
lake breeze.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 757 PM EDT Fri May 22 2020
VFR conditions are in place across the area at 00z. There are a few
locations reporting MVFR ceilings off to the east and south, but
these are scattered and will likely lift to VFR this evening. The
main question is will we developing fog and stratus tonight with
light winds and skies trying to clear some with the loss of
daytime heating. The short answer is yes, but it should not we
widespread and low.
We are expecting some fog and stratus to develop tonight, with the
best chances being along the I-94 corridor. BTL and JXN are the TAF
sites that we hit the hardest with IFR conditions expected towards
daybreak. Conditions should improve to VFR once again in all areas
Saturday morning.
Winds will be light and variable tonight becoming southeast at 5 to
10 knots on Saturday.
&&
.MARINE...
Issued at 315 PM EDT Fri May 22 2020
Easterly winds will continue into Saturday and result in minimal
wave heights. A few thunderstorms could pose a hazard to mariners
Saturday night and on Memorial Day. Areas of dense fog are likely
to develop Sunday through Memorial Day as a much more humid
airmass overruns relatively cold lake waters.
&&
.HYDROLOGY...
Issued at 315 PM EDT Fri May 22 2020
The crest on the Grand River is now passing through downtown Grand
Rapids, and will be arriving along the lakeshore (Robinson Township)
by Saturday morning. Major flooding continues in Comstock Park,
though the river has begun to drop. Flooding also continues along
the Muskegon River, as well as many of the smaller tributaries
around our area. Here are some of the noteworthy crests experienced
so far on the Grand River:
Ionia: 7th highest crest on record (1.20 feet less than 2018)
Lowell: 8th highest crest on record (0.97 feet less than 2018)
Ada: 3rd highest crest on record (0.94 feet less than 2018)
Comstock Park: 7th highest crest on record (0.45 ft less than 2018)
Grand Rapids: 4th highest crest on record (1.12 ft less than 2018)
Robinson Twp (forecast): 6th highest crest (0.48 ft less than 2018)
Rain returns to our area tomorrow night (Saturday night), and will
be mostly concentrated along the lakeshore counties. While this rain
is not expected to result in renewed rises on the rivers, ponding of
water on roadways and low spots is possible since the soils remain
completely saturated. Additional chances of rain will linger around
Lower Michigan for the bulk of next week.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
SYNOPSIS...Laurens
DISCUSSION...Laurens
AVIATION...Duke
HYDROLOGY...AMD
MARINE...Laurens
Area Forecast Discussion...Updated
National Weather Service Phoenix AZ
450 PM MST Fri May 22 2020
.UPDATE...Updated aviation discussion.
&&
.SYNOPSIS...
Near normal temperatures will last through the weekend while a
series a dry weather systems move north of the region. Breezy
to locally windy and dry conditions today will lead to elevated
fire weather conditions. Increasing high pressure through the
first part of next week will push temperatures to well above
normal readings by the middle of next week, potentially leading to
a period of excessive heat conditions by next Wednesday.
&&
.DISCUSSION...
Latest water vapor imagery reveals a well-defined trough across the
Great Basin. Ahead of this system, the pressure gradient has
tightened, resulting in a southwesterly flow and areas of
breezy/windy conditions across the Desert Southwest. The winds
combined with single-digit RHs will yield widespread elevated fire
danger. Latest HRRR depicts the strongest winds developing late this
afternoon across the wind-prone locations of southwestern Imperial
County, where localized gusts up to 50 mph will be possible.
Elsewhere, winds will generally gust to 20 to 30 mph before subsiding
this evening.
The aforementioned trough will migrate eastward Saturday, though a
reinforcing vort max diving down the West Coast will induce a trough
across Arizona. This will keep the afternoon breeziness going along
with providing a few degrees of cooling, with temperatures falling
below average. Sub-one-hundred degree high temperatures in the lower
deserts will hang on for one more day Sunday as well.
ECMWF and GFS ensembles continue to indicate a steady warming trend
through at least next Friday as the forecast area eventually becomes
situated between a cutoff low in the eastern Pacific and an upper
low across the southern Plains. Pseudo omega block will translate
into a prolonged period of well-above average temperatures. Forecast
was weighted heavily towards the latest NBM, which is exhibiting low
variability. Strongest EPS height anomalies appear to remain to our
north and west, though temperatures will still likely exceed the
95th percentile of climatology and even approach daily records. An
Excessive Heat Watch was issued early today for the lower deserts
and remains in effect for next Wednesday through Friday.
&&
.AVIATION...Updated at 2350Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Another upper level low passing by to the north will result in gusty
southwest to west winds for the remainder of the afternoon and
through the middle of the evening. There may be a bit of variability
thru about 01z but afterwards winds should be well mixed and hold
their directions better through midnight. Expect prime window for
peak gusts to be in the 01-04z range, with peak gusts to around
25kt. After midnight winds should taper off and return to the east
or southeast after about 09z and at KPHX winds likely to return to
the east at or after 10z. Winds should swing back to the
southwest/west after 19z Saturday but be a bit less strong and gusty
as compared to today. Otherwise, skies to be generally clear
although FEW-SCT high and thin cirrus decks are likely during the
TAF period.
Southeast California/Southwest Arizona including KIPL and KBLH:
An area of low pressure passing by to the north will lead to rather
breezy and gusty southwest to west wind for the remainder of the
afternoon and well into the evening hours today. Peak gusts could
approach 30kt at times with the best window for strong gusts in the
01z to 04z period. Winds will taper off gradually after 05z and into
the morning hours, becoming more northwest to north especially at
KBLH. During the day Saturday there will be much less wind,
typically speeds of 10kt or lower. Skies will be generally clear
with the potential for a few high thin cirrus decks at times during
the TAF period.
&&
.FIRE WEATHER...
Monday through Friday:
High pressure building into the region early next week will lead
to much warmer temperatures, with highs climbing above 100 degrees
starting Monday. High temperatures eventually climb above 105
degrees starting Tuesday or Wednesday. Winds into next week
will be fairly light day to day with only locally breezy afternoon
conditions. Although red flag thresholds are not expected to
be reached, excessive heat appears likely late in the week,
which could promote new fires. Through the period, expect Min RH
values to dip below 10% on the lower deserts (below 15% higher
terrain) with Max RH values around 20-30% for lower desert locations
and 30-40% for higher terrain locations.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Watch from Wednesday morning through Friday
evening for AZZ530>551-553>556-559.
CA...Excessive Heat Watch from Wednesday morning through Friday
evening for CAZ561>570.
Wind Advisory until 5 AM PDT Saturday for CAZ562.
&&
$$
DISCUSSION...Hirsch
AVIATION...CB
FIRE WEATHER...Hirsch/Smith/Kuhlman
Area Forecast Discussion
National Weather Service Reno NV
215 PM PDT Fri May 22 2020
.SYNOPSIS...
Low pressure will bring breezy winds, cooler temperatures, and
showers with a few thunderstorms today mainly for west-central
Nevada. Tonight will be chilly with freezing temperatures possible
for some valleys. Memorial Day weekend will be dry with a major
warmup through next week. A few thunderstorms may develop as early
as Wednesday with increasing chances later in the week.
&&
.DISCUSSION...
Isolated showers and gusty winds will continue through this
afternoon as a cold front sweeps through the Sierra and western
Nevada. A band of showers is currently stretching from just north
of I-80 from Chico, CA, all the way to Lovelock, NV. There are
additional bands of showers south of I-80 as well near
Stagecoach/Hazen and even more showers across Mineral and
Churchill counties. HRRR shows these showers slowly migrating
south across the Sierra and western Nevada through the afternoon,
but then largely dissipating by sunset.
Surface winds will drop off for most locations tonight, except for
the higher elevations where breezy east to northeast winds will
increase through early Saturday. Temperatures will fall into the 30s
for most areas tonight, with a cooler, drier air mass in place. Lows
below freezing will be possible for some rural locations and plan
for 20s in the Sierra valleys. Another night of keeping watch of
those cold-sensitive spring plants, but it should be the last for
awhile.
Dry conditions along with light winds will be in place for much of
the Memorial Day weekend as high pressure returns to the West. Not
to jinx it or anything, but it will be prime BBQ weather this
weekend, before it really heats up next week. The coming week is
looking quite warm with high pressure strengthening overhead. We
will start to see temperatures climb into the low-to-mid 90s by
midweek for western Nevada. Plan for above normal temperatures
much of next week. There will be some potential for slightly
cooler temperatures later in the week as cloud cover from
thunderstorms may provide some relief. Generally for much of the
Sierra and western Nevada, there will be above normal
temperatures, light winds, and relatively sunny skies through at
least Wednesday.
Thunderstorm potential will be tricky this many days in advance, but
we are seeing some parameters consistently highlighting the
potential for it, especially given the weather pattern. High
pressure with a weak low sweeping in warrants chances each day
for storms starting on Wednesday afternoon/evening. NBM
thunderstorms probs also targeting this time, with 10-20% chances
each afternoon/evening starting on Wednesday. Primary areas of
thunderstorm potential will be the Sierra (roughly Alpine, Mono
counties) Wed-Thurs, and then the chances for thunderstorms spread
into Lassen/Plumas counties as well.
If you have outdoors plans (e.g. camping, hiking, boating, etc.)
be sure to keep an eye on the 2x/daily updates from the National
Weather Service. It will be quite summer-y next week, so a good
rule of thumb is to complete your outdoor activities before the
afternoon when the thunderstorm risk goes up! Or be sure to have a
backup plan for taking shelter from hail, rain, and lightning.
-Edan
&&
.AVIATION...
A cold front dropping through the region this afternoon will keep
gusty winds across the Sierra and western Nevada along with some
showers with maybe a couple of thunderstorms. The best potential for
thunderstorms will be east of Highway 95, but a band of showers just
north of the I-80 corridor will likely hold together through the
evening with light-to-moderate showers and lower ceilings. HREF
showing the band of showers slowly breaking up as it migrates
slowly south through the evening, so KRNO may get very little if
not any precipitation.
Surface winds will decrease behind the front this
evening, but east to northeast winds may be breezy in the Sierra.
There will still be an enhanced potential for turbulence across
and west of the Sierra with the breezy east winds.
High pressure builds in with lighter winds Sunday and continue into
next week. By the middle of next week we should be seeing afternoon
and evening thunderstorms developing along the Sierra.
-Edan
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno
Area Forecast Discussion
National Weather Service Springfield MO
645 PM CDT Fri May 22 2020
.SHORT TERM...(This evening through Saturday)
Issued at 248 PM CDT Fri May 22 2020
After a very active morning across southeast Kansas and the Missouri
Ozarks, the showers and storms were exiting the eastern Ozarks. This
morning convection has really worked over the atmosphere and current
indications that recovery will be quite limited for additional
severe storms this afternoon and evening. In addition, the storms
were proficient rain makers with locally heavy rain and flooding
being reported. Hi-Res CAMS still showing the potential for a few
storms late this afternoon and evening, with the NAM Nest the most
robust and the latest HRRR now showing development as well. However,
still uncertain if enough instability can develop for anything
severe. Did lower overall probabilities this evening with only
isolated to scattered storms expected at best and this would be
mainly through 06Z. Some weak upper level ridging builds in late
tonight through Saturday and should for the most part should squelch
much in the way of showers and storms. Did keep lower end
probabilities going, especially Saturday afternoon with the moist
and unstable airmass in place. Saturday looks to be a warm and humid
day with highs in the lower to middle 80s and dewpoints in the upper
60s. Again relatively quiet weather is expected Satruday night with
lows in the 60s.
.LONG TERM...(Saturday Night through Friday)
Issued at 248 PM CDT Fri May 22 2020
At this point it looks as though upper ridging will hang on into
Sunday morning before pushing off to the east Sunday afternoon.
However, still high precipitable water values along with modest
instabilities will result in mainly diurnally driven convection on
Sunday, The pattern for Monday and Tuesday is for a trough over the
mid section of the conus with ridging along the east coast. By
Tuesday afternoon medium range guidance suggests an upper low
forming over Oklahoma and then slowly sagging southward into Texas
by Thursday and Friday. This will keep the area in a southerly moist
flow through the period with high precipitable water values along
with periodic rain chances. Given antecedent soil conditions this
will only aggravate the flooding potential. Overall, temperatures
through the period will be seasonal with highs right around 80 and
lows in the 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 637 PM CDT Fri May 22 2020
Models continue to show a decrease in coverage of showers and
storms this evening. As such, did not include any precipitation in
this TAF issuance. Can`t rule out some isolated storms this
evening at all sites, and possibly overnight at KBBG, but
potential is too low at this point to put in the forecast.
Additional showers and storms will be possible Saturday afternoon
and evening.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
SHORT TERM...Raberding
LONG TERM...Raberding
AVIATION...Titus
Area Forecast Discussion
National Weather Service Shreveport LA
910 PM CDT Fri May 22 2020
.UPDATE...
The latest run of the HRRR is capturing the ongoing severe convection
in S OK/N TX quite well and has it moving into the I-30 corridor
just before midnight tonight. Currently, only McCurtain County is
in a Severe Thunderstorm Watch in our area; will have to closely
monitor this situation as the evening progresses. This activity will
spread slowly eastward into SW AR into the early morning hours,
thus will not make any major changes to the forecast at the
moment. /35/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 71 90 71 87 / 30 30 10 50
MLU 71 91 72 89 / 10 30 10 40
DEQ 67 87 68 85 / 50 20 10 50
TXK 70 88 70 85 / 50 30 10 50
ELD 70 90 70 88 / 40 30 10 30
TYR 70 88 72 84 / 30 30 10 60
GGG 70 89 71 86 / 30 30 10 60
LFK 73 91 72 87 / 20 30 10 60
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$