Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/06/20
Area Forecast Discussion
National Weather Service Cheyenne WY
527 PM MDT Fri Jun 5 2020
.SHORT TERM...(This evening through Saturday)
Issued at 224 PM MDT Fri Jun 5 2020
Current satellite imagery shows Cu developing along the Laramie
Range with a few weak echos being returned to radar. Scattered
showers will continue to develop later this afternoon and early
evening. Biggest issue will be which areas remain capped through
the afternoon. Latest SPC mesoanalysis shows 1000-1500 J/kg of
MLCAPE cutting across Converse Co. through the southern Nebraksa
Panhandle with 50 kts of effective shear over northern portions of
the CWA. However, MLCIN still needs to be overcome for storm
development. High-res models have been consistent to initiate a
few storms along the South Laramie Range that are short-lived. One
spot to watch tonight is up near Bill, WY where HRRR and NAMNest
runs have been initiating a stronger storm. A few attempts at
deep moist convection have been ongoing across Natrona Co. over
the last hour. Would expect more successful attempts over the next
two hours as more favorable instability is located farther east
along with impressive turning of winds with height supporting 0-3
km SRH around 200 m2/s2. Severe threat is possible tonight, but
should remain fairly isolated.
The upper level cutoff low off off the California Coast will
finally begin to propagate northeastward this evening. Large scale
upper level support will move over the area by early Saturday
morning with showers possible. Convective activity looks to begin
early in the afternoon Saturday as the vort max moves through the
Rockies. One area of concern will be the instability available for
strong convective updrafts to develop. Development of initial
shower activity could limit late morning insolation, especially
along the Laramie Range. Currently, models are hinting at a short-
lived period from 18-21z of 2500 J/kg MLCAPE over the Nebraska
Panhandle. A cap looks to remain in place through the day, however
upper level support should be strong enough to aid in initially
elevated convection across this area. Strong upper level winds
will support fast storm motions and the potential for strong TSTM
wind gusts with 700 mb winds exceeding 50 kts. Shear profiles are
fairly unidirectional with effective shear 60-70 kts. Despite
limited hodograph curvature, elongated shear profiles still
suggest noteworthy 0-1 km helicity values. High-res guidance has
been suggesting primarily linear storm mode with discrete cells
possible farther northeast and multiple waves of storms passing
through with leading shortwave energy ahead of the main vort max.
Main threats Saturday will be strong wind gusts to 60 MPH likely
with storms and severe hail east of the Laramie Range. Largest hail
potential will remain with the greater instability over western
Nebraksa. Possibility of a tornado is still there, but remains low.
SPC has highlighted areas within the CWA east of the Laramie Range
with a Slight Risk of Severe Thunderstorms while an Enhanced Risk
sits over the northern Nebraska Panhandle extending to the northeast
of the CWA in South Dakota.
.LONG TERM...(Saturday night through Friday)
Issued at 251 AM MDT Fri Jun 5 2020
Warm and mainly dry conditions expected Sunday ahead of the upper
trough over the western CONUS. A few showers or storms possible
out west in the afternoon as a cold front edges east during the
day. Much cooler and unsettled conditions set in for Monday and
Tuesday as the upper trough moves across the region with showers
and a few storms especially late Monday. Dry and warmer Weds and
Thursday as an upper ridge amplifies over the Rocky Mountains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 523 PM MDT Fri Jun 5 2020
VFR flight conditions expected through 06Z, despite VCSH causing
brief, erratic wind gusts near vicinity of terminals. Wind gusts
of 20-30 knots are likely due to the nearby rain showers for the
WY terminal sites. CDR could also stay gusty past 06Z in addition
to the WY terminals mentioned before. AIA, BFF, and SNY should see
winds approximately 15 knots or less through 6Z. The approaching
weather system from the southwest will begin to increase chances
of rain from west to east after 6Z. This will be mentioned in the
next update around 0530Z.
&&
.FIRE WEATHER...
Issued at 224 PM MDT Fri Jun 5 2020
Afternoon temperatures have reached the 80s for most locations
with relative humidity dropping into the low 20s and teens along
and west of the Laramie Range. Wind gusts 20-25 MPH bring
conditions to near Red Flag Criteria, but critical fuels are not
ready. Widespread wetting rain is expected Saturday with
thunderstorms and strong winds. Cooler temperatures are on the way
early next week, but relative humidity in the southern Nebraska
Panhandle will drop into the teens before then on Sunday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...MB
LONG TERM...CLH
AVIATION...BW
FIRE WEATHER...MB
Area Forecast Discussion
National Weather Service Des Moines IA
639 PM CDT Fri Jun 5 2020
.DISCUSSION.../Tonight through Friday/
Issued at 258 PM CDT Fri Jun 5 2020
Synoptic Overview:
Short-wave trough with 70 kt H5 jet streak is moving from the upper
Midwest into the northern Great Lakes Region as of this morning.
Weak, broad ridging has been occurring over the Northern Rockies, and
the axis is sliding eastward toward the northern Plains with another
trough off the NW Pacific Coast. Surface low pressure is also
pushing eastward, with surface high pressure over the northern
Plains strengthening with the AVA under the ridge setup. This has
been slowly pushing a boundary southeast across the Missouri River
Valley today.
Today:
Strong WAA over the Plains will result in amplification of the H5
ridge that is shifting eastward across the central and north central
CONUS. This afternoon, that will result in mid-level flow briefly
being northwesterly. On the backside of the surface low over the
Great Lakes and with surface high pressure over the northern Plains,
near surface flow will also be generally northwesterly. As a result,
this will push the boundary southeastward throughout this afternoon.
Since 12z, CAM guidance has backed away from placing light showers
and weak thunderstorms in southwest Iowa later this afternoon and
early evening. Exploring the soundings of the HRRR and RAP, the
solutions indicate rather dry air between 850 mb and 650 mb, which
certainly would suppress shower activity. However, lapse rates in
the low to mid levels are somewhat steep, and with clouds clearing
and plenty of insolation will likely be realized. This may be just
enough for a few parcels to rise and result in a few weak showers.
Thus, have slightly decreased POPs for later this afternoon and
evening, but have not gone completely dry. As for temperatures this
afternoon, expecting a decent recovery as clouds clear in plenty of
time for peak heating. Northern and northwest Iowa will remain
cooler on the north side of the boundary, with temperatures in the
lower 80s. Central and southern Iowa will reach the mid to upper
80s. South of the boundary, with dewpoints in the upper 60s to lower
70s, heat index values will be in the lower 90s. This will make for
an overall muggy day across central and southern Iowa.
Saturday and Sunday:
Saturday the synoptic pattern will begin to get interesting with
the northward progression of what is now Tropical Depression
Cristobal, moving into the open Gulf of Mexico off the Yucatan
Peninsula. The axis of the amplified H5 ridge will attempt to slide
east, being set in motion by a negatively titled short-wave trough
in the southwest CONUS and an Aleutian low centered off the NW
Pacific Coast. As surface high pressure slides eastward with the
ridge axis advancement, low-level flow turns southerly which will
advect a warm-moist airmass back into the upper Midwest immediately
after seeing the passage of the weak cold front from Friday
afternoon. Afternoon high temperatures will recover back into the
upper 80s for western and southern portions of the forecast area.
Rain shower and thunderstorm chances Saturday will be highly
dependent on the role of Cristobal has in blocking the eastward
advancement of the ridge axis, as the short-wave trough quickly
ejects northeastward into the Plains with a 70 kt H5 jet streak.
This will provide a shot of CVA on the backside of the ridge and
tries to force sudden height falls over the upper Midwest. However,
12z GFS/NAM//ECMWF guidance currently depicts Cristobal halting any
eastward progress of the mid-latitude flow. Thus, this would keep
heights steady Saturday while forcing the quick ejecting short-wave
trough into the Canadian Prairie Provinces. This will certainly lead
to some kind of perturbation in the mid-level flow across the upper
Midwest, but 12z cycles of most guidance now keeps the better
forcing for precipitation in the eastern Dakotas and western
Minnesota. The GFS is only the model that attempts to have any kind
of light rain shower activity in northern Iowa. Most ensembles
members remain dry Saturday, thus will keep POPs and rain showers
chances extremely limited across northern Iowa. Sunday, the large
scale pattern remains roughly the same as Cristobal continues to
track inland. The short-wave trough axis continues to swing
northeastward into Canada. Another shot of weak CVA may reach the
northern extent of the forecast area, which could force out a light
shower. Thus have a brief period of low POPs north of U.S. Hwy. 18
going for Sunday. As with any extratropical cyclone, changes in the
track will greatly influence these limited precipitation chances.
The main weather story for the rest of the forecast area on Sunday
will be brisk winds, as surface-cyclone associated with the short-
wave tracks through the central Plains and increases the strength of
the pressure gradient. At this time, expecting wind gusts to remain
well below wind headline criteria.
Extended Forecast:
Warmer temperatures will continue through Monday while the H5 ridge
remains in place across the upper Midwest and southerly flow
continues to move in. Cristobal (or what is left of it) will bring
rain shower and thunderstorm chances Tuesday through Wednesday. The
12z cycle of the GFS and ECMWF are actually in decent agreement
about brining widespread rainfall to Iowa with this cyclone. The GFS
is just a tad faster, but overall both models track the center of
the cyclone along roughly the same track. Expect thick cloud cover
Tuesday through Wednesday, which accompanied by heavy rain showers
will help to reduce temperatures across the state thorugh the middle
and end of the next work week. QPF will need to be monitored closely
with rainfall associated with Cristobal. While several areas will be
able to handle a decent amount of rainfall, other areas may begin to
see flooding issues, and will also need to be concerned about river
levels. As QPF becomes more certain, will have further discussions
about hydrology concerns across the state.
&&
.AVIATION.../For the 00Z TAFS through 00Z Saturday evening/
Issued at 639 PM CDT Fri Jun 5 2020
A warm front will be located to the south and west of Iowa during
the day Saturday. Precip may form in these areas but for Iowa, VFR
conditions will prevail. Afternoon mixing will yield wind gusts to
between 15 and 20 kts mainly across northern TAF locations.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Krull
AVIATION...FAB
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
957 PM EDT Fri Jun 5 2020
.UPDATE...
Waning instability coupled with intrusion of dry air and subsidence
behind the cold frontal boundary will end all rain chances over the
next hour, with the exception of portions of the northern Thumb where
an area of residual moisture holds on. Any shower activity observed
will be light in nature with no thunderstorm activity expected. This
will lead into a mostly clear and calm night with a secondary weak cold
front expected to pass through SE MI by the late morning/early
afternoon hours. Dry air and weak frontal forcing will preclude any
rain chances tied to secondary front.
&&
.PREV DISCUSSION...
Issued at 731 PM EDT Fri Jun 5 2020
AVIATION...
Ongoing passage of a cold front combined with a subtle low-level
boundary located just north of the Metro terminals have produced
weak isolated showers confined mainly just north of the Metro area,
with secondary showers wedged between KMBS to KFNT. This subtle
forcing combined with a slight uptick in instability will continue
to produce a low-end rain shower or short-lived thunderstorm through
01Z. Given the isolated coverage and low-confidence for development,
rain and thunderstorms will be left out of this TAF issuance with
the exception of KDET, where two convective cells reside. Broadscale
subsidence has and will continue to fill in behind the front which
will effectively end all rain chances and will produce VFR cigs
through the overnight hours. Gradually wind shift from west to
northwest will take place tonight and overnight, with northwesterly
flow expected to hold through the bulk of TAF issuance.
For DTW...
Low-end chance for showers or an isolated thunderstorm through 01Z,
tied to a subtle northerly boundary, otherwise, dry weather and VFR
cigs overnight.
DTW THRESHOLD PROBABILITIES...
* Low for an isolated thunderstorm through 01Z
PREV DISCUSSION...
Issued at 526 PM EDT Fri Jun 5 2020
DISCUSSION...
Forecast reasoning provided in the Update Discussion Issued at 1103
AM EDT regarding the severe weather potential this afternoon and
early evening hours remains valid.
Low level thetaE warm sector will remain in place across all of
Southeast Michigan through 00Z as 6 hr 1000-500mb geopotential
height falls remain centered over the area. Depth of antecedent dry
air with rapid onset to lower level thetae continues to wreak havoc
in the forecast soundings. The latest HRRR solutions are somewhat
puzzling not giving any credit to the lower to middle 60 dewpoints
that are surging across western Lower Michigan in tow of this
initial shower and thunderstorm activity. The potential still exists
for an isolated strong to possibly severe wind gust with deep
convection through 35.0-40.0 kft agl. However, relatively slow cell
movement of 25 mph and weak environmental wind field less than 25
knots through 10.0 kft agl will be a significant negative on
convective environment/potential. Latest CAM signal suggests
thunderstorm potential through approximately 23Z.
Low level thetae scours out rapidly 03-06Z as a cold front pushes
across the area. Low to midlevel wind trajectories will then
transition to anticyclonic, supporting very efficient isentropic
downglide on the 310-307Ke surfaces. Forecast soundings do show a
clear signal for aggressive subsidence centered at 650mb by 06Z
tonight.
Strong support within the models for surface based ridging this
weekend. Models showing very strong stability from 3.0 through 15.0
kft agl. Very quiet and ideal summer weather for Southeast Michigan.
Highs this weekend are expected to reach middle 70s to around 80
degrees both Saturday and Sunday. Little cloud cover is anticipated.
High amplitude upper level ridge is then forecasted to develop over
the Central Great Lakes for the beginning of next week. Models
indicate H5 heights potential exceeding 588 dam. Current forecast
information suggests highs reaching the low 90s will be possible on
Tuesday. Main item to be monitoring will be the forecast trends
regarding Cristobal remnants as its forecasted to lift due northward
into the Midwest. Uncertainty exists with timing of interaction
between tropical moisture and strong upper level trough/PV over
western United States. Important, because eventual track of
Cristobal will bring with it a heavy rainfall and flooding risk.
MARINE...
Areas of gusty showers and thunderstorms are advancing across Lake
Erie this evening which may lead to locally higher waves. A cold
front moves through late this evening bringing about additional
showers and thunderstorms followed by northwesterly flow. Wind
speeds will increase on Saturday as the surface gradient strengthens
due to stronger high pressure building to the northwest and a
deepening low over the Northeast. High pressure over northern
Ontario shifts eastward on Sunday with a secondary high over
northern Lake Huron causing winds to veer toward the northeast
drawing slightly cooler and drier air into the central Great Lakes.
A warming trend begins on Monday as high pressure influence keeps
conditions dry with lighter winds veering southeasterly. The
remnants of TS Cristobal arrive mid-week presenting timing and
precipitation uncertainty.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
UPDATE.......AM
AVIATION.....AM
DISCUSSION...CB
MARINE.......KK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service North Platte NE
628 PM CDT Fri Jun 5 2020
.SHORT TERM...(This evening through Saturday night)
Issued at 301 PM CDT Fri Jun 5 2020
A few of the CAMs show isolated storm development this evening
across the ern Panhandle. Winds aloft are strong with 35 kts at
h500mb and CAPE around 2000J/KG will be in place. Storm development
across the Front range and Laramie range should be underway by 21z
but as the storms move east toward wrn Nebraska, they will encounter
increasing amounts of warm air at h700mb effectively capping
development. If the cap is weaker than predicted by the models,
isolated strong or perhaps severe storm development is possible as
suggested by the HRRR and NSSL WRFARF models. Wind would appear to
be the primary hazard given large delta-T-TD spread in the lower
levels of the model soundings.
A strong warm front with low level winds of 40 to 65 kts lifts
through wrn and ncntl Nebraska tonight. These winds will continue
through Saturday and Saturday night. The RAP model suggested an
isolated thunderstorm chance as this occurs late tonight and
Saturday morning. It is the only model to show this and the forecast
is dry tonight. An area of morning stratus should develop across the
Sandhills with burn-off by 17z.
Severe storm development appears likely across wrn Nebraska from
about 21z Saturday afternoon through 06z Saturday night. One or more
clusters of storms should develop over the Cheyenne divide and nern
Colo/Sern WY which will move rapidly northeast through the Panhandle
and wrn Nebraska. The HRRR and NAMnest models show a forward storm
motion of 50 to 60 mph. This is likely a result of the strong winds
below 700mb and an approaching 50-70kt h500mb jet.
The NAM is also showing 0-1km layer helicity values increasing to
500 to 1000 m2/s2 Saturday evening along a stalled Pacific front
stretching north and south across all of wrn Nebraska. This is
likely the reason SPC posted a 2% TOR prob across nrn Nebraska.
SPC suggests bows and bow segments lifting rapidly northeast will
pose a significant wind damage threat. Given the steepening lapse
rates from an approaching upper level trof and very strong warm air
advection progged up the Colorado plains, very large hail is
possible also.
.LONG TERM...(Sunday through Friday)
Issued at 301 PM CDT Fri Jun 5 2020
Sfc low pressure will lift through Nebraska Sunday and the latest
model blend suggests a lull in storm development. This likely the
result of the best focus shifting north into the Dakotas and a
strong cap across Nebraska. The NAMnest suggests storms could
still fire north and south near or between highways 83 and 61, but
it is the only model showing this. The forecast follows the model
consensus which is dry.
The model consensus is in good agreement for storm development
Monday evening across ncntl Nebraska and a portion of southwest
Nebraska. The models have been consistent with this feature for a
couple of days now. A Pacific cold front aligned north and south
across ncntl Nebraska will be the focus for development, winds aloft
are strong at 50-65kt and MLCAPE should be around 3000J/KG.
The Pacific front should be east of ncntl Nebraska Tuesday and
cooler temperatures are in place through Friday. Shower and
thunderstorm chances continue Tuesday associated with cold air aloft.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 628 PM CDT Fri Jun 5 2020
Thunderstorms and winds are the primary aviation weather threats
for western and north central Nebraska. Isolated storms are
possible in the panhandle and far northern Neb. late tonight into
Saturday morning. Otherwise, VFR will continue with low level wind
shear affecting most terminals overnight. Winds turn more
southerly for Saturday and strengthening with gusts 30+ kts in
the afternoon. Storm chances also increase late afternoon,
starting with the western terminals.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Snively
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
624 PM CDT Fri Jun 5 2020
.SHORT TERM...
254 PM CDT
Through Saturday night...
Isolated severe risk through early evening:
The convective potential this afternoon-evening continues to
be uncertain, and if thunderstorms occur, coverage is expected to
be low/isolated to perhaps widely scattered. There remains a
conditional strong to severe thunderstorm risk, covered well by
SPC`s Marginal (level 1) Risk. Expansive convective blow-off
cirrus has been shrouding the region, though temperatures have
been able to warm into the mid to upper 80s. A recent aircraft
sounding out of MDW indicates a lingering cap to surface based
convection there, though SPC/RAP Mesoanalysis suggests cap is
eroding from the northwest. Lake breeze boundary is stalled out
from the Cook County North Shore area to the eastern portion of
Lake County.
Potential scenario for convective initiation (CI) this afternoon
into the evening is similar to earlier posted update. It will be
tied to low level frontal convergence, enhanced by lake breeze
convergence, likely with an emphasis on the lake breeze/cold front
inflection. Visible satellite imagery shows most congested
cumulus near the lake breeze in southeast Wisconsin and far
northeast Illinois and there was an attempted shower near Kenosha
around 2pm. Farther upstream, cumulus field not all that
impressive looking and winds have already turned northwesterly in
the northwest portion of the CWA with a pre-frontal wind shift. It
appears true frontal boundary stretches from near the MS River to
southwest Wisconsin.
MLCAPE values may top out in the 1500-2500 j/kg range as
suggested by recent mesoanalysis, which is more than sufficient
given northwesterly deep layer shear of 30-40 kt. Biggest
question mark continues to be the coverage of thunderstorms, if
any, ahead of the front. 12z sounding from Aberdeen SD sampled
exceedingly dry air in the 700-500 mb layer and model forecasts
suggest this is in the process of being advected overhead. Lack
of large scale mid and upper level forcing and relying solely on
frontal convergence also adds to the uncertainty. The mid-level
dry air entrainment could be tough for incipient updrafts to
overcome and mature into thunderstorms, which may have been the
case with attempted CI over southeast WI.
Dew points have also mixed out a bit over portions of the Chicago
metro, though this is not uniformly the case. It is apparent that
some of the more aggressive 12z CAM solutions, namely the 3km
NAMNest and NSSL WRF, will be overdone with dew points along the
front, which helps explain their more concerning depiction. The
above limiting factors in mind, am still concerned that a couple
storms may be able to overcome the dry air entrainment,
particularly in the vicinity of the lake breeze/cold front
inflection through early evening where convergence will be
maximized. *If* a storm or two should tap into the favorable
parameter space on the instability, shear, mid-level lapse rate
spectrum, there is a concern for an isolated robust severe storm.
Main threats if a storm does become severe would be damaging
downburst winds given steep low level lapse rates and plenty of
DCAPE from aforementioned dry air aloft. In addition, with
favorable shear vector orientation to cold front, any supercells
would also have a large hail threat.
Recent HRRR runs have been steadfast in little/no development with
the front, with the aforementioned WRF based guidance on the other
end of the spectrum. The latest observational trends seem to point
toward coverage being low at most, but still don`t want rule out
the possibility of a thunderstorm or two getting going. Will need
to monitor satellite and radar trends closely. With all the
uncertainty described, kept PoPs capped at 20% to 30%. The storm
motions should be 30-40 mph off to the southeast, so while any
thunderstorm would certainly produce brief heavy downpours, not
expecting a flash flood threat. If convection occurs, it will sag
south and gradually dissipate with diurnal stabilization by the
mid to late evening near and south of the Kankakee River. Timing
for isolated severe risk could be as early as 3-4pm in the far
north to 8-9pm south of I-80.
Skies will clear out tonight behind the front as the cooler and
drier/less humid air mass advects in for the weekend. After a
relatively cool start to the day, Saturday will be a pleasant
early summer day with plenty of sunshine despite 500 mb heights
from mid-level ridging over the central CONUS typically being
supportive of warmer readings. This will be due to expansive high
pressure taking on backdoor characteristics as is centers over the
Great Lakes. Dew points are likely to drop to the 40s to around 50
Saturday afternoon, which will make it comfortable for outdoor
activities. Highs will top out in the lower to mid 80s well inland
(warmest south) and 70s downwind of Lake Michigan, with mid to
upper 60s lakeside due to steady northeast winds. It appears that
the magnitude of the northerly winds will be just shy of producing
waves more concerning from a dangerous waves and currents
perspective at the beach. Saturday night will feature lows in the
50s area wide, and can`t rule out an isolated upper 40s reading in
far northern Illinois.
Castro
&&
.LONG TERM...
303 PM CDT
Sunday through Friday...
Sunday through Monday night: The southwest extent of high pressure
drifting across the northern Great Lakes will remain across the area
during this time as a pronounced mid/upper ridge builds eastward.
With 850 hPa temps surging into the 20-22C range Sunday night into
Monday, afternoon highs Monday are expected to reach the low 90s for
all but the immediate lakeshore of northeast Illinois. With
dewpoints in the upper 50s and low 60s under a decent amount of
sunshine, some localized readings tapping into the mid 90s cannot be
ruled out. With the less humid conditions, heat index values should
remain capped at values near the air temperature.
Tuesday through Wednesday: Focus remains on local impacts from
Tropical Storm Cristobal currently drifting north off the Yucatan
Peninsula. Atmospheric Rex blocking from the aforementioned
mid/upper ridge over the area Sunday into Monday creates some
forecast challenges with regards to Crisotbal`s movement through mid-
week, but the overall forecast is for a broad and deep trough over
the western CONUS this weekend to nudge the ridge eastward and pick
up Cristobal`s remnants on Tuesday. Guidance has been fairly
consistent on this overall evolution, though placement and timing
have varied enough due to phasing issues to preclude too much
specificity in the forecast at this time. Consensus guidance brings
the remnants northward just west of the Mississippi River through
Tuesday morning before a northeast shift across the western Great
Lakes Tuesday night. With it will come a tropical air mass with
PWATs in excess of 2" and potentially strong winds in response to an
anomalously deep surface low. While current indications are for the
heaviest associated rains to remain just west of the CWA late
Tuesday afternoon into Tuesday night, the CWA is well within the
ensemble envelope of solutions to potentially fall within the axis
of heaviest rain. Those with forecast sensitive interests Tuesday
into Wednesday should continue to monitor the latest forecast
through the weekend.
Thursday through Friday: The western trough will deamplify to some
extent while gradually lifting northeast into eastern Canada during
this time. Most of this period should be dry with the exception of
scattered precip along a potential cold front dropping south into
the area on Friday.
Kluber
&&
.AVIATION...
For the 00Z TAFs...
624 PM...Only forecast concern this period are the winds.
There remains a small chance for an isolated thunderstorm this
evening ahead of a cold front moving into northern IL. Nothing has
developed so far and much of the short term guidance keeps the
area dry this evening and no precip mention with this forecast.
Winds are slowly turning northwesterly across northern IL and will
likely become more northerly this evening...possibly turning to
the north/northeast at ord/mdw but confidence is low. Winds should
settle back on a light north/northwest direction overnight and
winds will then turn northeasterly Saturday morning. Speeds should
increase into the 10-12kt range and its possible some gusts into
the upper teen kt range may develop late morning into the
afternoon. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
Visit us at weather.gov/chicago
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/NWSChicago
www.twitter.com/NWSChicago
www.youtube.com/NWSChicago
Area Forecast Discussion
National Weather Service Little Rock AR
238 PM CDT Fri Jun 5 2020
.Short Term...Tonight thru Sunday...
Remnant MCS drifted out of MO this afternoon and started to
intensify as it moved to the southeast. The vast majority of this
ended up east of the LZK forecast area, but one storm became strong
enough to warrant the issuance of a warning.
The area remains on the eastern edge of an upper level ridge. There
is a significant amount of mid-level instability in place across the
area with relatively little CIN in place. Wind shear is minimal. The
dynamics of the ridge seem to be keeping most of the storms over the
eastern portions of the state for the time being.
The short term models have been all over the place in regards to how
to handle the situation today and tonight. NAMNest and WRF models
have been much more prolific with the convection, taking it well
into the western portions of the state. HRRR model families have
been more conservative, and while far from perfect, have been closer
to the current situation. Models show the potential for further
development mainly across the southeast quarter of the state, and I
have gone with this trend. The potential for severe wind gusts
certainly remains thru tonight.
Ridging will continue across the area thru the period, and daily max
temps will remain in the 90`s with dewpoints generally in the
70`s.
&&
.Extended Term...Sunday Night thru Friday...
The main story during the extended period forecast will be the
arrival of Tropical Depression Cristobal. The tropical system is
expected to move into the Gulf of Mexico this evening, and
strengthen into a Tropical Storm as it approaches the United States.
Late this weekend and into early next week, Cristobal is expected to
move through portions of Louisiana, Mississippi, and Arkansas.
Although Cristobal should weaken as it moves through Arkansas, much
of the state will see widespread rainfall Monday through Tuesday
night. Through this period, much of the central and eastern sections
of the state could see between 3 and 5 inches of rain, with lesser
amounts around 2 to 3 inches across western portions of the state.
This will likely change as we proceed through the weekend and into
early portions of the coming week, as any changes to the strength or
path of the storm could alter the forecast. Strong and gusty winds
may also be possible, especially across the southern portions of the
state.
Remnants of the storm will likely merge with troughing across the
Plains regions by mid week, allowing a storm system approaching from
the west to push through the Natural State. An associated surface
cold front will also swing through the state, and help clear out
rain chances on Wednesday and Thursday. Behind this feature, high
pressure will return and help keep conditions dry.
Conditions will be warm and humid, but cloud cover and rainfall from
Cristobal, and the passage of a cold front, will help keep
temperatures more mild than what we`ve recently seen. In fact, for
most of the period, temperatures should be near normal values for
this time of year.
&&
.PRELIMINARY POINT TEMPS/POPS...
Batesville AR 73 92 72 92 / 20 10 0 0
Camden AR 72 94 73 94 / 20 30 0 10
Harrison AR 70 91 70 89 / 10 20 0 0
Hot Springs AR 73 93 72 93 / 20 20 0 0
Little Rock AR 74 93 74 93 / 30 20 0 0
Monticello AR 73 92 74 92 / 40 30 0 10
Mount Ida AR 71 92 70 92 / 10 30 0 0
Mountain Home AR 71 92 71 91 / 20 10 0 0
Newport AR 71 92 75 94 / 20 20 0 0
Pine Bluff AR 73 92 73 92 / 30 20 0 10
Russellville AR 72 94 73 93 / 20 20 0 0
Searcy AR 72 92 73 93 / 30 10 0 0
Stuttgart AR 74 92 74 93 / 30 20 0 0
&&
.LZK Watches/Warnings/Advisories...NONE.
&&
$$
Short Term...53 / Extended Term...69
Area Forecast Discussion
National Weather Service Miami FL
853 PM EDT Fri Jun 5 2020
.Update...
Models have backed off on chances of showers and thunderstorms
tonight, which has been the case this evening. Even so, there is
still a chance for some to develop periodically, especially along
the coastal areas, where some coastal convergence may occur. With
a tropical system even having a minor influence, also can not rule
out some of the storms obtaining strong thunderstorm
characteristics, such as rotation or funnel clouds.
&&
.Prev Discussion... /issued 728 PM EDT Fri Jun 5 2020/
Aviation...
A relatively quiet spell is expected overnight, with some showers
and thunderstorms still possible across the Gulf and West Coast.
Scattered to widespread showers and thunderstorms are expected to
develop across the area again tomorrow, with gusty winds,
lightning, funnel clouds, heavy rain all possible. Mostly VFR
conditions are expected outside of convection.
Prev Discussion... /issued 350 PM EDT Fri Jun 5 2020/
Short Term...
Today through tonight...
Previous mesoscale discussion still valid through 22z...
While highly uncertain, a localized conditional risk of a couple
strong to locally severe thunderstorms could arise across portions
of South Florida beginning early this afternoon and lasting into
the late afternoon hours. This conditional risk appears to be
greatest across the southern interior portions of South Florida
early this afternoon, becoming focused over the Lake
Okeechobee/interior areas later this afternoon. The primary
concern with any of the stronger storms that develop this
afternoon will be locally heavy rainfall -- which may lead to
urban flooding, isolated strong to locally severe convective wind
gusts, and frequent lightning.
Important Note - An additional conditional risk of a few strong
to locally severe storms may arise later this evening into the
overnight hours. This threat may be greatest across the Gulf Coast
of South Florida, though there is plenty of uncertainty regarding
this threat at this time. Please keep up with the evolving
forecast.
In the low-levels, South Florida is under the influence of the
western periphery of an Atlantic subtropical high, allowing for deep
southeasterly flow up to near 800 mb. Rich moisture advection is
quite evident in the low-levels along this southeasterly flow,
acting to keep dew points in the low to mid 70s across the eastern
portions of South Florida. This rich low-level moisture will likely
continue to spread across South Florida from the Atlantic Coast
towards the Gulf Coast, acting to strengthen low-level buoyancy.
In addition, brief cloud clearing/thinning is evident across the
southern and interior portions of South Florida from GOES-16
visible and water vapor imagery loops. This is also acting to
strengthen surface-based instability by locally steepening 0-3 km
lapse rates across the southern interior and western portions of
South Florida, where horizontal convective rolls and agitated
cumulus fields are currently evident.
In the upper-levels, strengthening southwesterly flow in association
with Tropical Depression Cristobal and an upper-level trough over
the northern Gulf of Mexico is providing differential divergence
across the region, leading to weak, albeit some synoptic ascent.
This synoptic ascent may act to enhance/focus mesoscale
convergence/ascent this afternoon along differential heating
boundaries and horizontal convective rolls. As Tropical
Depression Cristobal continues northward today, deep layer
flow/shear will gradually strengthen across South Florida. This
shear enhancement should first be realized across the Gulf Coast
of South Florida later this afternoon into the evening hours when
a southerly low- level jet may develop.
While the flow/shear should remain relatively weak across South
Florida during afternoon convection today, deep rich moisture
combined with modestly steep mid-level lapse rates near 6.8 C/km and
steepening low-level lapse rates may allow for a few strong
convective wind gusts, with a highly conditional risk of a damaging
wind gust. This threat may be enhanced by precipitation loading and
modest updraft parcel accelerations in the low to mid-levels where
mesoscale ascent becomes locally maximized.
While there are some notable limiting factors for the development of
a few strong to locally severe storms this afternoon (including
lacking deep-layer flow/shear which will limit updraft separation
and weak synoptic forcing for ascent), a conditional risk does
appear to be present at this time. Please keep up with the latest
forecast information from NWS Miami as the aforementioned
threats/convective hazards will likely evolve with time.
After 22z...
After the initial convection moves to the north this evening,
models are indicating a brief respite from active weather.
However, by around 03/04z the HRRR is showing an extreme outer
band of Cristobal may work its way into the area, especially the
Gulf waters and the western half of the area. There appears to be
a weak boundary somewhere north of the lake region, which may act
to enhance some convective coverage tomorrow in the Lake region,
although the entire area may see showers and storms through the
day.
Long Term...
Saturday night through Thursday night...
There is high uncertainty in the forecast after Saturday night.
As Cristobal moves further north, away from the area, there is
some uncertainty as to where an extreme outer band may set up.
The GFS has a more distinct band, but keeps it offshore. The ECMWF
looks to be trying to establish the out band, but is being
affected by the lingering boundary. Either way, the best chances
for rain Saturday night look to be off the Gulf coast. However,
there is still too much uncertainty and there is a chance of
showers and a slight chance of a thunderstorm through the night.
For Sunday, while Cristobal should be getting ready to make
landfall somewhere along the Central Gulf coast, the boundary over
Central Florida keeps moisture and convection in the forecast,
with the best chances in the Lake region, but again, can occur
anywhere across South Florida through Sunday night, into Monday.
Monday night should see improving conditions, although there is
still a slight chance of showers through the night. By Tuesday,
high pressure tries to build to the northeast, bringing the
easterly flow back to the area, with ample moisture to keep
periods of showers and thunderstorms through the entire week, with
quieter period during the overnight hours. With the easterly flow,
the Gulf coast and western interior will have the best chances for
showers and storms each day, although they can not be ruled out
for the east coast of eastern interior areas as well.
Marine...
A rather tight pressure gradient across South Florida between high
pressure NE of the Bahamas and TS Cristobal will continue the
moderate and gusty SE to S wind across the local waters through
Sunday. The Gulf of Mexico waters will be at marginal small craft
advisory levels as winds approach 20 knots and seas build due to
wave energy/swells from Cristobal. The Atlantic waters will likely
stay at cautionary wind/sea levels. Periodic bands or even squally-
type of showers and thunderstorms with affect the Gulf waters this
weekend, with more scattered showers/isolated thunderstorms over the
Atlantic. TS Cristobal is forecast to make landfall along the north-
central Gulf coast on Sunday, then move inland near the Mississippi
Valley region early next week. High pressure over the Atlantic will
build closer to Florida early next week. As a result, the pressure
gradient is expected to relax, leading to overall lower wind and
seas. Periods of showers and thunderstorms can still be expected
over most of the local waters for the early to middle part of the
next week.
Beach Forecast...
The breezy SE winds will keep a high risk of rip currents at the
Atlantic beaches for most of the weekend. The rip current risk will
also increase at the Gulf beaches beginning Saturday, and
potentially to high risk levels on Sunday as wave energy from
distant TS Cristobal should bring small to moderate swells to the
surf zone.
The wave energy and swells will also cause minor coastal flooding
along portions of the Collier County coast this weekend, primarily
around the times of high tide which will be during the afternoon
hours, with a lower chance during the overnight time frame.
&&
.Preliminary Point Temps/PoPs...
West Palm Beach 76 86 78 87 / 30 50 40 60
Fort Lauderdale 78 86 80 87 / 30 40 40 50
Miami 78 87 79 88 / 30 40 40 50
Naples 74 87 77 87 / 30 50 50 60
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...Flood Watch through Saturday evening for FLZ063-066>075-168-
172>174.
High Rip Current Risk through Saturday evening for FLZ168-172-
173.
AM...None.
GM...None.
&&
Update...13
Area Forecast Discussion
National Weather Service Mobile AL
909 PM CDT Fri Jun 5 2020
.NEAR TERM /Now Through Saturday night/...A longwave ridge over
the central states advances slowly eastward towards the western
Great Lakes to the mid Mississippi River valley through Saturday
night. The upper ridge also meanwhile begins to build into the
extreme southeast states, gradually eroding an upper level
weakness currently in place over the north central Gulf coast
region. This transition in the upper level pattern over the region
still looks set to play an important role in steering Tropical
Storm Cristobal in a northerly direction across the central Gulf
to approximately 100 miles south of the coast of southeast
Louisiana by 12Z Sunday. Currently, a weakening Mesoscale
Convective System over central Mississippi/Alabama has sent a
decelerating outflow boundary into the interior portion of the
forecast area. The outflow boundary continues slowly further
southward into the forecast area overnight with showers and storms
along the boundary gradually diminishing. Given the weakening
trends seen in satellite and radar data, severe storm development
is not expected with this feature. As Cristobal advances
northward, easterly winds on Saturday increase to 10-20 mph, with
the higher values near the coast, and similar values continue into
Saturday night. Deep layer moisture steadily increases through
the period, with precipitable water values of 1.5-1.8 inches
increasing to 1.8-2.4 inches by Saturday night. Expect mainly
scattered showers and storms to develop across the area on
Saturday, then coverage increases over the southern portion of the
area Saturday night as Cristobal approaches. A Tropical Storm
Warning remains in effect for coastal Alabama to along the western
Florida panhandle coast. A high risk of rip currents remains in
effect, and a high surf warning and coastal flood advisory are in
effect beginning Saturday afternoon. Lows tonight and Saturday
night range from the lower 70s inland to the mid 70s at the coast,
and highs on Saturday will be in the mid to upper 80s. /29
&&
.PREV DISCUSSION... /issued 654 PM CDT Fri Jun 5 2020/
AVIATION...
00Z issuance...Scattered showers and storms have developed over
southeast Mississippi as well as over portions of coastal and
south-central Alabama. Meanwhile, a line of showers and storms is
moving southward over central Mississippi and central Alabama.
Therefore, showers and thunderstorms will continue this evening.
Kept mention of storms for BFM and MOB to account for this. Not
expecting much activity around PNS. Any showers and storms are
then expected to decrease overnight. With the advancement of
Tropical Storm Cristobal northward towards the Gulf coast, showers
and storm chances will increase Saturday morning and through the
day. Lowering CIGs will accompany this, with MVFR conditions
expected by late afternoon/early evening. Generally light
southerly winds tonight will become more easterly by Saturday
morning and increase through the day. By late afternoon, expecting
sustained winds between 10 and 15 knots along the coast with wind
gusts around 20 knots. Inland areas will generally remain under
10 knots during this time. /26
PREV DISCUSSION... /issued 535 PM CDT Fri Jun 5 2020/
NEAR TERM UPDATE /Now Through Saturday/...The region remains in an
area of upper level weakness today, with ridges dominating areas
to the east and west. This pattern will begin to break down
overnight tonight with the advancement of Tropical Storm Cristobal
northward towards the Gulf coast. Meanwhile, some scattered
showers and storms have persisted over the open Gulf waters and
along the coast this afternoon. Furthermore, an MCS is moving
southward over Mississippi and central Alabama. Although, the HRRR
shows this feature breaking up somewhat by the time it gets
closer to the northern Gulf coast. This will continue to be
monitored. With the loss of daytime heating, the chances of rain
and storms will then decrease late this evening and overnight.
Rain chances (as well as thunderstorm chances) will increase once
again Saturday morning from the south due to an outer rain band
from Tropical Storm Cristobal as it progresses north. PWATs will
increase from around 1.8 inches this afternoon to over 2 inches by
Saturday afternoon. Although, the heavier rain associated with
Cristobal is not expected to begin until late Saturday into early
Sunday. Winds will begin to increase along the coast late Saturday
afternoon as well, but again, the stronger winds are not expected
to begin until Saturday night. The Tropical Storm Watch was
upgraded to a Tropical Storm Warning this afternoon and now also
includes all Florida Gulf waters as well as most bays (except for
Eastern Choctawhatchee Bay).
Low temperatures are expected to be in the lower to mid 70s
tonight due to increased moisture. Areas right along the coast
could see even warmer lows, in the upper 70s. With increased cloud
cover and rain chances, highs tomorrow will likely only reach the
mid to upper 80s (with slightly cooler temperatures at the
beaches).
The HIGH RISK of rip currents continues for the coastal Alabama
and northwest Florida panhandle beaches through early next week
due to increased swell from Tropical Storm Cristobal. /26
SHORT TERM /Saturday night Through Monday night/...Tropical Storm
Cristobal is forecast to be centered over the central Gulf of
Mexico Saturday evening, and track northward before moving inland
across southern Louisiana Sunday evening, and then move northward
across the state of Louisiana throughout the day Monday. Deep
layer moisture will be high through early next week, with
precipitable water values increasing to between 2.2 to 2.7 inches
Saturday night and Sunday due to the surge of tropical moisture
around the northern edge of Cristobal`s large scale circulation.
Considering the amount of deep tropical moisture in place, some of
the more defined storms will be efficient, locally heavy rainfall
producers bringing potential of localized flooding. Bands of
heavy rainfall approaching from the south and will be most focused
across extreme southwest Alabama and the inland southeast
Mississippi where a Flash Flood Watch is now in effect. The latest
rainfall forecast indicates potential for 3 to 6" of rain with
locally higher amounts possible for these areas. Heavy rates will
potentially lead to flooding of urban/low lying areas.
Key take-aways for Cristobal impacts in our area at this time
include:
- The eastern wind field will expand outward as Cristobal
approaches the coast, so a Tropical Storm Warning is now in
effect for the coastal counties as far east as Destin, Florida.
This warning may be expanded further northward over the next 24
hours, and will be highly dependent on storm intensity,
location, and track.
- Our highest confidence is in the threat of dangerous high surf
and rip currents.
- At least minor coastal flooding looks likely this weekend,
particularly around the time of high tide on Sunday. If the
storm tracks closer to the area, then the threat of storm surge
would increase.
- Heavy rainfall is possible, and amounts will ultimately
be dependent on the track of the storm. The heaviest rain is
expected to fall in areas that are still in drought, so urban
and low lying areas currently appear most susceptible to
flooding.
- There is the potential for isolated tornadoes developing
Sunday into Sunday night within outer rain bands over the
southern portion of the area.
Lows Saturday night will be in the upper 60s to lower 70s inland,
with mid 70s along the beaches. Lows Sunday and Monday nights
will range from 70 to 75 degrees inland, with upper 70s along the
beaches. High temperatures Sunday and Monday will range from 80 to
85 degrees. /22
EXTENDED TERM /Tuesday Through Friday/...Cristobal continues to
move inland and becomes absorbed into an upper trough early to
middle of next week. A very moist pattern looks to remain over our
region, so we will keep a numerous to definite coverage to
showers/storms across the forecast Tuesday and Wednesday, with
mainly scattered coverage of showers/storms overnight and on
Thursday and Friday. Additional rainfall amounts up to 1" will be
likely with locally higher amounts possible during the expected
period. /22
MARINE...Light to moderate southeasterly winds will prevail through
this evening. Winds will then become more easterly and increase
Saturday as Tropical Storm Cristobal advances northward across the
Gulf towards the coast of Louisiana. Seas will also increase
during this time. Winds will then shift to be from the south by
Sunday night as Cristobal moves over Louisiana and Mississippi.
Please refer to the National Hurricane Center for the latest
advisory on Cristobal. /26
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...Flash Flood Watch from Sunday morning through Monday evening for
ALZ261>266.
Tropical Storm Warning for ALZ263>266.
High Rip Current Risk through late Monday night for ALZ265-266.
Coastal Flood Advisory from 1 PM Saturday to 7 AM CDT Monday for
ALZ263>266.
High Surf Warning from 1 PM Saturday to 7 AM CDT Monday for
ALZ265-266.
FL...Tropical Storm Warning for FLZ202-204-206.
High Rip Current Risk through late Monday night for FLZ202-204-
206.
Coastal Flood Advisory from 1 PM Saturday to 7 AM CDT Monday for
FLZ202-204-206.
High Surf Warning from 1 PM Saturday to 7 AM CDT Monday for
FLZ202-204-206.
MS...Flash Flood Watch from Sunday morning through Monday evening for
MSZ075-076-078-079.
GM...Tropical Storm Warning for GMZ630>635-650-655-670-675.
Small Craft Advisory from 7 PM Saturday to 7 AM CDT Monday for
GMZ636.
&&
$$
This product is also available on the web at:
http://weather.gov/mob
Area Forecast Discussion
National Weather Service Nashville TN
745 PM CDT Fri Jun 5 2020
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...
Other than minor adjustments to hourly temp and dew point trends,
tonight`s forecast remains on track. Latest HRRR still suggesting
an isolated shower or storm in our southwest counties over the
next couple of hours. Otherwise, some patchy late night fog
expected.
&&
.AVIATION...
00Z TAF DISCUSSION.
VFR conditions are expected at airports this evening with
decreasing cumulus clouds and some cirrus. Areas of fog overnight
look to bring MVFR to IFR visibility to airports between 06-13Z
with improvement back to VFR afterwards. Light and variable to
calm winds are anticipated tonight into tomorrow morning.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......13
AVIATION........Shamburger