Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/05/21
Area Forecast Discussion
National Weather Service Birmingham AL
644 PM CDT Tue May 4 2021
.UPDATE...
For 00Z Aviation.
&&
.SHORT TERM...
/Updated at 0149 PM CDT Tue May 04 2021/
Through this Evening.
Strong to severe thunderstorms continue along the I-20 corridor
producing gusty winds, torrential rainfall, and abundant lightning.
These storms are being fueled by a very warm and moist southern
stream which has allowed temperatures to rise above previous
forecast highs. Evidence of backbuilding and training of storms
will lead to a continued threat for flash flooding in the
Birmingham metro area and along the I-59 corridor where hourly
rain rates are as high as 3 to 4 inches per hour. There are
several sites south of I-20 which have measured air temperatures
in the lower 90s with dewpoints in the lower 70s. This is prime
evidence of strong surface-based instability of 3500-4000 J/kg
per RAP mesoanalysis. This area has also seen little coverage of
rainfall thus far today which indicates a thermodynamic parameter
space primed for strong convective initiation.
A broad area of thunderstorms is currently tracking across the Lower
MS River supported by the right entrance region of the upper-level
jet and associated surface front over western Louisiana. As the low-
level jet strengthens to around 50-60 kts late this afternoon &
evening, these storms will likely become better congealed into an
organized convective line as they enter western AL with the
potential for strong, damaging winds increasing with time. The
expected QLCS will reach our western counties as early as 4 PM and
exit southeast of the I-85 corridor around 10 PM posing the risk
of a potentially widespread damaging wind event across Central AL,
especially in the southwest quarter of the forecast area where a
Moderate Risk of severe storms has been defined. Due to the robust
nature of the updrafts, large hail may accompany stronger cells
as well as the potential for a few tornadoes embedded within the
line. The addition of heavy rainfall accumulations upwards of 1 to
2 inches will produce a continued concern for Flash Flooding in
areas that have already received amounts of 2-3 inches, especially
near and north of the I-20 corridor.
Overnight through Tomorrow.
The heavier activity will outrun the cold front and should exit the
area shortly before midnight as the front begins to enter
northwestern AL. Highest rain chances will be south of I-85 tomorrow
morning and will decrease throughout the day as the trough ejects
towards the east coast. During the afternoon, expect diminishing
cloud cover with a mild, post-frontal airmass which will accompany
the northwesterly flow. Highs will be in the lower 70s northwest to
lower 80s southeast.
86
.LONG TERM...
/Updated at 0341 AM CDT Tue May 04 2021/
Wednesday night through Monday.
The frontal boundary should be exiting Central AL by Wednesday
evening, ending any significant rain chances for our area. Cooler
and drier northerly flow will build in as the upper level trough
axis swings through our region during the day on Thursday. This will
lead to high temperatures running a few degrees below normal for
both Thursday and Friday. Ridging builds in across the Gulf States
Friday into Saturday as the upper level flow transitions to quasi-
zonal regime. This will lead to continued rain-free through the
early part of the weekend. High temperatures do being to increase by
Saturday as surface high slides to our east, shifting our winds out
of the south, which will bring in the warmer air mass from the Gulf.
A surface low develops across the Central Plains on Saturday, but
quickly moves eastward under the generally zonal flow. Because the
zonal flow persist, the frontal boundary associated with this low
has a hard time pushing south. Mode guidance suggests the boundary
will slow or stall across the Ohio Valley and remain well to our
north through early next week. However, broader scale ascent due to
isentropic lift in the warm/moist airmass to the south of the
boundary could lead to scattered showers and thunderstorms for
portions of Central AL Sunday and Monday. There`s still a good
amount of uncertainty on where this precip lines up, so for now,
I`ll keep 30-40% chance of rain across the northern half of Central
AL on Sunday, becoming 40-50% by Monday.
25/Owen
&&
.AVIATION...
00Z TAF Discussion.
A line of strong to severe storms is moving eastward across
southern portions of Central Alabama, impacting MGM at issuance
time and locations to the east through 04Z. Behind and north of
the line, an area of moderate rainfall continues with occasional
embedded lightning strikes. Winds will become westerly overnight
then northwesterly Wednesday morning, with speeds generally below
10kts.
As rainfall ends from west to east this evening, expect lower
cigs to develop with heights falling to IFR by sunrise Wednesday
morning. Cigs slowly improve through the day Wednesday.
Note: AMD NOT SKED until further notice at KASN due to ongoing
equipment issues.
14
&&
.FIRE WEATHER...
Widespread rain and thunderstorms are expected today as a cold
front moves through the area. Winds will increase from the south
and become southwesterly today. Strong, gusty winds can be
anticipated along and ahead of the line of thunderstorms that move
through today. Drier air arrives for Thursday through Saturday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 60 75 48 73 47 / 100 10 0 0 0
Anniston 63 76 50 74 49 / 100 10 0 0 0
Birmingham 63 75 52 75 50 / 80 10 0 0 0
Tuscaloosa 62 76 52 76 52 / 50 0 0 0 0
Calera 64 76 53 75 52 / 90 10 0 0 0
Auburn 65 77 55 75 52 / 100 50 0 0 0
Montgomery 67 79 57 79 54 / 100 50 0 0 0
Troy 67 80 58 78 55 / 100 60 10 0 0
&&
.BMX WATCHES/WARNINGS/ADVISORIES/...
None.
&&
$$
Area Forecast Discussion
National Weather Service Denver/Boulder CO
745 PM MDT Tue May 4 2021
.UPDATE...
Issued at 745 PM MDT Tue May 4 2021
Batch of showers and thunderstorms have progresses east-southeast
across the area and are over the eastern plains. The strongest
storms produced wind gusts up to 40 mph and pea sized hail.
Additional showers and a few weak storms are over northwest
Colorado and Wyoming. The left exit region of the jet is helping
to trigger this. Scattered showers and perhaps a storm or two will
track across the Front Range and eastern plains later this
evening and into the overnight hours. With the loss of daytime
heating, this activity should be weaker with few showers. By
sunrise Wednesday morning, the showers and storms will be east of
Colorado. Going forecast in good shape with only minor
adjustments.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 236 PM MDT Tue May 4 2021
Primarily showers developing over the mountains, foothills and
Cheyenne Ridge this afternoon. The latest HRRR still shows the
coverage increasing this afternoon as the showers with a few
embedded thunderstorms move northwest to southeast across the
forecast area. CAPES generally less than 500 j/kg with fairly good
storm motions expected. As a result, still looks like the stronger
storms could produce 0.10 to 0.25 inches of rainfall in one hour.
Late this afternoon and evening, a weak upper level disturbance
embedded in the flow aloft will produce a period of mid and upper
level weak QG ascent. Northeast Colorado will be under the left
exit region of the upper jet passing across northern CO. Weak
instability associated with this feature could allow some showers
to linger after midnight. Overall, snow accumulations in the
mountains will be light however with up to 2 inches expected.
On Wednesday, a little drier and a little warmer. In the mid and
upper levels, weak QG descent or subsidence will be over northern
CO but enough instability and residual moisture around to produce
isolated to scattered showers. Snowfall totals in the mountains
will again be light, with localized amounts up to 2 inches
possible.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 236 PM MDT Tue May 4 2021
For Wednesday night the upper trough has pushed east with a ridge
building over the Great Basin. Colorado continues in northwest flow
with lift continuing across the eastern portions of the state. There
is enough moisture and instability to continue showers across the
eastern plains into Thursday evening before subsidence moves in and
drier flow brings an end to precipitation. The upper ridge will move
overhead Thursday with +6-7C at 700 mb bringing high temperatures
into the mid-70s for Thursday under mostly sunny skies. The ridge
will be overhead by Friday afternoon with a building surface low
over the foothills pulling increased southwest flow and pushing 700
mb temperatures to +10-12C. This will help to bring highs on the
plains back into the lower 80s and 50s to 60s in the high country.
For Saturday, the next weather system will move into the Pacific
northwest pushing out the ridge and introducing additional moisture
and QG lift to the region. Currently, models have a cold front that
is projected to move across the plains mid-day Saturday which could
help to set up some unsettled weather for Saturday evening into
Sunday. There is still some uncertainty with the progression of the
overall trough but current ensemble trends have the low staying to
the north with only weak troughiness across the Central Rockies for
Sunday into Monday. Temperatures at 700 mb are still on the cold
side in the post-frontal airmass with rain and even some lower
elevation snow possible. There is still some uncertainty here but
another round of decent precip is possible with temperatures
responding with highs on Saturday in the lower 70s top 50s for
Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 745 PM MDT Tue May 4 2021
Additional showers with a slight chance for thunderstorms will be
possible after 04Z. Main impact is expected to be a wind shift to
the north with the activity. After 06-07Z, showers should be east
of the area and the wind will return to a southerly direction.
Winds become northerly after 15Z Wednesday. Another weak system
will bring scattered showers along with a few weak thunderstorms
Wednesday afternoon.
&&
.HYDROLOGY...
Issued at 236 PM MDT Tue May 4 2021
The flash flood threat in the burn areas should remain low into
this evening due to the relatively fast storm motions. The
stronger showers/storms could produce from 0.10 to 0.25 inches of
rainfall, but most locations will see less than 0.10 inch of an
inch of rain. There will be another period of scattered showers
again on Wednesday, with just isolated thunderstorm coverage.
Consequently,the flash flood threat will remain in the low
category for the burn areas.
We`ll see our next chance of storms Saturday afternoon and
evening, but right now the threat of storms and isolated heavier
rainfall seems limited. Sunday and Monday would bring a chance of
more significant precipitation, but if that occurs snow levels
may end up pretty similar to what they were with this last event
dropping down to 6000-7000 ft, thus minimizing potential flooding
threats in the burn areas. Still some uncertainty this far out.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Meier
SHORT TERM...Cooper
LONG TERM...Bowen
AVIATION...Meier
HYDROLOGY...Cooper/Bowen
Area Forecast Discussion
National Weather Service Boston/Norton MA
1059 PM EDT Tue May 4 2021
.SYNOPSIS...
Low pressure system brings another round of rainfall tonight
and into tomorrow morning. Intermittent periods of rain on
Wednesday will precede weak high pressure building over southern
New England on Thursday and Thursday night. The unsettled, wet
weather continues Friday into early next week. Does appear that
the coastal low for Friday/Saturday stays southeast of the area.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Mainly minor tweaks late this evening, mostly to precipitation
timing. Leaned heavily upon the last several runs of the HRRR
and the NationalBlend. Noted some lightning upstream, but the
environment over our region is not nearly as favorable to
support convection. expectation is for convection to weaken as
it moves east across our region overnight. That said, still left
a mention of isolated thunderstorms in the forecast, especially
across the western half of southern New England.
730 PM Update...
Forecast is generally on track and have only brought things in
line with the latest observations. Main change was to increase
sky cover based on the satellite and surface observations.
4 PM update...
Short-wave trough aloft ejects over the Atlantic waters along with
surface low pressure this evening. This will bring an end to
any remaining light showers along the MA east coast, Cape, and
Islands. We`ll dry out briefly this evening as a weak-upper
level ridge builds in ahead of a more robust upper-level trough
aloft. This upper-level disturbance will produce another
surface-low pressure system off the Mid-Atlantic coast that will
result in substantial rainfall for southern New England
beginning late tonight and ending Thursday morning.
Expect showers to begin to spread into the western areas
shortly before midnight, before gradually moving eastward with
the surface low overnight. Both deterministic and ensemble
forecast guidance are in good agreement that the axis of
heaviest rainfall will be over the central areas of southern New
England including eastern/CT, northern RI, and central/eastern
MA with lower amounts to the north and south. Also can`t rule
out some embedded thunder as hi-resolution model guidance has
hinted at at least a couple hundred J/Kg of CAPE. Areas along
the south coast are progged to have the most instability, and
therefore the greatest chance of seeing some showers with
embedded thunder (albeit low chances).
Look for the east/northeasterly winds we`ve seen today to
transition to a more east/southeasterly direction by day-break.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
.Wednesday.
More unsettled weather on Wednesday. As low-pressure passes
south of New England, we`ll see periods of rain showers
throughout the day Wednesday. Currently expecting the
heaviest/most persistent rainfall to occur in the morning
through early- afternoon as this time will coincide with the
best forcing aloft. As we head into the mid- late afternoon
hours, we may see showers become more scattered in coverage as
the surface lows makes its way east of southern New England and
the forcing aloft weakens. Rain and cloud-cover will keep
temperatures somewhat on the cooler side for early May in
southern New England with highs in the low-mid 50s.
.Wednesday Night.
Showers begin to taper off as the upper-level trough propagates
east of southern New England late Wednesday night. When all is
said and done most of southern New England should be left with a
much needed 0.75-1.00" of new rainfall. As a cold front pushes
into the region behind the upper-level trough, northwesterly
winds will advect cooler/drier air into the region Wednesday
night into Thursday morning. This will result in clear skies by
daybreak on Thursday with lows in the mid-upper 40s. Furthermore
the CAA aloft will support gusty northwest winds in the 15-20
mph range.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Highlights
* High pressure brings dry and quiet weather on Thursday.
* Unsettled pattern returns for the weekend into early next week
with sporadic shower chances.
* Temperatures remain near to cooler than seasonable for this time
of year.
Weak ridge builds into and through southern New England on Thursday.
This keeps the weather dry and quiet with high pressure in control.
Cyclonic flow in place late in the week through the weekend with
several waves moving through. This will bring sporadic chances of
precipitation into early next week.
Thursday...
Looking like the pick of the week if you are looking for dry and
quiet weather across southern New England. High pressure builds over
southern New England keeping the weather dry in wake of a cold
front. It may be a bit breezy at times given the northwesterly cold
air advection in wake of the front bringing +3 to +8 degree Celsius
air overhead at 925 hPa. Could have some gusts of 20-25 mph at
times. High temperatures range from the upper 50s to mid 60s which
is slightly cooler than normal for this time of year.
Friday through Saturday...
Trough lifts from the OH Valley early on Friday into the eastern
Great Lakes/Mid Atlantic by Friday evening. The trough eventually
lifts offshore by late on Saturday into early Sunday. As previous
shift stated the coastal low should remain far enough offshore to
the southeast. However, we will have a broad surface low/trough
across the Mid Atlantic that may bring some light showers to
southern New England. Have kept things in the slight chance to
chance category with the trough lifting through, but the best shot
for precipitation will be across the interior.
Still expecting near to seasonably cool temperatures with low level
flow out of the E/SE bringing in the cooler ocean air. Do have some
differences amongst guidance here with respect to wind direction
especially on Saturday, so have leaned on the NBM guidance during
this timeframe for temperatures. Highs in the upper 50s to mid 60s
on Friday and 50s on Saturday.
Sunday through Monday...
Still under cyclonic flow through this period with a cutoff/trough
digging in from Ontario/Quebec. Does appear that there will be some
sort of frontal boundary sitting nearby or just south of the region.
Looking actually somewhat similar to how things evolved this week
with a low riding along this boundary and potentially bringing shots
of precipitation. Guidance is all over the place with how things
progress, so have once again leaned on the NBM due to the
uncertainty. This will also greatly influence the temperatures
across the region depending on where the boundary is situated. Right
now looks like the better shot for precip is on Monday versus
Sunday. Have tried to reflect this with slightly higher chances of
precipitation on Monday as opposed to Sunday. Temperatures remaining
near to seasonable cool with readings in the upper 50s to mid 60s.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels.
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight...High confidence in trends moderate in timing.
Conditions deteriorating from MVFR/IFR to IFR/LIFR as the next
round of precipitation spreads in from SW to NE after 03Z.
Should see some visibility reduction due to the showers. Cape
Cod and the Islands are already seeing visibility reductions due
to ocean stratus and fog. Could have some isolated thunder,
with the greatest risk across the south coast and western
terminals, however confidence too low in the coverage at this
point in time to include in the latest TAFs. Light E to SE
winds.
Wednesday...Moderate confidence.
IFR to LIFR conditions persist with rain showers. May see some
improvement later in the afternoon as winds shift from an
easterly direction to the NW. Could see conditions begin
improving to MVFR from SW to NE.
Wednesday night...High confidence.
Any lingering showers come to an end. Conditions continuing to
improve from SW to NE and should eventually become VFR. Will be
a bit breezy out of the NW with sustained speeds of 5-10 kts and
gusts between 15-20 kts late.
KBOS TAF...High confidence in trends, but moderate in timing.
KBDL TAF...High confidence in trends, but moderate in timing.
Outlook /Thursday through Sunday/...
Thursday: VFR. Breezy.
Thursday Night: VFR.
Friday: VFR. Slight chance SHRA.
Friday Night: VFR. Chance SHRA.
Saturday: Mainly VFR, with local MVFR possible. Chance SHRA.
Saturday Night: VFR.
Sunday: VFR. Breezy. Slight chance SHRA.
&&
.MARINE...
Small Craft Advisories posted for some of the waters tonight
into Wednesday. This is mainly for marginal rough seas, but a
few gusts up to 25 kt are not out of the question. Widespread
showers and areas of fog begin late tonight and last into
tomorrow morning as low-pressure tracks south of New England. A
passing cold front tomorrow night will result in gusty
northwesterly winds by Thursday morning.
Outlook /Thursday through Sunday/...
Thursday: Winds less than 25 kt. Seas up to 5 ft.
Thursday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft.
Friday: Winds less than 25 kt. Slight chance of rain showers.
Friday Night: Winds less than 25 kt. Chance of rain showers.
Saturday: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers.
Saturday Night: Winds less than 25 kt. Seas up to 5 ft.
Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Slight chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ250.
Small Craft Advisory until 8 PM EDT Wednesday for ANZ254>256.
&&
$$
SYNOPSIS...BL/RM
NEAR TERM...Belk/BL/RM
SHORT TERM...RM
LONG TERM...BL
AVIATION...Belk/BL/RM
MARINE...BL/RM
Area Forecast Discussion
National Weather Service Cleveland OH
932 PM EDT Tue May 4 2021
.SYNOPSIS...
A cold front will continue to move southeast across the area
through this evening as low pressure continues eastward across
the eastern Great Lakes. A ridge of high pressure will move east
the area Wednesday night into Thursday. A weak low and
associated cold front will move eastward across the area
Thursday night into Friday.
&&
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
Showers are making some attempt to diminish well upstream from
the area at this time. Current forecast of chance POPs look
reasonable with a bit up an uptick in POPs across the south due
to the upper level positive vorticity maximum expected to move
through the area later tonight. No major changes with this
update.
Previous Discussion...
A large-scale trough is located over the central CONUS, with several
downstream shortwave troughs working their way northeast across our
forecast area this afternoon and through tonight. At the surface a
cold front is located near Marion and extending northeastward
towards the Cleveland area. Areas east of this region should expect
thunderstorm development this afternoon, and in fact we can see a
line of thunderstorms on radar moving northeast into the region
already. RAP SPC Mesoanalysis shows SBCAPE of around 1000 J/kg east
of this cold front, with varying wind shear values, depending on
what depth you look at (and what time). Effective bulk shear is at a
minimum right now according to mesoanalysis but should be on the
rise through the next several hours. Hodographs initially have
curvature in the vertical wind shear but it becomes linear with
primarily speed shear present this afternoon. Either way, organized
convection will pose a small risk for severe weather this afternoon,
primarily for the for southeastern part of our CWA. Damaging wind
and large hail will be the primary severe weather hazards given
moderate DCAPE available and marginal MUCAPE in the hail growth zone
(-10 to -30 C). However, wouldn`t completely count out the occurrence
of a tornado given low LCL heights near 500 ft and 0-3 km shear
around 30 kts. Low level wind shear (0-1 km bulk shear and SRH) does
slowly diminish through the afternoon though, which does
significantly decrease the chance for tornadogenesis.
The cold front slowly pushes southeast through the afternoon and
this evening, reducing severe weather risk and subsequent
thunderstorm chances. However, as additional short wave troughs move
through, rain chances do increase again tonight, with main wave of
rain between 06-12Z Wednesday. light rain showers likely to linger
across the eastern part of the CWA Wednesday morning, mostly done by
the afternoon hours. Cold air advection will bring temperatures
down while lake induced cloud cover limits daytime heating,
keeping temperatures below normal with most areas experiencing
high temperatures generally in the 50s. Chilly temperatures are
expected Wednesday night with lows down into the mid to upper
30s. Parts of inland northwest Pennsylvania could see some
frost.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
The overall weather pattern becomes very amplified for the end of
the week with a big upper level ridge over the western CONUS and
deep trough over the eastern CONUS. The center of the Polar Vortex
will drop down to the southern end of Hudson Bay Thursday into
Friday. This setup will keep our region in a somewhat cloudy,
cooler, and showery weather pattern. There will be a weak shortwave
rounding the base of the upper level trough Thursday afternoon into
Thursday night and bring a chance for scattered rain showers.
Another weak shortwave will also drift across the region on Friday
afternoon into Friday night with additional scattered rain showers.
Temperatures for the end of the will be chilly and below average
with highs in the 50s and overnight lows around 40.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
The weather pattern will become more zonal and our region will be in
the westerlies this weekend. There will be stalled front near the
Ohio River Valley and our local area will continue to be on the cool
side with a weak surface northerly or northeasterly flow. We will a
mixture of clouds with some peaks of sun this weekend. There could
be a few spotty showers coming off the lakes on Saturday. Low
pressure will develop and move along the stalled boundary near the
Ohio River on Sunday. It looks like the better rain chances will be
further south of our area Sunday. Weak high pressure will build
across the Great Lakes on Monday and bring a little more
sunshine.
&&
.AVIATION /00Z Wednesday THROUGH Sunday/...
Low ceilings will continue across the forecast area tonight as
surface low pressure and trailing surface trough move east of
the area. Visibilities in fog and showers could drop as low as 2
statute miles and mainly across the eastern half of the area.
Otherwise, 4 statute miles or greater elsewhere. Ceilings will
be IFR/LIFR through the night improving slowly during the day
tomorrow as low pressure system pulls out. Winds should remain
from the northwest at 5 to 10 knots through the forecast period.
Outlook...Periods of rain showers with non-VFR possible
Thursday afternoon through Saturday. Isolated thunderstorms are
also possible Friday afternoon.
&&
.MARINE...
Northerly winds will be in the 10 to 15 knots range tonight over
the lake. The winds will increase 15 to 20 knots on Wednesday
along with higher waves. We may need a Small Craft Advisory.
Winds decrease Wednesday night into Thursday with weak high
pressure moving over the lake. It should be mostly quiet through
Friday with another slight increase by Friday night and
Saturday morning early. Not expecting any small craft conditions
for the latter part of the week.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...Saunders
NEAR TERM...Lombardy/Saunders
SHORT TERM...Griffin
LONG TERM...Griffin
AVIATION...Lombardy
MARINE...Griffin
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1013 PM EDT Tue May 4 2021
.SYNOPSIS...
A COLD FRONT WILL SLOWLY APPROACH FROM THE WEST WEDNESDAY AND CROSS
WEDNESDAY NIGHT. A LOW PRESSURE SYSTEM WILL AFFECT THE REGION LATE
IN THE WEEK WITH COOLER WEATHER THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 1010 PM Tuesday...Strong/severe convection has ended for
the most part across eastern NC. There was some isolated severe
weather with an injury from a collapsed tent and some trees
snapped in northern portions of the CWA earlier this evening,
along with reports of pea-sized hail. An isolated thunderstorm
embedded in the leftover stratiform precipitation is possible
for the next few hours, but see mostly light showers at best.
Did keep in a slight chance PoP into the overnight hours. Latest
infrared satellite showing widespread cirrus left from the
convection and that should keep skies mostly cloudy overnight.
This cloud cover should hold overnight lows very close to 70
degrees, quite warm for early May.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
AS OF 240 PM TUESDAY...THE UPPER RIDGE BECOMES SHUNTED SOUTHEAST
AWAY FROM THE REGION WEDNESDAY AS A BROAD UPPER TROUGH APPROACHES
FROM THE WEST. THE SURFACE LOW WILL DEEPEN AS IT MOVES THROUGH NEW
ENGLAND THEN OFF THE NE COAST BY LATE AFTERNOON. THE TRAILING
SURFACE COLD FRONT WILL CONTINUE TO MOVE EAST INTO THE REGION
THROUGHOUT THE DAY, PLACING ENC IN THE WARM SECTOR AGAIN. CLOUDS AND
LACK OF SHEAR WILL BE LIMITING FACTORS IN CONVECTIVE DEVELOPMENT
WEDNESDAY. TEMPS WILL BE A FEW DEGREES COOLER THAN TODAY, HIGHS IN
THE MID TO UPPER 80S AREA WIDE. SOUTHWEST WINDS WILL PERSIST THROUGH
WEDNESDAY, GUSTING UPWARDS OF 25-30 MPH FOR THE COAST AND OBX AREA.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
AS OF 320 AM TUE...COLD FRONT MOVES THROUGH THE AREA WEDNESDAY NIGHT
WITH HIGH PRESSURE BRIEFLY IN CONTROL THURSDAY. LOW PRESSURE IS
EXPECTED TO DEVELOP WELL OFF THE COAST FRIDAY ALTHOUGH IT COULD
BRING WET CONDITIONS TO CLOSE OUT THE WORK WEEK. WEEKEND APPEARS DRY
BEFORE THE NEXT FRONTAL SYSTEM IMPACTS THE AREA.
WEDNESDAY NIGHT THROUGH THURSDAY...A COLD FRONT WILL PUSH THROUGH
THE REGION OVERNIGHT INTO THURSDAY MORNING. SCATTERED CONVECTION
WILL LIKELY CONTINUE OVERNIGHT AS THE COLD FRONT MOVES THROUGH, BUT
COVERAGE AGAIN REMAINS UNCERTAIN. TEMPS WILL REMAIN VERY MILD OUT
AHEAD OF THE FRONT, BUT THEN CRASH DOWN INTO THE UPPER 50S TO LOW
60S BEHIND IT THURSDAY MORNING. COOLER AIR WILL CONTINUE TO MOVE
INTO THE AREA THE REST OF THURSDAY WITH HIGHS ONLY EXPECTED TO REACH
THE UPPER 60S TO LOW 70S.
FRIDAY THROUGH MONDAY...STILL QUITE A BIT OF UNCERTAINTY REGARDING
THE PLACEMENT OF A COASTAL LOW EXPECTED TO DEVELOP OFFSHORE DURING
THE PERIOD. FAVORED MORE OFFSHORE GUIDANCE WITH NAM BEING A NOTABLE
NEAR-SHORE OUTLIER. COOLER AND WETTER WEATHER IS EXPECTED ALTHOUGH
TO WHAT DEGREE WILL REMAIN UNCLEAR UNTIL GUIDANCE COMES INTO BETTER
AGREEMENT. CHANCE POPS REMAIN FOR THIS FORECAST.
DRY WEEKEND IS EXPECTED WITH WARMTH RAPIDLY RETURNING COURTESY OF
INCREASING SOUTHWESTERLY FLOW. BY SUNDAY HIGHS SHOULD RETURN INTO
THE LOW TO MID 80S, AND THEN UPPER 80S BY MONDAY. NEXT FRONT
APPROACHES THE REGION FROM THE NORTH BRINGING BACK A CHANCE FOR
SHOWERS AND POTENTIALLY A FEW THUNDERSTORMS.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
SHORT TERM /THROUGH 00Z Thursday/...
As of 715 PM Tuesday...Some briefly reduced conditions in
convection possible through about 02z, followed by VFR
conditions through the remainder of the night with cirrus
blowoff likely from this afternoon and early evening`s
convection. Scattered high clouds, along with gusty SW winds are
expected for Wednesday.
LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS OF 325 AM TUE...LONG TERM PERIOD BEGINS WITH THE POTENTIAL
FOR SCATTERED SUB-VFR CONDITIONS AS SHOWER AND THUNDERSTORM
COVERAGE INCREASES AHEAD OF A COLD FRONT. PREDOMINANTLY VFR
CONDITIONS EXPECTED WITH THE EXCEPTION OF A COASTAL LOW
DEVELOPING OFF THE COAST, ALTHOUGH UNCERTAINTY WITH SUB-VFR
CONDITIONS ASSOCIATED WITH THIS FEATURE IS HIGHER THAN NORMAL.
&&
.MARINE...
SHORT TERM /THROUGH WEDNESDAY/...
As of 1010 PM Tuesday...Bulk of the convection has moved
offshore with only some leftover light precipitation over the
next few hours. In the wake of the convection, winds are in a
bit of a lull with SW winds 5-15 knots and seas 2-4 feet. Latest
HRRR and 3km NAM show winds increasing again overnight at SSW/SW
15-25 knots and seas building closer to 4-6 feet by morning.
Small Craft Advisories are in effect for the waters south of
Oregon Inlet and for the Pamlico Sound. SCA conditions continue
on Wednesday due to gradient with high pressure offshore and
approaching cold front.
LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 330 AM TUE...SCA CONDITIONS LIKELY TO BEGIN THE PERIOD.
DEVELOPMENT OF A COASTAL LOW OFFSHORE FRIDAY AND SATURDAY COULD
LEAD TO PERSISTENTLY POOR BOATING CONDITIONS ALTHOUGH
UNCERTAINTY REMAINS ON HOW FAR OFFSHORE THE CYCLONE WILL
DEVELOP, AND THEREFORE ITS IMPACTS TO NEARSHORE WATERS.
SW WINDS 20-25 KTS CONTINUING INTO THE NIGHT WEDNESDAY NIGHT BEFORE
A COLD FRONT PUSHES THROUGH THE COASTAL WATERS AND TURNS WINDS
AROUND TO THE N AT 20-25 KTS BY THURSDAY MORNING FOR NORTHERN
AND CENTRAL WATERS, 15-20 KT FOR SOUTHERN WATERS. STRONG
NORTHERLY FLOW WILL DIMINISH THROUGH THE DAY, WITH WINDS
BECOMING NNE 10-15 THURSDAY AFTERNOON. WINDS BACK WESTERLY AS
AFOREMENTIONED LOW DEVELOPS AND PASSES WELL OFFSHORE. RIGHT NOW
FORECAST SHOWS NW WINDS 15-20 KT FRIDAY NIGHT, BUT IF LOW TRENDS
CLOSER TO THE COAST HIGHER WINDS ARE PROBABLE. WINDS BACK SW ON
SATURDAY WITH DEPARTING LOW.
SEAS HIT A PEAK OF 6-8 FEET LATE WEDNESDAY NIGHT INTO THURSDAY AHEAD
OF THE COLD FRONTAL PASSAGE, THEN EBBING TO 2-3 FEET BY FRIDAY
MORNING. NW WINDS BEHIND COASTAL LOW WILL NUDGE WATERS TO 2-4 FEET
OVERNIGHT FRIDAY INTO SATURDAY.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Beach Hazards Statement from 8 AM EDT Wednesday through
Wednesday evening for NCZ195-196-199-204.
MARINE...Small Craft Advisory until 9 PM EDT Wednesday for AMZ135.
Small Craft Advisory until 2 AM EDT Thursday for AMZ152-154-
156-158.
&&
$$
SYNOPSIS...MHX
NEAR TERM...CTC
SHORT TERM...DAG/CQD
LONG TERM...SGK/MS
AVIATION...DAG/CTC/MS
MARINE...DAG/CTC/MS
Area Forecast Discussion
National Weather Service Marquette MI
721 PM EDT Tue May 4 2021
.SHORT TERM...(This evening through Wednesday)
Issued at 400 PM EDT TUE MAY 4 2021
WV imagery and RAP analysis indicated a mid/upper level low over
northeast Manitoba and northwest Ontario with broad trough extending
through the central CONUS. A weak shortwave trough was located near
Thunder Bay Ontario. At the surface, a trough extended into
northeast Lake Superior from low pressure near the southern end of
Georgian Bay. Although the rain has diminished or ended over the
Keweenaw, web cams still indicated low clouds and possibly a few
sprinkles from Munising eastward supported by cyclonic flow with
abundant low level moisture along with weak upsloping or low level
convergence near the shoreline.
Tonight, expect some clearing into the west half of Upper Michigan
as high pressure and drier air builds toward the area. Otherwise, a
few light showers or sprinkles or showers will remain possible
over the northeast where sfc troughing and the higher low level
moisture persists. Diminishing winds and clouds over the west will
allow temps to drop to around 30 inland while min temps in the
mid 30s are expected along the Great Lakes and over the east.
Wednesday, some lingering sprinkles may be possible early east. High
pressure building over the area will bring more sunshine even as the
cool weather remains. 850 mb temps in the -1C to -3C range will
only support max temps in the low to mid 50s south while onshore
keeps readings in the 40s over the north. Low level convergence
inland central and steep low level lapse rates may also support
some isolated light showers or sprinkles by mid afternoon.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 347 PM EDT TUE MAY 4 2021
The long-term pattern continues to look seasonably cool and mostly
dry, with no significant changes from prior forecasts over the past
few days. Broad but anomalously deep upper-level troughing is
expected to cover the region from Hudson Bay to the Great Lakes
through at least Saturday per the major models and their ensembles.
Sunday through the middle of next week, the deep trough is forecast
to exit to the east over the Canadian Maritimes, but weaker negative
height anomalies are likely to persist into the middle of next week.
Wednesday night, weak NW flow aloft will be ongoing across the area
with skies remaining partly cloudy. Lows should range from the upper
20s interior west, to the upper 30s south central where the cloud
cover will be thickest.
On Thursday, numerous subtle short waves embedded within the
broad/messy long wave trough will lead to continued mostly cloudy
skies as well as a chance for passing light showers. The chance for
rain increases Thursday night and Friday when models resolve a
stronger short wave embedded in the flow dropping southeastward
across the Upper Midwest. During this period there will probably be
additional scattered (mostly light) showers across the area. The GFS
resolves a few hundred J/kg of MUCAPE on Friday so while it`s not
likely, an isolated rumble of thunder or graupel shower can`t be
completely ruled out. Have not included thunder grids right now. 850
mb temps look to be around the 10th percentile of climatology
Thursday through Saturday, or around -4 to -6 C with tight
clustering among the ensemble members. This will translate to highs
generally in the upper 40s to mid 50s each day.
Previously, it looked like by Sunday the lowest heights aloft would
be moving out. The 12z deterministic EC shows the ULL digging
farther south which would make Sunday another cool and cloudy day
with instability showers around. However, since that`s a bit at odds
with the ensemble consensus, have opted to leave the NBM and its dry
POPs in for now. Heights over the Great Lakes then begin to rise
Monday and Tuesday next week in response to long wave troughing
digging in across the western CONUS, leading to a gradual warming
trend into the middle of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 720 PM EDT TUE MAY 4 2021
With high pressure slowly building in...ceilings continue to improve
over the western TAF sites with VFR conditions prevailing there for
the forecast. KSAW still under the influence of MVFR ceilings and
gusty winds to 22 knots early this evening, but conditions will also
gradually improve there with VFR ceilings and winds at or below 10
knots by 9Z this morning. VFR conditions will then prevail there
through the forecast.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 400 PM EDT TUE MAY 4 2021
A tight pressure gradient over the east will still support 25-30
knot northwest winds into this evening. With the gradient flow
diminishing tonight, expect northwest winds to fall below 20 knots.
A quiet period with winds below 20 knots is expected for the
remainder of the week and into the weekend.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...RJC
AVIATION...RJT
MARINE...JLB
Updated for 00Z aviation forecast discussion.
&&
.SHORT TERM...(Tonight through Thursday night)
Issued at 337 PM CDT Tue May 4 2021
Starting to get a few healthy showers going along the cold front
over the Pennyrile from Providence toward Calhoun. The latest
HRRR is not indicating anything terribly robust, but does have
some scattered cells along and ahead of the front through 01Z when
it should be through the entire region. Individual cells should
move east and it may be a struggle to get lightning, let alone
severe. We will keep an eye on it.
More widespread showers and possibly a few brief storms are
expected to spread east across the region as the upper trough
moves through this evening. Most of this activity should be done
by 06Z.
Wednesday will be dry, but the models continue to bring a swath of
QPF southeast through the region with another upper impulse
Thursday afternoon. The instability signal seems to be increasing,
so we will maintain the small chances of thunderstorms as well.
This activity should be east of the region by or shortly after 00Z
Friday, and Thursday night should be dry throughout the region.
Once the cold front passes this afternoon/evening, temperatures
will be below normal through the short term period.
.LONG TERM...(Friday through Tuesday)
Issued at 337 PM CDT Tue May 4 2021
A full latitude trough will be centered to our east Friday, but an
impulse diving down its backside could bring a few showers through
the EVV Tri State through the day. It would be very scant QPF, and
the NBM has not caught on to it, but it does show up in the 12Z
GFS and ECMWF, so we will need to keep an eye on this possibility.
Warm advection showers will begin to lift north across southeast
Missouri and southern Illinois late Friday night and then blossom
over northern and western portions of the area Saturday. There is
no consensus on whether it will push north of the area Saturday
night allowing us to dry out a bit, but we will keep PoPs through
the period. West Kentucky will definitely be the driest Saturday
and Saturday night.
The models begin to diverge Sunday into next week, but there is a
decent signal that an upper-level disturbance will push eastward
across the region Sunday into Sunday night. How strong it will be
and how effective it will be in drying us out is in question. We
will have healthy PoPs Sunday and Sunday night, but will also keep
chance PoPs going Monday and Tuesday just in case the front stalls
out not far south of the region, as in the GFS.
&&
.AVIATION...
Issued at 637 PM CDT Tue May 4 2021
MVFR ceilings are commonplace across most of the terminals at the
time of this writing. Scattered showers will continue this evening
as a cold front progresses southeast. Thunderstorms should be
isolated and are not included in the forecast. The showers will
end from west to east through the late evening and overnight
hours. IFR cigs and MVFR vsbys may develop in the heavier showers.
MVFR cigs may linger after the rain for a bit, but satellite
shows this band of clouds making good eastward progression, so
will continue with optimistic clearing btwn 08-10Z. Lingering low
level moisture may result in the development of a sct to possibly
MVFR deck in the morning or afternoon. North winds will be
strongest this evening at KCGI and KPAH where a few gusts over
20kts will be possible.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...CW
Area Forecast Discussion
National Weather Service Pittsburgh PA
837 PM EDT Tue May 4 2021
.SYNOPSIS...
Shower and thunderstorm activity will end with passage of a cold
front on Wednesday.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
A band of showers continues near a frontal boundary that currently
lies across the northwestern CWA, with more scattered activity to the
east. At this point, there is too little CAPE to allow sufficient
height to these cells for any lightning generation, and also to allow
the showers to take advantage of 40 knots of 0-6km shear.
The front will make little progress initially, waiting for an upper
trough axis to swing into the Ohio Valley to provide a push. A weak
wave of low pressure will ride along the boundary overnight, reaching
the Central Appalachians by sunrise. It is this wave which will take
advantage of anomalously high PWAT, especially across our south, to
produce another round of widespread showers late tonight/early
Wednesday morning. CAMS like the HRRR and the NAM Nest still bring a
round of possibly heavy rain to the previously issued Flash Flood
Watch area, a lot of which has 3 hour flash flood guidance values of
under an inch. So, no change to the watch at this time.
Given the lack of instability, elected to greatly reduce thunder
coverage in the forecast for now, although trends will need to be
monitored. Temperatures will begin to drop off late tonight as the
front starts to make progress, with readings in the 40s expected in
the northwest counties by 12Z.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
Showers and thunderstorms will remain possible until cold frontal
passage Wednesday. Once this occurs, partial clearing and overall drying
is anticipated as high pressure moves in behind the front.
An overall quiet day is expected on Thursday, until another trough
approaches the OH Valley on Thursday night which will bring the
chance for precipitation back to the area.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Model ensembles then indicate periodic precip chances and cooler
than average temperatures with crossing troughs in an amplified
pattern late week through the weekend.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Expect ceilings to deteriorate through MVFR to IFR at most terminals
tonight, as a wave of low pressure rides northward along a slow-
moving frontal boundary. Abundant low-level moisture and sufficient
lift will also provide widespread showers late tonight, the heaviest
of which may occur at MGW.
The front will finally be kicked east of the area by late morning on
Wednesday, with rain pulling east. However, only slow improvement to
ceilings is expected, with MVFR conditions likely lingering into the
afternoon. Wind will shift to northwest behind the front, with some
15 to 20 knot gusts possible tomorrow afternoon.
.Outlook...
The next chance of general restrictions will arrive with low pressure
Thursday night/Friday.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Flash Flood Watch until 8 AM EDT Wednesday for PAZ031-075.
OH...None.
WV...Flash Flood Watch until 8 AM EDT Wednesday for WVZ012-021-509.
&&
$$
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
801 PM EDT Tue May 4 2021
.AVIATION...
Prevailing VFR through the period with breezy southerly winds
becoming southwest to west 10-15 knots during the afternoon
tomorrow.
&&
.MARINE...
Ridge of high pressure remains stretched across the Peninsula
through tomorrow before a frontal boundary pushes across the
waters late Thursday into Friday. Cautionary headlines may be
necessary Friday as breezy north winds will be likely. High
pressure will then build back over the area for the weekend.
Elevated winds may lead to a light chop across the waters, but
no hazards are anticipated at this time.
&&
.Prev Discussion... /issued 652 PM EDT Tue May 4 2021/
UPDATE...
It was hot out there this afternoon with widespread low to mid
90s observed across West Central and Southwest Florida. This
afternoon heating has contributed to moderate buoyancy, analyzed
by the 23Z RAP showing MLCAPE of 2000-2500 J/kg extending from
Glades northward into Polk counties. This is firing off some early
evening convection. These will continue to gradually work their
way NNE over the next few hours. Only made minor tweaks to the
short-term PoPs with tomorrow`s hot temperatures still on track.
&&
.Preliminary Point Temps/PoPs...
TPA 77 90 77 87 / 0 10 10 30
FMY 75 93 74 91 / 10 20 10 30
GIF 75 95 74 91 / 20 20 0 50
SRQ 75 88 74 86 / 10 10 10 20
BKV 70 91 70 87 / 0 20 10 40
SPG 77 88 78 85 / 0 10 10 30
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
PREVIOUS DISCUSSION/AVIATION/MARINE...Norman
DECISION SUPPORT...Sobien