Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/25/18
Area Forecast Discussion
National Weather Service Green Bay WI
1034 PM CDT Wed Oct 24 2018
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Thursday
Issued at 211 PM CDT Wed Oct 24 2018
The latest RAP analysis and satellite/radar imagery show high
pressure centered across Lake Michigan and a trough of low
pressure over the northwest Great Plains early this afternoon.
Scattered clouds are lingering over eastern WI where there is some
residual low level moisture off Lake Michigan. Meanwhile, clouds
are increasing over the Plains and northern Mississippi Valley
ahead of the next system. As this system moves closer to the
region, cloud trends and precip chances are the main forecast
Tonight...The high pressure system will gradually shift east of
the region as shortwave energy moves across the Dakotas. Mid and
high clouds will be on the increase through night ahead of this
system. Models rotate deeper lower level moisture north of the
U.P. border, and progged soundings indicate that dry air will
remain below about 700mb, so the threat of precip appears low.
With considerable more cloudiness by morning, warmer lows ranging
from the upper 20s to middle 30s at most locations.
Thursday...The shortwave energy and trough of low pressure will
continue to inch closer to the region. Ample mid and high clouds
will be overhead for much of the day, which should result in
mostly cloudy skies. However, low to mid level moisture transport
axis is progged to remain west of the region through the day, with
dry air positioned below 10 kft as it recycles around the exiting
surface high. So continue to think most of the day will be dry,
but did leave a small chance of a shower over north and west of
Rhinelander late in the afternoon. Raised temps slightly based on
the latest trends, with highs mainly in the lower 50s.
.LONG TERM...Thursday Night Through Wednesday
Issued at 211 PM CDT Wed Oct 24 2018
Pattern during first part of long term characterized by several
shortwave trofs moving across the region. Latest GFS and ECMWF
model runs show some discrepencies in location of weekend waves
and resultant precipitation amounts, so will continue with blend
of models for precip location and amounts.
Ridging at surface and aloft moves in early next week before next
chance of precipitation. Although there are model differences
again, both the GFS and ECMWF indicate a stronger system ejecting
out of the SW sometime during the second half of next week.
Max temps through the period will be a couple degrees either side
of late October averages. Lows will be a couple degrees above
average given expected cloud cover during the period.
.AVIATION...for 06Z TAF Issuance
Issued at 1030 PM CDT Wed Oct 24 2018
Moisture will gradually return to the area as high pressure
departs to the east and a storm system slowly organizes over the
Plains. But the initial return of the moisture will occur at
middle and upper levels, so low clouds will be slow to develop
across the area. As a result, VFR conditions are anticipated
throughout the TAF period.
Area Forecast Discussion
National Weather Service Houston/Galveston TX
1010 PM CDT Wed Oct 24 2018
The heaviest rain is now confined to the coast but additional
showers continue to develop over the region in response to an
upper level trough over North Texas, favorable jet dynamics and
abundant moisture. SE TX will lie in a RRQ overnight so although
the radar is looking more benign to the west, am hesitant to
lower PoPs too significantly. Will lower PoPs to likely after 06z
and reevaluate at that time.
Had some flooding in Brazoria and Galveston counties this evening.
Some cars were flooded in Santa Fe and several roads had high
water in Dickinson. An automated gage in Santa Fe reported 5
inches of rain and the NWS office had 4.24 inches of rain. 43
.PREV DISCUSSION... /ISSUED 701 PM CDT Wed Oct 24 2018/
Showers and light rain continue across most of the terminals this
evening, with isolated thunder embedded south of I-10 at LBX,
GLS, and HOU. Short term guidance shows a clearing line with the
passing of the upper level disturbance starting in the western TAF
sites around 07-09Z and clearing most terminals by 10-13Z. IFR
ceilings and visibilities will be possible overnight, with some
potentially lowering to LIFR criteria at our more vulnerable
sites. These ceilings and visibilities will stick around through
most of the morning tomorrow until the drier air begins to filter
in. Winds will also back out of the NW overnight. Winds are
currently out of the NE and are still gusty at times along the
coastal TAF sites, but should lower in speed overnight. By the
afternoon hours ceilings should begin to lift with mostly high
MVFR and VFR prevailing by the early evening hours.
PREV DISCUSSION... /ISSUED 328 PM CDT Wed Oct 24 2018/
Key forecast messages:
- Storms tonight should be fast moving but could still produce
locally heavy rainfall.
- Storms done and out of area by rush hour Thursday morning.
- Next cold front Sunday night into Monday.
- Dewpoints in the 40s behind the front on Monday? Yes please.
- Return flow with a few showers possible for Halloween.
NEAR TERM [Through Tonight and Thursday]...
Overall the near term portion of the forecast has not changed
much from the last day. Surface analysis of 20Z observations show
the surface low developing off the coast from Matagorda Bay. The
warm front swings out of it just inland from PSX to GLS with 70
dewpoints just on the coast. Water vapor imagery at the mid and
low level channels picks up on the remnants of Willa or its
associated vorticity. There is also a potent upper level low over
New Mexico which has a strong jet streak pushing up through the
Texas Panhandle. Large scale lift with the vorticity from Willa
should move over the area tonight and likely deepen the surface
low some. It looked like this low may stay just off the coast but
with the warm front pushing just inland, this area of low pressure
may follow along the front as it moves NE tonight. HRRR and a few
of the WRF runs have the surface low just inland and think this
is probably going to be the trend forward. This may open an
opportunity for a few low topped storms to rotate as we have seen
off the coast prompting special marine warnings. Still agree with
SPC that the severe threat will be low since instability will be
marginal at best just inland along the warm front. Any ins
will be driven by warm advection and doubtful there will be true
surface based convection that can truly take advantage of the low
level shear. Nonetheless, something to monitor basically now
through about midnight.
Overall the threat for heavy rainfall will be fairly localized.
The line of showers and storms with this system can produce a good
1 inch of rainfall across the area with maybe 2 inches being the
high end. An isolated 3 inches cannot be ruled out but those areas
may be where there has already been some rainfall today. Highest
totals look to be along the coast with the surface low and warm
front to maybe as far inland as I-10. There does look to be a
second max in rainfall mainly from Brenham to Lufkin northward.
Biggest impacts from the rainfall will be street/urban flooding
with rapid rises on the bayous but bayous should be able to handle
the rainfall. There may be some subtle rises on rivers but mainly
this additional rainfall will just increase how long the rivers
will take to come down from any flood/action stages.
The main timing for convection looks to be basically from 6PM to
9PM with a peak in the activity 9PM to Midnight. Activity should
be moving out of the area after midnight and be done Thursday
SHORT/LONG TERM [Thursday Night Through Wednesday]...
A cold front will push through the area on the back side of the
low pressure and remnants of Willa for Thursday. This should
allow for low temperatures in the 50s with offshore winds. This
provides a good opportunity to open the windows and air out the
house if you need. The next cold front looks to come through
Sunday night into Monday morning with out any precipitation. Upper
level pattern will be quite favorable for this kind of frontal
passage with a ridge developing over the 4 Corners and a broad
trough over the Great Lakes and eastern half of the U.S. Dewpoints
should drop into the 40s behind this front for even drier
conditions to start next week. The pattern then becomes more
progressive with the upstream ridge moving over the Plains and a
trough developing in its place over the Great Basin. As this
system moves towards the Rockies lee troughing and return flow
develops so there may be a few warm air advection showers for
Winds and seas are generally diminishing across the Gulf waters, and
so the small craft advisory will be allowed to expire as scheduled.
However, caution flags will remain up through at least the evening.
Additionally, locally higher winds and waves can be expected, along
with the potential for waterspouts, through at least this evening.
On the backside of the coastal low, winds will become northwesterly,
with this shift occurring overnight. There may be another brief need
for caution flags late tonight into tomorrow, but conditions will
improve into the end of the week as the coastal low exits the area.
Tides are now running nearly two feet above astronomical tide
levels, and the upcoming low tide is only expected to fall to around
2.5 feet above MLLW. This sets the stage for a high tide this
evening of at least 3.5 feet above MLLW, and 4 feet is not
impossible. Because of this, will keep the current setup of beach
hazard statements and coastal flood advisories in place. However, if
water levels begin rising more than expected, that may have to be
reevaluated. At the very least, flood prone roads are expected to
have water - particularly Highway 87/124, and possibly the Blue
Water Highway as well - around high tide. East to northeast winds
also means that rip currents will also continue to be an issue.
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 58 65 52 75 54 / 100 0 0 0 0
Houston (IAH) 61 68 53 75 55 / 90 10 0 0 0
Galveston (GLS) 67 70 60 74 63 / 100 20 0 0 0
TX...High Rip Current Risk until 4 AM CDT Thursday for the following
zones: Brazoria Islands...Galveston Island and Bolivar
Coastal Flood Advisory until 11 PM CDT this evening for the
following zones: Brazoria Islands...Galveston Island and
GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 11 PM CDT this evening
for the following zones: Galveston Bay...Matagorda Bay.
SMALL CRAFT SHOULD EXERCISE CAUTION until 10 AM CDT Thursday for
the following zones: Coastal waters from Freeport to
Matagorda Ship Channel TX out 20 NM...Coastal waters from
High Island to Freeport TX out 20 NM...Waters from Freeport
to Matagorda Ship Channel TX from 20 to 60 NM...Waters from
High Island to Freeport TX from 20 to 60 NM.
Area Forecast Discussion
National Weather Service Key West FL
942 PM EDT Wed Oct 24 2018
.DISCUSSION...In the middle and upper levels( 700-200 mb), latest
available GOES-R satellite imagery overlaid with model streamline
analysis as of 900 pm, detail the developing NW to SE oriented
negatively tilted axis of the next burgeoning trough over the
spine of the Central and Southern Rocky Mountains. Just downstream
of that, a full latitudinal ridge is in place from Northern
Minnesota down to the Central Gulf of Mexico. And east of that,
there is a full latitudinal trough from Maine south southeast to
near 25N 65W. The Florida Keys are beneath deep and warm ridging
on the right side of the aforementioned ridge.
At the surface and in the lower to mid levels(Surface to 700 mb),
latest available GOES-R satellite imagery overlaid with marine
and land surface observations and surface analysis, depict a 1033
mb cool anticyclone situated over Northern Michigan. Well south of
that, a weak cold front is snaking across South Florida, with the
attendant frontal boundary extending westward to low pressure off
of the SE Texas Coast. As as result, last evenings 00Z sounding
illustrated a gentle north to northeast flow from off the surface
to 800 mb, backing to between northwest and north from 800 mb back
to 600 mb, then increasing. Total columnar PWAT of 1.84 inches lends
to a fairly moist lower to mid troposphere.
.CURRENTLY...As of 900 pm, skies are mostly clear across the
islands and surrounding waters. A few showers are now developing
along boundaries developing across the Nearshore Gulf waters north
of the Middle Keys. Temperatures along the Florida Keys are in the
upper 70s to around 80 with dewpoints in the middle to upper 60s.
C-man stations along the Florida Reef are recording northeast
winds and 10 to 15 knots and island sensors are recording
north to northeast winds at 5 to 10 mph.
.SHORT TERM...Overnight, HRRR and GFS models continue with a
gentle to moderate north to northeast flow across the islands and
adjoining waters,as the frontal boundary is still north of the
Keys. Some weak low level confluence will provide development of
isolated showers which will drift south to impact the islands or
develop over some locations, but any rainfall amounts will be
slight. For that reason will maintain the slight chances for
showers already in the forecast. No changes attm.
.MARINE...Overnight, Light to gentle northeast flow expected,
with gentle to moderate out on the Straits. No SCEC or SCA.
VFR conditions expected at both terminals with light northeasterly
to easterly winds through the period.
On this date, the record high temperature of 89 degrees was last set
in 1990. We tied this daily record today, reaching 89 degrees at the
Key West International Airport.
Upper Air/Data Collection......SD
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Area Forecast Discussion
National Weather Service Tulsa OK
851 PM CDT Wed Oct 24 2018
Large area of light rain continues to push off to the northeast
with dry air across northeast Oklahoma and northwest Arkansas
eating away at the northeast edge of the rain shield. The heaviest
rain, as expected, remains across southeast Oklahoma and into
portions of west central Arkansas. The dry slot is not far to the
southwest of the area and will likely move into parts of
southeast Oklahoma near midnight and push northeastward through
sunrise. The main changes to the going forecast have been to
retool the POPs according to the above thinking, generally
decreasing them in far northeast Oklahoma and far northwest
Arkansas through mid evening and across southeast Oklahoma after
midnight. Also decreased the QPF after midnight in the south.
.PREV DISCUSSION... /Issued 642 PM CDT Wed Oct 24 2018/
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
An area of rain will cross the TAF sites from tonight through
Thursday morning. Flight conditions will deteriorate in
the region to IFR ceilings by late tonight. IFR ceilings
are expected to persist area wide on Thursday as the rain
diminishes from west to east. Winds will be light through
the forecast period.
PREV DISCUSSION... /Issued 329 PM CDT Wed Oct 24 2018/
The main forecast concerns are rain chances/timing/amounts
tonight and Thursday, rain chances Saturday night into Sunday and
winds on Sunday. Finally, rain chances on Halloween.
A southern stream shortwave trough, with embedded PV max over
eastern NM, is ejecting into the Plains this afternoon. Light rain
is spreading northeast per radar/mesonet data across OK ahead of
the system and will continue to do so this evening and overnight.
The latest HRRR guidance suggests a faster progression across the
region tonight than what the blended PoP guidance would suggest,
and thus some tweaks were made. A faster ramp up and ramp down was
made in the PoP grid trends. Rain amounts should remain light
with no suggestion of any convective assistance with the
instability tied up well to our south closer to the Gulf surface
front. Some lingering chance PoPs were maintained across the north
on Thursday as a PV anomaly rotates around the basal portion of
the ejecting trough and over our area. After this system and the
trough axis passes, PoPs will come to a quick end from west to
east Thursday night.
Lows tonight should be a bit warmer than last night in most places
with widespread cloud cover, and a low diurnal variation is
expected on Thursday with clouds hanging on until the second wave
passes. High temps ramp up quickly with more sunshine to near
normal Friday and will peak on Saturday above normal ahead of the
next cold front.
The upper pattern will transition from the current split flow
regime to more of a consolidated and amplified western ridge-
eastern trough pattern over the CONUS by the weekend, with a
trend toward progressive thru next week.
A strong system in the NW flow will pass by to our northeast this
weekend and will bring a low chance for showers to far NE OK/NW
AR Saturday night into Sunday. A concomitant cold front will knock
temps back below normal Sunday, while also increasing winds.
Looks like a classic deeply mixed airmass behind the front, and
favorable for momentum transfer. Winds will be gusty during the
day, especially across NE OK and NW AR. Went above blended
guidance for winds.
The next storm system will affect the region by Halloween and the
first of Nov. The timing of this system still remains in
question, with the GFS faster than the ECMWF. For now, will not go
any higher than chance PoPs and will wait for the details to be
resolved before a more aggressive approach is taken. Regardless,
there is definitely a chance that Halloween evening festivities
could be wet.