Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/12/19
Area Forecast Discussion
National Weather Service Huntsville AL
713 PM CDT Fri Oct 11 2019
For 00Z TAFS.
Issued at 713 PM CDT Fri Oct 11 2019
The dearth of instability over northern Alabama was ultimately the
downfall of the line of showers and thunderstorms that approached the
area this evening. A few lingering showers will continue, but have
removed any chance for thunderstorms this evening. Rainfall amounts
will be negligible from this line. The HRRR shows another line of
showers developing overnight along the surface frontal boundary,
which is currently stretched from the southwest corner of Mississippi
northeast toward just west of Nashville. Northwesterly winds behind
the front can already be seen just northwest of Florence and Muscle
Shoals. As this front moves through, there will be a noticeable drop
in temperature and increase in northerly winds. Cloud cover and wind
should help to keep temperatures from dropping too low tonight, but
temperatures will fall into the mid to upper 40s across most of the
area, making for the coldest night of the Fall so far.
.SHORT TERM...(Saturday through Sunday)
Issued at 245 PM CDT Fri Oct 11 2019
Northerly flow and continued cloud cover (maybe a few showers) should
keep highs in the lower to mid 60s. If cloud cover dissipates sooner
than expected, insolation could keep highs a tad warmer. Most
guidance weakens and pushes the front southeast into central/southern
Alabama during the late afternoon hours. Very light winds and the
very dry air being advected in the area should allow temperatures to
drop into the upper 30s to mid 40s primarily. Some models show
dewpoints actually in the mid 30s Saturday night. If this occurs, not
sure lows couldn`t drop a bit lower and we could see some frost in
NW Alabama and portions of southern middle Tennessee. Leaving that
out for now and keeping lows in the upper 30s due to uncertainty with
Expect the weak boundary to push back to the north into central
Alabama Sunday morning. There looks to be just enough lift and
moisture for some isolated to scattered precipitation to return to
the area. At this point, not expecting any thunderstorm activity with
little if any instability shown in guidance. However, could cover
associated with this boundary should keep highs cooler, despite some
warmer 925 temperatures and thickness values moving into the area.
Highs in the mid to upper 60s look reasonable given cloud cover and
the expected cold start to the morning.
This activity should dissipated with the loss of daytime heating by
the late evening hours, but cannot rule out an isolated shower
lingering towards Cullman or Dekalb county.
Warmer conditions are expected on Monday, as more sunshine and zonal
flow aloft should help temperatures to climb into the lower to mid
.LONG TERM...(Monday night through Thursday)
Issued at 245 PM CDT Fri Oct 11 2019
A brief dry spell on Monday will come to an end Monday night into
Tuesday, as the frontal boundary that passed across the area on
Friday night heads back northward as a warm front. The returning
front/moisture from the south, along with another cold front moving
in from the northwest, will bring more clouds and chances for showers
and thunderstorms to the Tennessee Valley. The forecast upper air
pattern between the various upper air model camps begins to vary
towards the mid/latter part of next week --- especially in the way
they handle an upper system moving ESE from the Gulf of Alaska to the
Great Lakes region. The ECMWF more strongly develops it, with the
Canadian in-between and the GFS the weaker solution. The stronger EC
solution with this low brings higher rain chances and more QPF for
the Tennessee Valley, with the GFS and Canadian a bit lighter.
The system next week should swing to the east of the area during
Wednesday, with rain tapering off in a west to east manner. Cool high
pressure to our NW will build somewhat to the SE, bringing another
cooler change for the mid/latter half of next week. Highs on Wed/Thu
should range in the mid/upper 60s to around 70. Low temperatures Wed
night will cool in the low/mid 40s. A few readings in our normally
cooler spots could chill into the mid/upper 30s, making light/patchy
frosting a possibility. A zonal flow and quick moderation should
bring low/mid 70s for high temperatures on Friday.
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 713 PM CDT Fri Oct 11 2019
VFR conditions persist along the line of showers ahead of the front.
Showers are weakening and dissipating. The surface front is just to
the northwest of MSL, and should move through by 02Z. With that,
expect cigs to plunge and northerly winds to increase behind the
front. Cigs behind the front right now at SNH are bkn009, and CRX is
ovc004. Expect this trend to continue eastward with low IFR
conditions making it to HSV around 05Z. Cigs should improve right
around sunrise around 12Z, and be VFR by 15Z at the latest. Clouds
decreasing Saturday morning means VFR conditions through Saturday
For more information please visit our website
Area Forecast Discussion
National Weather Service Indianapolis IN
1146 PM EDT Fri Oct 11 2019
The AVIATION Section has been updated below.
Issued at 204 PM EDT Fri Oct 11 2019
A strong cold front will exit Indiana this evening. Rain showers
will sweep across Indiana early this evening ahead of the front.
In the wake of the front...the coldest air thus far of fall will
arrive in Central Indiana for the weekend.
Saturday through Monday night...dry and cool weather will be
expected with below normal temperatures as high pressure moves
across the area.
More rain chances will return to the area on late Tuesday into
Wednesday as an area of low pressure is expected to push across
.NEAR TERM /Tonight/...
Issued at 841 PM EDT Fri Oct 11 2019
Cold front has cleared the eastern zones, with areas of rain
within the post frontal zone. Short term model guidance and
extrapolation suggests the rain should pass off into Ohio around
120400Z or so. Clearing line currently approaching the western
border zones at this time, so skies should start to clear out from
the west over the next couple of hours.
Made some minor adjustments to the PoPs for the rest of the
evening, based on above, otherwise current forecast still looks
good for the most part.
Previous discussion follows.
Surface analysis early this afternoon shows a cold front over the
Wabash...quickly moving east across Indiana. GOES16 shows an
abundance of cloud cover and moisture ahead of the front across
Indiana. Surface flow was southerly with dew points in the mid
60s. A very different air mass was found in the wake of the the
front as temperatures in the middle 40s were found across
Illinois. Radar shows scattered showers over SW Indiana...poised
to push across Central Indiana through the afternoon.
HRRR suggests the cold front will continue to push across Indiana
this afternoon exiting the state near 00Z. Still some light
showers look to be possible in the wake of the front...and time
heights and forecast sounds keep some lower level moisture
lingering between 00Z-03Z. Thus will keep some some lower chance
pops for the first part of the evening as the lingering moisture
By 06Z forecast soundings and time heights dry out dramatically
amid northwest winds and strong cold air advection. 850mb temps
fall to near 0c by 12Z. Of note...people outside this evening will
note falling temperatures and very changeable conditions from 6pm
to 11PM with temperatures falling to the lower 40s by late
evening. So, if you are going to be outside this evening...
listen to your mom and wear your coat.
Winds overnight should not fall to calm
overnight as a significant pressure gradient will remain in place.
Surface ridging and strong subsidence should allow for clearing
through. Thus will trend lows close to the NBM.
.SHORT TERM /Saturday through Monday/...
Issued at 204 PM EDT Fri Oct 11 2019
Through Monday the GFS and NAm continue to keep a strong area of
low pressure in place over Ontario. This results in cyclonic flow
aloft over Indiana along with cooler NW flow. At the surface
strong high pressure looks to be in place stretching from
the northern plains to the Tennessee Valley. Time heights and
forecast soundings show a dry column through the period. Thus will
trend toward mostly sunny and cool days and mostly clear and cool
nights. Will trend temps at or below the NBM given the cooler air
mass in place across the area.
.LONG TERM /Monday night through Friday/...
Issued at 310 PM EDT Fri Oct 11 2019
The long term will keep near to below normal temperatures in
place, with some chances for rain and an isolated storm on
Tuesday. Otherwise dry conditions will be the rule with a surface
high moving across the area and relatively flat upper flow
Wednesday through Friday. Right now Wednesday night/Thursday
morning lows dip into the middle 30s and may have to monitor for
frost as we get closer.
.AVIATION /Discussion for the 120600Z TAFS/...
Issued at 1144 PM EDT Fri Oct 11 2019
Some limited cloud cover around 050 expected overnight, but the
more extensive cloud cover and associated ceilings, look to stay
north of the terminals tonight.
Surface winds 270-300 degrees at 6-9 kts overnight will gradually
back around to 240-260 degrees by midday Saturday. Occasional
surface gusts around 20 kts possible by then as well, especially
in the KLAF area.
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1003 PM CDT Fri Oct 11 2019
Updated for evening discussion.
Mid evening surface analysis had the cold front nearing the
Interstate 59 corridor. Very little precipitation was noted along
and ahead of the cold front and satellite imagery showed very
little cloud cover in our west with drier air filtering into our
CWA. Latest HRRR also shows the precipitation tapering off the
next several hours. Have updated cloud cover and removed pops
after midnight. Otherwise, much cooler and drier air will continue
to filter into the CWA with morning lows in the 40s across the
delta and in the 50s to the southeast. /22/
Prior discussion below:
This Evening through Tomorrow Morning: The well advertised and
much anticipated cold front is currently working its way
southeastward across our forecast area this afternoon. It was
stretched from roughly Starkville to Natchez as of 330 PM. Modest
instability and wind shear ahead of the cold front have been able
to sustain a few stronger thunderstorms in addition to scattered
warm advection showers so far today. Expect the front to continue
its eastward journey through the evening, with the chance for
thunderstorms mostly dropping off by sunset. Some thunder will
linger in the Pine Belt in southeastern MS through early tonight
before drier and more stable air moves in behind the front. Some
light showers/sprinkles will continue to be possible across the
forecast area through early Saturday morning, and then drier air
will prevail in the lower levels as the post- frontal air mass
builds in. Low temperatures tonight will range from 30 to 40
degrees cooler than what we observed for high temperatures today.
Temperatures could be as cool as near 40 degrees in the Delta by
sunrise tomorrow. /NF/
Saturday through Friday:
Much drier air will filter into our forecast area by tomorrow
afternoon, with relative humidity expected to be as low as 30-40
percent across much of the area. A Limited threat for fire weather
conditions has been added to the Hazardous Weather Outlook text
and graphics for areas generally north and west of a line from
Natchez to Greenwood, MS tomorrow. Despite the rainfall across
parts of the area today and the last few days, be sure to obey
local burn bans as low humidity and north winds of 5 to 10 mph may
still make grass and brush fires a concern in these areas.
Some modification of the air mass will occur through early next
week as high pressure builds in at the surface and flow aloft
becomes zonal, but with the old frontal boundary hanging near the
Gulf Coast, isentropic lift over the cooler air mass will keep
some cloud cover and a chance for showers in the forecast into
early next week. Model guidance remains in fairly decent agreement
for increasing chances for showers and possibly some
thunderstorms from Monday night through Tuesday night as a
southern stream shortwave slides east across the Gulf Coast
region. A powerful jet streak just to our north will aid in
isentropic lift and moisture advection as a developing low
pressure system over east TX/OK lifts a warm front north through
our area on Tuesday. This frontal boundary may serve as a focus
for a corridor of heavier rain during that time, with guidance
continuing to point to an area just north of the Interstate 20
corridor. A surge of anomalously deep moisture associated with
tropical activity in the eastern Pacific will be lofted northeast
by the westerlies, and this deep moisture interacting with the
front will likely result in locally heavy rainfall rates. Westerly
flow at in the low levels may support some training along the
front as well. Therefore have added a Limited threat area for
Flash Flooding north of I-20 to the HWO. Another cold front will
dip south as the low pressure system moves eastward Wednesday
night into next Thursday. /NF/
00Z TAF discussion:
A cold front was moving across east Mississippi at 2330Z.
Scattered TSRA/SHRA will precede the cold front and may reduce
flying conditions but after fropa, MVFR cigs wl develop and
continue most of tonight in west and cntrl MS but take until
Saturday aftn before improving to VFR in the east and se. VFR
conditions wl prevail areawide Saturday evening. /22/
.PRELIMINARY POINT TEMPS/POPS...
Jackson 53 68 52 69 / 9 7 10 52
Meridian 53 70 54 72 / 13 12 9 52
Vicksburg 50 68 50 68 / 5 7 11 53
Hattiesburg 58 71 58 77 / 20 11 5 34
Natchez 52 68 53 72 / 8 7 9 41
Greenville 43 65 46 67 / 4 1 12 48
Greenwood 46 65 46 66 / 6 2 11 50
Area Forecast Discussion
National Weather Service Key West FL
959 PM EDT Fri Oct 11 2019
.DISCUSSION...In the middle and upper levels(700 to 200 mb),
latest available satellite imagery overlaid with available model
streamline analysis as of 900 pm, continues to depict a cold core
cyclone that is moving east and is centered over Northern
Minnesota, situated within a full latitudinal trough encompassing
the the Upper Midwest, Central and Northern Plains, and the
Northwestern United States, with zonal 50 to 75 knotters at 250 mb
moving across from California to the Lower MS Valley where it
splits into a narrow ridge axis extending northwards to Western
Quebec, with a narrow southern trough axis over Florida. Just east
of that is a regional scale negatively titled trough axis from
Southern Canada to the NW Atlantic with a cyclone embedded in
that near the Benchmark. Water Vapor imagery shows middle level
dry air being advected across Southern Florida and the Keys.
At the surface and in the lower to middle levels (Surface to 700
mb), latest available marine and land surface observations as of
900 pm, depicts Subtropical Storm Melissa, which as of 500 pm, was
located near 38.2N 69.5W, ambling about with a slight southward
movement at 3 mph. This storm is producing wind gusts to 50 mph
across SE New England, mainly Cape Cod and the islands. West of
that, positively oriented near 1025 mb surface ridging is
positioned from Eastern New York States southwest down to near
Atlanta. As a result, the 00Z sounding at Key West illustrated the
developing surface pressure gradient associated with this synoptic
pattern, with fresh northeast breezes developing above 950 mb up
to about 650 mb, and total PWAT at 1.76 inches.
.CURRENTLY...As of 900 pm, skies are partly cloudy across the
entire Keys island chain and surrounding waters. Radar shows
isolated small showers mostly confined to boundaries that have
moved well south of the Reef and into the Florida Straits attm.
C-man stations along the Florida Reef are already northeast
between 15 and 20 knots, with gusts to 20 to 25 knots, as well as
at Smith Shoal Light. Island sensors are around 15 mph.
Temperatures across the islands are in the upper 70s to around 80
with dewpoints are in the mid 70s.
.SHORT TERM...Tonight and Saturday, given the aforementioned MSLP
gradient as represented in the synoptic pattern, local winds
should begin to freshen across the islands and surrounding waters
overnight. They have already begun to do so across the Eastern
locations along the Reef as of this writing. Available non-
hydrostatic models, BOTH HRRR and the local WRF indicate another
surface-850 mb perturbation within the NE flow will move southwest
across the islands after midnight. Given a moderately moist and
unstable airmass, rain chances will continue to be above normal.
Currently have middle of the chance for pops, 405, overnight and
again during the day on Saturday. The increased convergence on
Saturday would also allow for slightly more coverage of faster
moving showers as well. No changes on this cycle attm.
Small Craft Should Exercise Caution tonight as northeast to east
winds increase to 15 to 20 knots. Small Craft Advisory may be
required Saturday across the Straits of Florida.
.AVIATION... VFR will be the predominant conditions tonight.
Additional shower activity is developing as a night time wind surge
moves in from the east. Most of the showers and isolated
thunderstorms will stay over the Florida Straits with low confidence
of showers skirting across the island terminals. For now will not
include VCSH. Wind direction will continue to be favorable for a
cloud line to develop in the late morning early afternoon hours of
Upper Air/Data Collection......NB
Visit us on the web at weather.gov/key
Follow us on Facebook and Twitter at: