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Storm Prediction Center


09/19/2019 12:39 PM
SPC - No watches are valid as of Thu Sep 19 16:40:01 UTC 2019
No watches are valid as of Thu Sep 19 16:40:01 UTC 2019.
09/19/2019 12:39 PM
SPC - No MDs are in effect as of Thu Sep 19 16:40:01 UTC 2019
No Mesoscale Discussions are in effect as of Thu Sep 19 16:40:01 UTC 2019.
09/19/2019 08:33 AM
SPC Sep 19, 2019 1300 UTC Day 1 Convective Outlook
SPC 1300Z Day 1 Outlook
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0727 AM CDT Thu Sep 19 2019

Valid 191300Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY NEAR THE
UPPER TX COAST...AND THIS AFTERNOON/EVENING FOR PARTS OF THE CENTRAL
AND SOUTHERN HIGH PLAINS...

...SUMMARY...
Thunderstorms capable of isolated damaging winds and marginally
severe hail will be possible in parts of the central and southern
High Plains this afternoon and evening.  A brief tornado or two will
also be possible near the upper Texas coast.

...Central/southern High Plains this afternoon/evening...
A midlevel trough will move eastward over NV/ID and UT by tonight,
with subtle/diffuse speed maxima preceding the trough from the
southern Rockies to the central High Plains.  An associated broad
surface low will form in WY and move toward the northern High Plains
by early Friday, with a lee trough extending southeastward into
eastern CO.  Surface heating and boundary-layer dewpoints in the 60s
east of the lee trough will contribute to MLCAPE near 2000 J/kg this
afternoon/evening.

Forcing for ascent will be weak at best on the larger scale, with
storm initiation relying on surface heating to remove convective
inhibition.  Still, scattered thunderstorms are expected to form
this afternoon and persist into this evening along and east of the
lee trough, and along the northwest edge of a midlevel moisture
plume across the southern High Plains.  Steep lapse rates will
promote some potential for strong outflow winds with downbursts, as
well as marginally severe hail.  Deep-layer vertical shear will be
weak across western KS where multicell clusters will be the main
storm mode, and slightly stronger across the TX Panhandle where some
transient supercell structures will be possible. 

...Southeast TX today...
Extreme rainfall has occurred overnight between Houston and Beaumont
with training convection which has been maintained by 35 kt
south-southwesterly inflow of 100 mb mean mixing ratios near 19 g/kg
(77-80 F dewpoints) into a stationary, rain-reinforced boundary. 
Back-building to the west will become more probable during the day
with the stronger low-level inflow focused into the west flank of
the ongoing convection, and as surface heating occurs to the west. 
There will still be sufficient low-level shear/hodograph curvature
for a few rotating storms and a brief/weak tornado or two in this
band the first half of the day, with a gradual decrease in low-level
flow/shear is expected by later this afternoon.  

...Northern High Plains through tonight...
The richer low-level moisture is confined to NE/KS this morning, and
moisture is likely to remain limited across eastern WY through most
of the afternoon.  Moisture will increase farther west and north
tonight, but this will also be accompanied by a capped boundary
layer.  Since the limited moisture will likewise limit buoyancy
during the diurnal heating cycle, severe storms appear unlikely this
afternoon.  The cap and only weak forcing for ascent until Friday
morning also suggests that any severe threat overnight will remain
too low to warrant an outlook area.

..Thompson/Kerr.. 09/19/2019

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09/19/2019 12:12 PM
SPC Sep 19, 2019 1630 UTC Day 1 Convective Outlook
SPC 1630Z Day 1 Outlook
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1108 AM CDT Thu Sep 19 2019

Valid 191630Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE HIGH PLAINS...AND OVER PORTIONS OF THE TEXAS AND LOUISIANA
COAST....

...SUMMARY...
Thunderstorms capable of isolated damaging winds and marginally
severe hail will be possible in parts of the central and southern
High Plains this afternoon and evening.  A brief tornado or two will
also be possible near the upper Texas and southwest Louisiana coast.

...High Plains...
A large upper trough is present over the western states today, while
a broad upper ridge dominates the weather in the east. 
Southwesterly flow aloft persists over the High Plains, where full
sunshine and dewpoints in the 60s will result in steep low-level
lapse rates and moderate CAPE.  A weak midlevel impulse over NM will
likely aid in the development of scattered thunderstorms by
mid-afternoon over southeast CO and western portions of the TX/OK
Panhandles.  This activity will spread northeastward into western KS
during the evening.  Midlevel winds are relatively weak, which may
limit overall organization of the storms.  However, potential exists
for gusty/damaging winds and hail in the strongest cells through the
early evening.

...LA/TX...
TD Imelda continues to affect portions of the upper TX and southwest
LA coastal region.  Transient rotating storms have been noted this
morning near the Sabine river.  Increasingly discrete convection on
the southwest flank of the circulation may also pose a risk of a
brief spin-up or two farther south along the upper/middle TX coast
later today.

..Hart/Gleason.. 09/19/2019

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09/19/2019 12:39 PM
SPC Day 1 Fire Weather Outlook
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook Image
Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1137 AM CDT Thu Sep 19 2019

Valid 191700Z - 201200Z

...CRITICAL FIRE WEATHER AREA FOR FAR SOUTHEAST NEVADA...NORTHWEST
ARIZONA...AND A LARGE PORTION OF UTAH...

No changes are needed to the ongoing forecast of critical fire
weather conditions across portions of southeastern Nevada,
northwestern Arizona, and Utah (see previous discussion below). 
Strong insolation ahead of an approaching upper-level trough has
already resulted in some locations reporting RH values this morning
below 20% along with wind gusts approaching 30 mph.  As boundary
layer mixing continues through the afternoon, widespread critical
fire weather conditions are expected across the region with the
potential for strong wind gusts (i.e., approaching 50 mph).

..Jirak.. 09/19/2019

.PREV DISCUSSION... /ISSUED 1246 AM CDT Thu Sep 19 2019/

...Synopsis...
A strong mid-level jet will spread across the Great Basin today
ahead of a mid-level closed low. Some of these strong winds are
expected to transport toward the surface through deep vertical
mixing. Surface winds could be quite strong (30 to 35 mph) in
northwest Arizona and southwest Utah with some gusts approaching 50
mph. In addition, this pre-frontal airmass will feature dry surface
conditions and RH values around 10 to 20 percent. 20 to 30 mph
surface winds are expected farther northeast into most of Wyoming
where relative humidity will also be in the 15 to 20 percent range.
Isolated critical conditions will be possible in this region, but no
critical area was added here due to borderline relative humidity and
relatively sparse fuels.

...Please see www.spc.noaa.gov/fire for graphic product...

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