Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Norman OK
651 am CDT sun may 24 2015
aviation discussion for the 12z tafs is below.
have low confidence in the tafs.
Patches of MVFR or lower conditions will affect the area through
21z. Western Oklahoma and western North Texas appears to have the
highest chances for MVFR or lower conditions.
Conditions are expected to improve to VFR at all sites by 21z.
Additional MVFR or perhaps IFR conditions will likely form at
sites after 06z.
Isolated-scattered thunderstorms and rain may form across the area over the next 24
hours...but did not mention in tafs due to much uncertainty
with the placement...location...and timing of thunderstorms and rain.
Previous discussion... /issued 350 am CDT sun may 24 2015/
Short term... today through Tuesday night
Flooding is the main concern.
Cancelled the Flash Flood Watch west of a Henrietta Texas to
Purcell to Chandler line where heavy rain has ended through Monday
morning. The axis of heavy rainfall today will be east of this
line where the low level jet will be strongest.
Today...think the flash flooding threat and additional heavy
rainfall has shifted east. These locations in the Flash Flood
Watch east of the line mentioned above may get another 1 to 3
inches of rainfall. West of the line above including Oklahoma
City...Wichita Falls...and Lawton...think the heavy rain has ended
today and lowered rain chances accordingly. Most models have
mishandled the amount of cool and stable air that currently exists
across much of the area. Went below model guidance highs due to
cool stable air and abundant cloud cover. There is an outside
chance for fog formation this morning across parts of the
area...but did not mention due to low confidence.
As for severe potential through this evening...think potential
remains low. Will monitor a mesoscale convective vortex and the potential for a weak
tornado spinnup or two near Durant and Atoka through 8 am this
morning. Overall...the air seems to be too stable for severe for
much of today. There is an outside chance destablization occurs
this afternoon...especially over western Oklahoma and western
North Texas if a middle/upper dryslot moves overhead. This would
possibly allow for a few severe storms with large hail and
damaging winds to occur. Overall...think cool low level air and
abundant cloud cover...especially at high levels...will keep
severe potential quite low.
Tonight...kept low chances for storms across the area...but
appears most locations will remain dry due to weak subsidence.
Would not be suprised if some fog formed...but did not mention
due to low confidence.
On Monday...another round of storms may occur...especially over
southern Oklahoma and North Texas during the afternoon and evening
hours. Additional heavy rainfall...flash flooding...and severe
storms with hail and wind may occur. The air will be moist and
unstable. For now...will not issue a Flash Flood Watch for this
time frame...but will closely monitor.
Late Monday night through Tuesday night...low storm chances will
continue as the air remains moist and unstable...though coverage
should decrease. Any storm may move slowly...be strong to severe
with hail and wind...and produce locally heavy rainfall.
Long term... Wednesday through Saturday...
active pattern will continue through the extended. However... did
not make any major adjustments to the preceding forecast. Long
range guidance appears to have some decent synoptic consistency.
Devil in the details will be the subtle short wave troughs riding
the weak ridge over the southern U.S. Wednesday-Friday ahead of another advancing
western trough. Will need to continue with slight to chance probability of precipitation through
Thursday... but given confidence in coverage... it's difficult to
pin down locations with the best chances. For Friday... scenario
gets a skosh clearer... with both the GFS and European model (ecmwf) grabbing a hold
of a more definite short wave trough lifting NE across the
panhandles Thursday night through Friday. Expect decent moisture return
through the ll on Thursday ahead of this wave... so felt confident to up
probability of precipitation to chance and likely through Friday across most of the region.
Kept chance probability of precipitation going through Saturday as the cold front stalls
across the Southern Plains... remaining a focus for precipitation development
through the weekend as the larger trough broadens and shifts east/NE
over the central U.S.
Preliminary point temps/pops...
Oklahoma City OK 72 64 79 64 / 50 20 30 30
Hobart OK 75 60 80 61 / 30 20 30 20
Wichita Falls Texas 77 65 80 64 / 50 20 40 30
gage OK 76 58 81 58 / 30 20 20 20
Ponca City OK 73 63 80 64 / 40 20 20 20
Durant OK 74 66 78 64 / 90 30 50 50
OK...Flash Flood Watch through Monday morning for okz026-030>032-
Texas...Flash Flood Watch through Monday morning for txz090.