Scientific Forecaster Discussion
fxus64 koun 241954
Area forecast discussion
National Weather Service Norman OK
154 PM CST Fri Nov 24 2017
the primary focus continues to be on fire weather (see fire weather
section below for details). Otherwise, one low-end precipitation
event is possible late Tuesday through Tuesday night. We'll see some
day to day variation in temperature with a few anomalously warm
On the synoptic scale, a broad/deepening trough will build across
the eastern half of the country while mean ridging persists in the
west. In this pattern, northwesterly flow will continue and
strengthen across our region. As the mid-upper trough moves east, it
will force a cold front through this evening and tonight. Gusty
southerly winds this afternoon will subside somewhat before becoming
northerly behind the front and increasing later this
evening/tonight. No precipitation is expected.
Post frontal air mass will be cooler. Saturday's temperatures are
expected to be about 10 to 15 degrees cooler than today's. Eastward
shifting ridge and return of west-southwesterly mean low level flow
will support anomalous warmth again Sunday, especially in the west
where low 70s will be common for highs.
On Monday, 850 hpa trajectories from the San Andres/Sacramento
Mountain region and across the Llano Estacado into our area will
support quite an anomalous warm/dry plume to mix into. Furthermore,
strengthening mass response to deepening trough over the Great Basin
further supports the warm, dry, windy pattern. We didn't hesitate to
use the warmer statistical guidance to assign temperatures for
Monday and near record/record high temperatures across western
Oklahoma seem probable. The orientation of the trough and
amplification of the preceding mean ridging generally doesn't
support extensive cirrus over the area, so forecast confidence is
Moisture return Tuesday isn't robust but sufficient when combined
with forcing for ascent from trough to result in some rain showers.
We added isolated thunderstorms for northeast portions of the area
during the evening given mid-level cooling supporting very meager
instability. Activity should shift east by Wednesday morning, unless
significant slowing in models occurs.
We deviated significantly from the blends at the end of the weak
given the influence of GFS on pop fields. Several GFS ensembles do
not support the deterministic's depiction of a positively tilted
trough and rain chances across the area. European model (ecmwf) is completely out of
phase, and so we discarded GFS as an outlier at this time, and went
with the European model (ecmwf) and eps/gefs ensemble mean which has ridging and dry
conditions over the area.
low relative humidity and modest south-southwest breezes in combination with erc
values approaching the 75th percentile are supporting elevated
fire weather conditions across mainly southwest Oklahoma and
western North Texas this afternoon. For any ongoing fires into the
evening, area fire managers need to be aware of a wind shift with
a cold front that will progress from northern Oklahoma early this
evening through the rest of the area into the night.
Breezy north winds and lowest relative humidity behind the front tomorrow should
be misaligned for a more significant fire weather concern.
Elevated conditions probably won't be met.
Despite a dry air mass and warm temperatures Sunday, winds should
be fairly light precluding a more widespread fire threat.
Monday is the greatest day of concern for the next several.
Anomalous warmth, similar to today, and mixing/drying, along with
dry/dormant fuels will support widespread elevated fire weather
conditions across all of western Oklahoma and portions of central
Oklahoma and western North Texas.
Preliminary point temps/pops...
Oklahoma City OK 49 63 37 68 / 0 0 0 0
Hobart OK 48 65 36 68 / 0 0 0 0
Wichita Falls Texas 48 68 36 69 / 0 0 0 0
gage OK 40 62 35 73 / 0 0 0 0
Ponca City OK 46 62 36 68 / 0 0 0 0
Durant OK 45 69 39 69 / 0 0 0 0