Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Shreveport la
1144 PM CST Friday Nov 27 2015
lower lows a couple of categories for shv and lfk.
the rain is helping to chill the air via evaporation and update
lows would just not hold west of the front through the overnight.
No other changes at this time. /24/
Previous discussion... /issued 1047 PM CST Friday Nov 27 2015/
widespread IFR ceilings will gradually begin to affect
ktxk...ktyr...and kggg. A very slow moving cold front creating strong
inversion to keep IFR ceilings in place. This front currently over the
kshv terminal. South winds around 5 kts becmg north 5 to 10 kts
Post frontal. Widespread rain lagging north of frontal boundary.
Low visibilities will accompany IFR ceilings already in place with rain at
times. Keld and kmlu will remain mostly low VFR with just occasional
lower ceilings for next several hours./Vii/.
Previous discussion... /issued 1002 PM CST Friday Nov 27 2015/
tweak lows down over the west and into portions of northwest la.
we have gone forward with the same pop/weather through the remainder of
the overnight. The cold front has just eased into Shreveport and
has pushed over into the northern third of Bossier Parish. If you
look closely at the reflectivity you can just make out the
boundary drifting eastward. Working in the back door will take
more time than usual with the cold front only easing into
Arkadelphia now. Barring the good push down across Arkansas into
our County Warning Area from the back door poses a huge challenge to how much
farther the front door push can go. For the last two hours...the
boundary has been wrapping around Shreveport for instance slowly
working over the topography...thus the better go into bossiers
At any rate where we will end up by daybreak is still perhaps more
of a guess than anything. We have loaded in new NAM winds which
likewise lacks a real push. The water vapor shows the upper low
spinning its wheels over Nevada for the most part...nearly
stationary. The high pressure now over northwest New Brunswick is at 1038 mb and is
forecast to weaken to 1030mb over kn/IA/mi by the end of our Flood
Watch early Sunday morning. We may even need to go beyond that
time frame with the new NAM data showing quantitative precipitation forecast well across Sunday
and into Monday. /24/
Previous discussion... /issued 141 PM CST Friday Nov 27 2015/
cold front as of 20z this black Friday afternoon extended from near
deq through ggg and jso line. This front should continue to push into
northwest la and southern Arkansas before finally becoming stationary through the
weekend across S central Arkansas...northwest la...and deep East Texas.
Upper low currently centered over southern Nevada to slowly eject east through
the central U.S. Through the middle of next week.
Currently...the forecast area is really receiving three sources of
moisture. At the surface to about 850 hpa...southeast Gulf of Mexico inflow
of some 30 knots continues along and ahead of the cold front.
Second...the upper low is steering a strong subtropical jetstream
into the central United States. Note this subtropical jet originates
from west of the Hawaiian islands...a typical feature of El Nino.
Finally...deep tropical moisture continues to advect NE from eastern
Pacific Hurricane Sandra located off the west central Mexico coast.
With the above said...will obviously continue the Flash Flood Watch
through Sunday morning near sunrise. We may need to extend the watch
in time and also include additional counties in East Texas...S Arkansas...and northwest
la along and ahead of the cold front.
Rainy and cool weather conditions remain forecast to continue through
much of the first week of December as the abovementioned persistent
subtropical jet provides impulses of energy and lift.
Unfortunately...yet another strong short wave trough is forecast to
develop and deepen across the desert SW next weekend with additional
heavy rainfall quite possible. /Viii./
Preliminary point temps/pops...
shv 49 63 54 58 / 60 60 90 80
mlu 65 73 61 69 / 30 30 40 60
deq 45 51 47 50 / 100 100 100 80
txk 48 55 49 52 / 100 90 100 80
eld 58 67 55 58 / 60 70 90 80
tyr 43 49 46 50 / 100 80 90 80
ggg 43 54 49 53 / 80 80 90 80
lfk 53 65 54 60 / 60 50 50 60
Arkansas...Flash Flood Watch through late Saturday night for arz050-051-
OK...Flash Flood Watch through late Saturday night for okz077.
Texas...Flash Flood Watch through late Saturday night for txz096-097-