Area forecast discussion
National Weather Service Houston/Galveston Texas
620 am CDT Friday may 24 2013
Discussion...
see the 12z aviation discussion below.
40
&&
Aviation...
a weak surface boundary will likely become a source for
thunderstorm development during the afternoon over the northern
counties. Expect that the best thunderstorm chances will occur
over kcll and kuts...and to a lesser extent at kcxo and kiah.
Chances go down toward the coast. With sunset this evening the
chances for MVFR conditions return. Felt that IFR is possible but
decided to wait for another model run or two. Any rainfall that
may fall will also affect the area as well.
40
&&
Previous discussion... /issued 356 am CDT Friday may 24 2013/
Discussion...
at 06z...a weak front extended from northern Louisiana...along the
Red River and then up towards the Texas Panhandle. A long lived
mesoscale convective system was located over southwest Texas and mesoscale convective vortex was forming southwest
of ksjt. At 850 mb...dew points were between 12-14c and a weak
850 mb trough was located over SW Texas and a second weaker trough
over western Louisiana. Several trough axes were noted at 700 mb
with one in eastern New Mexico...another in SW Texas and a third
across central Louisiana extending into eastern Texas. At 300
mb...weak upper level divergence was noted over southwest Texas
with weak ridging over the Southern Plains extending into East
Texas. The abundant moisture at 850 mb coupled with the numerous
850/700 mb boundaries should be enough to generate at least
scattered rain showers/thunderstorms and rain later today into tonight. The forecast sounding
for kcll at 21z is loaded with precipitable water values surging to 1.7 inches and
a k index at 42. Cape values approach 3000 and Li values are -8.
These parameters suggest that a few of the storms could be strong
to severe over mainly the northwest portion of the County Warning Area. Movement
will also be on the slow side today so if storms develop...some
locally heavy rain will result. The hi-res models did not perform
well yesterday but seemed to initialize a bit better today and
both the nmm and arw show development over the north this
afternoon so raised probability of precipitation to chance. Closer to the coast...
additional capping and lower moisture levels will limit rain
chances.
Moisture levels drop on Saturday but a weakness aloft under cutting
the ridge and daytime heating will still produce a few showers
over mainly the northwest half of the region. The upper ridge amplifies a
bit Sunday and Monday with warmer temperatures and little or no rain. Mex
numbers again look too cool with the upper ridge nearby...so again
went several degrees warmer than mex guidance and leaned toward
the warmer European model (ecmwf). Long range models are different this morning as
the upper ridge is prognosticated to shift further east by Wednesday as
an upper level trough moves into Arizona. The European model (ecmwf) is deeper with
the trough and this solution is supported by the Canadian. The GFS
is weaker and further north with the trough. Lift should increase
as the trough approaches Thursday/Friday so added low probability of precipitation back to the
forecast for next Thu/Fri. 43
Marine...
onshore winds will likely persist through the forecast period. Early
next week the computer models increase the wind speeds to at least
caution criteria and possibly advisory levels Monday night into
Tuesday night.
40
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Preliminary point temps/pops...
College Station (cll) 90 70 90 70 90 / 50 40 20 10 10
Houston (iah) 90 72 90 71 89 / 20 20 20 10 10
Galveston (gls) 84 75 84 74 85 / 10 10 20 10 10
&&
Hgx watches/warnings/advisories...
Texas...none.
GM...none.
&&
$$
Discussion...43
aviation/marine...40
