Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Houston/Galveston Texas
408 am CST Monday Dec 29 2014
low clouds, drizzle & fog across eastern 2/3 of the County Warning Area should
begin to erode late this morning. Might take a bit longer across
NE parts...which like Sunday...could play havoc with high temperatures
depending on timing & breaks of sun.
Leading edge or Arctic airmass now spilling into ncntl parts of
the country will begin filtering into southeast Texas on Tuesday. It'll be a
gradual process with cold air advection continuing Wed/Thu. One thing future
shifts will need to keep a close an eye on is precipitation chances new
years evening. Both the 00z & 06z runs of the nam12 show fairly robust
moisture ascent over cooler surface airmass with increasing -ra
coverage through the evening and overnight hours Wednesday. This is 12-18 hours
earlier than what global models/guidance have been and are still
indicating. Typically give more forecast weight to nam12 in these airmasses
and went ahead and bumped probability of precipitation up Wednesday night...but they may still
be significantly underdone.
Coldest day of the week should be New Years Day (thurs) with expected
clouds/precipitation limiting any warm-up.
Coastal trough takes shape late Thursday and Friday as surface high pressure moves
off to the east and upper trough slowly approaches from the west.
Combination of upglide, messy SW flow aloft & coastal trough will
provide continued good chances of precipitation through Sat afternoon. Fwiw this
far out - the 00z guidance doesn't bring the warm sector nearly
as far inland as past runs. Pacific front clears the precipitation out
late Sat as upper trough departs. 47
generally light north/northeasterly winds to prevail the next day (or so) before
strengthening Tuesday in response to the upper level storm system deep-
ening out to the west. We could see scec/Small Craft Advisory flags for the Upper Texas
coastal waters by Tuesday night...lingering on into late Thursday. S/southeasterly
winds prognosticated to return Friday as a warm front moves ashore.
foggy start to the day with LIFR visible/ceilings prevailing across the southern
two thirds of the forecast area. These conditions could be slow to clear given
the very light winds just above the surface...but we should see VFR ceiling
by the afternoon. 41
Preliminary point temps/pops...
College Station (cll) 55 39 51 34 42 / 0 0 0 10 10
Houston (iah) 57 42 56 37 48 / 0 0 0 0 0
Galveston (gls) 54 49 56 43 51 / 0 0 0 10 10