Area Forecast Discussion
Issued by NWS Brownsville, TX
FXUS64 KBRO 051815 AAC
Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
1215 PM CST Mon Dec 5 2016
.DISCUSSION...Updated for latest /18Z/ aviation discussion below.
.AVIATION...Rare does it occur in the Valley behind cold fronts,
but rarely does the region see a coastal low act like a
"Nor`easter" when, in places like the Mid-Atlantic, northwest flow
near the surface combined with southwest flow above the surface
prior to the passage of the upper low that helped develop the
offshore surface low - as well as remaining low level moisture
post-rainfall. All these factors have combined to lock in a MVFR
deck between 1500 and 2000 feet AGL late this morning and early
afternoon. Model soundings were a little hasty in clearing out the
deck/mixing down dry air, but that has begun across the Rio Grande
Plains and should arrive in the Valley between 2 and 4 PM.
Based on this expectation, decreased the MVFR clouds during this
time, soonest at McAllen/Miller, and cleared everything else by or
just after sunset. Thereafter, clear skies and light winds
dominate the forecast through midday Tuesday. One thing to watch
is possible development of BCFG/MIFG ("field fog") especially at
Harlingen after midnight/early Tuesday morning. With surface flow
laying down but turning light southerly just off the deck, as well
as temperatures falling to the modest dewpoints, would not
surprise to see some development. Not enough confidence to include
visibility restrictions but something to watch later this evening.
GM...Small Craft Advisory until noon CST today for GMZ150-155-170-175.
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