Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus64 kmob 272324 aaa 

Area forecast discussion...updated
National Weather Service Mobile Alabama
624 PM CDT Tue Jun 27 2017

Discussion...updated for latest aviation discussion below.


00z issuance...VFR conditions expected this evening. High based
clouds to continue to stream eastward over the central Gulf Coast.
Winds light. /10


Previous discussion... /issued 357 PM CDT Tue Jun 27 2017/

Near term /now through Wednesday/...a weak frontal boundary is
currently stalled just offshore, with isolated shower and
thunderstorm activity ongoing along the immediate northwest
Florida Panhandle coastline. This boundary will lift to the north
and east as low-level winds veer to more southerly in response to
high surface pressure building into the western Atlantic. Aloft,
an upper-level shortwave trough axis extending from middle
Mississippi River valley southwest into central Texas begins to
push east tonight into Wednesday, with a weak mid-level low
developing over Louisiana and the northwest Gulf as a result. As
this low develops, mid-tropospheric winds back from westerly to
southwesterly, which when coinciding with onshore flow near the
surface, will help to return more seasonal deep-layer moisture
(pwats increasing from 1.50 inches to around 2.00 inches) by
Wednesday afternoon. Given the weakening height field aloft and
returning deep moisture, currently expecting thunderstorm chances
to increase from west to east Wednesday morning and afternoon.
Thus, have kept chance pops across much of the area Wednesday
afternoon, with the exception of some likely pops over far
southwest portions of the forecast area where local enhancement
from mesoscale features and the mid/upper waves will overlap. In
terms of temperatures, expect lows tonight to range from the mid
60's inland to mid 70's along the immediate coast, and highs
Wednesday to range from mid to upper 80's inland to low to mid
80's along the immediate coast. /49

Short term /Wednesday night through Friday night/...deep layer
moisture will continue to expand northward across the forecast
area Wednesday night into Thursday as an upper level ridge of high
pressure continues to build northwest over the western Atlantic
and adjacent Florida Peninsula, and also as an upper level low lifts
from the vicinity of the northwestern Gulf of Mexico/southern la
toward the central Gulf Coast region during this time frame.
Precipitable water values are forecast to climb back into the 2.0"
to 2.25" range Wednesday night into Thursday, with the highest
values anticipated along the coast. The available increased deep
layer moisture along with lift ahead of the approaching trough
axis should generate increasing coverage of showers and a few
thunderstorms across our area late Wednesday night into Thursday,
and will have pops rising to 50-60% over southern areas late
Wednesday night into early Thursday morning, with 60-70% coverage
expanding northward across the remainder of the County Warning Area into the day
Thursday. We will need to monitor for locally heavy rainfall and
perhaps localized flooding Thursday where heavier showers and
storms develop. Lows Wednesday night will range from around 70
inland to the mid 70s along the immediate coast. Highs Thursday
will be a little cooler courtesy of increased cloud/precipitation
coverage, with readings currently forecast to range in the lower
to mid 80s.

The upper level ridge axis will continue to expand westward into
the eastern and central Gulf of Mexico Thursday night through
Friday night, while embedded shortwave impulses within west to
southwest flow aloft on the northern periphery of this feature
continue to move across our area during this period. Plentiful
deep layer moisture will remain intact over our area through
Friday night, with precipitable water values continuing to average
around or just above 2 inches. Rain chances may become better
focused near the coast and offshore Thursday night, but coverage
should then increase inland with time during the day Friday, with
pops rising back to 50-60%. Lows Thursday night once again range
from around 70 inland to the mid 70s near the immediate coast and
beaches. Highs Friday should warm into the mid to upper 80s. /21

Long term /Saturday through Tuesday/...a similar weather pattern
should persist into the weekend as our area remains underneath
a moist zonal mid level flow pattern on the base of stronger
westerlies spreading across much of the eastern Continental U.S. And on the
northern periphery of the ridge axis stretched across the Gulf of
Mexico. A similar diurnal pattern should persist through the
weekend with at least scattered showers and storms developing
during the day, with decreasing coverage during the evening hours.
The upper ridge axis may attempt to build a little farther
northward across the Gulf Coast states by early next week, which
may lead to less convective coverage (primarily focused on the
seabreeze) and more heat and humidity Monday and Independence
day. /21

Marine...light easterly winds continue into tonight before veering
to more southerly Wednesday in response to building high pressure
over the western Atlantic and eastern Gulf. Light to occasionally
moderate onshore flow then persists through the latter half of the
week before shifting to southwesterly and then westerly Sunday into
early next week as the aforementioned high pressure builds into the
central Gulf. Shower and thunderstorm coverage increases from the
southwest Wednesday through the remainder of the week before
settling some over the weekend. Waves will remain around 1 to 2 feet
through the period, with the exception of some waves up to around 3
feet well offshore Thursday and Friday during the peak intensity of
those onshore winds. /49


Mob watches/warnings/advisories...

National Weather Service Glossary of Abbreviations