219 
FXUS64 KMOB 220505 AAC
AFDMOB

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
1205 AM CDT Mon Jun 22 2020

.AVIATION...
06Z issuance...VFR conditions are expected to prevail through the
period, except for localized upper-end MVFR conditions in/near 
increasing convection on Monday between 22.15z and 22.24z. 
Light southerly flow overnight will increase to around 10 knots 
on Monday. /22

&&

.PREV DISCUSSION... /issued 1050 PM CDT Sun Jun 21 2020/ 

NEAR TERM /Now Through Tuesday Afternoon/...Area radars are 
currently detecting a weakening line of showers with a few 
embedded thunderstorms along an outflow boundary just entering 
into our far northwest zones. This convection was primarily driven
by a shortwave upper trough located near the mid Mississippi 
River valley that is moving off to the east. This convection will 
continue to encountering a more stable environment as they slowly 
progress toward the southeast, and should dissipate after 
midnight. A lone shower had developed near the southern 
Mississippi coast, and this shower activity will increase in 
coverage (mainly isolated) overnight and move east-northeast into 
our southeast Mississippi and southwest Alabama zones by daybreak 
Monday. The temperatures for tonight are trending as previously 
forecast, but are not expected to drop off to much as we expect 
overnight lows to remain in the 70 to 75 degree range inland 
areas, and from 75 to 79 degrees along the coast.

The central states upper trough will continue to amplify on 
Monday and also advance slowly eastward, while two shortwaves at
the base of the trough approach the area from the west. The first
is expected to pass over Louisiana and Mississippi Monday and
Monday evening, and then weaken as it moves into eastern Alabama 
late monday night. The second is expected to move out of Texas
and over Louisiana throughout the day Tuesday. A surface ridge
will remain over the northern Gulf and promote a light southerly 
flow over the forecast area, and this pattern will continue a 
trend of improving deep layer moisture during the period, with 
precipitable water values rising from 1.5-1.75 inches to near 2.0 
inches on Monday and remain so through Tuesday. With a weak sea 
breeze expected to develop both Monday and Tuesday in an 
environment with MLCAPE values of 1500-2000 J/kg, will result in 
scattered to numerous showers and storms developing during the 
day Monday, and numerous to definite showers and storms on
Tuesday. DCAPE values of 700-900 J/kg are possible, and based on 
the current data it appears that precipitation loading looks to be
the main initiating mechanism for downdrafts which will then be 
accelerated in the subcloud environment. Will continue to monitor 
for strong storm development Monday and Tuesday afternoons.
Widespread rainfall totals Monday through Tuesday afternoon are
forecast to range from one-half to one inch northwest of I-65, and
from two-tenths to one-half inch to the southeast. Localized 
heavier rain may result in some locations receiving two to three 
inches, especially northwest of I-65.

High temperatures on Monday will range from 86 to 91 degrees,
although a few locations across south central Alabama could reach
93 degrees due to more breaks in the clouds. Lows Monday night 
will range from 68 to 73 degrees inland areas, and from 74 to 79 
degrees along the coast. High temperatures Tuesday will range 
from 84 to 89 degrees. /22

PREV DISCUSSION... /issued 340 PM CDT Sun Jun 21 2020/ 

NEAR TERM UPDATE /Now Through Monday/...A shortwave trof located mainly 
near the mid Mississippi River valley moves off to the east through 
tonight while a larger scale upper trof amplifies over the central 
states. The central states upper trof continues to amplify on 
Monday and also advance eastward slowly. A surface ridge remains 
over the northern Gulf and promotes a light southerly flow over 
the forecast area, and this pattern will continue a trend of 
improving deep layer moisture during the period, with precipitable
water values rising from 1.5-1.75 inches to near 2.0 inches on 
Monday. A weak sea breeze is expected to develop today which along
with daytime heating will support mainly isolated showers and 
storms to develop this afternoon and linger into the evening 
hours. MLCAPE values this afternoon will be near 1500 J/kg, and 
model soundings show some mid level dry air which will enhance 
downdrafts with the stronger storms. Following upon this, DCAPE 
values are near 1000 J/kg during the mid to late afternoon hours 
and indicates that strong wind gusts are certainly possible. As 
the central states upper trof begins to advance eastward, a series
of shortwaves will move across the region which when combined 
with a weak sea breeze in an environment with MLCAPE values of 
1500-2000 J/kg, will result in scattered to numerous showers and 
storms developing during the day. DCAPE values of 700-900 J/kg are
possible, and based on the current data it appears that 
precipitation loading looks to be the main initiating mechanism 
for downdrafts which will then be accelerated in the subcloud 
environment. Will continue to monitor for strong storm development
Monday afternoon. Lows tonight range from around 70 inland to the
mid 70s at the coast. Highs on Monday range from the lower 90s 
inland to the upper 80s at the coast. A low risk of rip currents 
continues through Monday. /29

SHORT TERM /Monday night Through Wednesday night/...An upper trough 
stretches south over the Mississippi River through Tuesday night 
before an upper ridge over the Gulf of Mexico/Caribbean begins to 
build west. This shifts the base of the trough from over the Lower 
Mississippi River Valley west to over the Southern Plains. With a 
very most airmass over the Southeast, and the proximity of the upper 
trough just to the west of the forecast area, a wet period is in 
store for the forecast area. Even after the upper trough begins to 
shift west Wednesday and Wednesday night, a series of upper 
disturbances move through the trough and east over the Southeast, 
extending the wet period into mid week. There is expected to be a 
downward trend in convection coverage overnight Tuesday and 
Wednesday nights with the loss of the day's heating, as limited as 
it will be. Local tools continue to advertise a moderate to high 
chance of strong downburst winds. Adding DCape into the equation, 
guidance continues to advertise values rising to around 700-900J/kg, 
especially Tuesday, adding to the strength of the downburst winds. 
Will continue to monitor as this period approaches.

With the widespread convection each day, high temperatures will be 
limited to below seasonal levels. High temperatures in the mid 80s 
to around 90 are expected Tuesday, low to mid 80s Wednesday over 
most of the forecast area. Overnight low temperatures will see 
around to a bit above seasonal norms with the decrease in overnight 
radiational cooling, ranging from around 70 well inland to low to 
mid 70s closer to the coast and upper 70s along the beaches.
/16

EXTENDED TERM /Thursday Through Sunday/...Thursday into the weekend, 
guidance is advertising the Gulf/Caribbean upper level ridge 
building north over the Southeast. Increasing upper subsidence will 
help to decrease the chance of convection through the Extended, even 
with the soupy airmass remaining in place, along with bringing an 
increase in daytime temperatures into the weekend. High temperatures 
Thursday are expected to range in the mid to upper 80s, with chance 
to low end likely (mainly west of the Alabama River) PoPs. By the 
weekend, high temperatures ranging from around 90 to the mid 90s are 
expected. Low temperatures through the period are expected to range 
from around 70 to low 70s north of Interstate 10 to mid/upper 70s 
south. 
/16 

MARINE...Locally higher winds and waves are possible near isolated 
to scattered showers and thunderstorms. Otherwise, no impacts are 
expected. /29

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&

$$

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