397
FXUS64 KMOB 210500
AFDMOB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
1200 AM CDT SAT SEP 21 2019
DISCUSSION
UPDATED FOR LATEST AVIATION DISCUSSION BELOW.
AVIATION
06Z ISSUANCE...VFR CONDITIONS PREVAIL THROUGH THE FORECAST PERIOD.
GENERALLY LIGHT EASTERLY WINDS TONIGHT BECOME BREEZY AND SHIFT TO
SOUTHEASTERLY DURING THE DAY SATURDAY. /49
PREV DISCUSSION
/ISSUED 855 PM CDT FRI SEP 20 2019/
DISCUSSION...SEE UPDATED INFORMATION FOR LAND AREAS BELOW.
UPDATE...MADE A FEW MINOR TWEAKS TO THE CURRENT FORECAST PACKAGE
TO CAPTURE CURRENT TRENDS AND DROPPED OVERNIGHT LOWS A DEGREE OR
TWO AT A FEW LOCATIONS. ALSO, KEPT SLIGHT CHANCE OF POPS OVER THE
MARINE AREA. /08
PREV DISCUSSION... /ISSUED 401 PM CDT FRI SEP 20 2019/
NEAR TERM /NOW THROUGH SATURDAY/...THE BACKDOOR COLD FRONT THAT
MOVED WEST ACROSS THE AREA YESTERDAY IS NOW OFF TO THE WEST AND
BECOMING SOMEWHAT DIFFUSE. IT IS HARD TO FIND THE BOUNDARY IN THE
WIND OBSERVATIONS, BUT NOTICEABLE IN A DEWPOINT GRADIENT ORIENTED
MORE OR LESS ALONG THE MISSISSIPPI RIVER (60S TO THE EAST AND 70S
TO THE WEST). SURFACE HIGH PRESSURE RIDGING IN FROM THE EAST WILL
BE THE DOMINANT FEATURE CONTROLLING THE WEATHER FOR OUR AREA IN
THE NEAR TERM PERIOD. VERY DRY LOW LEVELS ACCOMPANY THE RIDGING,
WITH SLIGHTLY MORE MID LAYER MOISTURE, AS VERIFIED BY MID AND LOW
LEVEL WATER VAPORY IMAGERY CHANNELS. WITH THIS PATTERN IN PLACE,
THE NEAR TERM LOOKS TO BE PRIMARILY RAIN FREE, EXCEPT FOR MAYBE A
COASTAL SHOWER OR TWO LATE TONIGHT INTO EARLY SATURDAY MORNING.
MUCH MORE COMFORTABLE CONDITIONS EXPECTED, WITH LOWS TONIGHT
FALLING INTO THE MID TO UPPER 60S ACROSS ALL INTERIOR LOCATIONS
(GENERALLY ALONG AND NORTH OF I-10) WITH LOWER 70S SOUTH OF I-10
AND A FEW MID TO UPPER 70S POSSIBLE ALONG THE IMMEDIATE COAST.
EVEN THOSE WARMER TEMPS NEAR THE COAST WILL FEEL NICE THOUGH, AS
DEWPOINTS WILL BE DOWN IN THE 60S. FOR SATURDAY, A MOSTLY SUNNY
AND SOMEWHAT "MILD" DAY COMPARED TO RECENT DAYS, WITH HIGHS NEAR
THE NORMAL UPPER 80S ACROSS THE ENTIRE AREA. DEWPOINTS
TEMPERATURES WILL BE REMAINING IN THE 60S ON SATURDAY AS WELL, SO
IT WILL AGAIN FEEL RATHER NICE ON SATURDAY, MUCH LIKE TODAY. 12/DS
SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...AN UPPER
LEVEL SHORTWAVE SYSTEM MOVING EAST OVER THE NORTHERN CONUS ROTATES
THE UPPER RIDGE STRETCHING NORTH ALONG THE EASTERN SEABOARD
CLOCKWISE TO OVER THE OPEN ATLANTIC, WHILST SHIFTING THE BASE OF
THE UPPER RIDGE (LOCATED OVER THE SOUTHEAST) A BIT WESTWARD,
WEAKENING IT A BIT IN THE PROCESS. A SURFACE RIDGE STRETCHING
SOUTHWEST OVER THE SOUTHEAST CONTINUES TO MOVE DRIER AIR WEST
OVER THE SOUTHEAST. FOR HIGH TEMPERATURES, THE DRIER AIRMASS WILL
HELP TO COUNTER-BALANCE A DECREASE IN SUBSIDENCE FROM THE UPPER
RIDGE AND BRING DAYTIME HIGH TEMPERATURES 5-8 DEGREES ABOVE
SEASONAL NORMS FOR SUNDAY AND MONDAY. HIGH TEMPERATURES IN THE
UPPER 80S TO AROUND EXPECTED SUNDAY FOR THE FORECAST AREA, AROUND
90 TO LOW 90S FOR MONDAY. THE DRY AIRMASS WILL HELP TO AID
RADIATION COOLING OVERNIGHT, AND BRING OVERNIGHT LOW TEMPERATURES
A FEW DEGREES ABOVE SEASONAL NORMS SATURDAY THROUGH MONDAY NIGHTS.
LOW TEMPERATURES IN THE MID 60S WELL INLAND TO LOW 70S ALONG THE
COAST ARE EXPECTED THROUGH THE PERIOD.
/16
LONG TERM /TUESDAY THROUGH FRIDAY/...GUIDANCE IS ADVERTISING A
SECOND UPPER LEVEL SHORTWAVE SYSTEM MOVING INLAND OVER THE
PACIFIC NORTHWEST SUNDAY INTO SUNDAY NIGHT, BEFORE MOVING THE
SYSTEM SOUTH-SOUTHEAST TO OVER THE DESERT SOUTHWEST, WHERE IT
MEANDERS AROUND THROUGH MID WEEK. ADDITIONAL UPPER LEVEL SHORTWAVE
SYSTEMS MOVE INLAND OVER THE PACIFIC NORTHWEST, AND IN COMBINATION
WITH THE UPPER SYSTEM OVER THE DESERT SOUTHWEST, DIGS AN UPPER
TROUGH OVER THE WESTERN CONUS WHILST AN UPPER LEVEL RIDGE BUILDS
NORTH ALONG THE EASTERN SEABOARD. THE SURFACE RIDGE STRETCHING
SOUTHWEST OVER THE SOUTHEAST SHIFTS SOUTH TO OVER THE NORTHERN
GULF COAST, BRINGING A MORE DIRECT SOUTHEAST TO SOUTH FLOW OFF
THE GULF OF MEXICO TO THE REGION, AND WITH THE INCREASE IN GULF
MOISTURE, RAIN SHOWERS AND THUNDERSTORMS WILL RETURN TO THE
FORECAST AREA, THOUGH SUBSIDENCE WILL HELP TO LIMIT COVERAGE.
SUBSIDENCE FROM THE UPPER RIDGE WILL BRING HIGH TEMPERATURES 5 TO
10 DEGREES ABOVE SEASONAL NORMALS THROUGH THE LONG TERM. THE
INCREASED MOISTURE LEVELS COUNTERBALANCING OVERNIGHT RADIATIONAL
COOLING WILL ALSO WORK WITH THE UPPER LEVEL SUBSIDENCE TO BRING
OVERNIGHT LOW TEMPERATURES AROUND 5 DEGREES ABOVE SEASONAL
NORMALS.
/16
MARINE...A MODERATE TO OCCASIONALLY STRONG EASTERLY FLOW IS
EXPECTED TO CONTINUE OVER THE COASTAL WATERS THROUGH MOST OF
SATURDAY AND POTENTIALLY INTO SUNDAY AS A STRONG HIGH PRESSURE RIDGE
BUILDS TO THE NORTH OF THE MARINE AREA. A SMALL CRAFT ADVISORY IS IN
EFFECT FOR ALL GULF ZONES AS WELL AS SOUTHERN MOBILE BAY AND THE
MISSISSIPPI SOUND THROUGH MIDDAY SATURDAY AND MAY BE EXTENDED LATER
INTO THE WEEKEND. SMALL CRAFT SHOULD EXERCISE CAUTION OVER THE
REMAINDER OF THE MARINE AREA, PRIMARILY FOR WIND GUSTS. 12/DS
MOB WATCHES/WARNINGS/ADVISORIES
AL...HIGH RIP CURRENT RISK THROUGH SUNDAY EVENING FOR ALZ265-266.
FL...HIGH RIP CURRENT RISK THROUGH SUNDAY EVENING FOR FLZ202-204-206.
MS...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 1 PM CDT SATURDAY FOR GMZ631-632-650-
655-670-675.
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