482
FXUS64 KJAN 170229
AFDJAN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
929 PM CDT SAT OCT 16 2021
UPDATE
UPDATED FOR EVENING DISCUSSION.
DISCUSSION
THE FORECAST IS ON TRACK WITH CLEAR SKIES AND DIMINISHING WIND
MAKING FOR IDEAL OVERNIGHT COOLING CONDITIONS. NO SIGNIFICANT
ADJUSTMENTS WERE NECESSARY IN THIS UPDATE. /EC/
PRIOR DISCUSSION BELOW:
TONIGHT AND SUNDAY: DRY AND COOLER THAN NORMAL THROUGH THE PERIOD.
MID AFTERNOON SURFACE ANALYSIS HAD AN 1028MB HIGH CENTERED OVER
NORTH CENTRAL TEXAS. THE PRESSURE GRADIENT BETWEEN THE DEPARTING LOW
PRESSURE SYSTEM AND THIS HIGH WAS RESULTING IN A GUSTY NORTH WIND.
THE WIND GUSTS WILL SUBSIDE BY EVENING AND THE NORTH WIND WILL
BECOME LIGHTER BUT NOT DECOUPLE TONIGHT AS THE SURFACE HIGH REMAINS
TO OUR WEST UNTIL DURING THE DAY SUNDAY. UNDER SLIGHTLY LESS THAN
IDEAL RADIATIONAL COOLING TONIGHT, TEMPERATURES WILL DROP WELL BELOW
NORMAL AND BOTTOM OUT IN THE LOW TO MID 40S. OUR NORMALLY COLDER
LOCATIONS MAY SEE MORNING LOWS DIP INTO THE UPPER 30S. SUNDAY THE
UPPER LEVEL TROUGH WILL CONTINUE SHIFTING EAST OF OUR REGION WHILE
THE SURFACE HIGH SHIFTS EAST AND BECOMES CENTERED OVER NORTHERN
MISSISSIPPI. THIS WILL RESULT IN A LIGHTER WIND THAN TODAY AND ALLOW
TEMPERATURES TO TOP OUT A DEGREE OR TWO WARMER THAN THIS AFTERNOON.
HIGH TEMPERATURES SUNDAY WILL IN THE LOWER 70S AT MOST LOCATIONS.
/22/
SUNDAY NIGHT THROUGH NEXT WEEK ...
OUR PLEASANT WEATHER WILL CONTINUE INTO SUNDAY NIGHT WITH OVERNIGHT
LOWS STILL BELOW THE SEASONAL NORMALS. DRY AIR AT THE SURFACE AND
MOSTLY CLEAR TO PARTLY CLOUD SKIES WILL ALLOW FOR EFFECTIVE WARMING
DURING THE DAY MONDAY AND WE WILL SEE AFTERNOON HIGHS NEAR NORMAL
APPROACHING MID WEEK. LOOK FOR LOWS TO DIP DOWN INTO THE UPPER 40SF
AND LOWER 50S F AT NIGHT AND RISE INTO THE MIDDLE 70S F DURING THE
DAY.
AS THE SURFACE HIGH AND ASSOCIATED CONTINENTAL AIRMASS BEGINS TO
MODIFY AND THE CENTER OF THE HIGH MOVES TO OUR EAST, WE WILL BEGIN
TO SEE NORTHERLY WINDS SHIFT TO SOUTHERLY. THIS RETURN FLOW ON THE
BACKSIDE OF THE RETREATING HIGH WILL RESULT IN A DAY-OVER-DAY
WARMING TREND, INITIALLY MOST NOTICEABLE AT NIGHT. TUESDAY INTO
WEDNESDAY, WE WILL BE RETURNING TO NEAR NORMAL TEMPERATURES AND
INCREASED HUMIDITY. HIGHS WILL BE RETURNING TO THE LOWER 80S F WITH
OVERNIGHT LOWS IN THE LOWER TO MIDDLE 60S F.
BY LATER IN THE WEEK, A COMPLEX EVOLUTION OF UPPER TROUGHS WILL
INITIALLY BE MOST APPARENT BY INCREASING UPPER LEVEL CLOUDINESS. THE
CORE OF THE FIRST SHORTWAVE EMBEDDED IN LARGE SCALE TROUGHING
CENTERED OVER THE EASTERN THIRD OF THE CONUS WILL PASS LARGELY NORTH
OF OUR AREA WEDNESDAY INTO THURSDAY. AT THE 200-300MB LEVEL,
HOWEVER, THE TROUGH WILL BE A BIT BETTER DEFINED AS IT PASSES ACROSS
THE ARKLAMISS AND WIDESPREAD CIRRUS IS LIKELY TO DEVELOP. THIS WILL
LIMIT THE DEGREE OF RADIATIONAL COOLING WEDNESDAY AND THURSDAY
NIGHTS AND MAY IMPEDE HEATING DURING THE DAY AS WELL. A FEW SHOWERS
WILL BE POSSIBLE EACH DAY AS LOW LEVEL MOISTURE INCREASES BUT
MOST PLACES WILL REMAIN DRY.
THE PRIMARY AXIS OF THE LONG WAVE WILL DIG DEEPER HOWEVER HEADING
INTO FRIDAY. WHILE FLOW BECOMES LARGELY ZONAL, THE TROUGH SHOULD
STILL SLOWLY PUSH A FRONT FROM NORTH TO SOUTH ACROSS OUR AREA ON
FRIDAY. WITH THE FRONT-PARALLEL UPPER FLOW, THE BOUNDARY WILL
LARGELY BE FORCED BY DEEP COLD AIR ADVECTION IN THE LOWER LEVELS
ASSOCIATED WITH A POTENT ZONE OF SURFACE HIGH PRESSURE AND COOLER
AIR FORCING ITS WAY SOUTH. THIS WILL RESULT IN WIDESPREAD SCATTERED
SHOWERS ALONG AND AHEAD OF THE FRONT; PERHAPS WITH SOME THUNDER.
WITHOUT SIGNIFICANT UPPER LEVEL SUPPORT AND A BOUNDARY LAYER THAT
IS NOT FULLY MODIFIED (PARCEL TRAJECTORIES IN THE BOUNDARY LAYER
NOT FULLY SOURCED FROM THE GULF OF MEXICO WITH EAST-SOUTHEAST
DOMINANT FLOW), THE THREAT FOR STRONG TO SEVERE STORMS LOOKS LOW
AT THIS TIME. AFTER THE FRONTAL PASSAGE, TEMPERATURES AND HUMIDITY
WILL FALL TO BELOW CLIMATOLOGICAL NORMALS PARTICULARLY NORTH OF
I-20 WHERE BETTER FRONTAL PENETRATION IS LIKELY AS WE HEAD INTO
NEXT WEEKEND. /86/
AVIATION
18Z TAF DISCUSSION:
THE GUSTY NORTH WIND OF 20-25KTS WL SUBSIDE BY 00Z AND A LIGHT
NORTH WIND IS EXPECTED TONIGHT THROUGH SUNDAY MORNING. VFR
CONDITIONS WL PREVAIL THROUGH SUNDAY. /22/
PRELIMINARY POINT TEMPS/POPS
JACKSON 41 72 48 75 / 0 0 0 1
MERIDIAN 43 70 47 72 / 0 0 0 1
VICKSBURG 44 73 48 75 / 0 0 0 0
HATTIESBURG 46 72 48 74 / 0 0 0 1
NATCHEZ 45 71 50 74 / 0 0 0 0
GREENVILLE 45 72 46 74 / 0 0 0 0
GREENWOOD 44 73 46 75 / 0 0 0 0
JAN WATCHES/WARNINGS/ADVISORIES
MS...NONE.
LA...NONE.
AR...NONE.
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