307
FXUS64 KJAN 160927
AFDJAN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
327 AM CST THU JAN 16 2025
..NEW DISCUSSION
DISCUSSION
ISSUED AT 325 AM CST THU JAN 16 2025
TODAY AND TONIGHT...A SHORTWAVE IS IN THE PROCESS OF EXITING THE
LOWER MISSISSIPPI RIVER VALLEY THIS MORNING. AS THIS CONTINUES,
NORTHWEST FLOW ALOFT WILL SETUP ACROSS THE REGION THROUGH THE
PERIOD, WITH WEAK RIDGING ALOFT BUILDING THROUGH OVERNIGHT. AT THE
SURFACE, HIGH PRESSURE WILL STEADILY BUILD EAST INTO THE AREA
THROUGH TONIGHT. THIS'LL CAUSE SURFACE WINDS TO BECOME MORE
WESTERLY TODAY AND SOUTHERLY LATER TONIGHT.
OVERALL, QUIET CONDITIONS WILL EXIST ACROSS THE CWA TODAY INTO
TONIGHT. HIGH TEMPERATURES TODAY WILL BE SIMILAR TO THOSE ON
WEDNESDAY, AS THEY RANGE FROM THE UPPER 50S TO LOWER 60S UNDER
MOSTLY SUNNY SKIES. THEN WITH THE INCREASED SOUTHERLY FLOW TONIGHT,
LOOK FOR SLIGHTLY WARMER LOWS AS THEY RANGE FROM THE LOW TO UPPER
30S UNDER MOSTLY CLEAR SKIES. /19/
FRIDAY THROUGH THIS WEEKEND...FRIDAY REMAINS DRY WITH A WARMING
TREND CONTINUING AHEAD OF A TROUGH/FRONT THAT WILL BRING RAIN AND
ISOLATED TO SCATTERED THUNDERSTORMS INTO THE AREA. WE'LL ONLY
BRIEFLY BE OUT OF THE CHILL, HOWEVER, AND BOUNDARY LAYER
THERMODYNAMICS LIKELY WILL REMAIN UNSUPPORTIVE FOR SEVERE
CONVECTION. GENERALLY SOUTH OF I-20 WHERE THE BEST, BUT STILL
MODEST, MOISTURE AND TEMPERATURE RECOVERY IS EXPECTED, AN ISOLATED
NEAR-SURFACE BASED STORM RESIDING IN A SHEAR REGIME SUPPORTIVE OF
ORGANIZED THUNDERSTORM ACTIVITY COULD BE BRIEFLY STRONGER AND
SOME LOWER-END RISK FOR A STRONG GUST OR TWO CAN'T BE TOTALLY
RULED OUT. ELSEWHERE, FORECAST SOUNDINGS FROM VARIOUS PIECES OF
GUIDANCE SUGGEST ELEVATED INSTABILITY WILL BE ADEQUATE TO SUPPORT
ELEVATED THUNDERSTORMS AND LITTLE MORE. THIS ACTIVITY CLEARS OUT
INTO SATURDAY AND THE FRONT FOLLOWING WILL USHER IN POSSIBLY SOME
OF THE COLDEST AIR WE HAVE SEEN THIS YEAR.
COLD AIR ADVECTION BEGINS IN EARNEST SUNDAY WITH RAPIDLY RISING
SURFACE PRESSURES AND A TIGHT PRESSURE GRADIENT SIGNALING THE
LEADING EDGE OF CANADIAN/ARCTIC HIGH PRESSURE FLOODING INTO THE
AREA. WIND GUSTS ABOVE 20 MPH WILL BE POSSIBLE WITH TEMPERATURES IN
THE 30S AND 40S F WILL RESULT IN DAYTIME WIND CHILLS IN THE 20S F
EVEN THROUGH MIDDAY. WIND CHILLS BY SUNDAY NIGHT ONLY DROP COLDER AS
SURFACE TEMPERATURES FALL INTO THE 20S F, DIPPING INTO THE LOWER
TEENS FOR MANY. BITING COLD PERSISTS INTO MONDAY AND WHILE THE WIND
WON'T BE QUITE AS STRONG, WITH HIGHS NEAR OR JUST ABOVE FREEZING, IT
WILL REMAIN UNSEASONABLY (AND FOR MANY, QUITE UNCOMFORTABLY) COLD
EVEN DURING THE DAY.
AN "OUT OF THE FRYING PAN AND INTO THE FIRE" REFERENCE ALMOST SOUNDS
PLEASANT COMPARED TO WHAT WE MIGHT BE FACED WITH COME LATE MONDAY
NIGHT INTO TUESDAY AS THAT WOULD AT LEAST BE WARM.
FOR MANY FORECASTERS, PARTICULARLY IN THE SOUTH, WHENEVER BUZZ
BEGINS TO STIR REGARDING POTENTIAL WINTRY PRECIPITATION, THE
QUESTION WE GET THE MOST IS "WILL IT SNOW ?" AS IS ALWAYS THE CASE,
THAT WILL DEPEND ON NUMEROUS FACTORS, THE LEAST OF WHICH NOT BEING
WHERE EXACTLY A PERSON IS LOCATED. SMALL DIFFERENCES IN LOCATION
OFTEN RESULT IN SUBSTANTIAL DIFFERENCES IN OUTCOME. THIS LIKELY WILL
BE NO DIFFERENT.
SO LET'S TALK ABOUT IT.
SYNOPTIC SCALE TROUGHING IS A NEAR GUARANTEE FOR MUCH OF THE CENTRAL
AND EASTERD CONUS OVER THE NEXT WEEK AS A LARGE AIRMASS OF COLDER,
ARCTIC AIR SETTLES SOUTHWARD. WITHIN THIS LARGE SCALE TROUGH ARE
LIKELY TO BE EMBEDDED SHORTWAVE TROUGHS AND TO THE SOUTH OF THE VERY
LARGE TROUGHING FEATURE ROTATING INTO OUR AREA, A COUPLE OF
ADDITIONAL INTERESTING FEATURES ARE NOTABLE. ONE, AN ACTIVE SOUTHERN
STREAM JET SITUATED GENERALLY SOUTH OF THE GULF COAST, ANGLED FROM
SOUTHWEST NEAR MEXICO NORTHEASTWARD TOWARD FLORIDA, AND A CLOSED LOW
CURRENTLY OVER THE PACIFIC WEST OF OREGON/WASHINGTON.
AS THESE SHORTWAVE "SPOKES" OF ENERGY MOVE THROUGH THE UPPER
PATTERN, SOME GUIDANCE SUGGESTS SOME ALIGNMENT OR PHASING, OF THESE
FEATURES COULD BOLSTER THE OVERALL TROUGH DEPTH, PARTICULARLY SHOULD
THE PHASED TROUGH AXIS THEN PHASE ADDITIONALLY WITH A WAVE MOVING
EASTWARD WITHIN THE SOUTHERN STREAM CHANNEL ON ITS SOUTHERN
PERIPHERY. SOME COMPUTER GUIDANCE SUGGESTS THAT, ADDITONALLY, THE
CLOSED UPPER LOW MAY BECOME ENTANGLED WITHIN THAT EVOLVING STRUCTURE
AT SOME POINT AS WELL.
THIS YIELDS UNUSUALLY LARGE SPREADS OF POSSIBILITIES IN TH EXTENDED
FORECAST AS THESE FEATURES COULD BEHAVE CONSTRUCTIVELY, RESULTING IN
A HIGH-END WINTER STORM, OR DESTRUCTIVELY, RESULTING LITTLE IN THE
WAY OF LIFT AND DRY AND COLD WEATHER INSTEAD. THIS IS REFLECTED IN
THE MODEL GUIDANCE QUITE WELL AND THE ENSEMBLE SPREADS ARE INDEED
QUITE LARGE WITH A FEW MEMBERS SUGGESTING MULTIPLE INCHES OF SOME
FORM OF WINTRY PRECIPITATION AND OTHER COMPLETELY DRY. THIS YIELDS
EVEN LESS CONFIDENCE THAN NORMAL IN "BLENDED", DETERMINISTIC,
GUIDANCE AS THE INPUTS CAN BE MULTIMODAL.
AS AN EXAMPLE: THE 00Z GFS SHOWS ONLY A TRACE OF SNOW FOR THE ENTIRE
AREA WHILE THE 00Z CMC MODEL SHOWS MULTIPLE INCHES FOR ALL OF THE
AREA NORTH OF I-20. A BLENDED APPROACH OF THESE TWO PIECES OF
GUIDANCE, THEN, WOULD SUGGEST PERHAPS 2-4 INCHES FOR THAT NORTHERN
AREA DESPITE NEITHER OF THE TWO INDIVIDUAL MODELS SUGGESTING THAT
SPECIFIC OUTCOME.
WHAT THIS MEANS IS THAT THERE IS A LOT OF ROOM FOR ERROR WHEN TRYING
TO PIN DOWN WHAT MIGHT HAPPEN. WINTER WEATHER FORECASTING IS
CHALLENGING VIRTUALLY EVERY TIME WE ARE LOOKING AT A RISK IN THIS
AREA, ESPECIALLY AT RANGES MORE THAN A FEW DAYS AWAY. AND DESPITE
THAT ALREADY TYPICAL LOW CONFIDENCE, THIS SITUATION IS
SUBSTANTIALLY LOWER CONFIDENCE THAN THAT.
WHAT WE DO KNOW IS IT IS ABOUT TO BE QUITE COLD (AGAIN) AND THE
POTENTIAL FOR A HIGH IMPACT WINTER WEATHER EPISODE REMAINS ON THE
TABLE FOR EVERYONE IN OUR AREA. GIVEN THAT THE COLD IS THE MOST
CONFIDENT PIECE OF THE FORECAST (WHICH IS IN ITSELF ODD AS THE
OPPOSITE CASE IS MUCH MORE COMMON), AND THE MOISTURE IS LIKELY TO
ARRIVE WITH INCREASING VALUES THE FURTHER SOUTH YOU GO, OUR FORECAST
HAZARD LIKELIHOOD RISK GRAPHICS AND MESSAGING WILL CONTINUE TO
HIGHLIGHT THE SOUTHERN PART OF THE AREA AS HIGHER CONFIDENCE AS
OPOOSED TO THE NORTH. IN ADDITION, AREAS SOUTH OF I-20 WOULD ALSO BE
CLOSER TO THE SOURCE OF WARMER, MORE MOIST AIR WHICH COULD PRESENT
ITSELF AS A NARROW TONGUE OF ABOVE FREEZING AIR JUST OFF THE
SURFACE. THAT WOULD MEAN THAT THOSE AREAS ALSO HAVE THE HIGHEST RISK
FOR ICE/FREEZING RAIN OR MIXED PRECIPITAION WHICH ARE KNOWN TO MORE
EASILY RESULT IN TRAVEL AND INFRASTRUCTURE HAZARDS.
THIS OUTLOOK WILL CERTAINLY NEED TO BE ADJUSTED AS WE MOVE INTO THE
WEEKEND AND EARLY NEXT WEEK. READERS CONTINUES TO BE ADVISED TO
EXPECT SHIFTS, PERHAPS LARGE, IN THE FORECAST IN COMING DAYS. GIVEN
THE KNOWN AND NEAR CERTAIN INCOMING HAZARD OF SIGNIFICANT COLD
WEATHER, IT IS THEREFOR PRDENT TO BEGIN PREPARING FOR EXTENDED COLD
THAT COULD INCLUDE A PERIOD OF TIME WHERE TRAVEL COULD BE HAZARDOUS
AND UTILITIES IMPACTED. /86/
AVIATION
(06Z TAFS)
ISSUED AT 1139 PM CST WED JAN 15 2025
VFR FLIGHT CATEGORIES WILL PREVAIL AT AREA TAF SITES OVER THE
NEXT 24 HOURS. WINDS OVERNIGHT WILL BE LIGHT FROM THE WEST
NORTHWEST TO CALM. WINDS WILL INCREASE THROUGH LATE THURSDAY
MORNING, BECOMING MORE WESTERLY IN GENERAL, AND SUSTAINED BETWEEN
5- 10 KNOTS. /19/
PRELIMINARY POINT TEMPS/POPS
JACKSON 61 35 62 53 / 0 0 0 80
MERIDIAN 61 33 62 50 / 0 0 0 90
VICKSBURG 61 35 62 51 / 0 0 0 60
HATTIESBURG 63 35 65 53 / 0 0 0 80
NATCHEZ 61 37 62 53 / 0 0 0 60
GREENVILLE 59 35 58 49 / 0 0 0 50
GREENWOOD 60 35 61 51 / 0 0 0 70
JAN WATCHES/WARNINGS/ADVISORIES
MS...NONE.
LA...NONE.
AR...NONE.
19/86
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