275
FXUS63 KLMK 200820
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
320 AM EST THU FEB 20 2025
KEY MESSAGES
* SNOW SHOWERS WILL GRADUALLY TAPER OFF THIS MORNING, WITH LITTLE
IF ANY ADDITIONAL ACCUMULATION.
* ANOTHER COLD NIGHT TONIGHT WITH LOWS IN THE SINGLE DIGITS.
* MOSTLY DRY WEATHER THROUGH THE WEEKEND INTO EARLY NEXT WEEK.
TEMPERATURES WILL RISE ABOVE FREEZING FRIDAY OR SATURDAY, WITH
ABOVE NORMAL TEMPS NEXT WEEK.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 320 AM EST THU FEB 20 2025
SCATTERED LIGHT SNOW SHOWERS WILL CONTINUE TO BE POSSIBLE THIS
MORNING, PRIMARILY OVER THE BLUE GRASS, WITH SFC-850MB MOISTURE
PRESENT, THE UPPER LOW STILL NEARBY OVER THE UPPER OHIO VALLEY, AND
A LITTLE BIT OF HELP FROM FLOW OFF OF LAKE MICHIGAN. SNOW SHOWERS
LOOK LESS LIKELY THIS AFTERNOON AS AVAILABLE MOISTURE DECREASES
SLIGHTLY, THE UPPER LOW MOVES FARTHER AWAY, AND THE COMPONENT OF
FLOW OFF THE LAKE LESSENS...THOUGH SCT/BKN STROTOCU WILL PERSIST
UNTIL EARLY EVENING. NORTHWEST SURFACE WINDS FROM VERY STRONG
CANADIAN HIGH PRESSURE OVER THE MID-MISSOURI VALLEY ALONG WITH ONLY
PARTIAL SUNSHINE WILL GIVE US ANOTHER COLD DAY, WITH AFTERNOON
READINGS PEAKING AROUND TWENTY DEGREES.
TONIGHT THE SURFACE HIGH WILL BUILD DIRECTLY EAST INTO THE OHIO
VALLEY, CLEARING SKIES. WITH THE LOSS OF CLOUD COVER, LESSENING
WINDS, AND CONTINUING FRESH SNOW PACK, IT WILL BE ANOTHER FRIGID
NIGHT. WENT BELOW GUIDANCE WITH LOWS IN THE SINGLE DIGITS.
LONG TERM /FRIDAY THROUGH WEDNESDAY/
ISSUED AT 320 AM EST THU FEB 20 2025
SYNOPSIS...THE ACTIVE WEATHER PATTERN EXPERIENCED DURING THE LAST
SEVEN DAYS WILL SHORTLY COME TO AN END AS STRONG SURFACE HIGH
PRESSURE BUILDS OVER THE REGION THIS WEEKEND AND A MID-LEVEL RIDGE
ESTABLISHES ALONG THE WEST COAST AND THE CENTRAL US. AS A RESULT,
SHORTWAVE ENERGY INTRUSION WILL REMAIN MUTED WITH WEAK VORTICITY
ENERGY TRACKING FURTHER NORTH. BEST CHANCE FOR PATTERN AMPLIFICATION
WILL PROBABLY ARRIVE BY THE MIDDLE OF NEXT WEEK AS A DECENT PACIFIC
NW TROUGH MOMENTARILY BREAKS THE RIDGE AND ADVANCES TOWARDS THE EAST
COAST WHERE IT IS EXPECTED TO ELONGATE THANKS TO CONSTRUCTIVE
INTERFERENCE FROM ADDITIONAL SHORTWAVE ENERGY. THE AFOREMENTIONED
SCENARIO WILL LEAD TO WARMING TEMPERATURES AND INCREASING RAIN
CHANCES.
MODEL EVALUATION/CONFIDENCE...FORECAST CONFIDENCE REMAINS HIGH FOR
THE WEEKEND AND EARLY NEXT WEEK GIVEN GOOD MODEL AGREEMENT ON
TEMPERATURES AND LACK OF PRECIPITATION CHANCES. ON THE OTHER HAND,
DETERMINISTIC GUIDANCE STARTS TO DIVERGE BY THE MIDDLE OF NEXT WEEK
REGARDING THE INTENSITY, POSITION, AND STRUCTURE OF THE AMPLIFYING
MID-LEVEL TROUGH AND ASSOCIATED SURFACE LOW. THIS, IN TURN, HAS
IMPLICATIONS IN THE QPF SIGNAL OVER THE OHIO VALLEY. SO FAR, THE
LATEST GFS RUN (20/0Z) PRESENTS THE STRONGEST SURFACE LOW AND
WETTEST QPF FOOTPRINT WHILE THE ECMWF AND ESPECIALLY CMC ARE WEAKER
AND DRIER. ALL IN ALL, THERE IS SUFFICIENT MODEL-TO-MODEL AND RUN-TO-
RUN VARIABILITY TO ARGUE FOR LOW CONFIDENCE IN THE LATTER PORTION OF
THE FORECAST.
FRIDAY - SUNDAY...AFTER A FRIGID MORNING ON FRIDAY WITH SINGLE DIGIT
TEMPERATURES, HIGHS IN THE AFTERNOON WILL CLIMB TO THE FREEZING
POINT AS SURFACE HIGH PRESSURE PROVIDES DRY WEATHER WITH MUCH NEEDED
SOLAR RADIATION (AMID A THIN MID-LEVEL CLOUD LAYER). TEMPERATURES
WILL CONTINUE TO WARM UP SATURDAY AND SUNDAY AS THE SURFACE HIGH
MOVES TO THE SOUTHEAST AND LOW-LEVEL WINDS SHIFT TO THE SOUTHWEST.
ALTHOUGH A SMALL-AMPLITUDE VORT MAX WILL TRANSITION THROUGH THE
LOWER OHIO VALLEY SATURDAY MORNING, LACK OF LOW-LEVEL MOISTURE AND
HIGH STABILITY WILL MOST LIKELY PRECLUDE PRECIPITATION REACHING THE
SURFACE WITH ECMWF P-TYPE METEOGRAMS SHOWING LESS THAN 5% OF SNOW
CHANCES FOR LOUISVILLE OR LEXINGTON.
NEXT WEEK...SURFACE HIGH PRESSURE WILL CONTINUE TRACKING AND
WEAKENING ACROSS THE SOUTHEAST US WHILE A LOW PRESSURE AREA MOVES IN
FROM THE NORTH, ACCOMPANYING NORTHERN-STREAM SHORTWAVE TROUGHS OVER
THE GREAT LAKES. THIS WILL LEAD TO A SLOWLY STRENGTHENING PRESSURE
GRADIENT FORCE AND ENHANCED THETA-E ADVECTION. LIGHT RAIN CHANCES
WILL BRIEFLY RETURN TO THE FORECAST ON TUESDAY AS A WEAK COLD FRONT
APPROACHES FROM THE MIDWEST. HOWEVER, THE BEST CHANCES OF LIGHT TO
MODERATE RAINFALL ARE MORE LIKELY WEDNESDAY INTO THURSDAY AS A LOW
PRESSURE TRACKS NEAR OR OVER THE LOWER OHIO VALLEY. EVEN THOUGH
CONFIDENCE IN RAINFALL AMOUNTS AND LOCATION IS LOW AT THE MOMENT, IT
IS WORTH MONITORING THE EVOLUTION OF THIS SYSTEM GIVEN THE CURRENT
STATE OF RIVERS IN THE AREA.
AVIATION /06Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 1220 AM EST THU FEB 20 2025
STRATIFORM SNOW WILL STEADILY PUSH EAST DURING THE FIRST COUPLE
HOURS OF THE TAF PERIOD, FOLLOWED BY SEVERAL HOURS OF SCATTERED SNOW
SHOWERS. CEILINGS WILL BE VARIABLE, BUT SHOULD PREVAIL A FEW HUNDRED
FEET EITHER SIDE OF 2K'. THOUGH THE SNOW SHOWERS WILL TAPER OFF
EARLY THIS MORNING, STRATOCU WILL LIKELY PERSIST THROUGH MUCH OF THE
DAY THANKS TO 925-850MB RH TRAPPED UNDER A SHARP INVERSION. SKIES
WILL FINALLY CLEAR THIS EVENING AS A VERY STRONG DOME OF CANADIAN
HIGH PRESSURE APPROACHES FROM THE MID-MISSOURI VALLEY.
LMK WATCHES/WARNINGS/ADVISORIES
KY...WINTER WEATHER ADVISORY UNTIL 7 AM EST /6 AM CST/ THIS MORNING
FOR KYZ023>043-045>049-053>057-063>067-077-078.
COLD WEATHER ADVISORY UNTIL 11 AM EST /10 AM CST/ THIS MORNING
FOR KYZ023>043-045>049-053>057-061>067-070>078-081-082.
IN...WINTER WEATHER ADVISORY UNTIL 7 AM EST /6 AM CST/ THIS MORNING
FOR INZ076>079-083-084-089>092.
COLD WEATHER ADVISORY UNTIL 11 AM EST /10 AM CST/ THIS MORNING
FOR INZ076>079-083-084-089>092.
SHORT TERM...13
LONG TERM...ALL
AVIATION...13
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