Potential Flurries/1/7/10 - FL SNOW 1/9/10

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Thursday



Friday morning

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12z NAM 84


12z GFS 84


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12z GFS

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Bham alert level 3 for Thursday

Quote:THERE IS CHANCE OF SNOW ON THURSDAY. OVERALL CONFIDENCE IS
INCREASING. HOWEVER...UNCERTAINTY STILL EXIST ON AMOUNTS. STAY TUNED
TO FUTURE UPDATES.

VERY COLD...POSSIBLY RECORD BREAKING AT TIMES...TEMPERATURES ARE
EXPECTED TO CONTINUE THROUGH THIS WEEK.

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BMX

Quote:AS FOR THE WINTER STORM...GUIDANCE CONTINUES TO INDICATE A
POTENTIALLY SIGNIFICANT SYSTEM IMPACTING CENTRAL ALABAMA BEGINNING
ON THURSDAY...AND ENDING EARLY FRIDAY. IT IS WAY TO EARLY TO
SERIOUSLY TALK ABOUT TOTALS BUT CONFIDENCE CONTINUES TO INCREASE
THAT A LARGE PORTION OF CENTRAL ALABAMA WILL RECEIVE SOME SNOWFALL.

FORECAST SOUNDINGS LOOK LIKE THOSE FROM THE CENTRAL OR NORTHERN
PLAINS...INDICATING ALL SNOW AS FAR SOUTH AND EAST AS TROY. THE
CRITICAL WARM NOSE ALOFT IS ONLY AROUND 0.5C WITH SURFACE WET BULB
ZERO NEAR FREEZING AS FAR SOUTH AS PIKE AND BARBOUR COUNTIES. THUS
TOOK ALL MENTION OF NON-SNOW PRECIPITATION OUT OF THE FORECAST...A
MOVE THAT I WILL LIKELY NEVER GET THE OPPORTUNITY TO MAKE AGAIN ON
THE DAY 5 FORECAST IN CENTRAL ALABAMA.

STILL SOME DISCREPANCIES WITH THE POSITION AND STRENGTH OF THE GULF
LOW THAT WILL ENHANCE OUR CHANCE OF SNOW...BUT IT IS NOW LOOKING
MORE LIKE A "HOW MUCH" FORECAST AS OPPOSED TO AN "IF" FORECAST.
WHAT IS MORE CERTAIN IS THAN ANY SNOW THAT DOES ACCUMULATE WILL
LIKELY HANG AROUND FOR SEVERAL DAYS WITH SUCH COLD TEMPERATURES IN
PLACE.

BY FRIDAY AS THE WINTER STORM PUSHES EAST...NORTHERLY WIND WILL
INCREASE. A WIND ADVISORY MAY BE NEEDED AND WIND CHILL VALUES COULD
DROP INTO THE SINGLE DIGITS.

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WOW

Quote:ONG TERM...(WEDNESDAY THROUGH SATURDAY)...NO CHANGES IN THE OFFING
FOR EXXTENDED FORECAST CONTENT. THERE IS A CHANCE OF TEMPERATURE MINIMA
WEDNESDAY TO APPROAC OR MAKE SINGLE DIGITS IN NORTH SANTA ROSA COUNTY
NEAR THE CRESTVIEW AIRPORT (CEW). EVERGREEN AIRPORT (GZH) SHOWS A
CHANCE OF REACHING 12. OTHER MINIMA IN MID TEENS TO LOWER 20S, FROM
THE INTERIOR TO THE COASTLINE RESPECTIVELY, LOOK AS IF THEY HAVE THE
APPEARANCE OF ATTAINABILITY IN THIS EVENT WEDNESDAY. WE ARE ASSUMING AT THE
MOMENT THAT CLEAR SKIES AND LOW RH WILL PREVAIL, SO ANOTHER 2 OR 3
HARD FREEZE NIGHTS ARE WITHIN THE REALM OF POSSIBILITY. SPEAKING OF
WHICH, RECORD MINIMA FOR JANUARY IN MOBILE INCLUDE 9, 3, AND 16
DEGREES F ON 20-22 JANUARY 1985, AND 18, 8, AND 15 DEGREES F ON 23-25
JANUARY 1963. THIS EARLY IN THE MONTH IT GOT DOWN TO 14 DEGREES ON
THE 6TH. THE REAL RECORD WAS 12 TO 13 FEBRUARY 1899 WHEN THE
TEMPERATURE REACHED -1 ON THE 13TH. SOME HAVE ASSERTED THAT COLD LIKE
THIS EAST OF THE ROCKIES CAN BE ASSOCIATED WITH LA NINA. 1000-850
THICKNESS ALONG INTERSTATE 10 WILL REACH 1280 M AND 1260 IN THE
NORTHERN REACHES OF THE CWA. INDEED, WE MAY BREAK SOME RECORDS.

GULF WILL OPEN UP A BIT THURSDAY TO EARLY FRIDAY. MODEL RUNS
CONTINUE TO SYNC WITH CYCLOGENESIS LIKELY OCCURING OVER THE WESTERN
GULF LATE THIS WEEK. THE CURRENT 12Z RUN SHOWS THE NEW LOW WOULD MOVE
EAST ON A TRACK OF NEAR PASSAGE NOW A BIT CLOSER, 50 -80 KM OR SO, TO
THE SOUTH. THIS TRACK WOULD LEAVE MORE OF A PHASING PROBLEM FOR SNOW
MUCH LIKE LAST TIME WE WERE CONSIDERING THE POSSIBILITY EARLIER LAST
MONTH. THE TRACK A BIT FIRTHER OUT YESTERDAY LOOKED MORE FAVORABLE TO
SNOW. AS THE SURFACE FEATURE APPROACHES THE 850 TO 300 MB THICKNESS
RISES TO ABOVE 1350 M AS WATER VAPOR LADEN AIR PUSHES UP THE 305 K
ISENTROPIC SLOPE. AS THE FEATURE PASSES IT PICKS UP SPEED...A LOT...
AND WANTS TO BRING THE HUMIDITY WITH IT BEFORE THE THICKNESS HAS A
CHANCE TO DROP BELOW 1300 M. SO AT THIS JUNCTURE IT LOOKS MORE LIKE A
COLD RAIN WITH A BIT OD SNOW MIXED IN FURTHER EAST...BUT NONE OF US
ARE READY TO SAY FOR SURE. THE NEXT MODEL RUNS MAY BE DIFFERENT AND
CONVERGE TO THIS SCENARIO...OR THEY MAY CONVERGE TO ANOTHER SCENARIO.
SO WE ARE LEAVING THE WEATHER AS IS. MUCH UNCERTAINTY STILL PLAGUES
THE FINAL OUTCOME. /77


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Nashville

Quote:NATIONAL WEATHER SERVICE NASHVILLE TN
225 PM CST SUN JAN 3 2010

.DISCUSSION...THE FRIGID WX PATTERN WILL CONTINUE THROUGH THE
ENTIRE 7 DAY FORECAST PERIOD...AND BEYOND. ALONG WITH THE
PROLONGED COLD CONDITIONS...WE HAVE HIGH CONFIDENCE FOR
ACCUMULATING SNOW LATER THIS WEEK.

AFTER A START IN THE 11-14 RANGE FOR MOST STATIONS...AND A FEW
SINGLE DIGIT SITES...TEMPS HAVE ONLY RECOVERED INTO THE 20S AGAIN
TODAY. SKIES WILL REMAIN PARTLY CLOUDY INTO TONIGHT WITH PATCHES
OF MID LEVEL CLOUDS STREAMING OVERHEAD. RADIATIONAL COOLING WILL
BE GOOD ENOUGH TO TRIM A LITTLE FROM LAST NIGHT/S LOWS. WE EXPECT
MOST MAJOR REPORTING STATIONS TO FALL IN THE 10-13 RANGE WITH
NUMEROUS OTHER SITES IN THE SINGLE DIGITS...ESPECIALLY FOR THE
VALLEYS EAST OF I 65.

FOR MONDAY THROUGH WEDNESDAY...DRY AND COLD WX IS EXPECTED. ONE
MINOR EXCEPTION MAY BE THE PLATEAU AND ADJACENT AREAS WHERE A
PERIOD OF CLOUDINESS WITH SCATTERED FLURRIES WILL OCCUR. THIS
WILL BE MONDAY NIGHT INTO TUESDAY AS THE TAIL OF A SHORTWAVE CLIPS
THE AREA. WE WILL CONTINUE TO UNDERCUT MOS TEMP VALUES MOST
PERIODS. WEDNESDAY WILL BE THE "WARMEST" DAY OF THE FORECAST
PERIOD...WITH HIGHS WELL INTO THE 30S...EXCEPT AROUND 30 PLATEAU.

OTHER THAN THE COLD...OUR MAIN CONCERN FOR THE NEXT FEW DAYS WILL
BE THE SNOW MAKER FOR THURSDAY. MODELS ARE SHOWING SOME
VARIABILITY HANDLING THIS STRONG SHORTWAVE AND COLD FRONT.
ALTHOUGH THERE ARE QUESTIONS ABOUT THE DETAILS AND EXACTLY HOW
MUCH MOISTURE WILL BE AVAILABLE...WE ARE HIGHLY CONFIDENT THAT
ACCUMULATING SNOW WILL OCCUR...WITH ALL SNOW FALLING THROUGH THIS
EVENT. ACCORDINGLY WE WILL GO WITH LIKELY POPS FOR THURSDAY. QPF
TO SNOW CONVERSION FOR THIS COLD SNOW EVENT WILL BE HIGHER THAN
NORMAL FOR MID TN (MAYBE NEAR 15:1). THIS WOULD YIELD 2-4"
SNOWFALL FROM THE 12Z GFS QPF...1-3" FROM THE ECMWF. THE GARCIA
METHOD...AND MODEL SNOW PARAMETERS SHOW 2-4" POSSIBLE WITH THIS
SYSTEM. CERTAINLY THIS CAN CHANGE BACK AND FORTH SEVERAL TIMES AS
WE APPROACH THURSDAY.

A REINFORCING SHOT OF COLD AIR WILL BLAST INTO MID TN WITH THE COLD
FRONTAL PASSAGE THURSDAY. MID TN WILL FALL EVEN DEEPER INTO THE
ICE BOX BY NEXT WEEKEND WITH LOWS DIPPING TO THE SINGLE DIGITS
FOR MANY AREAS...ESPECIALLY IF THERE IS SNOW COVER. HIGHS WILL
BARELY REACH THE 20S FOR FRIDAY AND SATURDAY AS RESIDUAL LOW
LEVEL MOISTURE AND ADDITIONAL IMPULSES MAY KEEP FLURRIES
OR SNOW SHOWERS LINGERING OVER THE AREA.