[Email1] Morning AFD from NWS BMX

Sun Jan 5 07:15:49 CST 2014

Good Morning everyone. Please remember that there is a very cold forecast
for this evening.

Here is the latest Area Forecast Discussion from this morning:

AREA FORECAST DISCUSSION
<http://forecast.weather.gov/glossary.php?word=AREA%20FORECAST%20DISCUSSION>
NATIONAL WEATHER SERVICE BIRMINGHAM AL
623 AM CST SUN JAN 5 2014

...ARCTIC FRONT <http://forecast.weather.gov/glossary.php?word=FRONT>
TO BRING WINTER WEATHER TONIGHT THROUGH EARLY MONDAY
AND DANGEROUSLY COLD TEMPERATURES THROUGH TUESDAY...

.DISCUSSION...

WOW...WHAT A FORECAST. FOR THIS FORECAST PACKAGE...WE WILL ONLY
FOCUS ON THE SHORT TERM. THIS INCLUDES THE ARCTIC FRONTAL PASSAGE
WITH CHANCES OF WINTRY PRECIP...AS WELL AS THE DANGEROUSLY COLD
TEMPERATURES GOING OUT THROUGH THE DAY ON WEDNESDAY.

FIRST OFF...ISENTROPIC UPGLIDE HAS ALLOWED FOR DEVELOPMENT OF A GOOD
MID-LEVEL CLOUD DECK ACROSS CENTRAL ALABAMA. THE CLOUDS HAVE ALLOWED
TEMPERATURES TO RISE THROUGHOUT THE MORNING INTO THE UPPER 30S TO
LOWER 40S. RISING TEMPERATURES WILL BE FEATURED THROUGHOUT THE DAY
TODAY WITH GOOD WARM AIR ADVECTION
<http://forecast.weather.gov/glossary.php?word=ADVECTION> OUT AHEAD OF
THE ARCTIC FRONT
<http://forecast.weather.gov/glossary.php?word=FRONT>.
WE SHOULD EASILY WARM INTO 50S WITH SOME LOWER 60S SOUTH...SO
PERFECT WEATHER FOR THOSE LAST-MINUTE COLD WEATHER PREPARATIONS
THAT MAY BE ONGOING OUT THERE. NOW...LET`S MOVE ON TO THE FRONTAL
PASSAGE. LATEST GUIDANCE TRENDS HAVE SLOWED DOWN THE TIMING OF
THEFRONT <http://forecast.weather.gov/glossary.php?word=FRONT> BY A
COUPLE OF HOURS...SO I HAVE REFLECTED THIS IN THE
HOURLY TEMP/DEWPOINT/WIND GRIDS ACROSS THE CWA
<http://forecast.weather.gov/glossary.php?word=CWA>. THE FIRST WIND
SHIFT IS EXPECTED TO COME INTO MARION COUNTY IN THE 6-7PM
TIMEFRAME...THEN THE I-59 CORRIDOR BY 8-9 PM...AND THE I-85
CORRIDOR BY 10-11PM. TEMPERATURES WILL PLUMMET BEHIND THE FRONT
<http://forecast.weather.gov/glossary.php?word=FRONT>
WITH WINDS HOWLING OUT OF THE NORTHWEST WELL OVER 20 KNOTS.

THE CONCERN CONTINUES FOR THE CHANCES OF WINTRY PRECIPITATION AS
THEFRONT <http://forecast.weather.gov/glossary.php?word=FRONT> MOVES
THROUGH. WE`VE LOOKED AT MANY FORECAST SOUNDINGS INAWIPS
<http://forecast.weather.gov/glossary.php?word=AWIPS> AND BUFKIT
<http://forecast.weather.gov/glossary.php?word=BUFKIT> THIS
MORNING...AND ONE ASPECT STICKS OUT THAT IS
CONCERNING TO US. AS THE FRONT
<http://forecast.weather.gov/glossary.php?word=FRONT> PLOWS THROUGH
THE TEMPERATURE AT
THE SURFACE RAPIDLY DECREASES...BUT THERE IS A LAG
<http://forecast.weather.gov/glossary.php?word=LAG> TIME WITH
COOLING ALOFT. ALSO...DRY AIR WILL BE FILTERING IN VERY QUICKLY
ALOFT. USUALLY IN A WINTER WEATHER SITUATION YOU HAVE ICE CRYSTAL
FORMATION IN THE UPPER LEVELS WHEN TEMPERATURES ARE AROUND -10C
AND COLDER WITH A SATURATED PROFILE. THEN THE ICE CRYSTALS
<http://forecast.weather.gov/glossary.php?word=ICE%20CRYSTALS> FALL
THROUGH EITHER A WARM LAYER WHICH COULD MELT THE SNOW INTO ICE
PELLETS OR ALL RAIN...OR IT STAYS FREEZING AS SNOW ALL THE WAY TO
THE SURFACE. THIS SITUATION IS LOOKING VERY DIFFERENT...WITH
TEMPERATURES WARMER THAN -10C ALOFT WHERE THE SOUNDING
<http://forecast.weather.gov/glossary.php?word=SOUNDING> PROFILE IS
SATURATED. BY THE TIME TEMPERATURES COOL TO -10C ALOFT...THERE
APPEARS TO BE TOO MUCH DRY AIR INFILTRATING INTO THE UPPER LEVELS
TO REALLY GET A GOOD SNOW GROWTH REGION TO FORM. THEREFORE...WHERE
THE SOUNDING <http://forecast.weather.gov/glossary.php?word=SOUNDING>
IS SATURATED WE ONLY HAVE SUPERCOOLED WATER DROPLETS
THAT FALL TO THE SURFACE AS FREEZING RAIN IF TEMPERATURES ARE
BELOW FREEZING.

WITH THIS IN MIND...WE`RE PRIMARILY FOCUSING ON A MAIN THREAT OF
FREEZING RAIN FOLLOWING THE PASSAGE OF THE COLD FRONT
<http://forecast.weather.gov/glossary.php?word=FRONT>. THIS IS ONLY
GOING TO BE ABOUT A 3 HOUR PERIOD OF FREEZING RAIN/FREEZING DRIZZLE.
HOWEVER...IF ENOUGH FALLS AS FLASH
<http://forecast.weather.gov/glossary.php?word=FLASH> FREEZING
CONDITIONS ENTER INTO
THE PICTURE WE COULD HAVE A BIG PROBLEM ON OUR HANDS IN TERMS OF
ROADWAY CONDITIONS AND IMPACTS. SO...WE HAVE GONE AHEAD AND INCLUDED
COUNTIES ALONG AND NORTH OF THE INTERSTATE 20 CORRIDOR WITH A WINTER
WEATHER ADVISORY FOR FREEZING RAIN...OR ALONG AND NORTH OF A LINE
FROM CARROLLTON...TO CENTREVILLE...TO ROANOKE. THE WINTER WEATHER
ADVISORY WILL ALSO COVER THE CHANCES OF SNOW AS WELL...PRIMARILY FOR
OUR NORTHEASTERN COUNTIES. ENOUGH COLD AIR AND MOISTURE
<http://forecast.weather.gov/glossary.php?word=MOISTURE> LOOKS TO
EXIST IN THE UPPER LEVELS FOR A BETTER CHANCE OF SNOWFALL FOR
THOSE AREAS UP TO ONE HALF INCH WITH SOME ISOLATED
<http://forecast.weather.gov/glossary.php?word=ISOLATED> HIGHER
AMOUNTS.
ONCE TEMPERATURES FINALLY FALL IN THE ENTIRE COLUMN...LIGHT SNOW
AND FLURRIES WILL THEN BE POSSIBLE AS THE -10C LEVEL LOWERS ALL
THE WAY TO THE SHALLOW SATURATED LAYER BETWEEN 1 AND 3K FEET. LIGHT
SNOW AND FLURRIES WILL CONTINUE TO BE POSSIBLE THROUGH THE EARLY
MORNING HOURS WHICH COULD CAUSE A DUSTING FOR AREAS PRIMARILY ALONG
AND NORTH OF I-20.

THERE ARE SEVERAL UNCERTAINTIES IN THIS FORECAST. ARE THE MODELS
CORRECTLY TAKING INTO ACCOUNT THE PLUNGE OF ARCTIC AIR? WILL THE DRY
AIR ENTER INTO THE PICTURE FASTER AND END PRECIP CHANCES FASTER?
WILL THE HOWLING 20+ KNOT
<http://forecast.weather.gov/glossary.php?word=KNOT> WINDS EVAPORATE
ANY MOISTURE <http://forecast.weather.gov/glossary.php?word=MOISTURE>
AT THE
SURFACE BEFORE IT CAN FREEZE
<http://forecast.weather.gov/glossary.php?word=FREEZE>? WE HAVE
THOUGHT ABOUT ALL THESE
SCENARIOS...AND THEY DON`T MAKE THE FORECAST PROCESS ANY EASIER.
HOWEVER...WITH ALL THE DATA THAT WE HAVE BEEN ABLE TO PROCESS THIS
MORNING WE FEEL CONFIDENT ENOUGH TO PLACE FREEZING RAIN IN THE
FORECAST AND ISSUE A WINTER WEATHER ADVISORY
<http://forecast.weather.gov/glossary.php?word=WINTER%20WEATHER%20ADVISORY>.
WE WILL CLOSELY
ANALYZE THE LATEST DATA OVER THE NEXT SIX HOURS AND UPDATE THE
FORECAST ACCORDINGLY. MAKE SURE TO VIEW OUR HOMEPAGE AS WELL AS
OUR SOCIAL MEDIA PAGES OFTEN THROUGHOUT THE DAY FOR THE LATEST
FORECAST UPDATES.

NEXT...LET`S FOCUS ON THE EXTREME COLD AND THE HAZARDS ASSOCIATED
WITH IT. REGARDLESS OF WHAT OCCURS WITH THE WINTRY PRECIP...WE WILL
BE PLUNGED INTO THE DEEP FREEZE
<http://forecast.weather.gov/glossary.php?word=FREEZE>. WIND CHILLS
ARE FORECAST TO DROP
BELOW ZERO AFTER MIDNIGHT IN OUR NORTHERN COUNTIES DUE TO 20+
KNOTSPREVAILING WINDS
<http://forecast.weather.gov/glossary.php?word=PREVAILING%20WINDS> AND
GUSTS UP TO 30 KNOTS. AS THE COLDER AIR FILTERS
IN AREAWIDE...WIND CHILLS WILL RANGE FROM NEAR ZERO TO THE SINGLE
DIGITS ALL THE WAY TO OUR FAR SOUTHERN COUNTIES. THEREFORE...WE`VE
EXPANDED IN AREA THE WIND CHILL
<http://forecast.weather.gov/glossary.php?word=WIND%20CHILL> ADVISORY
TO INCLUDE THE ENTIRE CWA
<http://forecast.weather.gov/glossary.php?word=CWA>
BEGINNING TONIGHT AND LASTING THROUGH NOON TUESDAY FOR SIMPLICITY
SAKE. THE WIND CHILLS WILL BE VERY DANGEROUS...AND WE`RE
ENCOURAGING EVERYONE TO NOT VENTURE OUTSIDE IF YOU DON`T HAVE
TO...AND LAYER ACCORDINGLY IF YOU DO. I KNOW WE DON`T TALK
ABOUTFROSTBITE <http://forecast.weather.gov/glossary.php?word=FROSTBITE>
VERY OFTEN AROUND HERE...BUT WITH THESE EXTREME TEMPS AND
WINDS FROSTBITE
<http://forecast.weather.gov/glossary.php?word=FROSTBITE> WOULDN`T BE
OUT OF THE QUESTION IF NOT PROTECTED
PROPERLY.

TEMPERATURES ARE EXPECTED TO FALL INTO THE LOWER TEENS ALONG AND
NORTH OF I-20 BY 7AM MONDAY MORNING...TO THE MID 20S ALONG THE I-85
CORRIDOR. GUIDANCE HAS COME IN WITH TEMPERATURES A COUPLE OF DEGREES
"WARMER" FOR HIGHS MONDAY AFTERNOON BUT WE`RE STILL TALKING BRUTALLY
COLD. MID TEENS NORTH TO NEAR 30 SOUTH STILL APPEAR LIKELY
<http://forecast.weather.gov/glossary.php?word=LIKELY>...WHICH
HASN`T BEEN OBSERVED IN A FEW DECADES AROUND HERE. THEN COMES THE
SINGLE DIGIT TEMPERATURES FILTERING SOUTHWARD MONDAY NIGHT. THESE
EXTREMELY COLD TEMPERATURES ARE ASSOCIATED WITH THE 1057MB
SURFACERIDGE <http://forecast.weather.gov/glossary.php?word=RIDGE>
CURRENTLY IN ALBERTA THIS MORNING THAT WILL MOVE SOUTHEASTWARD.
SINGLE DIGITS WILL BE LIKELY
<http://forecast.weather.gov/glossary.php?word=LIKELY> AS FAR SOUTH AS
ALEX CITY WITH LOWER
TEENS ACROSS THE SOUTHERN COUNTIES. WIND CHILLS WILL BE EVEN MORE
DANGEROUS DURING THIS TIME BECAUSE OF THE ACTUAL TEMPERATURES
BEING SO LOW. THICKNESSES ARE BEING ADVERTISED TO FINALLY BEGIN TO
INCREASE BY TUESDAY AFTERNOON...BUT HIGHS WILL REMAIN BELOW
FREEZING AREAWIDE. ANOTHER HARD FREEZE
<http://forecast.weather.gov/glossary.php?word=FREEZE> WILL BE IN
STORE WEDNESDAY
MORNING WITH WINDS FINALLY DIMINISHING...THEN THE STREAK OF
CONSECUTIVE HOURS OF FREEZING TEMPERATURES WILL FINALLY BE BROKEN
BY WEDNESDAY AFTERNOON.

56/GDG

-- 
Ronnie King
WX4RON
205.745.1199
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