Area Forecast Discussion
Issued by NWS Birmingham, AL

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000
FXUS64 KBMX 090005
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
605 PM CST MON FEB 8 2016

.UPDATE...
FOR 00Z AVIATION.

&&

.DISCUSSION...
.TONIGHT THROUGH TUESDAY NIGHT...

LARGE CLOSED LOW IS ROTATING OVER MUCH OF THE EASTERN CONUS THIS
AFTERNOON...WITH STRONG NORTHWESTERLY FLOW BRINGING COLD AIR AND
THE POTENTIAL FOR SNOW SHOWERS TO CENTRAL ALABAMA BEGINNING THIS
EVENING. AREA RADARS TO THE NORTH SHOWING SCATTERED LIGHT SHOWER
ACTIVITY...WITH RAINFALL MAKING IT TO THE GROUND ACROSS FAR
NORTHWEST ALABAMA. SURFACE TEMPERATURES ACROSS CENTRAL ALABAMA
ARE IN THE LOW TO MID 40S ACROSS THE NORTH...AROUND 50 DEGREES ALONG
THE I-20 CORRIDOR...AND MID TO UPPER 50S ACROSS THE SOUTH.

COLD ADVECTION WILL OCCUR AT LOW LEVELS THIS AFTERNOON AND
EVENING...WITH SURFACE TEMPERATURES SLOWER TO RESPOND. THIS WILL
DRAMATICALLY COOL TEMPS ABOVE THE SURFACE RESULTING IN STEEP LOW
LEVEL LAPSE RATES...AND THE POSSIBILITY OF ISOLATED TO SCATTERED
SHOWERS. EXPECT THIS ACTIVITY TO START AS LIGHT RAIN AND
TRANSITION TO A RAIN/SNOW FROM WEST TO EAST ACROSS NORTH CENTRAL
ALABAMA AROUND SUNSET AND QUICKLY BECOME SNOW AS THE LOWEST 1KM
AGL COOLS. IT IS POSSIBLE SNOW WILL FALL WITH SURFACE TEMPS ABOVE
FREEZING THIS EVENING. AS THE SURFACE COOLS...LAPSE RATES WILL
WEAKEN AND SHOWER COVERAGE IS EXPECTED TO DECREASE LATE TONIGHT.
AS DAYTIME HEATING INCREASES TOMORROW AND LOW CAPE VALUES ARE
REALIZED...SHOWER COVERAGE WILL EXPAND ACROSS NORTH CENTRAL
ALABAMA. BEST CHANCES WILL BE ACROSS THE NORTHEAST WHERE A
MIDLEVEL MOISTURE MAX WILL ROTATE AROUND THE CLOSED LOW. ACROSS
SOUTH CENTRAL ALABAMA...CANT RULE OUT FLURRIES OR EVEN A BRIEF
LIGHT SHOWER...BUT CONFIDENCE IN AVAILABLE MOISTURE IS TOO LOW TO
INCLUDE A MENTION OF PRECIPITATION IN THE FORECAST.

GIVEN THE CONVECTIVE NATURE OF THIS ACTIVITY...SHOWER ACTIVITY
WILL NOT BE CONTINUOUS...AND ANY SNOW ACCUMULATIONS WILL NOT BE
UNIFORM. IT IS POSSIBLE A PORTION OF THE AREA WILL NOT SEE ANY
PRECIPITATION FALL. A HEAVIER SHOWER MIGHT RESULT IN A QUICK
0.25-0.5 INCH OF SNOW IN A VERY LOCALIZED AREA. GIVEN THE
UNCERTAINTY IN COVERAGE AND ISOLATED ACCUMULATIONS...WE WILL NOT
BE ISSUING A WINTER WEATHER ADVISORY THIS AFTERNOON. WE WILL RE-
ASSESS MODEL AND RADAR TRENDS OVERNIGHT FOR ANY AREAS THAT COULD
BECOME A FOCUS FOR TRAINING SNOW SHOWERS AND GREATER ACCUMULATIONS
DURING THE DAY TOMORROW.

TEMPERATURES WILL FALL TONIGHT INTO THE MID 20S TO LOWER 30S.
WINDS WILL REMAIN ELEVATED OVERNIGHT...AROUND 10MPH...AND BRING
WIND CHILL VALUES DOWN AREAWIDE INTO THE UPPER TEENS AND LOWER 20S
AROUND SUNRISE TOMORROW MORNING. CONTINUED COLD ADVECTION AND
CLOUD COVER WILL RESULT IN TEMPERATURES STRUGGLING TO WARM ABOVE
FREEZING TOMORROW AFTERNOON ACROSS THE NORTH. ACROSS THE
SOUTH...EXPECT LOWER 40S FOR AFTERNOON HIGHS. INCREASED WINDS
CONTINUE THROUGH THE DAY...AND DO NOT EXPECT WIND CHILL VALUES TO
RISE ABOVE FREEZING TOMORROW.

MOISTURE PULLS OUT TUESDAY NIGHT...AND SNOW SHOWER COVERAGE WILL
END FROM WEST TO EAST THROUGH THE EVENING HOURS. OVERNIGHT LOWS
WILL FALL INTO THE 20S AREAWIDE BY SUNRISE WEDNESDAY MORNING.

14

.WEDNESDAY THROUGH SUNDAY...

NORTHWESTERLY FLOW WILL CONTINUE INTO THE EXTENDED PART OF THE
FORECAST WITH A WARMING TREND BEGINNING ON WEDNESDAY...THOUGH IT MAY
NOT FEEL LIKE IT INITIALLY. A CHILLY AFTERNOON ON WEDNESDAY WILL
LEAD INTO A COLD NIGHT WITH LIGHT WINDS AND RADIATIONAL COOLING.
LOWS ARE EXPECTED TO RANGE FROM THE UPPER TEENS TO THE MID 20S. AS A
LARGE TROUGH OVER THE EASTERN CONUS RELAXES A BIT...WINDS IN THE
LOWER LEVELS WILL BECOME WESTERLY FOR THURSDAY INTO FRIDAY WITH MUCH
WARMER TEMPERATURES EXPECTED. HOWEVER...THIS WILL BE SHORT-LIVED
WITH MODELS INDICATING AN EXTREMELY COLD AIRMASS PLUNGING SOUTHWARD
FROM CANADA ON SATURDAY AS A LARGE VORTEX DEVELOPS OVER THE
NORTHEAST CONUS. THOUGH THE BRUNT OF THE COLD WILL STAY TO OUR
EAST...WE SHOULD STILL FEEL A SUBSTANTIAL CHILL ACROSS ALABAMA OVER
THE WEEKEND.

THERE IS GROWING SUPPORT FOR A SIGNIFICANT EPISODE OF WARM ADVECTION
ALOFT ON SUNDAY NIGHT INTO MONDAY AS A PLAINS SHORTWAVE APPROACHES
THE BACK SIDE OF THE EASTERN TROUGH. THIS SYSTEM WILL HAVE TO BE
WATCHED CAREFULLY WITH SUCH COLD ANTECEDENT CONDITIONS IN PLACE.
TIMING OF THIS WAVE IS UNCLEAR BUT IT DOES SEEM LIKELY THAT
PRECIPITATION WILL OCCUR AT SOME POINT BETWEEN SUNDAY NIGHT AND
TUESDAY...AND HAVE INTRODUCED 20-30 POPS WITH RAIN AND SNOW SUNDAY
NIGHT INTO MONDAY.

87/GRANTHAM

&&

.AVIATION...
00Z TAF DISCUSSION.

GUSTY WINDS FROM THE WNW WILL LESSEN SOMEWHAT OVERNIGHT AS HIGH
PRESSURE CONTINUES TO BUILD IN. CEILINGS WILL AVERAGE AROUND 5K TO
8K. A FEW LIGHT BANDS OF SNOW MAY BE POSSIBLE OVER THE NEXT 24
HOURS BUT NOTHING PREDOMINANT. WIND GUSTS WILL PICK UP AGAIN
TOMORROW MORNING AT AROUND 20 KTS FROM THE WEST TO NORTHWEST.

88

&&

.FIRE WEATHER...

NO FIRE WEATHER CONCERNS ARE EXPECTED AT THIS TIME. A STRONG
UPPER LEVEL SYSTEM WILL DOMINATE THE WEATHER ACROSS THE EASTERN
UNITED STATES EARLY THIS WEEK AND BRING MUCH COLDER TEMPERATURES
INTO CENTRAL ALABAMA THROUGH WEDNESDAY. PRECIPITATION CHANCES
RETURN TO PORTIONS OF THE AREA DURING THIS AFTERNOON...WITH THE
SYSTEM FINALLY EXITING LATE TUESDAY. BEST PRECIPITATION CHANCES
WILL BE ACROSS THE NORTH. PRECIPITATION WILL START AS A RAIN SNOW
MIX AND QUICKLY TRANSITION TO ALL SNOW THIS EVENING. ACTIVITY WILL
BE SHOWERS...AND WILL NOT BE CONTINUOUS. LIGHT ACCUMULATIONS
UNDERNEATH A HEAVIER SHOWER IS POSSIBLE. WINDS WILL BE GUSTY
THROUGH THIS EVENING FROM THE WEST TO NORTHWEST...DIMINISHING
SLIGHTLY OVERNIGHT AND TOMORROW.

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$


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