Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 112005
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
205 PM CST THU FEB 11 2016

.DISCUSSION...

HIGH PRESSURE AND A DRYING NORTHWEST TO NORTH FLOW WILL KEEP
CENTRAL ALABAMA DRY FOR THE NEXT SEVERAL DAYS. THE BULK OF THE
FOCUS OF THE FORECAST OVER THE NEXT 7 DAYS REMAINS THE SYSTEM
COMING IN HERE LATE SUNDAY INTO EARLY TUESDAY...AND THE
PRECIPITATION TYPE ISSUES THAT ACCOMPANY IT.

THE WEEKEND SURFACE AIR MASS WILL BE MARKED AS BEING QUITE DRY AND
COLD. A LARGE SURFACE HIGH IS FORECAST TO SETTLE ITSELF ALONG THE
MID-ATLANTIC COAST BY 00Z SUNDAY...IN A FAIRLY GOOD CAD/WEDGE
POSITION. MEANWHILE...A RATHER SIGNIFICANT SHORTWAVE TROUGH IS
FORECAST TO DROP INTO THE LOWER MS VALLEY ON MONDAY...AND SWING
ACROSS THE SOUTHEAST STATES MONDAY NIGHT. WHILE THE MODELS ALL
AGREE IN A GENERAL SENSE ON THE EXISTENCE OF THIS SHORTWAVE...
THEY ARE STILL A BIT APART ON THE SPATIAL AND TEMPORAL DETAILS.
THESE DIFFERENCES ALSO LEAD TO DIFFERENCES ON THE SURFACE
REFLECTION OF THE SHORTWAVE...NAMELY THE TRACK AND TIMING OF AN
ASSOCIATED SURFACE LOW.

JUDGING FROM PAST FORECAST DISCUSSIONS... IT SEEMS AS THOUGH THE
TREND HAS BEEN FOR THE MODELS TO BRING THE SURFACE LOW TRACK
FARTHER NORTH WITH TIME. THE 12Z RUNS OF THE ECMWF AND GFS SUGGEST
THAT THE LOW SHOULD TRACK FAR ENOUGH NORTH SO THAT WARM ADVECTION
SHOULD OVERWHELM THE RESIDUAL DRY/COLD AIR MASS THAT HAD
PREVIOUSLY BEEN IN PLACE. THUS...A MOSTLY LIQUID (NON-WINTRY)
FORECAST REMAINS THE MOST LIKELY OUTCOME. I WILL LEAVE THE MENTION
OF SLEET (SLIGHT CHANCE) IN FOR WHEN THE RAIN FIRST ARRIVES....TO
ACCOUNT FOR THE (SEEMINGLY) RANDOM SLEET REPORTS WE GET WHEN
SYSTEMS SUCH AS THIS FIRST ARRIVE. GROUND TEMPS ARE EXPECTED TO
BE ABOVE FREEZING AT THE TIME...AND GO UP EVEN MORE AS THE DAY
PROGRESSES...SO NO ISSUES ARE EXPECTED. ONE THING TO
WATCH...HOWEVER...WILL BE THE STRENGTH OF THE CAD WEDGE. A
STRONGER WEDGE WOULD MEAN LOWER TEMPS AND DEWPOINTS (WHICH MEANS
LOWER WETBULB TEMPS) IN THE EAST...WHICH COULD INSERT AN ICIER
SURPRISE INTO THE PICTURE.

ONCE THAT SYSTEM EXITS THE AREA ON TUESDAY...THE UPPER LEVEL
PATTERN ACTUALLY SHIFTS TO A MORE ZONAL SITUATION. THIS SHOULD...
IN TURN...LET TEMPS MODERATE QUITE A BIT TOWARD THE END OF THE
NEXT WEEK.

/61/

&&

.AVIATION...
18Z TAF DISCUSSION.

VFR CONDITIONS WILL PREVAIL THRU THE PERIOD. A WEAK FRONTAL
BOUNDARY IS DRAPED WEST-EAST ACROSS THE FORECAST AREA LEADING TO
LIGHT/VARIABLE WINDS FOR THE NORTHERN TERMINALS. WINDS REMAIN OUT
OF THE WSW AROUND 7-10 KTS IN THE SOUTH. EXPECT LIGHT WINDS AREA
WIDE OVERNIGHT WITH AN INCREASE IN CLOUD COVER.

19


&&

.FIRE WEATHER...

NO FIRE WEATHER CONCERNS ARE EXPECTED AT THIS TIME. STRONGER
WINDS ARE EXPECTED ON FRIDAY BUT RELATIVE HUMIDITY VALUES SHOULD
REMAIN ABOVE 30 PERCENT AGAIN. A MUCH DRIER...ARCTIC AIRMASS WILL
MOVE INTO THE REGION ON SATURDAY WITH DEW POINTS IN THE SINGLE
DIGITS AND BRISK NORTHERLY WINDS.

&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     31  57  27  37  22 /   0  10   0   0   0
ANNISTON    34  58  28  39  23 /   0  10   0   0   0
BIRMINGHAM  35  59  28  39  23 /   0   0   0   0   0
TUSCALOOSA  37  62  31  43  24 /   0   0   0   0   0
CALERA      38  61  31  42  25 /   0   0   0   0   0
AUBURN      41  64  32  44  26 /   0  10   0   0   0
MONTGOMERY  42  68  35  48  27 /   0   0   0   0   0
TROY        46  68  36  49  27 /   0   0   0   0   0

&&

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

&&

$$


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