Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 011151 AAA
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
651 AM CDT SUN MAY 1 2016

.UPDATE...
FOR 12Z TAFS

&&

.DISCUSSION...
/ISSUED 420 AM CDT SUN MAY 1 2016/
PARTLY CLOUDY SKIES AND NO WEATHER OF CONSEQUENCE WAS OCCURRING
ACROSS THE CENTRAL TENNESSEE VALLEY. SHOWER/THUNDERSTORM ACTIVITY IN
PROGRESS TO OUR NORTH AND EAST WAS SLOWLY MOVING FURTHER AWAY. NO
OTHER PRECIP (AT LEAST ON RADAR) WAS FORMING TO OUR SOUTH AND WEST AS
OF LATE. BUT MORE CLOUDS WERE ENCROACHING FROM THE SW...AS A WEAK
UPPER SYSTEM...POOLING GULF MOISTURE AND LATE NIGHT STRATUS FORM AND
MOVE FURTHER INLAND. THE REGION OTHERWISE WAS IN THE WARM SECTOR OF A
WEAK WESTERN OHIO VALLEY CYCLONE...WITH ITS WARM FRONT WELL TO OUR
NORTH. SOME COLD AIR DAMMING ALONG THE EAST COAST HAD PUSHED A WEAK
BOUNDARY ACROSS WESTERN GEORGIA.

A SPLIT FLOW/AMPLIFIED MID/UPPER PATTERN CONTINUED OVER THE CONUS.
TROUGHING EXTENDED SW FROM THE GREAT LAKES TO THE 4-CORNERS. A
FLATTENING TROUGH WAS MOVING ACROSS THE EASTERN CONUS PIEDMONT AND
EAST COAST...CARRYING SHOWERS AND THUNDERSTORMS FURTHER TO THE EAST.

A TOUGH FORECAST FOR THE NEXT FEW DAYS (ESPECIALLY TODAY INTO EARLY
MONDAY). THE WATER VAPOR VIEW AND VORTICITY FORECAST INDICATED
ANOTHER WEAK TROUGH HEADING EASTWARD FROM THE LOWER MISSISSIPPI
VALLEY REGION. THIS FEATURE AS IT NEARS SHOULD BRING MORE CHANCES OF
SHOWERS AND STORMS...ESPECIALLY THIS AFTERNOON. MODEL OUTPUT...
ESPECIALLY FROM THE HIGHER RESOLUTION (HRRR/RAP/ARW) WAS INDICATING
THE BEST FORCING/LIFT NEAR AND SOUTH OF OUR AREA. SO THIS
MORNING...HAVE A RATHER SHARP GRADIENT POPS WISE WITH THE BEST RAIN
CHANCES SOUTH OF THE TENNESSEE RIVER. THOSE MODELS SOLUTIONS
DEFINITELY DIVERGE THIS AFTERNOON/EVENING. SO STAYED NEAR CONTINUITY
AFTERWARD WITH SCATTERED TO LIKELY RAIN CHANCES FOR THE REGION.

BUSINESS PICKS UP ON MONDAY...AS A STRONGER UPPER DISTURBANCE AND
ASSOCIATED SURFACE SYSTEM TRAVERSE THE SOUTHERN PLAINS...DEEP
SOUTH...AND SOUTHERN APPALACHIANS. THIS SHOULD BRING THE AREA A GOOD
CHANCE FOR MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY. THE GFS WAS
THE WETTEST AND FASTEST BRINGING MOISTURE AND INSTABILITY FROM THE
GULF COAST FURTHER INLAND...WITH THE ECMWF SHOWING A SIMILAR BUT
SLOWER TREND. WENT WITH A SLOWER TREND CLOSER TO THE EC. GIVEN
UNCERTAINTY WITH EXACT TIMING...STAYED WITH LIKELY RATHER THAN
CATEGORICAL RAIN CHANCE MON. THUNDERSTORM STRENGTH DURING THE NEXT
COUPLE OF DAYS LOOKS TO BE A LITTLE WEAKER THAN THEY WERE LAST WEEK.
THAT BEING SAID...A STRONG TO MARGINALLY SEVERE STORM CANNOT BE
TOTALLY RULED OUT WITH THE ACTIVITY LATER TODAY THROUGH MONDAY.
STRONG TO DAMAGING WIND GUSTS...AND MAYBE SOME SMALL HAIL APPEAR TO
BE THE MAIN RISK POSED BY THE MORE HEFTY STORMS.

A COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL MOVE IN A WEST TO EAST
MANNER MONDAY NIGHT...ENDING THE SHOWER ACTIVITY ON TUESDAY...AND
STARTING A TREND OF COOLER TO COLDER CONDITIONS FOR MUCH OF THE NEW
WEEK. SINCE LAST WEEK...DAILY HIGH TEMPERATURES HAVE BEEN ABOVE TO
WELL ABOVE SEASONAL NORMS (76-77F THEN)...INTO THE 80S. COLDER AIR
FILTERING IN FROM THE NORTH WILL RESULT IN HIGHS `ONLY` IN THE 70S
THIS WEEK. A REINFORCING COLD FRONT WILL SWEEP ACROSS THE REGION LATE
WED/EARLY THU...WITH HIGHS ON THU/FRI REMAINING IN THE 60S FOR FAR
NORTHERN ALABAMA AND OUR SOUTHERN MIDDLE TENNESSEE. ALONG WITH COOLER
TEMPERATURES...HAVE LIGHT SHOWERS IN FOR OUR TENNESSEE GROUP DURING
WED/WED NIGHT. AS THE COLD HIGH PRESSURE MODERATES UNDER A STRONG
EARLY MAY SUN...HIGH TEMPERATURES BY THE END OF THIS FORECAST PERIOD
(FRIDAY) SHOULD RETURN INTO THE LOW/MID 70S. NORMAL HIGHS BY THEN
SHOULD BE AROUND 80.

RSB

&&

.AVIATION...
FOR 12Z TAFS...VFR CONDS PREVAIL AT BOTH MAIN TERMINALS THIS MORNING
WITH MAINLY MID/HIGH CLOUDS IN PLACE ACROSS THE AREA. SHRA/TSRA ARE
AGAIN XPCTED LATER TODAY...ALTHOUGH EXACT TIMING REMAINS UNCERTAIN.
BEST CHC FOR CONVECTION IS LATE THIS AFTERNOON INTO EARLY THIS
EVENING...AND HAVE MAINTAINED PROB30 GROUP IN THE TAFS AFTER 21Z.
CIGS/VIS MAY BE BRIEFLY REDUCED IN/NEAR SOME OF THE HEAVIER PRECIP.
OTHERWISE...MID/HIGH CLOUDS LOOK TO REMAIN IN PLACE INTO THE EVENING
HRS...WELL AHEAD OF AN APPROACHING COLD FRONT FROM THE W. SFC FLOW
OUT OF THE SSW WILL ALSO INCREASE NEAR 10KT WITH HIGHER GUSTS THIS
AFTERNOON BEFORE DIMINISHING THIS EVENING.

09

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

$$

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE
AT WEATHER.GOV/HUNTSVILLE.


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