Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 031033
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
533 AM CDT TUE MAY 3 2016

.DISCUSSION...
CURRENT SATELLITE DATA INDICATES THAT A POSITIVELY SHEARED MID-LEVEL
LONGWAVE TROUGH REMAINS IN PLACE ACROSS MUCH OF THE EASTERN CONUS
THIS MORNING -- EXTENDING FROM ONTARIO/QUEBEC SOUTHWESTWARD INTO THE
SOUTHERN ROCKIES. THIS HAS EFFECTIVELY MAINTAINED SOUTHWEST FLOW
ALOFT AND WEAK ASCENT ACROSS THE CENTRAL TN VALLEY...WITH A FAIR
AMOUNT OF STRATUS/ALTOSTRATUS CLOUDS NOTED -- EVEN IN THE WAKE OF A
COLD FRONT NOW EXITING THE SOUTHEASTERN COUNTIES. ALTHOUGH THE
THREAT FOR RESIDUAL SHOWER ACTIVITY ASSOCIATED WITH THE COLD FRONT
SHOULD END BEFORE 12Z...SHORT TERM MODEL GUIDANCE REMAINS CONSISTENT
IN FORECASTING A PAIR OF MID-LEVEL VORTICES -- CURRENTLY DROPPING
SOUTHWARD ACROSS NE/KS -- TO MAINTAIN ELEVATED FORCING FOR ASCENT
ACROSS THE REGION TODAY AS THEY CONGEAL INTO A SINGLE WAVE AND
TRAVEL SOUTHEASTWARD ACROSS THE CENTRAL PLAINS. THIS MAY LEAD TO A
REGENERATION OF ISOLATED SHOWER ACTIVITY DURING PEAK OF THE DIURNAL
WARMING CYCLE THIS AFTERNOON...BUT WITH PWAT VALUES IN THE 0.5-0.75
INCH RANGE AND LACK OF A LOW-LEVEL FORCING MECHANISM WE WILL KEEP
POPS AROUND 20%. ISOLATED SHOWERS MAY CONTINUE INTO THE EARLY
EVENING BEFORE DISSIPATING AS THE BOUNDARY LAYER COOLS/STABILIZES
AND AXIS OF THE MID-LEVEL WAVE CROSSES TO THE SOUTHEAST OF THE
FORECAST AREA.

BY TOMORROW...A MID-TROPOSPHERIC RIDGE POSITIONED ACROSS THE ROCKIES
IS FORECAST TO AMPLIFY FURTHER DOWNSTREAM FROM ANOTHER LONGWAVE
TROUGH APPROACHING THE PACIFIC COAST. THIS WILL LEAD TO
AMPLIFICATION OF TROUGH ACROSS THE EASTERN CONUS...WITH A MORE
INTENSE VORT MAX EMBEDDED WITHIN THE TROUGH EXPECTED TO DIG SOUTHWARD
ACROSS THE CENTRAL GREAT LAKES REGION TUESDAY NIGHT/WEDNESDAY AND
INTO THE SOUTHERN APPALACHIANS BY 12Z THURSDAY. A STRONG REINFORCING
COLD FRONT RELATED TO THIS FEATURE SHOULD ARRIVE IN THE NW PORTION OF
THE CWFA BY 00Z THURSDAY...WITH A GUSTY WEST WIND AND MOSTLY SUNNY
SKIES PRIOR TO FROPA ALLOWING TEMPS TO WARM INTO THE LOWER 70S EARLY
WEDNESDAY AFTERNOON. ALTHOUGH DEEP-LAYER MOISTURE WILL REMAIN FAIRLY
LIMITED... STRONG CONVERGENCE ALONG THE APPROACHING COLD FRONT
COUPLED WITH SIGNIFICANT HEIGHT FALLS ALOFT SHOULD SUPPORT THE
DEVELOPMENT OF A BAND OF SHOWERS AND A FEW THUNDERSTORMS ALONG THE
ADVANCING FRONT. POPS HAVE BEEN TAILORED TO REFLECT EXPECTED POSITION
OF FRONT AROUND 00Z THURSDAY...WITH LINGERING EVENING SHOWERS/STORMS
CONFINED TO SOUTHEASTERN PORTION OF THE FORECAST AREA. ALTHOUGH
FORECAST SOUNDINGS SUGGEST THAT MLCAPE WILL PEAK IN THE 250-500 J/KG
RANGE... DRY ADIABATIC LAPSE RATES IN THE BOUNDARY LAYER MAY ENHANCE
DOWNWARD TRANSFER OF HIGHER MOMENTUM AIR ALOFT WITH WIND GUSTS OF
30-40 MPH POSSIBLE IN ANY STRONGER STORMS.

THE UPPER LOW IS PREDICTED TO DIG SOUTHEASTWARD INTO GEORGIA AND THE
CAROLINAS ON THURSDAY BEFORE LIFTING NORTHEASTWARD ALONG THE MID-
ATLANTIC COAST THURSDAY NIGHT. A FEW SHOWERS WILL STILL BE POSSIBLE
IN THE EAST ON THURSDAY...AS LINGERING MID-LEVEL ASCENT ASSOCIATED
WITH THE UPPER LOW MAY INTERACT WITH ENHANCED ORAGRAPHIC LIFT
GENERATED BY 10-15 KNOT NNW FLOW IN THE LOW-LEVELS. EVEN STRONGER
WINDS ARE ANTICIPATED DURING THIS PERIOD IN ELEVATED TERRAIN ABOVE
1000 FT... BUT FORECAST GRIDS ARE JUST BELOW WIND ADVISORY CRITERIA
AT THIS POINT. THE REMAINDER OF THE PERIOD FROM THURSDAY NIGHT-
SATURDAY WILL FEATURE DRY/TRANQUIL WEATHER AS A SURFACE RIDGE BUILDS
SOUTHEASTWARD FROM THE OZARKS INTO THE CENTRAL GULF COAST AND 500-MB
HEIGHTS RISE WITH THE APPROACH OF A SHORTWAVE RIDGE FROM THE SOUTHERN
PLAINS. STRONG LOW-LEVEL COLD ADVECTION WILL PREVENT HIGHS FROM
REACHING 70 ON THURSDAY...BUT A STEADY WARMING TREND IS EXPECTED INTO
THE WEEKEND WITH TEMPS REACHING THE U70S/L80S BY SATURDAY. ELEVATED
NNW WINDS MAY PREVENT THE FULL IMPACT OF RADIATIONAL COOLING FROM
BEING REALIZED THURSDAY NIGHT...BUT LOWS SHOULD STILL FALL INTO THE
L/M 40S. DURING THE END OF THE EXTENDED PERIOD...DEVELOPING SOUTHWEST
FLOW ALOFT WILL TRANSLATE TO AN INCREASE IN LOW/MID-LEVEL MOISTURE --
WHICH SHOULD RESULT IN HIGHER CHANCES FOR SHOWERS/THUNDERSTORMS EARLY
NEXT WEEK. WE WILL NEED TO WATCH THE SUNDAY AFTERNOON/EVENING PERIOD
CLOSELY FOR INCLUSION OF POPS IN FUTURE FORECASTS...AS REMNANT
OUTFLOW BOUNDARY FROM A LARGE MCS OVER THE OHIO VALLEY SATURDAY NIGHT
MAY APPROACH THE REGION DURING THIS PERIOD. HOWEVER...A MORE ACTIVE
CONVECTIVE PATTERN WILL LIKELY UNFOLD MONDAY NIGHT-TUESDAY.

70/DD

&&

.AVIATION...
/ISSUED 1155 PM CDT MON MAY 2 2016/
FOR 06Z TAFS...BOTH HSV AND MSL WILL CONTINUE WITH BORDERLINE IFR
CEILINGS AND MVFR CEILINGS UNTIL BETWEEN THE 11Z-12Z TIME FRAME.
MVFR CEILINGS ARE THEN EXPECTED AT BOTH HSV AND MSL UNTIL THE 15Z-16Z
TIME PERIOD...WHEN VFR CONDITIONS ARE THEN EXPECTED THROUGH THE END
OF THE FORECAST PERIOD.

TT

&&

.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE    71  50  72  47 /  20  20  40  30
SHOALS        71  50  73  48 /  20  20  50  20
VINEMONT      70  49  71  47 /  20  20  30  40
FAYETTEVILLE  68  47  69  45 /  20  20  50  20
ALBERTVILLE   70  51  71  47 /  20  20  20  40
FORT PAYNE    71  46  70  45 /  20  20  30  40

&&

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

$$

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



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