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000
FXUS64 KHUN 201505 AAB
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1005 AM CDT MON MAY 20 2013

.UPDATE...
MORNING UPDATE.

&&

.DISCUSSION...
TEMPERATURES ACROSS THE TENNESSEE VALLEY ARE SLOW TO RISE THIS
MORNING THANKS TO THE LOW CLOUD DECK ENCOMPASSING MUCH OF THE AREA.
AS A RESULT, HOURLY TEMPERATURES ARE LAGGING 4-6 DEGREES BELOW WHAT
WAS ORIGINALLY FORECAST. IN ADDITION, MORNING FOG IS FINALLY
DISSIPATING ACROSS PORTIONS OF NORTHEASTERN ALABAMA AND SOUTHERN
MIDDLE TENNESSEE (AND HAS BEEN FORMALLY REMOVED FROM THE FORECAST).
ONCE THE CLOUDS CLEAR BY MIDDAY, TEMPERATURES WILL QUICKLY RESPOND TO
THE INSOLATION, TOPPING OUT IN THE MIDDLE TO UPPER 80S.

WITH UPPER LEVEL RIDGING BUILDING INTO THE REGION FROM THE WEST, A
DRY FORECAST IS EXPECTED TODAY. OTHER THAN CHANGES TO HOURLY GRIDS
AND TWEAKS TO MORNING SKY GRIDS, THE REST OF THE FORECAST HANDLES
BOTH ONGOING/EXPECTED TRENDS FOR TODAY.

WILL RESEND THE ZONES SHORTLY.

12

&&

.AVIATION...
/ISSUED 613 AM CDT MON MAY 20 2013/
LOW CLOUDS RAPIDLY DEVELOPING/ADVECTING ACROSS NRN AL WITH CIGS
GENERALLY BETWEEN 008-015 AGL. BELIEVE MVFR CIGS /1000-2000FT/ WILL
PREVAIL...BUT COULD SEE PERIODIC DIPS TO IFR CAT (NOT ENOUGH TO
MENTION AT EITHER TERMINAL). SHORT RANGE /RAP/ MODELS SHOWING
MOISTURE AND LOW CIGS COULD HANG AROUND THROUGH 15-17Z. BY 17Z...SRLY
WINDS WILL PICK UP AND HEATING WILL DISSIPATE MAJORITY OF SHALLOW LOW
CLOUDS. VFR CONDITIONS WILL THEN PREVAIL THROUGH 12Z/TUES...THOUGH
LOW CLOUDS AND SHALLOW FOG COULD REDEVELOP BRIEFLY ONCE AGAIN TOWARD
DAYBREAK.

DJN.83

&&

.PREV DISCUSSION...
/ISSUED 402 AM CDT MON MAY 20 2013/
AN UNSEASONABLY DEEP MID/UPPER LOW OVER THE NORTHERN PLAINS HELPED
TO PRODUCE AN EPISODE OF SEVERE WEATHER ACROSS THE GREAT PLAINS. A
REPEAT IS EXPECTED TODAY A BIT FURTHER EAST...AS THIS LOW SLOWLY
TRACKS TO THE EAST. HOWEVER...BROAD UPPER RIDGING OVER THE EAST COAST
WAS HELPING TO BRING WARM CONDITIONS ACROSS THE MOST OF THE DEEP
SOUTH. A WEAK DISTURBANCE IN THIS RIDGE...NOTED FROM GEORGIA TO
VIRGINIA WAS RESPONSIBLE FOR THUNDERSTORMS AND HEAVY RAINFALL...
MAINLY JUST TO OUR EAST. YESTERDAY...DOPPLER RADAR INDICATED THIS
SYSTEM LIKELY PRODUCED OVER 5 INCHES ACROSS PARTS OF EASTERN TN...NW
GA...AND FAR NE AL. RESIDUAL MOISTURE FROM THAT RAIN HAS RESULTED IN
AREAS OF FOG...SOME LOCALLY DENSE AFFECTING PARTS OF NE ALABAMA.
LIGHTER FOG/MIST WAS DEVELOPING ELSEWHERE. OVERNIGHT LOWS SO FAR HAVE
FALLEN INTO THE UPPER 50S TO UPPER 60S WITH LIGHT WINDS.

THE UPPER DISTURBANCE EAST OF THE REGION SHOULD PROGRESS FURTHER TO
THE EAST TODAY...HELPING TO END RAIN CHANCES ACROSS THIS PART OF THE
TENNESSEE VALLEY TODAY. WITH UPPER RIDGING IN PLACE...AND SURFACE
HIGH PRESSURE TO OUR EAST...MORE WARM/MUGGY CONDITIONS ARE EXPECTED
TODAY. HIGHS SHOULD WARM INTO THE MID/UPPER 80S UNDER PARTLY CLOUDY
SKIES. SOMEWHAT WARMER CONDITIONS ARE FORECAST FOR TUE...WITH HIGHS
NEARING 90 ACROSS PARTS OF NW ALABAMA. A SOUTHERLY 5-15 MPH FLOW WILL
CONTINUE A FEED OF MOISTURE ACROSS THE REGION. SURFACE DEWPOINTS ARE
EXPECTED TO RISE INTO THE MID/UPPER 60S TODAY...AND MID 60S ON TUE...
WITH CORRESPONDING HEAT INDICES INTO THE UPPER 80S/LOWER 90S.

THE SYSTEM FORECAST TO BRING MORE STRONG STORMS TO THE GREAT PLAINS
TODAY AND ON TUE. AS A COLD FRONT WITH THIS SYSTEM NEARS...RAIN
CHANCES WILL RETURN TO THIS REGION TUE AFTERNOON...WITH A SLIGHT
CHANCE OF SHOWERS/THUNDERSTORMS. CHANCES FOR CONVECTION WILL INCREASE
FOR THE ENTIRE AREA TUE NIGHT INTO THUR...AS THE FRONT GETS EVER
CLOSER. GIVEN THE PRECIP WILL BE MORE SHOWERY IN CHARACTER...WILL
HOLD OFF ON LIKELY POPS THIS GO AROUND FOR WED. SOME OF THE STORMS
PRECEDING THE COLD FRONT COULD BECOME STRONG...WITH GUSTY WINDS...
SMALL HAIL AND HEAVY RAINFALL THE PRIMARY THREATS. THE STRONGER SHEAR
AND OTHER DYNAMICS WITH THIS SYSTEM SHOULD REMAIN TO OUR NORTH.

THE FRONT EAST OF THE VALLEY THU/FRI WILL RESULT IN RAIN CHANCES
DECREASING BY THE TIME THE NEXT WEEKEND ARRIVES. CANADIAN HIGH
PRESSURE FOLLOWING THE FRONT WILL BRING BRING SLIGHTLY COOLER HI/LO
TEMPS FOR THE WEEKEND...WITH VALUES CLOSE TO SEASONABLE LEVELS.

RSB

&&

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

$$

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