FXUS64 KHUN 142047 AFDHUN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HUNTSVILLE AL 247 PM CST SUN DEC 14 2014 .DISCUSSION... AS OF 21Z...CLOUDS ARE CONTINUING TO ERODE SE TO NW ACROSS THE FORECAST AREA. ALTHOUGH THE NAM DID VERY WELL YESTERDAY/OVERNIGHT...IT WAS SLOW TO CLEAR THE CLOUDS OUT TODAY. MET GUIDANCE DID HOWEVER PICK UP ON THE TIMING PRETTY ACCURATELY. THERE IS SOME INDICATION...ESPECIALLY IN NAM SOUNDINGS...OF MORE LOW LEVEL MOISTURE DEVELOPING THIS EVENING WITH TEMPS COOLING QUICKLY UNDER CLEAR SKIES. DEW POINTS WILL ALSO BE DROPPING AS A NE FLOW ADVECTS DRIER AIR IN. IT LOOKS LIKE THERE COULD BE SOME VISIBILITY RESTRICTIONS TONIGHT INSTEAD OF LOW CLOUDS/STRATUS. WITH THE POSSIBILITY OF A FEW LOW CLOUDS FLOATING AROUND...WILL KEEP SOME CLOUDS IN THE FORECAST OVERNIGHT. THE UPPER RIDGE WILL CONTINUE TO BREAK DOWN OVERNIGHT AND INTO MONDAY AS AN UPPER TROUGH DIGS IN FROM THE WEST. THE SURFACE HIGH WILL ALSO TRACK TO THE EAST AS A COLD FRONT MOVES IN. CLOUDS WILL INCREASE AGAIN MONDAY AFTERNOON MOSTLY AT THE MID-HIGH LEVELS AHEAD OF THIS SYSTEM. HIGH TEMPS WILL BE TRICKY...RIGHT NOW GUIDANCE HAS THE THICKER CLOUDS MOVING IN DURING THE AFTERNOON SO TEMPS COULD WARM QUICKLY IN THE MORNING. HOWEVER THE BREAKING DOWN OF THE RIDGE SUPPORTS COOLER 850 TEMPS SO NOT SURE IF MID 60S IS IN THE CARDS. WILL GO WITH THE LOWER 60S...NEAR GUIDANCE VALUES. RAIN CHANCES WITH THE FRONT INCREASE AFTER 18Z MONDAY WITH RAIN LIKELY FROM 00-06Z. MODELS HAVE BEEN VERY CONSISTENT OVER THE LAST FEW DAYS WITH THIS TIME FRAME HAVING THE HIGHEST LIKELIHOOD OF RAINFALL WHICH IS WHY POPS WERE INCREASED. WILL CONTINUE THE NO THUNDER FORECAST AS WELL. INSTABILITY IS VERY WEAK EVEN ABOVE THE SURFACE LAYER. DECENT SHEAR VALUES WILL HELP SUSTAIN SOME MODERATE RAIN SHOWERS BUT OVERALL EXPECT RAIN AMOUNTS TO BE LESS THAN A QUARTER OF AN INCH. BEHIND THE FRONT...SKY COVER PROBLEMS START AGAIN. NAM/GFS ARE BOTH INDICATING SOME LINGERING MOISTURE WITH THE NAM BEING MUCH MORE AGGRESSIVE WITH THE LOWER CEILINGS. ALL MOISTURE IS ONCE AGAIN TRAPPED UNDER THE INVERSION AND BELOW 925MB. WITH LIGHT WINDS AND MOISTURE ADVECTION FROM THE NORTH...WILL GO WITH PARTLY TO MOSTLY CLOUDY FOR NOW UNTIL WE GET CLOSER. QUITE A BIT OF MODEL DIFFERENCES IN TERMS OF SYNOPTIC FEATURES FOR THE SYSTEM MOVING INTO THE AREA THURSDAY THROUGH SATURDAY ESPECIALLY IN REGARDS TO THE NORTHERN/SOUTHERN STREAM PHASING. 00Z ECMWF WAS PHASING THE TWO TO OUR WEST LEADING TO A STRONG SURFACE LOW...STRONGER WINDS AND MORE PRECIP. HOWEVER...A GLANCE AT THE 12Z SHOWS A MUCH WEAKER SYSTEM. IT IS STILL STRONGER THAN WHAT THE GFS IS SHOWING...WHICH IS BASICALLY NO PHASING AND A WEAK SYSTEM. BOTH ARE AGREEING VERY WELL ON TIMING OF THE HEAVIEST RAINFALL AND THAT IS FRIDAY NIGHT/SATURDAY MORNING. THE UNCERTAINTY WILL COME WITH THE OVERRUNNING PRECIP AT THE BEGINNING AND WHAT HAPPENS BEHIND IT. WITH A WEAKER SYSTEM...FROZEN PRECIP WOULD BE OUT OF THE QUESTION. WILL NEED TO CONTINUE TO MONITOR THIS. IN TERMS OF TEMPS THROUGH THE PERIOD...BEHIND THE COLD FRONT ON TUESDAY...EXPECT MUCH COOLER TEMPS FOR HIGHS...UPPER 40S FOR WED-SUN WHICH IS A FEW DEG BELOW NORMAL. LOWS WILL BE NEAR NORMAL AND ONLY FLUCTUATE WITH CHANGES IN CLOUD COVER. && .AVIATION... /ISSUED 1120 AM CST SUN DEC 14 2014/ FOR 18Z TAFS...MVFR CEILINGS WILL INITIALLY BE PREDOMINANT AT BOTH HSV AND MSL. EXPECT THAT CEILINGS WILL SCATTER OUT AT HSV BETWEEN 19Z-20Z WITH VFR CONDITIONS EXPECTED THERE THROUGH THE REST OF THE FORECAST PERIOD. WILL KEEP MVFR CEILINGS IN LONGER AT MSL DUE TO IR/VISIBLE SATELLITE TRENDING. EXPECT BY AROUND 01Z...THAT VFR CONDITIONS WILL RETURN TO MSL THROUGH THE REST OF THE FORECAST PERIOD. TT && .PRELIMINARY POINT TEMPS/POPS... HUNTSVILLE 34 61 48 55 / 10 40 70 10 SHOALS 36 62 45 55 / 10 40 70 10 VINEMONT 34 62 48 55 / 10 40 70 10 FAYETTEVILLE 34 60 47 53 / 10 40 70 10 ALBERTVILLE 32 59 45 55 / 10 30 70 10 FORT PAYNE 32 59 45 56 / 0 30 70 10 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.
Posted on: Sun, 14 Dec 2014 20:49:06 +0000
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