984
FXUS64 KHUN 242241
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
541 PM CDT WED APR 24 2019
UPDATE
FOR 00Z TAFS.
NEAR TERM
(TONIGHT)
ISSUED AT 300 PM CDT WED APR 24 2019
SCATTERED MID AND HIGH-LEVEL CLOUDS CONTINUE TO SPREAD ACROSS THE
FORECAST AREA THIS AFTERNOON, IN THE WEST-SOUTHWEST FLOW REGIME
DOWNSTREAM FROM A BROAD LONGWAVE TROUGH ENCOMPASSING MUCH OF THE
CENTRAL/SOUTHERN PLAINS. HOWEVER, INSOLATION HAS BEEN STRONG ENOUGH
TO SUPPORT TEMPERATURES IN THE U70S-L80S AS OF 2 PM, AIDED BY LOW-
LEVEL SOUTH-SOUTHWESTERLY FLOW ALONG THE RIM OF A NARROW RIDGE AXIS
CENTERED ACROSS THE FL PENINSULA.
WE EXPECT A FAIRLY RAPID INCREASE IN CLOUD COVER TO OCCUR THIS
EVENING, AS A LEAD MID-LEVEL VORT MAX (CURRENTLY LIFTING
NORTHEASTWARD ALONG THE TX/LA GULF COAST) BEGINS TO APPROACH THE
REGION. ALTHOUGH THIS DISTURBANCE AND IT'S ASSOCIATED VERTICAL MOTION
FIELDS ARE NOT PARTICULARLY STRONG, WE HAVE INCLUDED A LOW CHANCE
POP FOR SHOWERS AND A FEW THUNDERSTORMS, MAINLY BETWEEN 03-09Z. LOWS
WILL BE A BIT WARMER TONIGHT DUE TO THE INCREASE IN CLOUDINESS AND A
LIGHT BUT PERSISTENT SOUTH-SOUTHWEST WIND, WITH TEMPS EXPECTED TO
ONLY FALL INTO THE LOWER 60S (PERHAPS A DEGREE OR SO COOLER IN
NORTHEAST AL). ASSUMING THAT PORTIONS OF THE AREA DO RECEIVE
MEASURABLE RAINFALL OVERNIGHT, PATCHY FOG WILL ALSO BE POSSIBLE IN
THE HOURS AROUND SUNRISE.
SHORT TERM
(THURSDAY THROUGH FRIDAY NIGHT)
ISSUED AT 300 PM CDT WED APR 24 2019
MODELS STILL SUGGEST THAT A CLOSED LOW WITHIN THE BASE OF THE TROUGH
TO OUR WEST WILL OPEN INTO A WAVE AS IT SHIFTS EASTWARD INTO EASTERN
AR/WESTERN MS ON THURSDAY. DEEP-LAYER FLOW WILL BACK FURTHER TO THE
SOUTHWEST AND STRENGTHEN CONSIDERABLY THROUGHOUT THE DAY AS THIS
OCCURS, SUPPORTING AN INCREASE IN PWAT VALUES INTO THE 1.2-1.4 INCH
RANGE. AT THIS POINT, WE EXPECT FAIRLY WIDESPREAD CONVECTION IN THE
WAA REGIME TO THE EAST OF THE TROUGH TO SHIFT EASTWARD INTO THE TN
VALLEY THROUGHOUT THE DAY, BEGINNING DURING THE LATE MORNING HOURS
FOR LOCATIONS WEST OF I-65 AND ADVANCING EASTWARD THROUGHOUT THE
AFTERNOON. IT STILL APPEARS AS IF A QUICK TRANSITION TO MOIST
ADIABATIC PROFILES ALOFT WILL LIMIT INSTABILITY IN OUR REGION,
REDUCING THE POTENTIAL FOR STRONG-SEVERE STORMS. HOWEVER, BULK SHEAR
WILL INCREASE DURING THE LATE AFTERNOON, AND THIS COULD YIELD SOME
ORGANIZATION TO THE CONVECTION AND THE THREAT FOR A FEW LOCALLY
STRONG WIND GUSTS. ALTHOUGH THE SHOWERS/THUNDERSTORMS IN THIS REGIME
WILL LIKELY BE ENDING ACROSS THE SOUTHEASTERN ZONES AROUND OR SHORTLY
AFTER SUNSET, A SEPARATE ROUND OF CONVECTION MAY DEVELOP ALONG THE
COLD FRONT ASSOCIATED WITH A NORTHERN STREAM WAVE DIGGING
SOUTHEASTWARD INTO THE OH VALLEY. THE AREAL COVERAGE OF THIS ACTIVITY
IS A BIT MORE UNCERTAIN, AND FOR THIS REASON WE HAVE REDUCED POPS
FOR ALL AREAS, ESPECIALLY AFTER MIDNIGHT. THE COLD FRONT WILL CROSS
THE FORECAST AREA DURING THE MID-LATE MORNING HOURS ON FRIDAY, WITH
ANY LINGERING SHOWERS EXPECTED TO END IN THE EASTERN ZONES SHORTLY
AFTER SUNRISE. GUSTY NORTH-NORTHWEST FLOW IN THE WAKE OF THE FRONT
WILL ADVECT A COOLER AND DRIER MODIFIED NORTH PACIFIC AIRMASS INTO
THE REGION, WITH LOWS SATURDAY MORNING FALLING BACK INTO THE M-U 40S.
LONG TERM
(SATURDAY THROUGH TUESDAY)
ISSUED AT 300 PM CDT WED APR 24 2019
A LARGE AREA OF HIGH PRESSURE AT THE SFC WILL CONTINUE TO MOVE EWD
OVER THE REGION HEADING INTO THE SECOND HALF OF THE WEEKEND PERIOD.
THE LATTER HALF OF THE GLOBAL MODEL SUITES ALSO SHOW A LOW PRESSURE
SYSTEM OUT OF THE NRN/MID PLAINS MOVING ESE INTO THE MIDWEST STATES
DURING THE DAY SAT. THIS FEATURE SHOULD ALLOW A COLD FRONT TO
APPROACH THE TN VALLEY SAT EVENING, WITH PERHAPS SOME SHOWERS/TSTMS
DEVELOPING ALONG/JUST AHEAD OF THE SFC BOUNDARY. HOWEVER, MOISTURE
RETURN AHEAD OF THE FRONT IS NOT THAT STRONG, COUPLED WITH THE LOW
LEVEL CONVERGENT FIELD BEING FAIRLY WEAK. THE FRONT ITSELF ALSO LOOKS
TO WEAKEN AS IT SETTLES MORE INTO THE CNTRL TN VALLEY. AS SUCH, RAIN
CHANCES ALONG/AHEAD OF THE FRONT WILL BE IN THE ISO CAT AT BEST, AND
SHOULD TAPER OFF BY SUN MORNING.
ANOTHER AREA OF HIGH PRESSURE THEN BEGINS TO BUILD EWD INTO THE
MIDWEST/OH VALLEY STATES FOR THE SECOND HALF OF THE WEEKEND IN THE
WAKE OF THE FRONTAL PASSAGE, WHICH SHOULD TRANSLATE INTO FAIRLY NICE
WX FOR THE LOCAL AREA. AFTER A SEASONABLY WARM DAY SAT, WITH HIGHS IN
THE MID/UPPER 70S FOR MOST LOCATIONS, AFTERNOON TEMPS SUN AGAIN LOOK
TO CLIMB INTO THE MID/UPPER 70S, WITH CLOUDS DIMINISHING. THE START
OF THE NEW WORK WEEK LOOKS QUIET AS WELL, AS THE BERMUDA HIGH BECOMES
ESTABLISHED OFF OF THE MID/SRN ATLANTIC COASTS AND WEAK UPPER RIDGING
BEGINS TO BUILD OVER THE GULF REGION. OVERALL TEMPS ALSO LOOK TO BE
JUST ABOVE SEASONAL TRENDS, WITH HIGHS IN THE LOWER 80S AND LOWS
CLIMBING INTO THE UPPER 50S/LOWER 60S NEAR THE END OF THE PERIOD.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 541 PM CDT WED APR 24 2019
VFR CONDITIONS ARE EXPECTED THROUGH MUCH OF THE TAF PERIOD. SOME
VERY LIGHT SHOWERS MAY BE POSSIBLE AT EITHER KMSL OR KHSV BETWEEN
04Z AND 09Z. CONFIDENCE IS VERY LOW (THIS MAY BE JUST VIRGA), SO JUST
KEPT VCSH IN THE FORECAST DURING THAT PERIOD. THERE IS SOME QUESTION
IN GUIDANCE JUST HOW MUCH LIGHTER WINDS MAY BECOME OVERNIGHT. HOWEVER,
FOR NOW WILL LEAVE MVFR VSBYS IN THE FORECAST AT BOTH TERMINALS
BETWEEN 10Z AND 13Z FOR POSSIBLE LIGHT FOG DEVELOPMENT. HOWEVER, IF
WINDS REMAIN BETWEEN 5 AND 10 KNOTS AS SOME GUIDANCE SUGGESTS, THIS
MAY BE REMOVED IN THE 06Z ISSUANCE. FOR NOW LEFT OUT, A MORE PREDOMINANT
PERIOD OF -TSRA OR -SHRA LATE TOMORROW AFTERNOON, BUT THIS WILL
LIKELY BE ADDED IN 06Z ISSUANCE.
HUN WATCHES/WARNINGS/ADVISORIES
AL...NONE.
TN...NONE.
NEAR TERM...70/DD
SHORT TERM...70/DD
LONG TERM...09
AVIATION...KTW
FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE
AT WEATHER.GOV/HUNTSVILLE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page