Monday, October 25, 2010

Area Forecast Discussion - South Central/Southwest Missouri

FXUS63 KSGF 251827
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
127 PM CDT MON OCT 25 2010

..UPDATE TO PUBLIC AND AVIATION...

UPDATE...

MADE A COUPLE OF CHANGES TO THE GOING FORECAST INTO THIS EVENING.
FIRST OFF...A FAIRLY THICK CIRRUS SHIELD WILL PERSIST FOR THE
REMAINDER OF TODAY. THEREFORE INCREASED CLOUD COVER AND KNOCKED
DOWN TEMPERATURES A CATEGORY OVER MOST AREAS.

OF BIGGER CONCERN IS THE WIND POTENTIAL FOR THE NEXT 18 HOURS. AN
INTENSE LOW PRESSURE SYSTEM CONTINUES TO DEEPEN ACROSS THE CENTRAL
HIGH PLAINS. THE SURFACE LOW IS ALREADY DOWN TO 985 MB AND WILL
LIKELY APPROACH 980 MB BY SUNSET. LATEST ISALLOBARIC TENDENCIES
INDICATE STRONG PRESSURE FALLS ACROSS NORTH CENTRAL
KANSAS...WITH STRONG RISES ACROSS NORTHEAST COLORADO.

THE GREATEST SURFACE RESPONSE IN OUR NECK OF THE WOODS WILL OCCUR
FROM MID AFTERNOON INTO EARLY THIS EVENING. SURFACE PRESSURE
FIELDS WILL EASILY SUPPORT 20 TO 30 MPH WINDS ACROSS SOUTHEAST
KANSAS AND WESTERN MISSOURI. OF PERHAPS GREATER CONCERN IS THE
GUST POTENTIAL BY LATE THIS AFTERNOON. ALTHOUGH MIXING WILL BE
LIMITED TODAY DUE TO THE CIRRUS SHIELD...SHORT RANGE MODELS
INDICATE 50 KNOT WINDS AT 900 MB PUSHING INTO WESTERN MISSOURI BY
LATE THIS AFTERNOON. THESE MOMENTUMS WILL BE ATTAINABLE WITH
TEMPERATURES WARMING INTO THE LOWER 70S...WHICH MOST AREAS HAVE
ALREADY DONE. THEREFORE ISSUED A WIND ADVISORY EARLIER THIS
MORNING FOR MUCH OF WESTERN MISSOURI AND EXTREME SOUTHEAST
KANSAS.

WINDS WILL REMAIN BRISK AND GUSTY INTO THIS EVENING AS A COLD
FRONT APPROACHES. WILL NEED TO WATCH HOW QUICKLY WE DECOUPLE...IF
WE DO AT ALL...AS WINDS JUST OFF THE DECK INCREASE EVEN FURTHER.

WILL THEN HAVE TO WATCH FOR FORCED CONVECTION LATER TONIGHT ALONG
THE COLD FRONT. LATEST HIGH RESOLUTION MODELS INDICATE A THIN LINE
OF CONVECTION DEVELOPING BETWEEN THE HIGHWAYS 71 AND 65 CORRIDORS
AFTER MIDNIGHT. ALTHOUGH INSTABILITY WILL BE LIMITED...STRONG
WIND SHEAR MAY STILL RESULT IN A SEVERE THREAT. A SHEAR DOMINANT
SQUALL LINE IS DEFINITELY PLAUSIBLE IN THIS ENVIRONMENT...WITH THE
POTENTIAL FOR THIS LINE TO TRANSPORT HIGHER MOMENTUMS TO THE
SURFACE. VERY STRONG LOW LEVEL SHEAR ALSO WARRANTS THE POTENTIAL
FOR A FEW SPIN UPS WITH THIS LINE.

INTERESTINGLY...MAY ALSO HAVE TO WATCH THE SYNOPTIC WIND POTENTIAL
BEHIND THE LINE. MAY SEE A COUPLE OF HOUR PERIOD WHERE ISALLOBARIC
ACCELERATIONS CONTRIBUTE TO WINDS ONCE AGAIN APPROACHING WIND
ADVISORY CRITERIA.

SCHAUMANN

&&

DISCUSSION...

PESKY UPPER LOW HAS FINALLY EXISTED TO OUR EAST THIS MORNING...WITH
SUBSIDENCE BEHIND IT CLEARING SKIES OUT ACROSS THE REGION.
HOWEVER...EXTREMELY POWERFUL STORM SYSTEM IS PUNCHING INTO THE
INTERMOUNTAIN WEST AT THIS HOUR...AND WILL BE OUR MAIN WEATHER
PLAYER OVER THE NEXT 24 HOURS OR SO.

EXPECT THE DAYTIME HOURS TO BE DRY TODAY...WITH STRONG SOUTHWEST
SURFACE FLOW USHERING IN NEAR-RECORD HIGH TEMPERATURES. DON'T THINK
THAT WE'LL BE BREAKING ANY OF THE TEMP RECORDS IN PLACE (85 AT
SGF...83 AT JLN/UNO/VIH)...BUT WILL CERTAINLY BE CLOSE. WILL NEED
TO ALSO WATCH SFC WINDS DURING THE DAY TODAY AS THEY GUST INTO THE 30-40
MPH RANGE. REALLY DON'T THINK THAT WE'LL BE GETTING INTO ADVISORY
CRITERIA (30 MPH SUSTAINED...GUSTS 45+)...BUT IT'LL BE QUITE WINDY
NONETHELESS. 160 KT UPPER JET EXPECTED TO BE ROUNDING THE BASE OF
THE UPPER TROUGH BY THIS EVENING...WHICH WILL RESULT IN BEGINNINGS
OF BOMB CYCLOGENESIS OVER THE GREAT LAKES REGION. FORTUNATELY FOR
THIS NECK OF THE WOODS...WE'LL ONLY BE DEALING WITH A STRENGTHENING
OF THE SFC PRESSURE GRADIENT AND SHARPENING OF A STRONG COLD FRONT
AS IT SWEEPS ACROSS THE REGION OVERNIGHT TONIGHT. CURRENT
ANTICIPATION IS TO SEE THE FRONT BEGIN TO APPROACH THE NORTHWESTERN
CWA AROUND 00-03Z...AND BE EAST OF THE FORECAST AREA BY OR SHORTLY
AFTER 12Z. WOULD ANTICIPATE SEEING AREA OF RAIN AND EMBEDDED
THUNDER ALONG THE LEADING EDGE OF THE FRONT AS IT MOVES THROUGH THE
AREA. INSTABILITY PROGGED TO BE QUITE MINIMAL AHEAD OF THE
FRONT...BUT EXTREME DYNAMICS OF THE SYSTEM COULD MAKE UP FOR THE
LACK OF APPRECIABLE CAPE AT TIMES. IF NOTHING ELSE...VERY STRONG
WINDS JUST OFF THE DECK WON'T REQUIRE MUCH TO BE MIXED TO THE
SURFACE...AND COULD ACHIEVE 50 KT MARK WITHOUT TOO MUCH TROUBLE.
STILL THINK THAT THREAT IS RATHER LIMITED...THOUGH PER SPC DY1
OUTLOOK...CERTAINLY NOT ZERO.

FRONT PASSES THROUGH THE AREA BY 12-15Z TUESDAY...WITH RAPIDLY
CLEARING SKIES IN ITS WAKE. SFC PRESSURE GRADIENT EXPECTED TO STILL
BE PRETTY HEALTHY OVER THE NORTHERN FORECAST AREA. EXPECT TUESDAY
TO QUICKLY REMIND US THAT ITS LATE OCTOBER...WITH TEMPS SOME 10-15
DEGREES COOLER THAN ON MONDAY...ALONG WITH A BRISK WESTERLY BREEZE.

FOR THE EXTENDED...SWIFT ZONAL FLOW MIDWEEK LOOKS TO GIVE WAY TO
NORTHWEST FLOW AS UPPER RIDGING AMPLIFIES OVER THE ROCKIES AND
EVENTUALLY TRANSLATES EAST BY THE END OF THE WEEK. DEEP CANADIAN
HIGH PRESSURE PROGGED TO DROP OVER THE CWA THURSDAY NIGHT...WHICH
SHOULD RESULT IN EXCELLENT RADIATIONAL COOLING CONDITIONS. WITH
THAT IN MIND...HAVE TRENDED LOWS DOWN A COUPLE OF DEGREES FROM
MODELS THAT EVENING. OTHERWISE...SOME HINTS OF LOW END POPS TOWARD
THE WEEKEND WITH POSSIBLE TROUGH PASSAGE AND COLD FROPA...BUT
CONFIDENCE IS TOO LOW TO INCLUDE IN THE FORECAST ATTM.

BOXELL

&&

AVIATION...

STRONG AND GUSTY SOUTHERLY WINDS WILL CONTINUE INTO THIS EVENING.
LOW LEVEL WIND SHEAR WILL DEVELOP THIS EVENING AS A LOW LEVEL JET
SHIFTS INTO THE AREA. A COLD FRONT WILL THEN PUSH THROUGH THE AREA
LATE TONIGHT. A THIN LINE OF THUNDERSTORMS MAY DEVELOP ALONG THE
FRONT...WITH THE BETTER CHANCES AROUND KSGF AND KBBG. MAINTAINED
CB AND VCSH MENTION AS CONFIDENCE IS STILL SOMEWHAT LOW ON WHERE
AND WHEN THE LINE WILL DEVELOP. MAY THEN SEE A PERIOD OF STRONG
AND GUSTY WESTERLY WINDS BEHIND THE COLD FRONT. WINDS MAY DECREASE
FOR A TIME INTO EARLY TUESDAY MORNING...BUT BECOME BRISK AND GUSTY
ONCE AGAIN BY MID MORNING.

SCHAUMANN

&&

FIRE WEATHER...

SFC TEMPS TODAY EXPECTED TO WARM INTO THE LOW 80S AT MOST
LOCATIONS...WITH SOUTH WINDS SUSTAINED BETWEEN 20 AND 25 MPH WITH
GUSTS 30 TO 35 MPH DURING THE DAY AND THIS EVENING. WHILE RH
VALUES EXPECTED TO REMAIN WELL ABOVE RED FLAG CRITERIA...WARM
TEMPS AND STRONG WINDS MAY RESULT IN FIRE CONCERNS. STRONG COLD
FRONT WILL SHIFT WINDS TO WEST THIS EVENING AND OVERNIGHT...AND
BRING WITH IT LOWER RH VALUES FOR MUCH OF THE REMAINDER OF THE
WEEK. CURRENT FORECASTS INDICATE THAT RH VALUES TUES-FRI WILL BE
IN 25-35% RANGE IN MANY PLACES...WITH WINDS 10-15 MPH. WILL REALLY
NEED TO WATCH CONDITIONS FOR TUESDAY AFTERNOON AS WESTERLY WINDS
INCREASE AND BECOME GUSTY. WOULD NOT BE SURPRISED TO SEE LOCALIZED
AREAS APPROACH CRITICAL FIRE WEATHER CONDITIONS.

BOXELL/SCHAUMANN

&&

SGF WATCHES/WARNINGS/ADVISORIES...
MO...WIND ADVISORY UNTIL 8 PM CDT THIS EVENING FOR MOZ066-077>079-
088>090-093-094-101-102.

KS...WIND ADVISORY UNTIL 8 PM CDT THIS EVENING FOR KSZ073-097-101.

&&

$$

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