000
FXUS63 KGID 181815
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
115 PM CDT SAT MAY 18 2013

...A SEVERE WX OUTBREAK CONTS SLATED FOR THE 6PM-10PM TIMEFRAME...

.UPDATE...
ISSUED AT 115 PM CDT SAT MAY 18 2013

MULTI-MEDIA WX BRIEFING POSTED TO OUR YOUTUBE CHANNEL/WEBSITE AT
11 AM.

STRATUS CONTS TO ERODE. HOWEVER...MID-LVL ACCAS ARE INCREASING AS A
SHRTWV TROF IS CURRENTLY LIFTING THRU WRN KS. RADAR SUGGESTS A
COUPLE SPRINKLES COULD OCCUR...BUT THEY WILL BE FIGHTING
TREMENDOUS LOW-MID LVL DRY AIR. HIGH TEMPS HAVE BEEN RAISED INTO
THE MID-UPR 80S AND DWPTS HAVE BEEN ADJUSTED UP AS WELL.

12Z UPR AIR: LOW-LVLS HAVE MOISTENED CONSIDERABLY IN THE LAST 12
HRS ON LBF/OAX SOUNDINGS. DDC SOUNDING IS THE "LOADED GUN".
DDC/LBF HAVE LAUNCHED 18Z SOUNDINGS AND WE/LL HAVE THEM SHORTLY.
WE ARE WATCHING THE 50 KT JET STREAK OVER AZ-NM ROUNDING THE BASE
OF THE TROF.

DEEP LAYER WIND DIRECTION WILL BE ABOUT 35 DEGS OFF THE DRYLINE.
SO WE ARE EXPECTING DISCRETE SUPERCELLS INITIALLY OVER WRN KS.
WILL BE INTERESTING TO SEE HOW LONG CELLS CAN REMAIN DISCRETE. 0-5
KM SHEAR IS FAVORABLE. IT ALL DEPENDS ON HOW MANY STORMS INITIATE.
THE MORE THAT INITIATE...THE FASTER STORM INTERACTIONS WILL LEAD
TO UPSCALE GROWTH INTO A MULTICELL LINE. SUPERCELL STORM MOTION
WILL BE 240 AT 20 KTS. LEFT MOVERS WILL MOVE DUE N. IF A LINE
FORMS...FORWARD PROPAGATING CORFIDI VECTORS SUGGEST NE MOVEMENT
AROUND 50 KTS.

FAIRLY MODEST HODOGRAPHS WILL UNDERGO SUBSTANTIAL ENLARGING 6PM-
8PM AS LLJ DEVELOPS. THIS WILL INFLUENCE STORM MODE AND INCREASE
THE TORNADO THREAT...ESPECIALLY FOR ANY STORMS THAT CAN REMAIN
ISOLATED.

EXTRA STAFFING IS ALREADY PLANNED FOR THIS EVNG.

PLEASE MONITOR FUTURE GID ASSESSMENTS REGARDING SEVERE POTENTIAL AS
WELL AS THOSE OF SPC VIA THEIR SWOMCD AND SWODY1 UPDATES.

SKYWARN: NEED TO BE ALERT FOR ACTIVATION IN THE 22Z-03Z TIME FRAME
THIS EVNG.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM CDT SAT MAY 18 2013

AN INTERESTING DAY IS SHAPING UP ACROSS THE REGION AS THE LONGWAVE
TROUGH ACROSS THE INTERMOUNTAIN WEST IS EXPECTED TO SLOWLY
TRANSITION EASTWARD TOWARDS THE ROCKIES BY AFTERNOON. AHEAD OF THE
UPPER LEVEL TROUGH...A LEE TROUGH HAS DEVELOPED ACROSS THE HIGH
PLAINS AND IS AIDING IN MOISTURE TRANSPORT FROM THE SOUTH THIS
MORNING. AT THE SAME TIME...AN EXPANSIVE AREA OF LOW LEVEL STRATUS
IS SPREADING NORTHEASTWARD FROM WESTERN KANSAS...AS EVIDENT IN
SATELLITE IMAGERY...AND EXPECT AT LEAST THE POTENTIAL FOR CLOUDS TO
OVERTAKE THE ENTIRE FORECAST AREA BY DAYBREAK. WHILE SO FAR
OBSERVATIONS HAVE BEEN FREE OF PRECIPITATION WITH THIS
STRATUS...LATEST MODEL DATA CONTINUES TO HINT AT THE POTENTIAL FOR
SOME EMBEDDED LIGHT DRIZZLE...AND KEPT THIS POSSIBILITY IN THE
FORECAST THROUGH THE MID MORNING HOURS. ADDITIONALLY...WITH THIS
STRATUS INVADING THE REGION THIS MORNING...WENT AHEAD AND TWEAKED
DOWN AFTERNOON TEMPERATURES A FEW DEGREES TO COMPENSATE FOR A
SHORTER PERIOD OF DIURNAL HEATING...BUT STILL EXPECT THE STRATUS TO
EVENTUALLY CLEAR/MIX OUT BY LATE MORNING...ALLOWING INSTABILITY TO
BUILD ACROSS THE REGION.

FOCUS FOR AFTERNOON CONVECTION CONTINUES TO BE THE DRYLINE
POSITIONED TO THE WEST. WHILE INITIALLY...EXPECT THE STRATUS AND
WARM MID LEVELS WILL PUT A DAMPER ON ANY CONVECTIVE
DEVELOPMENT...THE CAP IS EXPECTED TO EVENTUALLY ERODE...ALLOWING FOR
EXPLOSIVE CONVECTION ALONG THE DRY LINE. THIS CONVECTION WILL THEN
BE ADVECTED EASTWARD DURING THE LATE AFTERNOON AND EARLY EVENING
HOURS. WITH PLENTY OF INSTABILITY TO WORK WITH...LARGE HAIL AND
STRONG WINDS WILL DEFINITELY BE A POSSIBILITY...WITH SHEAR
INCREASING AFTER 00Z...AND THE POSSIBILITY FOR TORNADIC STORMS...AS
THE LOW LEVEL JET STRENGTHENS AND BECOMES FOCUSED ACROSS CENTRAL AND
EASTERN NEBRASKA. WITH ALL THE FAVORABLE INGREDIENTS...FELT
CONFIDENT ENOUGH TO INCLUDED WORDING FOR SEVERE THUNDERSTORMS INTO
THE FORECAST THIS MORNING...FOR ROUGHLY THE 00Z-09Z PERIOD...WHERE
THE 00Z WRF IS FOCUSED AS WELL AS ABOUT THE TIME THE LATEST
RAP AND NAM BEGIN TO SPREAD CONVECTION OUR WAY. LATEST SPC
OUTLOOKS INDICATE A SLIGHT RISK FOR SEVERE STORMS TO AFFECT THE
ENTIRE FORECAST AREA...WITH A MODERATE RISK FOR SEVERE WEATHER
MAINLY WEST OF HIGHWAY 183.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 405 AM CDT SAT MAY 18 2013

BY 12Z SUNDAY...THE 500MB TROUGH WILL BEGIN TO SLIDE OVER THE
ROCKIES AND INTO THE GREAT PLAINS. AT THE SURFACE...ONE LOW IS
FORECAST TO SET UP OVER THE CWA...OR JUST SOUTH OF THE CWA...AND
ANOTHER SURFACE LOW IS FORECAST FOR EASTERN PARTS OF NORTH DAKOTA.
A COLD FRONT WILL EXTEND NORTHWARD THROUGH OUR CWA INTO THE
DAKOTAS...BASICALLY A LINE CONNECTING THE TWO LOWS. THIS COLD
FRONT WILL TRANSITION EASTWARD SUNDAY THROUGH BOTH NEBRASKA AND
KANSAS...WHICH WILL BE THE PRIMARY FOCUS OF THUNDERSTORMS. AHEAD
OF THE COLD FRONT WILL BE ADEQUATE MOISTURE...WHICH SHOULD RESULT
IN CAPE VALUES RANGING BETWEEN 1500 AND 2500 J/KG...ESPECIALLY
OUR EASTERN COUNTIES. THE NAM IS THE MOST AGGRESSIVE WITH REGARDS
TO 0-6 KM BULK SHEAR...INDICATING VALUES OF 50 KTS BY THE
AFTERNOON. THE GFS AND ECMWF STILL SUGGEST VALUES ROUGHLY BETWEEN
25 AND 35 KTS. AT 12Z...MODELS ARE ALSO SUGGESTING RELATIVELY
DECENT 0-1 KM SHEAR VALUES...MAINLY OUR EASTERN COUNTIES...BUT
QUICKLY DIMINISHES IN THE AFTERNOON. WITH ALL THIS BEING
SAID...THERE IS A GOOD CHANCE FOR SOME STRONG TO SEVERE
THUNDERSTORMS TO LINGER AROUND INTO SUNDAY ACROSS OUR
CWA...ESPECIALLY OUR COUNTIES EAST OF HIGHWAY 281. WOULD NOT BE
SURPRISED IF A FEW THUNDERSTORMS MET SEVERE CRITERIA ON SUNDAY
BEFORE DIMINISHING IN STRENGTH LATER IN THE DAY.

BEGINNING MONDAY...AND ESSENTIALLY THROUGH THE EXTENDED
PERIODS...THERE IS A MENTION OF SLIGHT CHANCE AND CHANCE POPS
THROUGH FRIDAY...WITH ONLY THE MENTION OF RAIN SHOWERS. THE LACK
OF INSTABILITY AND LIFT INDICATES THUNDERSTORMS ARE UNLIKELY AT
THIS TIME.

TEMPERATURES ON SUNDAY WILL BE ABOVE NORMAL. THEN TEMPERATURES WILL
COOL DOWN A LITTLE OVER THE WORKWEEK. IT APPEARS TUESDAY WILL BE THE
COLDEST DAY NEXT WEEK WITH MOST OF THE OUTLOOK AREA BELOW NORMAL.
OTHERWISE...TEMPERATURES NEXT WEEK WILL BE VERY CLOSE TO NORMAL.
NORMAL HIGHS ACROSS THE TRI-CITIES ARE IN THE LOWER 70S...WHILE LOWS
ARE USUALLY AROUND 50 DEGREES THIS TIME OF YEAR.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 115 PM CDT SAT MAY 18 2013

THIS AFTN: MVFR CIGS WILL BECOME VFR. THERE IS A CHANCE THAT MVFR
CIGS COULD TEMPO RETURN TO THE TERMINAL. SE WINDS CONT AROUND 15
KTS AND WILL BEGIN GUSTING 20-25 KTS.

TNGT: A PERIOD OF IFR TSTMS APPEARS LIKELY 02Z-04Z. THEN CLEARING
IFR/LIFR STRATUS CIGS PROBABLE AFTER 06Z. FOG IS LESS CERTAIN DUE
TO SFC WINDS. IF WIND IS LIGHTER THAN FCST AND RAIN DOES FALL THIS
EVNG...THEN 1/4SM FG VV001 WILL BE LIKELY.

SUN THRU 18Z: IFR/LIFR STRATUS AND FOG? GRADUALLY BEGIN TO LIFT BY
16Z.

CIG CONFIDENCE: AVERAGE
VSBY CONFIDENCE: HIGH UNTIL 08Z THEN AVERAGE
WIND CONFIDENCE: HIGH EXCEPT IN ANY TSTMS
WX CONFIDENCE: AVERAGE

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

$$

UPDATE...HALBLAUB
SHORT TERM...SAR
LONG TERM...GUERRERO
AVIATION...HALBLAUB